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Cylinder head

This component is part of Engine.

Definition

Define the component. Include, if known, the german language word for the component, as well as the English or American equivalent. Show a picture, a diagram.

  • Its technical name & common name(s)
  • part # - start year & end year
  • which area it belongs to - engine, transmission, body, injection etc, link back to the relevant section

Function

Describe, in general terms the function of this component. Meaning what is it there for and what role it plays. Describe how it works, the inside mechanism. Use diagrams to explain.

Cylinder Head Identification and Head Gaskets

The 230SL heads are based on the old M180 or M127 2.2 liter sedan engines. The mechanical injection required all the heads have wider chain galleries in the front compared to the carbureted sedan versions of the era. The 230 SL engine (M127) was a four main bearing engine. There were different heads for the 230SL during its production, but the differences were just minor improvements or upgrades and all the 230SL heads are interchangable. You can identify a 230SL head by its casting number. The 230SL head also holds its six injectors above its intake ports in the head. The M127 injected sedan heads did not accomodate any injectors since its mechanical injection used a two piston injection pump and all of its injectors were placed on the intake manifold. Also identify a 230 SL head by the 14mm valve adjusters (as opposed to the 17mm on a 280SL head).

The 250SL engine (M129) is basically a 230SL engine. The major diff. between the two blocks is that the M129 (250 series) uses a seven main crankshaft instead of the four mains in the 230series. The 250SL head is very similar to the 230SL head but does have some design improvements like larger valves. All the 230SL head and 250SL heads are interchangeable. Some 230SL owners upgrade there engines with the larger valve 250SL cylinder head. The fuel injected 250SE sedan engines of the time are (also M129) and use the exact same heads as the SL. So the 250SE sedan head is a 250SL head or vice versa. Consequently the 250SE sedan engine can be a cylinder head donor for a 250SL or an upgrade head for a 230SL! These 250 series engines were all seven main bearing engines.

The M130 280 engines were very much different to the 230 and 250 engines even though the external size is identical. The cylinder diameters increased and the spacing between cylindes became dangerously close. It became so close that a cooling slot had to be machined in the narrow space between cylinders. There are two distinctly different 280 (M130) engines, the early version and the late version. The heads are not interchangable. Use the casting number on the head or the engine number to identify which version head. I refer to the early heads as "square" combustion chamber heads or the later as "oval" combustion chamber heads. Use my "Cylinder Head Chart" and the head casting number to quickly identify the two types. The fuel injected 280SE sedan engines of the era also used the same heads and they are the same on the 280SLs. However early and late heads and blocks DO NOT interchange! There are some reports that the late 280 injected "oval" combustion chamber heads can be used on a 230 or 250 injected engine. I do not have any direct exprience on this matter.

Use the Head Gasket Chart below to identify your Cylinder Head

Maintenance

Describe common maintenance procedures, and common faults that may occur. Describe how these may be diagnosed and resolved. Again, include diagrams, photographs and explanations. Where possible, include measures, tolerances, weights etc.

  • Torque Head
  • Symptoms when it faults
  • How to test if it is faulty - what tools to use
  • How to fix / change

Link to related components where appropriate.

Old Yahoo content

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What is a fair price to pay for a complete valve job on a 230 SL? My car blows a small cloud of smoke in the morning and the valve guides are loose. My mechanic said that it would cost $2800 parts and labor.

I am searching for a camshaft with bearings for my 230 SL. The camshaft is stamped "84" on the end. What are good sources for finding a cam in the USA. I would like to find a used parts source.

Will Samples says: Can you tell us how the camshaft got broken and what steps have been taken to prevent a replacement cam from breaking? It is not an easy job to replace a cam.

Will, The camshaft was broken when the timing chain broke. Appearently the piston comes up and hits a valve that is down. This drives the valve up, and since the cam is not moving, something has to give. In my case the cam and rear cam bearing broke. This was not a suprise to my mechanic. He predicted the cam would be broken before I removed the valve cover. The engine was overhauled by the previous owner. I suspect the timing chain was not replaced. If the last owner had replaced the timing chain when he overhauled the engine, I probably wouldn't have this problem now.

Will says: I am going to suggest something more was taking place than an old timing chain. The chain, even if totally worn out, will usually just stretch and start to rattle and scrape the inside of the valve cover. The chain usually gives lots of notice that there is a problem. Be sure to change not only the chain, but also the tensioner. Tensioners go bad just because they feel like it, or because the car has sat for a long time, etc. Also, the previous rebuild may have been done wrong so as to allow the chain to hang up on something internally. These are just guesses. But be on the lookout for other contributing factors.

Somebody recently mentioned that they had a performance camshaft for their 280sl. Where is this available? Also, what are the differences between the US and European versions as far as engine performance is concerned? Did they change pistons, camshaft, ignition and timing and fuel injection pump settings?

Frank says: The Euro 280 SL and 300 SEL/8 have camshafts that give about 10hp more than the USA 280 SL/300 SEL. Injection pump settings are also different, and USA cars also have add-ons such as pump cutoff and ignition timing control, but the basic engines are essentially the same. I have been trying to find a Euro camshaft at a reasonable price for a number of years without success.

Pete Lesler says: Believe it or not but the Euro cam really makes a difference at the upper range of RPMs. I wiped out two exhaust lobes of my only "09" cam two years ago and replaced it with a US spec 280 SE cam. A big negative difference. I found out that the 230, 250 and early 280 cams all use the same style bearings and can be interchanged. The 230 cam is the hottest cam of them all. The last 280SE cam is the mildest. The "09" is the part number stamped on the end of the cam (facing the firewall). This cam was used on Eurospec 280 SL and most 300 SEL-2.8 engine cars. It gave 10 more horsepower and a higher usable rpm range. Its complete part number is 180-051-0935.

Frank: you probably don't want the "09" cam for your '70 280 SL. Later cars used a camshaft with the same profile, marked "02". The 02 cam uses different cam bearings than the 09, and possibly that cam is still available from Euro MB dealers.

Pete Lesler: In response to the enquiries regarding the "09" cam. I found it in a US spec 300 SEL 2.8. At least I believe it was a US spec car as I found it in a bone yard. I bought the complete engine and drive train. When I pulled off the valve cover, I was amazed to see the "09" cam. All Euro 280 SL's and 300 SEL's with the early M130 engine used the '"09" cam. Later engines with the differently shaped combustion chambers and the shorter, squarer intake manifold used the later style "02" cam with different cam bearings. The later cam is the only one currently available from the factory. The complete part number is 114-051-0201. The cam lists for over $900, not to mention the cost of the different bearings, should you need them. So those extra ponies are mighty expensive indeed. The Euro cars also used a different fuel injection pump which was calibrated to run richer throughout the range and without the pesky shut down solenoid at the back of the pump.

Frank: Take a mirror, remove the valve cover, and see what number is stamped into the rear of your camshaft. If it's "02" or "09", you have the high output cam; anything else, you don't. High output cams were originally installed only in the Euro version 280SL and 300SEL/8.

The original timing chains on 230 SL are endless and must be spot ground to remove the original chain.

There is a timing indicator on the cam front end that lines up when the engine timing mark at the front damper is at TDC.

These timing chains should be replaced at around 100,000 mi. The original chains are endless. The endplates on these original chains are “figure 8” shaped. The replacements are improved, stronger oval shaped endplates. These endless chains can be left intact during head or cam removal by removing the front cam sprocket first without splitting the chain. The cam timing will get a little late as the chain stretches. The hydraulic tensioner takes up the slack. As the chain stretches the tensioner may reach its mechanical limit or malfunction and jump one or more teeth. Since a tooth equals about 18 degrees of timing on the crankshaft pulley, the problem is easy to check. Turn the crank by hand in the normal rotation, check the crankshaft timing marks and the front camstand/sprocket mark. If the timing is off more than 18 degrees the chain has jumped. If it has jumped the chain is stretched and should be replaced. Owners should try to get the service history for their cars so important procedures like chain replacement can be documented. An experienced 113 technician can replace the timing chain, re-torque the cylinder head and adjust the valves in two to three hours.

Pete Lesler: you can replace the cam without taking the head off. Here's how I did it: first release the pressure in the cooling system by backing off the radiator cap. You may also wish to drain of some coolant, but it is not necessary. Do this job while the engine is cold as you will need to do a valve clearance adjustment as soon as you are done as well as retorque the head. Assuming you have removed the valve cover, the first thing you must do is align as perfectly as you can the number one mark which is a notch on the washer mounted in front of the cam with the arrow mark which is cast into the first cam bearing pedestal. Make certain that number one piston is at TDC and the rotor on your distributor is pointing to the small notch in the outer rim or the number one spark plug lead in the distributor cap. This is important so you can replace the chain sprocket into the exact same position from which it was removed. Remove the large 22mm nut on the front of the cam which holds the cam sprocket in place. Gently tap off the cam sprocket and cam. Be careful not to lose the position of the sprocket on the chain. Might be wise to mark it so if it pops off or you loose the position, you can find it. Tie the cam and sprocket off with some wire. Next step is to remove the head bolts that hold down the metal brackets that the valve cover is tightened down onto and the cam oiling tube. Once you remove the brackets and the oiling tube, you can run those head bolts back down and partially torque them. This will hold the head in place and maintain a seal as you remove the remaining head bolts that hold down the cam bearing pedestal. You must then remove the cam and the cam bearings. Do not forget that there is a small 8 mm bolt which also holds down the cam bearing pedestals. In reinstalling the cam, you must realign the notch on the cam washer and the arrow on number one cam bearing pedestal. I always remove the rocker arms before I tighten down the cam bearings. Even though you are using a different cam, keep them in order, or better yet, replace them especially if you are installing a new cam. It is strongly advised to use new rockers with a new cam. They are easily installed after the cam is aligned and the cam sprocket is reattached. Reinstall the rockers by doing the ones with the cam lobe pointing up or at right angles to the lobe mating surface of the rockers. The rockers should slip right on. First place the tip of the rocker onto the notched thrust piece over the spring. Then using a 17 mm open end wrench gently lift the other end over the adjuster. You may have a difficult time installing those where the cam lobe is pushing on the mating surface, i.e. the cam lobe is pointing down. Since you now have the sprocket installed, you can turn the engine over by hand to orient those rockers in a more favorable position. Then turn the engine until the notches in the cam bearings and the distributor are aligned to make certain nothing has slipped. Go ahead and retorque the head to specs and do a valve adjustment. Retorque again after a brief run time and go over the adjustments one more time.

We just purchased this car as a restoration project. The head is missing. I understand from the MBCA discussion groups that I have a 'late' engine (130983-12-008948) and that I can use a head from a 280 SE if I change the cam towers. But what years? The 280 SL (W 113) ended in '71, at least in North America, but the 280 SE continued.

The 280 SE W 108 ended in 1971 too but was superseded by the W 116 model with the same engine. Problem is that not all the heads are identical, as I discovered when I tried to fit to my W 108 280 SE the head of another scrap W 108 280 SE! They had different water passages. I'll try to find the engine numbers which fit yours. I'll keep you posted.

The W 116 cars had the twin cam M 110 engine instead of the single cam (M 127?) engine that was in W 108s and W 113s.

Below is the list of "suitable" engines (i.e. the ones with SOHC):

 W 113 280 SL => eng.no. 130.983 (127 was the 230 SL, 129 was the 250 SL)
 W 108 280 SE => eng.no. 130.980
 W 111 280 Coupé/Cabrio => eng.no 130.980 (same as W 108 sedan). 

Unfortunately I don't know if that little "3" makes a great difference but, as I said in my previous post, not even the same engine no.s are perfectly identical, so one must check anyway.

I found definite answers: as I was afraid of, the W113 engine was different from the W 108/W 111 one. Besides (as it happened to the sedan) some parts changed during their production lifespan. In particular, it seems that the head changed at the no.8785.

The cylinder head in our car is "deteriorating", according to our mechanic--probably due to lack of correct coolant mixture in the engine the whole time it was not driven for all those years. So much so that oil pours from #5 and #6 spark plug openings when the engine is warm and running, and although this can be temporarily stopped by welding, etc., it comes back soon afterward. We were told to replace the head. So, what are our options? New, rebuilt, used, complete, bare? What should we expect to pay? What should we look for, or avoid? Who is the best source for heads?

Joe Alexander replies: welding the head for an oil leak is a real mystery to me? Head deterioration from improper coolant usually results in some sort of coolant leak. Oil seepage around the spark plugs is usually due to a leaky valve cover gasket or oil seepage from around the threaded bases of the ball stud adjusters under the valve cover. These can be removed, resealed and re-installed. If your engine is burning oil, your valve guides may need replacing (valve job) or worse. Find a shop experienced with these models so you can sort through your options. Even a good used head should be re-conditioned or checked before re-installing. Head work is labor-intensive especially if your car has factory AC. You want to make sure everything is right before putting it back together. Timing chain replacement is also recommended while the engine is open if it is streched. Save lots of labor by replacing the inexpensive waterpump at this time also. Mercedes dealers sell factory rebuilt waterpumps for less than $30! Be aware that there are two types of heads on the 280 SLs and they are not interchangeable. Use your engine or head number when shopping for a used head. The fuel injected 280 SE sedans 1968 through 1971 shared the same heads as the SLs. But remember that the early and late heads are different in the sedans as well as the SLs. The camshafts may also be different. Oftentimes one can find an entire running sedan parts car for a few hundred dollars. Most wrecking yards will not have a 113 parts car but may have several sedans with the head you need. It must be a 280 SE 1968 through 1971 (six cylinder fuel injected, single overhead cam engine). Check the part numbers! If you’re not a member of the Mercedes Club you may want to join and find some members in your area with same model who can advise and recommend sources of service and parts.

I'm with Joe, I don't understand the correlation of an external Oil leak, with internal corrosion of the cylinder head. Did it corrode into an oil passsage in the head? If so you would be getting coolant into the oil. A very bad situation! Anifreeze is a very poor lubricant, and when it mixes with the oil, develops a sludge in the crank-case. When I purchased my 67 230 SL the previous owner told me that when he located the car, it had sat in storage for many years with only water in the cooling system. Consequently, it had channel corrosion, resulting in small holes into the combustion chamber. Cast aluminum has been known to corrode in long slender finger-like projections; referred to as galvanic corrosion (if I remember my terms correctly). Since he was initially unable to locate a head, he had it welded. After completing the rebuild, he came across a new head. Sure enough, after operating the car for several months, I noticed a cylinder miss on startup. This progressed to bubbles appearing in the radiator cap opening, especially when the throttle linkage was surged. I replaced it with the new head and have had no problems since.

Dan says: re-torquing the head bolts, after the initial head assembly, should be done after a few hours of running on a warm engine. Undo each bolt one at a time only. Start in the middle just like a regular sequence and undo a bit and then tighten up to the final amount which is usually a bit more than the inital setting. You should get another 1/8 turn out of some of them. Also use a bit of oil on the threads and washers so they screw down evenly.

Just did this - before you retorque, make sure there's no pressure in the cooling system. Loosen the overflow canister cap and re-fit. The sequence of the bolts is from the inside out, there's a diagram in the Haynes manual. Loosen each bolt for at least a half a turn, then tighten to 60 lbs (double check your engine specs to be sure). It's easy to do with a relatively long 10 mm Allen key. Don't forget the bolts in the timing chain housing. Modern head gaskets are said to not need re-tightening, but do it anyway to be sure. After you do the bolts, check the valve clearances.

Dan says: water directionals in the head are the tubes that are pressed into the bottom of the head. They direct the coolant at the hotter places inside of the casting. Usually pointed towards valve seats and other areas like that. They're important for proper cooling.

Was out last night in the SL driving rather fast. When I came off the highway, there were clouds of white smoke from the exhaust and missfire so I carefully drove home. Thought I may have blown the head gasket as it seems water is coming thru the exhaust but there is no bubbling at the water header tank. Can't figure it out!

I think it's the head gasket. I have an old pickup truck that did something similar. The head gasket leaked between a cylinder and a water passage, but it only leaked one way, from the water passage to the cylinder. No bubbles, but it sucked the water out of the system and blew it out the exhaust. Don't know why it didn't blow bubbles, but the gasket was definitely blown when I pulled it out.

The 230 and 250 heads are different but they will still interchange. It's the block that's really different. It has 7 main bearings and the engine was stroked to give it those extra 200 cc's. The 230SL engine only has 4 main bearings and a short stroke. The heads are different in these ways: different valves, keepers, and retaining cones, bigger exhaust valve guides. It has 9.5:1 compression the 230SL has 9.3

My 250 SL engine valves seem to click even thought they run smooth, especially at higher speeds. They could not have been this noisy when new. Were they? What causes this? My mechanic tells me he can tighten them down but I will lose power. He says it's the nature of them. How can it be fixed to be as quiet as a new engine? It's not real loud, but I expect these engines to be quieter. Without the muffler they sound like a truck!

Dan Caron says: I suppose it depends on how you define the noise of a truck. The valves are "lifted" directly by the camshaft; there are no noiseless hydraulic lifters as you would find in a later model car. Thus, you will hear the valves click as the engine runs. As long as the cam and valves are getting the proper oil and the valve clearances are correct, the clicking should be very audible, but certainly not like a truck. Those of us who love to drive these cars (and other SOHC or DOHC cars) view the clicking as though it was a heartbeat. My advice: get the valves adjusted to factory spec, make sure that they are getting enough oil, then learn to love the click.

If the cam lobes are still smooth you can replace the rockers only. There was a time when you could buy just the ball stud portion of the assembly. Now you have to buy the whole thing. I've removed them and actually flattened them back out on top the way they were when new. What happens is the rocker seems to catch on the ball stud where the small hole is . When you take the rocker off you will see that there's a point of metal left from years of wear. If you grind this off the rocker can move freely without hanging up on this point. All this makes useful sense IF you have that kind of wear. I set valves to .003 and .007 with a fair bit of drag on the feeler gauge. Not a bad idea to replace the retainer springs on the rockers. They help to keep the rocker tight against the lash cap on the top of the valve and absorb a fair bit of vibration so help to keep the noise down. Anyone care to know how the adjusters work on the ball studs? Pretty slick idea really. If you ever remove one you will see that there's a gap in the thread. It's there for a reason. Every single thing on this car is there for a reason. It may take years to find out what that hole is there for but it had a purpose. The ball stud has two out of sync threads. They cut the top thread and then move the piece a little bit in the lathe and then cut the bottom part. The two threads don't line up with each other and so it makes it hard to turn . Loose enough you can turn it yet tight enough it won't turn on it's own (usually). If you have one that won't turn don't force it, just pop the rocker off with a screw driver and use a socket on it and brake it loose.

Subject: leaking rocker arm pivot bolts. I'm planning on sealing off two of my engine's rocker arm pivot bolts that are leaking oil into the spark plug area through the threads. I understand this can be cured by removing them and resealing. How was this done at the factory. Did they also use some type of sealant. What should I use so that I can still move the bolts for future valve adjustment?

Joe Alexander: you'll need a sealer like Permatex or Locktite. Avoid silicone sealer oil which will degrade over time. These must be sealed and re-torqued in so they do not loosen under normal valve adjustment. You'll need a torque wrench, 1/2" breaker bar, and some 1/2" drive sockets. (24mm and 14mm on 230-SL and early 250-SL) or (24mm and 17mm on later 250-SL and 280-SL). Use six point sockets if available. Keep the rocker arms in order. Valve adjustment should be done at finish. Make sure you have a good deep valve adjuster wrench (17mm or 14mm depending on year).

I need new rocker arm thrust pieces, but there are three sizes. Which do I start with? If my info is correct, the sizes are 2.5, 3.5 and 4.5. Since all the parts in the valve train are new, I think I should start with the thinnest. A good assumption?

I'd start with the std size if that's what you have from the original head--can't remember which it is. I'd try using only a few at a time to see if you can adjust each valve to the right clearance. My head has been rebuilt twice--the first time around, all the std size thrust pieces allowed the proper clearance. 25 years later when I had the head redone, I used all std size thrust pieces except for one. I could not get the proper clearance and had to order a thinner piece for that one valve. I replaced all my valves, guides, recut the valve seats, springs, rocker arms and attaching hardware. It's hard to say what you will run into on yours, but again I'd start by trying the std ones you have and then go from there.

Naj - I need to change the head gasket on a '65 230 SL. Would appreciate any experiences, comments, warnings etc.

Naj, I have no experience with these heads, but here are some generalities that you probably already know: Disconnect the battery and tape the terminals, you want no chance of accidentally activating the starter with the cam chain loose. I think Benz Dr. would recommend replacing the chain while you're at it. If you don't plan to rebuild the head, it's a good idea to check it anyway for warpage while you have it off. Make sure all edges exposed to the combustion chambers are deburred to prevent hot-spots. You could look at port alignment and do a bit of grinding if necessary to be sure there is a smooth transition from manifold to head (intake) or head to manifolds (exhaust). Plan ahead: the head is heavy and expensive, prepare a place to put it down before you pick it up. You might want to make a place to put the head down immediately next to the engine, especially if you work alone. These are wide cars and you may be streched out and off-balance when you pull it off. Be careful lifting it off: don't drop it, and don't hurt your back. Good luck, we're all jealous of your opportunity to do this! Right...

Last week a member inquired about replacing a head gasket. Stu Ritter of MBCA mentioned the need for placement of additional gasket compound on the gasket head. I do not have that issue of the Star but it was in the May/June issue of 2000 on page 18. Could someone find that article and give us a synopsis?

Dan Caron: what additional material would this be? I sometimes paint the gasket with aluminum paint for a better seal but never would I use any sealer.

MB US technical expert (not Stu Ritter but Bill Darling): the only available head gasket for the 127 motor in the 230SL does not adequately seal the coolant passages. When replacing the gasket, hand-paint a 'thin bead' [emphasized] of Permatex-brand aviation sealant on the head and the block around the coolant passages (at least two coats) before installing it. Unless the head is warped more than 0.002 - inch, this will work great. Otherwise there is a good chance that when you fill the cooling system after replacing the gasket, coolant will run out of the head/block joint at the middle of the block. This is a major waste of time and money, believe me.

Dan Caron: I only had this happen once. It turned out to be that the block was warped which is not all that common on engines with aluminum heads. I suspect that this may be something that should be checked carefully during rebuilds. Never had leaking problems on any that I've done. I have an original head gasket from an early engine so I'll compare it to what's offered for replacement. Frankly, I wonder how sealant is going to help if the gasket doesn’t line up with the holes as suggested. Either the raised area of the gasket is pressed tight or it isn't. Come to think of it , this one leaked in the middle on the spark plug side. Probably a warped block.

The block can be warped too. This can be checked with a machinists straight edge. An ordinary ruler isn't accurate enough. It's a safe bet that this leaking problem isn't a head gasket problem at all. I find it hard that MB would sell a gasket that is known to 'not fit'.

Joe Alexander: I use a heavy metal straight edge to check warpage of head or block surfaces. The straight edge should be big enough to extend from one end of the head or block to the other. A rafter square (contractor's square) works nicely. After cleaning the surface, feeler guages are used to measure any gaps between the head surface and the straight edge. (0.1mm) warpage is allowable. The original thickness of the cylinder head new is 84.8 to 85mm. Total permissable removal is 1.0mm or a finished heigth of 83.8 to 84mm. A accurate micrometer or caliper must be used to measure the heigth of the head. Cutting the head just to clean the surface is done by many machine shops. I try to avoid cutting the head unless absolutely necessary. If the lower surface is warped, the top surface also needs flattened, so that the camshaft runs true. In addition as the head becomes shorter, the timing chain gets longer and the compression becomes uneven since the cylinder head is cut mainly at the end cylinders in the process. If it is flat, just clean it and do nut cut it. You may need the extra thickness to flatten the head in the future. I have heard that some shops can now straighten or partially straighten warped heads? Sounds like a better alternative. Block warpage is rare and can be checked in the same manner. Many new Mercedes production head gaskets for older engines have an adhesive strip near some coolant passages. The originals and nos gaskets did not. Should you use a sealer on the gasket? I always have. I am sure that this is a point of debate. Anyway re-tighten the head after first warm-up and again around 500 miles, with valve adjustment.

Dan Caron: I agree with most everything except the machining of the top of the head. The top and bottom are often a long ways from being parallel on every head I've ever measured. They can be thicker at one end than the other and from side to side. None of this matters at all. What is important , is that the top of the head is flat enough to allow the camshaft to turn freely and that's all that you should worry about. If it won't turn after you torque it down , then you have problems. Cutting the top of the head may in fact ruin the head forever if it's already near or at minimum thickness. Don't think a carpenters square is remotely accurate enough to determine a few .000's . You might cut a head or block that's actually flat. Only a machinists straight edge or a proven flat bar should be used. I've seen them heat straightened but then the cam wouldn't turn – both surfaces milled and then it was too thin. I guess all this takes careful consideration of all the possible methods of repair. No one way will work for all situations or owners.

Joe again: hello Dan, meet me behind the barn and bring your gun! Just kidding. I think we are in basic agreement. First only cut the head when absolutely necessary, top or bottom. Top rarely needs cut unless as mentioned the cam binds, I have seen some top decks so warpred that the valve cover gasket does not ever seal. Also just make sure whatever you use to check straightness is known to be straight. My $90 machinist straightedge says my $5 Home Depot rafter square is straight when checked. Spend whatever makes you happy, or just ask your neighborhood machinist to check it for you. The moral of the story is don't cut and be straight!

Would you by any chance know what the numbers(the ones stamped into the cam itself) for the Euro cam were?

Dan Caron: that should be 04 on the end.

Pete Lesler: early Euro cams, (used in 280SL as well as 300SEL 2.8 cars) were stamped 09. Later cars (1970 and 1971) have the cam stamped 02. Complete part numbers were 180-051-0935 and 114-051-0201 respectively. If any one finds a cache of these cams out there reasonably priced, please post it. I can feel the difference the extra 15 HP makes at 5000-6500 RPM.

Cees: As far as I know these 280SL euro cams are normally available here in Europe from W113 parts sellers (like Van Dijk, Niemoller, SLS, DB Depot etc etc), and go for something like $500. Not sure about whether the MB Classic Center carries them and at what price, I just bought their (M130) engine catalog with part numbers and prices, but it has not come in yet.

Joe Alexander: There were quite a few different cams used in the 280-SE sedans over the years. Some were improved materials or construction. Some were to conform with emissions. Depending on the year and delivery destination certain cams yielded better performance. The latter engines had different cam holders (larger inside diameter) since these cams have larger main journals. I think most of the group understands that the #09 gave the best performance, being the most radiacal. Few realize that the earlier cam #02 had the exact same specs, but was an earlier design. The next best performers was #11 and #86 (# 11 utilizing improved steel over 86). Camshafts #01,05, are detuned for USA emmissions with #05 having improved steel over #01. The least performers are camshaft numbers #04, #08, #60 #61. Your #08 is an improved steel over #04. Almost any of these cams will work in a pinch. However at times the four cam supports must be changed with the camshafts since some early and later cams had different size main journals. Also the early 113 engines (230-SL, earliest 250-SL), had different size cam lobes, rockers, and ball stud adjusters. The camshaft for the 230-SL #76 and 84 was also a fairly "hot" cam. It's valve timing was a little different than the #09 280-SL "hot cam" but the total valve open duration of the two were the same. The two are NOT easily interchangeable. I have compiled a fairly extensive chart for cam comparisons if anyone is interested.

Pete Lesler: you can replace the (standard with a Euro cam on a 280 SL) without taking the head off. Here's how I did it: First release the pressure in the cooling system by backing off the radiator cap. You may also wish to drain of some coolant, but it is not necessary. Do this job while the engine is cold as you will need to do a valve clearance adjustment as soon as you are done as well as retorque the head. Assuming you have removed the valve cover, the first thing you must do is align as perfectly as you can the number one mark which is a notch on the washer mounted in front of the cam with the arrow mark which is cast into the first cam bearing pedestal. Make certain that number one piston is at TDC and the rotor on you distributor is pointed the small notch in the outer rim or number one spark plug lead in the distributor cap. This is important so you can replace the chain sprocket into the exact same position from which it was removed. Remove the large 22mm nut on the front of the cam which holds the cam sprocket in place. Gently tap off the cam sprocket and cam, Be careful not to lose the position of the sprocket on the chain. Might be wise to mark it so if it pops off or you loose the position, you can find it. Tie the cam and sprocket off with some wire. Next step is to remove the head bolts that hold down the metal brackets that the valve cover is tightened down onto and the cam oiling tube. Once you remove the brackets and the oiling tube, you can run those head bolts back down and partially torque them. This will hold the head in place and maintain a seal as you remove the remaining head bolts that hold down the cam bearing pedestal. You must then remove the cam and the cam bearings. Do not forget that there is a small 8 mm bolt which also holds down the cam bearing pedestals. In reinstalling the cam, you must realign the notch on the cam washer and the arrow on number one cam bearing pedestal. I always remove the rocker arms before I tighten down the cam bearings. Even tough you are using a different cam, keep them in order, or better yet, replace them especially if you are installing a new cam. It is strongly advised to use new rockers with a new cam. They are easily installed after the cam is aligned and the cam sprocket is reattached. Reinstall the rockers by doing the ones with the cam lobe pointing up or at right angles to the lobe mating surface of the rockers. The rockers should slip right on. First place the tip of the rocker onto the notched thrust piece over the spring. Then using a 17mm open end wrench gently lift the other end over the aduster. You may have a difficult time installing those where the cam lobe is pushing on the mating surface, i.e. the cam lobe is pointing down. Since you now have the sprocket installed, you can now turn the engine over by hand to orient those rockers in a more favorable position. I then turn the engine until the notches in the cam bearings and the distributor are ligned to make certain nothing has slipped. Go ahead and retorque the head to specs and do a valve adjustment. I would retorque again after a brief run time and go over the adjustments one more time.

Joe Alexander: I think some early USA 280-SL's may hve been equipped with the 09 camshaft also. I have seen an original USA 1969 280-SL with the "09" camshaft. There may have a brief period before stronger USA emmission regulations took place. I cannot find any distinct documentation on a strictly separate European or USA camshaft. The "02" camshaft was probably the latest improved material and according to the data book, had larger diameter bearing journals. Anyone wishing to use a "02" camshaft would also have to invest in the four new cam supports also.

Pete Lesler: I think you may be correct on your statement about some of the early cars may have some 09 cams installed. I took an engine out of a 1968 300SEL-2.8 and low and behold it had the 09 cam. I am convinced that it was a US spec car. But is was a very early car. he Euro 300SEL -2.8 engine 109 chassis all had the 09 cam installed. Probably to compensate for the extra weight. If you switch over to the "02" cam you must replace the four cam bearings as well. I have done this on my race car, it works fine.
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