Con Rod Bearings. One hole or two ?

[alpina]

I hope you guys will be able to give me some advice. I am currently having the crankshaft and associated
Bearings replaced on an early 280SL.
The connecting rod bearings supplied have only one oil hole. Where the originals coming out have two.

Is it okay to use the bearings with one hole which obviously blocks one of the holes?
I have read posts on here from Benz Dr.  indicating this would be okay. As the original two holes caused
Excessive oil consumption.

So please put my mind at rest, and confirm it is okay for the guys doing the work to use the one hole bearings.
I need to know pretty quick, not to delay the work.

Best regards  DM.

[jpinet]

Hi,
The 127 engine (1965 230 SL) has shells with only one hole. I know 280 engine is somewhat different, but not that much. You could call Mike at Metric Motors  (818-712-9881) who specializes in rebuilding these engines and ask for his opinion.

[alpina]

Okay, so todays update. I have now spoken to two Mercedes Engine builders in the UK.
(Crewe engines ltd and Roger Edwards),  both say they would drill the extra hole to match the
Existing bearings, If they were building the engine.
So unless someone can provide a compelling reason not to drill the hole to match
The originals, this is what I guess we will do.  Matching the holes with what is coming out surly can’t be
Wrong, and I presume the safest option.
All opinions gratefully received.

DM

[ja17]

I have always matched the replacement set to the originals. I have literature to support this. You might want to check with Metrics also.

[Benz Dr.]

Don't drill the extra hole, is what Mike at Metrics told me. MB found that it wll make your engine use oil. Anything coming off of the crank will be enough to lube the cylinders.
Early 230SL's had gun drilled conecting rods and the pin bushings were lubed under pressure. The hole you have in your bearing is there for that application but on later engines the pin bushings are splash lubed so the center hole on the bearing isn't even needed.

[alpina]

Thanks for your confirmation. The question arose from reading the threads below. And comments for Benz Dr.
Who was told the info by Mike @ Metrics.

http://www.sl113.org/forums/index.php?topic=21652.0

http://www.sl113.org/forums/index.php?topic=15740.0

I think now we will be drilling the extra hole to match the originals.

[alpina]

Dan. I think I wrote my last reply before reading your last post. Surely there can
Be no adverse effects by matching the bearings that are being removed, or am I missing something here ?
Why would all the other advise be to replace like with like ?
Obviously I am no engineer, I just do not want to do anything that could cause damage further down the line.

[Benz Dr.]

If the extra hole/holes were supposed to be there, they would be made that way from the supplier. I've been called on this before and this time I know I'm right.

 Install them as is and you'll be OK.

[tel76]

On this occasion I agree with Dan, you can safely fit them, do NOT drill another hole.
Make sure when you fit the conrods/pistons into the block you position the oil hole to the THRUST side.

[Benz Dr.]

On this occasion I agree with Dan, you can safely fit them, do NOT drill another hole.
Make sure when you fit the conrods/pistons into the block you position the oil hole to the THRUST side.

That's not what I'm saying. You don't need to line up any holes or drill any new ones. The small notches on the connecting rod that locate the bearings go to the left or distributor side of the block but any oil holes drilled into the rod are of no importance. MB quit using them when they started replacing short blocks under waranty due to heavy oil consumption.

[tel76]

So are you saying that the plain shells could be fitted in the con-rods and not the cap ?

[Benz Dr.]

The rod bearings come with 6 shells that have holes in the center position in case you need them for gun drilled connecting rods and 6 shells that have no holes for the caps. No other holes are needed. 

[tel76]

The rod bearings come with 6 shells that have holes in the center position in case you need them for gun drilled connecting rods and 6 shells that have no holes for the caps. No other holes are needed. 

The latest con-rod bearings supplied for the 280sl are supplied with ONE oil hole and that hole is offset (NOT in the central position), when you fit the con-rod the said hole must be positioned facing the RHS/MANIFOLD side, this allows oil to be supplied to the thrust side of the piston.
As noted the plain ones are fitted to the caps.

[Benz Dr.]

I just built two different 280SL engines and niether of them had holes for oiling the thrust side. Some connecting rods have these holes on the manifold or thrust side; I've seen them; and some have two holes, or one for each side of the cylinder but none are actually needed.

 So, should I expect my rebuilds to blow up any time soon? 

[tel76]

Have a look at the picture at the top of this thread ,the picture of the new shell on the right is what is supplied with the offset hole for lubricating the thrust side, if you have fitted plain shells in your con-rods the recipient of those engines should be concerned.
This thread is going nowhere, you build your engines how you want to but please be careful not to pass on wrong information to members on this forum.

[Benz Dr.]

Have a look at the picture at the top of this thread ,the picture of the new shell on the right is what is supplied with the offset hole for lubricating the thrust side, if you have fitted plain shells in your con-rods the recipient of those engines should be concerned.
This thread is going nowhere, you build your engines how you want to but please be careful not to pass on wrong information to members on this forum.

Really? It's one thing for you to disagree with me but it's a whole other thing to say to me and everyone on this site that I'm passing on wrong information and apparently, by your tone; I'm doing it on purpose. What possible motive could I have in doing that? Trust me, being right, or thinking I am, isn't close to enough reason to even respond. However, inferring that I'm a fraud crosses the line.........
 
I can be as wrong as anyone around here and I'd be the first one to admit it too. If I'm not sure I say, '' I'm not sure....'' If I'm fairly sure I say, I believe, or I think this or that about a certain subject, and if I know I'm right about something, and I'm certain about it, I say so. In this rare and partiular case, I'm sure about it.

I buy a certain amount of engine parts from Metric Motors in CA. They build about 300 engines per year; I believe all of them are MB. When this question arose some time ago I asked Mike ( the owner ) how to deal with this issue. This is what he told me: ( I asked his permission to quote )

“ NOTE: THESE BEARINGS SUPPLIED ARE AN UPDATED/SUB TO VERSION. OIL HOLES IN ROD BEARING WILL NOT ALIGN WITH THOSE IN ROD... THE HOLES ARE IRRELEVANT. NO PASS THROUGH OIL HOLE IS REQUIRED. AS MOST 130 TYPE RODS HAVE NO OIL HOLES ANYWAY. RUN AS SUPPLIED.”

 For the record – This comes from old Germans that were working these vehicles back in the day. Mercedes was having trouble with oil consumption on the M130 engine types partly due to too much oil squirting from the rod to the cylinder wall. So in 1971 they omitted the holes in the rod to alleviate such. We have flipped the bearing around to do the same for over 25 years without any consequence. In fact it’s only an improvement. ''

 
 If Metric Motors is wrong, then I'm also wrong and all of the rebuilt engines done in this manner are apparently junk. Will your engine fail if you use the holes in the rod? I doubt it, but when an enlighted view from an expert comes along does it not behoove a serious student of these cars to pay attention?


 

[tel76]

It was not my intention to continue with this tread but I will address two allegations you have made.
1 - The comments that I have made were NOT suggesting that you are a fraud, you have read something in my reply that was not there.
2 - The comment from Metric Motors !MOST 130 TYPE RODS HAVE NO OIL HOLES ! In all the engines I have done I have never seen any 280sl/130 con-rods with no holes and also all the bearings that have been supplied by MB had the one oil hole that lined up perfectly with the one in the con-rod.
One other item worth noting is the last engine I overhauled (late last year) was out of a 1970 280sl, this car had a Mercedes replacement short block fitted in 1973/4, when I stripped the engine the con-rods had one hole fitted and the holes in the shells matched perfectly,  before you say it could have been old stock,( which it was not) it was the latest block fitted with the inserts for the longer bolts, I also sent you a picture of it and at the time you said you had never seen such a block.
If Mercedes advocated plain shells in the con-rod end or any other modification then they would have issued a technical bulletin to that effect, I have never seen or read any such bulletin.

[stickandrudderman]

Here's an 130 engine we're stripping at the moment.
There are things that are most definitely wrong in this picture:


I'll let Tel 76 and Dan fight it out as to what exactly is wrong!

[mbzse]

.../...There are things that are most definitely wrong in this picture.../...

Oooh, I know, I know!  [eagerly waving hand]   /hans

[Benz Dr.]

I think the plain shell bearing might be located in the wrong place ( have to check in the manuals ) and they didn't blank off the holes the con rods.

   

[Benz Dr.]

And it looks like the con rods were installed backwards.

[ja17]

Yes, plain shell in the wrong place and connecting rods in backwards, good observations Dan!

[Benz Dr.]

In other words.......... a complete CF.

[stickandrudderman]

And here's how the cylinders look after only a few thousand miles.

It's lucky we've picked this up early as this engine was heading for a very premature demise.

[Benz Dr.]

There's a posibility that it was over heated or that the cylinders were running hot. Do the score lines run all the way to the top edge of the cylinder or only as high as the top ring? It's hard to see in the shadows.

[tel76]

The condition of the bores reinforces the argument that the con-rods should be fitted the correct way around and shell bearings fitted into the con-rod with the oil holes aligned and supplying oil to the thrust side.

[Rolf-Dieter ✝︎]

I like to say a word or two, having worked 18 years in an engineering office and 35 years in the field with medium and large rotating equipment up to 300 MW as well as gas turbines in my working life. I've drawn and handled in the field many different sizes of bearing shells. Even on a large turbine the number 1 bearing is of the shell design.

Bearing shells and there respective housings should have been so designed and machined in the first place so that the bearing shells cannot be installed incorrectly by anyone. On other rotating equipment be it large or small (pumps, blowers, compressors, turbines [steam or gas] and other machinery this is the way it is done. The housings and bearing shells are machined with notches so that installation is foolproof all the time.

It is my humble opinion that the Mercedes design team overlooked this and never ever admitted this. Or they made those bearings so that they could be used in different engines. I further think that if a change was to be made like changing, like eliminating an oil hole or blocking it this then was only communicated to OEM shops period.

Auto manufactures don't like to admit they made a mistake, only when it becomes a serious safety issue do they issue recall instructions. Case in point unrelated to bearing shells and going off topic for a moment. I drove a BMW Z4 3.5 is with a 19 inch run low profile flat tire in 2009 when that car was interduced. I loved it since the roof was retractable and I wanted to take a trip across the U.S. along Route 66. I did this, unfortunately I ended up with a cracked wheel in two places. BMW did not replace my cracked wheel (model 296) the argument they put forth was that I had gone thru pot holes and that I caused the cracks. Many other Z4 drivers had cracks in exactly the same places and always the rear wheels. I knew why those failures occurred however my argument went against stone walls so to speak. It took 5 years and several class action law suites BMW now finally replaces those failed wheels. Sorry for briefly going off topic I just wanted to give a personal example.

Back on topic, rest assured if the housings and bearing shells would have been designed and manufactured correctly in the first place we would not be talking about this now. I'm of the same frame of mind as Joe A. When you take something apart and/or replace components, replace them with the same component in the same way as removed. Unless instructed otherwise by a higher level like the factory, product service or a outhorized vendor that gets there instructions from the manufacturer.

Bottom line, if you are not 100 percent sure when you take something apart take photos before you do and then put it back together excactly the way you found it be it the same part or a new one. Your photos will guide you and you never will be unsure. Those are my two cents on the subject.

[Benz Dr.]

The condition of the bores reinforces the argument that the con-rods should be fitted the correct way around and shell bearings fitted into the con-rod with the oil holes aligned and supplying oil to the thrust side.

Thanks for your POV. The extra oil you deem so critical is the exact reason why you shouldn't do it.

The connecting rods are in backwards but like a number of things in these engines, they can be installed either way. Small modifications or updates aside, the more knoweldge and expirience you have doing something the more likely the results will be satisfactory.
 
I asked about the score lines in the cylinders for a reason. Score lines that go to the very top edge of a cylinder indicate overheating, as in running your engine out of coolant or a broken fan belt. This damage is usually fatal and it can be found throughout the whole engine. Warped head, warped block, damaged pistons, scrored cylinder walls and many damaged seals and gaskets. Your engine would need a complete rebuild.This should not be confused with running too lean where the spark plugs will be burned away and the top of the pistons will be burned up or actually burned through.

 The only way oil can get into the cylinders on a fresh rebuild is either through the head ( which I feel is the most common ) or past the rings. If you are pouring far more oil on to the cylinder walls than what is actually required, and there's nothing wrong with the head, this would be a good suspect for high oil consumption. Remember, the complaint when these cars were still new, and under warranty, was that of high oil consumption. These being factory built, with an obvious design flaw, they were quickly replaced by MB dealers. Is there some other clear reason for a brand new factory installed and assembled engine to drink oil and then have be replaced under warranty? I think one can safely assume that it was asembled correctly by a highly trained work crew and that it wasn't a manufacturing flaw.

[Benz Dr.]

I like to say a word or two, having worked 18 years in an engineering office and 35 years in the field with medium and large rotating equipment up to 300 MW as well as gas turbines in my working life. I've drawn and handled in the field many different sizes of bearing shells. Even on a large turbine the number 1 bearing is of the shell design.

Bearing shells and there respective housings should have been so designed and machined in the first place so that the bearing shells cannot be installed incorrectly by anyone. On other rotating equipment be it large or small (pumps, blowers, compressors, turbines [steam or gas] and other machinery this is the way it is done. The housings and bearing shells are machined with notches so that installation is foolproof all the time.

It is my humble opinion that the Mercedes design team overlooked this and never ever admitted this. Or they made those bearings so that they could be used in different engines. I further think that if a change was to be made like changing, like eliminating an oil hole or blocking it this then was only communicated to OEM shops period.

Auto manufactures don't like to admit they made a mistake, only when it becomes a serious safety issue do they issue recall instructions. Case in point unrelated to bearing shells and going off topic for a moment. I drove a BMW Z4 3.5 is with a 19 inch run low profile flat tire in 2009 when that car was interduced. I loved it since the roof was retractable and I wanted to take a trip across the U.S. along Route 66. I did this, unfortunately I ended up with a cracked wheel in two places. BMW did not replace my cracked wheel (model 296) the argument they put forth was that I had gone thru pot holes and that I caused the cracks. Many other Z4 drivers had cracks in exactly the same places and always the rear wheels. I knew why those failures occurred however my argument went against stone walls so to speak. It took 5 years and several class action law suites BMW now finally replaces those failed wheels. Sorry for briefly going off topic I just wanted to give a personal example.

Back on topic, rest assured if the housings and bearing shells would have been designed and manufactured correctly in the first place we would not be talking about this now. I'm of the same frame of mind as Joe A. When you take something apart and/or replace components, replace them with the same component in the same way as removed. Unless instructed otherwise by a higher level like the factory, product service or a outhorized vendor that gets there instructions from the manufacturer.

Bottom line, if you are not 100 percent sure when you take something apart take photos before you do and then put it back together excactly the way you found it be it the same part or a new one. Your photos will guide you and you never will be unsure. Those are my two cents on the subject.

MB is like a dog on a bone - they won't let go. Think of 380SL timing chains and the 129 engine wiring harnes. Both were a disaster and both were up to the owner to sort out because their cars were out of warranty.

[tel76]

Thanks for your POV. The extra oil you deem so critical is the exact reason why you shouldn't do it.

The connecting rods are in backwards but like a number of things in these engines, they can be installed either way. Small modifications or updates aside, the more knoweldge and expirience you have doing something the more likely the results will be satisfactory.
 
I asked about the score lines in the cylinders for a reason. Score lines that go to the very top edge of a cylinder indicate overheating, as in running your engine out of coolant or a broken fan belt. This damage is usually fatal and it can be found throughout the whole engine. Warped head, warped block, damaged pistons, scrored cylinder walls and many damaged seals and gaskets. Your engine would need a complete rebuild.

In the case of a cylinder/s running hot you will have a different set of damages. The scoring will be the height of the top compression ring and will run as low as the ring moves. This is caused by too much oil entering the cumbustion chamber. This is often found as leaking valve guides but it can also be caused by incorrect installation of piston rings or excess oil on the cylinder walls. This damage will be more pronouned on a fresh engine with full compression and as an engine wears out extra oil moving up past the rings will not be as critical.  This should not be confused with running too lean where the spark plugs will be burned away and the top of the pistons will be burned up or actually burned through.

 The only way oil can get into the cylinders on a fresh rebuild is either through the head ( which I feel is the most common ) or past the rings. If you are pouring far more oil on to the cylinder walls than what is actually required, and there's nothing wrong with the head, this would be a good suspect for high oil consumption and scored cylinder walls. Remember, the complaint when these cars were still new, and under warranty, was that of high oil consumption. If the cylinders were running hot because of excess oil entering the cylinder thereby causing the walls to score, then it would really use oil. These being factory built, with an obvious design flaw, they were quickly replaced by MB dealers. Is there some other clear reason for a brand new factory installed and assembled engine to drink oil and then have be replaced under warranty? I think one can safely assume that it was asembled correctly by a highly trained work crew and that it wasn't a manufacturing flaw.



Well I have heard/read it all ! SCORING CAUSED BY TOO MUCH OIL !What a load of cobblers, as you will respond to that comment I will let you have the last word on the subject (AGAIN).
The members reading all the above will have to make there own decision on how they do the work on there engine.

[mbzse]

.../... It's lucky we've picked this up early as this engine was heading for a very premature demise

Colin, fortunate owner of that car/engine, indeed, that he ended up with his car in a workshop that knows what they are doing...
Apart from the two items discussed (Main bearing shell misplaced and con rods put in backwards, as Eric, Dan, JoeA and myself identified) were there additional issues with the previous assembly of this particular engine?
For instance, was the sealing rubber ring on top of the oil filter insert in place...?
/Hans in Sweden
.

[Benz Dr.]

Just a bit of explanation for everyone:
 The rod bearings I get from Metrics only have one hole, which is in the center of the bearing, and it's there for the early style connecting rods used on 230SL's. There was some confusion on my part during these discussions because I was not receiving bearing shells with the extra hole for oiling the cylinder wall. Having never seen this particular bearing type before, ( because that was what I was sent ) I asked Mike at Metrics if I should copy what came apart and drill the extra hole. He said no and I've added his comments to this thread, or another, for clairification only.

For the most part, you can't improve that much on MB design. There are times when you can use a modern method or part such as electronic ignition, which is actually a complete change from what was installed; it works OK and for those who don't want to change ponts and it offers a fairly good alternative.
 However, MB is not infallable - they make mistakes but are generally loath to admit to them. 280SL oil consuption was one of those rare mistakes. It looks like there wasn't a recall issued ( if they even did that back then ) and the problem was likely addressed on an ''as fail '' basis. This is fairly common where there's no recall but the item is still under waranty. No such luck for the single row timing chains in 380SE/SL engines. Most failed after several years and 50K miles so you were on your own. So much also for owner loyalty.


 Since I was never formaly trained, I asked a lot of questions and I made it a point to pick the brains of experts who knew what they were doing. This is exactly what members of this forum do every day - they ask questions of people who know these cars. However, quoting experts does not make one an expert as well and a great deal of expirience and knowledge generally has to enter into the picture first.
When I started back in 1977 I knew next to nothing about old MB cars and there was no one to ask and no one to go to for answers. One had to figure it out on their own and those few who did know didn't give it up willingly. Be very happy you have a place like this where you can find just about any info you need - even if we don't always agree upon the answers.  


This is also covered below in these posts and also first hand testement from owners back in the day who had engines replaced due to high oil consuption.

http://www.sl113.org/forums/index.php?topic=15740.0

 
 

[stickandrudderman]

For instance, was the sealing rubber ring on top of the oil filter insert in place...?

This, at least, was found to be correct.