Pagoda SL Group
W113 Pagoda SL Group => General Discussion => Topic started by: peterm on November 22, 2004, 21:36:01
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Cooling problem, I have brought this up before, no luck with recoring, fan clutch replacement, shroud, timing reset. Am thinking the higher "efficiency" radiator before going with an electric fan. Anyone have a good source for these?
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a cooling problem in your Autumn/winter?
hmmmmm
Does the car run too lean?
back flushed the system?
Thermostat ok?
Hoses ok?
anti-freeze replaced?
water pump ok?
rear emergency brakes not grabbing just a bit?
fuel economy ok?
Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto
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Is the gauge accurate ?
Regards,
Ben in Ireland.
'64 230SL 4sp.
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Pete's overheating issues:
http://www.sl113.com/forums/index.php?topic=2365
http://www.sl113.com/forums/index.php?topic=2293
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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My 1971 280SL overheated badly with the AC on, even on a normal day, when stopped or moving slow. On a 100+ Georgia summer day, it overheated without the AC in these conditions.
I installed a 13" (I think--maybe 12") pusher fan in front of the radiator on two 1/8" X 1" metal strips about 12" long bolted to the front face of the cross piece below the radiator. I wired it to the AC on/off switch through a relay so it runs whenever the AC is turned on.
That helped at low speeds, but didn't completely solve the problem and it helped very little when stopped. I tested by putting a big industrial fan on the ground in front of the car---it made almost no difference. That convinced me that the overheating problem when stopped (ie, at idle) was attributable in part to poor coolant flow.
So I ran a 3/8" hose from the thermo switch outlet at the left rear of the cylinder head to the return hose between the thermostat housing and the top radiator tank. It worked better than I could imagine. Now it doesn't overheat, even in stop and go traffic on hot days.
It is hard to imagine that the small amount of coolant flowing from the rear of the head, through the 3/8" hose, and into the radiator could make that much difference, but it does. In fact, in winter if I do not disconned or block the 3/8" hose, the engine will never warm up (because the hose bypasses the thermostat).
This suggests that coolant flow in the rear of the head (where the temp guage sender is) is very poor.
For fittings, I got a metric/inch adapter kit for Autometer guages at the parts store for a few bucks to connect a hose barb to the cylinder head. I fabricated from old radiator inlet tubing a "tee" connection in the top radiator hose that a hose barb fits into.
Its not pretty, and one day I will get around to makeing it prettier, but it sure made my wife stop asking for a new car every summer.
Farmerford
Charles H. Ford, Jr.
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This follows my message of a few minutes ago. My memory is fuzzy, but I think that the largest fitting I could get on the rear of the cylinder head was 1/4" NPT. So after I screwed the 1/4" npt hose barb adapter into the metric/inch adapter, I drilled out the passages through the combined fittings as much as I could to increase coolant flow.
I planned to one day make a more elegant fitting for the rear of the cylinder head with an additional metric port to install the thermo time switch for the CSV. However, because I had already rewired the CSV I didn't need to do it and other projects have gotten ahead.
For what its worth, I had a terrible hot start problem. If the engine was hot and then turned off on a warm day, it would not restart without a lot of grinding. I decided that the gasoline in the fuel injector lines was vaporizing, just like the vapor lock problem on carbureted cars.
So I got an industrial solid state interval timer from McMaster Carr for about $80 and wired it to turn on the CSV for 1/2 second each time the ignition is switched to "on". Thus, even on a hot day (when the thermo/time valve would not activate the CSV) I would still get a 1/2 second shot of fuel at each start.
If I needed more fuel (on a particularly hot or cold day), I would just click the key to "on" one extra time before turning it to "start".
At first, before I removed the thermo/time switch to solve the cooling problem, the thermo/time switch was in parallel with the solid state timer. And I thought when I disconnected it that the 1/2 second shot of fuel that was needed for a hot restart in summer would not be enough for winter, but I was wrong. The 1/2 second is sufficient for winter here in GEorgia, but our lows are seldom less that 20 degrees (F). Colder days might take a double shot, but that's as easy as an extra click of the ignition switch.
If I have the time one day, I will experiment with different times for the fuel shot (it is adjustable in 1/10 second intervals) to see how much difference it makes.
Farmerford
Charles H. Ford, Jr.
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<<<<If I have the time one day, I will experiment with different times for the fuel shot (it is adjustable in 1/10 second intervals) to see how much difference it makes.>>
The stock Benz one is 1 second....
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<<It is hard to imagine that the small amount of coolant flowing from the rear of the head, through the 3/8" hose, and into the radiator could make that much difference, >>
This is also a complaint on a thermostat that does not fully open.
Quite common on an older thermo.. they have a start to open temp and a full open temp..common to see one that operates just fine until one sees high thermal load conditions . That is when the thermo needs full open to adequately handle the extra heat load.
If it does not open to full position, you will have your exact complaint.-- high temps under high ambient temps/load conditions.
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Peter,
Are you sure you got the coolest thermostat? I believe they are available in three temperature settings. I think the coolest is 71degrees C. I made the mistake of getting the 87 degree C one specified in the manual and it ran hot. Now, with the cooler edition, my car sits at 180 degrees F on my guage all day long. The A/C in in stop & go traffic will only push it to 190. A thermostat and gasket are about $17 and an hour of work.
Ray
'68 280SL 4-spd Coupe
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Available thermos for 113 are from 71,79,and 87C
These are Start to open specs.
In tropical climate , the 71C [ 160F] is best.
In normal temperate climates ,the 79C [175] is OK , specially w a/c
and cooler climates 87C [ 189F ] is fine ..
Both A/C and auto trans tend to increase the thermal load ....
Some owner that live in 4 Season climates actually change thermo w/season [ winter /summer]change....
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Here's a list of stuff that could be causing your problems, sorry if I repeat some stuff already here....
Temp gauge wrong, you can get "remote" temperature sensors to verify
Radiator cap:
Seals ok?
Pressure rating correct?
Hoses:
No colapsed hoses, kinks, blockages etc
Water Pump:
Although it may not be leaking I have seen some strange stuff! Including:
The pump "rotor" is loose on the shaft
The rotor vanes are eroded.
The housing is worn so that the pump is not as efficient.
Other Stuff:
You say that you had the radiator recored, was the old one silted up or had you lost the fins??
If silted up did you flush the rest of the system??
Possibility of an air lock???
The fan on "backwards" so it's trying to push air through the radiator (Been there, done that [:p])
HTH
Malc
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I had a local radiator shop recore my rad with a high efficiency core, cost was around $220. I think the h.e. core has dimpled tubes and a higher fin count, maybe some other attributes that increase efficiency. Seems to do the job, no problems after adding a/c. But I think the other suggestions in this thread are definitely worth checking out. I'd be inclined to replace the thermostat, check the pump out as Malc suggests and give the engine a good flush.
Good luck with it!
George Davis
'69 280 SL Euro manual
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A vapor lock is an interesting thought. I just put new radiators in my basement and had a very hard time getting the air out of the system. I'd assume the car is the same.
What are the best procedures for bleeding the cooling systems on these cars? I am going to replace my radiator and want to avoid this problem.
Shawn Rock
Philly, PA USA
1968 280 SL 4 speed
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Shawn,
It seems that some of our cars are different in this area. My car has a bolt on top of the thermostat housing that is used to bleed the air out of the system. My car is a 1969 with air conditioning. I have seen other cars that do not have this bleeding bolt. Air will seek the highest level in the cooling system. I believe the highest point is the heater core. I understand that some people have bled their cooling system by installing a valve near the radiator core.
However you manage to bleed the system, I strongly reccommend it. My car was running hot until I found out aout bleeding the system.
Regards,
Ted
1969 280SL 4 Speed
New Rochelle, NY
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You didn't say if you were using water or anti-freeze mixture. Anti Freeze might be a good option with it's higher boiling point, if you are currently using water.
Jim
Ottawa, Canada
quote:
Originally posted by peterm
Cooling problem, I have brought this up before, no luck with recoring, fan clutch replacement, shroud, timing reset. Am thinking the higher "efficiency" radiator before going with an electric fan. Anyone have a good source for these?
JLHunter
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Water will cool better that antifreeze, you might try a 75% water 25% antifreeze mix.
Mike Halleck
Chesterfield Mi
71 280SL
68 250SL (parts car)
94 E320 Coupe
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Charles,
I was hoping you could snap a picture or two of your homemade re-circulation system. I know others have made similar devices to help flow to the rear of the head but I'm not sure I've seen a picture. Others have used a MB recirculation kit and I'd love to see a picture of that if others are inclined.
thanks
tdun824259
Tim Dunagan, 71 280sl, auto
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I will try to do it this weekend.
Chuck Ford
Charles H. Ford, Jr.