Author Topic: Overheating and Remedy  (Read 6664 times)

John Betsch - "SADIE"

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Overheating and Remedy
« on: November 23, 2020, 14:53:27 »
I just found the attached dated October 1970. It is an eight page document addressing "overheating." 

So not to burden the site with 8 pages, is it something relevant to share?  I scanned just the first page. (the white on each side is simply an attempt to "help" the older xeroxing)

JB
JB; 1965 German market SL, Rot Met 571, Summary Code 213 Interior

WRe

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Re: Overheating and Remedy
« Reply #1 on: November 23, 2020, 15:26:28 »
Hi,
very interessting, thanks for sharing. Maybe you can put the whole document in the Technical Manual.
...WRe

dirkbalter

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Re: Overheating and Remedy
« Reply #2 on: November 23, 2020, 15:56:28 »
Yes, I would be very interested in that too.
Thank you
Dirk
66 230 SL
70 280 SEL
53 CHEVY 3100
18 C300 COUPE
05 HD FLSTNI

mdsalemi

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Re: Overheating and Remedy
« Reply #3 on: November 23, 2020, 16:48:20 »
Yes, please scan and post to tech manual.

Did anyone actually read it and notice that it says, "despite the presence of the supplementary electric fan"...

So, did we miss the prior "Advanced Service/Product Information (internal)" about this auxiliary fan?

I'm particularly interested in this first bulletin, as somebody sent me this bypass kit. I don't have overheating but having the instructions on how install would be helpful!
Michael Salemi
Davidson, North Carolina (Charlotte Area) USA
1969 280SL (USA-Spec)
Signal Red 568G w/Black Leather (Restored)
2023 Ford Maverick Lariat Hybrid "Area 51"
2022 Ford Escape Hybrid
2023 Ford Escape Hybrid

John Betsch - "SADIE"

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Re: Overheating and Remedy
« Reply #4 on: November 23, 2020, 16:55:55 »
I will try to clean up the xerox, scan and then if someone tells how or who to send to for inclusion in the TM, I can do that 

Of course, I have no idea if the bulletin suggestion is a good one or not.  Wouldn't want to have something in the TM that isn't viable.  As they say, once in print it's gospel

JB
JB; 1965 German market SL, Rot Met 571, Summary Code 213 Interior

mrfatboy

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Re: Overheating and Remedy
« Reply #5 on: November 23, 2020, 17:18:01 »
Just attach the the finished PDF here in this thread and I can place in TM.
1969 280sl (Aug 1968 build)
Signal Red
4 Speed

John Betsch - "SADIE"

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Re: Overheating and Remedy
« Reply #6 on: November 23, 2020, 18:33:58 »
attached as requested

jb
JB; 1965 German market SL, Rot Met 571, Summary Code 213 Interior

dirkbalter

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Re: Overheating and Remedy
« Reply #7 on: November 23, 2020, 18:49:58 »
Thank you. Appreciated.
Dirk
66 230 SL
70 280 SEL
53 CHEVY 3100
18 C300 COUPE
05 HD FLSTNI

GM

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Re: Overheating and Remedy
« Reply #8 on: November 23, 2020, 19:27:14 »
Thanks for sharing!
Gary
1971 280SL - Sold
(98 from the end of production)
DB180 Silver Gray Metallic
Black MB Tex

mrfatboy

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Re: Overheating and Remedy
« Reply #9 on: November 23, 2020, 20:02:49 »
The document has been added to the TM under the cooling section.  ;)
1969 280sl (Aug 1968 build)
Signal Red
4 Speed

doitwright

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Re: Overheating and Remedy
« Reply #10 on: November 24, 2020, 05:41:21 »


Did anyone actually read it and notice that it says, "despite the presence of the supplementary electric fan"...

So, did we miss the prior "Advanced Service/Product Information (internal)" about this auxiliary fan?



Late W108"s with AC had electric radiator fans.
Frank Koronkiewicz
Willowbrook, Illinois

1970 280SL Originally Light Ivory - Now Anthracite Gray Metallic

dirkbalter

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Re: Overheating and Remedy
« Reply #11 on: November 24, 2020, 17:11:04 »

Late W108"s with AC had electric radiator fans.

That is correct but it doesn't feel that it it very efficient. I can manually switch it on even if the AC is not running and I do not see the needle drop anywhere significantly.
« Last Edit: November 24, 2020, 17:15:46 by dirkbalter »
Dirk
66 230 SL
70 280 SEL
53 CHEVY 3100
18 C300 COUPE
05 HD FLSTNI

doitwright

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Re: Overheating and Remedy
« Reply #12 on: November 24, 2020, 22:32:15 »
That is correct but it doesn't feel that it it very efficient. I can manually switch it on even if the AC is not running and I do not see the needle drop anywhere significantly.

The heater core bypass has been discussed on these forums. Buds sells a kit modeled off the factory setup. One member did extensive testing including radiator recore, electric fan, water wetter, heater core bypass. If I recall, in his case, the most effective method of bringing down engine temp was the addition of an electric water pump.

The heater core bypass should be effective since it allows coolant normally supplied from the cylinder head to the heater core to circulate back to the water pump even when the cabin heat is not on. For cabin comfort purposes, when driving during warm weather seasons, the heater core valve is closed. This does not allow for continuous coolant circulation from the cylinder head. Add additional summer season factors such as higher ambient temperature and perhaps running a compressor from an AC system, the extra drag of the compressor and radiant heat off the AC condenser will increase engine operating temperatures.
« Last Edit: November 24, 2020, 22:56:00 by doitwright »
Frank Koronkiewicz
Willowbrook, Illinois

1970 280SL Originally Light Ivory - Now Anthracite Gray Metallic

mdsalemi

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Re: Overheating and Remedy
« Reply #13 on: November 24, 2020, 23:12:37 »
As I recall, Dan Caron (Dr. Benz) has always indicated that the ENGINE OIL carries a lot of the cooling load. I don't doubt him for one second.
Some, but not all of our cars have oil coolers, a mini-radiator on the side of the regular radiator.
Michael Salemi
Davidson, North Carolina (Charlotte Area) USA
1969 280SL (USA-Spec)
Signal Red 568G w/Black Leather (Restored)
2023 Ford Maverick Lariat Hybrid "Area 51"
2022 Ford Escape Hybrid
2023 Ford Escape Hybrid

John Betsch - "SADIE"

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Re: Overheating and Remedy
« Reply #14 on: November 24, 2020, 23:55:40 »
my apologies for stirring up such a discussion, promise not to do it again

jb
JB; 1965 German market SL, Rot Met 571, Summary Code 213 Interior

ja17

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Re: Overheating and Remedy
« Reply #15 on: November 25, 2020, 06:00:19 »
JB (Sadie), when you get such a discussion, it means your post was very engaging and a big success! Thank you, I now have some new factory "product information" to add to my library.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

WRe

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Re: Overheating and Remedy
« Reply #16 on: November 25, 2020, 09:21:41 »
Hi,
this document is very valuable because it shows that our cars have a construction-conditioned problem with overheating not only with an aircondition.
In my opinion the visco clutch/fan works not effective enough in critical situations because of low revs.
I never had problems with overheating except when it was really hot outside together with a traffic jam on the autobahn and stop-and-go same in the city or climbing on high Alpin passes.

I tried to optimize the original cooling system:
- flushing the cooling system with citric acid: there was a lot of deposit coming out of the system
- new visco clutch: more than one new clutch came already faulty
- new water pump and thermostat
- a fan shroud to optimize air flow
- a by-pass cooling water line
But nothing really helped. Maybe I should have rebuild the radiator too.

After that I've installed the electric fan instead the visco clutch I never had a critical situation with overheating. It's not a solution of striking simplicity but it helps.

I believe too that engine oil carries cooling load but I never had more than 80°C of oil temperature (temperature sensor in the oil pan instead of the drain plug).  Water gets hot very fast and corresponds with engine revs and driving situations. But "high" oil temperatures last some time and miles. In normal running situations my oil became only 60-70°C (with oil cooler). In my understanding this doesn't match together.
...WRe

dirkbalter

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Re: Overheating and Remedy
« Reply #17 on: November 25, 2020, 15:51:18 »
My experience is similar. I usually drive my 108 a couple of times to the office during the week. As long as I am moving, the temperature will stay at 175 F. On hot days 90 F+ and hitting stop and go traffic, I see the needle going up tp 190+. Turning the AC of and leaving the fan on, doesn't really seem to help a lot. If I put the car in neutral and rev the engine a little bit the needle will drop right away. I could see an electric water pump as suggested above helping.     
Dirk
66 230 SL
70 280 SEL
53 CHEVY 3100
18 C300 COUPE
05 HD FLSTNI

ja17

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Re: Overheating and Remedy
« Reply #18 on: November 25, 2020, 16:25:14 »
Upgrading the radiator seems to be the most significant improvement on cars that have overheating issues.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

mauro12

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Re: Overheating and Remedy
« Reply #19 on: November 25, 2020, 18:10:58 »
I think the 250sl model is the lowest risk car for overheating , compared to the 230 and 280. This is due to a bigger coolant capacity .
I’ve always wondered why the 250 was constructed with bigger radiator capacity compared to the 230 and 280.
By the way is very common issue the overheating for the 280sl.
What I do in my car is to use only mb blue coolant , 79degrees thermostat and new water pump and hoses .
Mauro Pisani
250sl 1967 5speed zf manual

dirkbalter

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Re: Overheating and Remedy
« Reply #20 on: November 25, 2020, 23:06:25 »
Upgrading the radiator seems to be the most significant improvement on cars that have overheating issues.

Joe, what exactly do you mean by upgrading the radiator?
Dirk
66 230 SL
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MikeSimon

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Re: Overheating and Remedy
« Reply #21 on: November 25, 2020, 23:14:59 »
As I recall, Dan Caron (Dr. Benz) has always indicated that the ENGINE OIL carries a lot of the cooling load. I don't doubt him for one second.
Some, but not all of our cars have oil coolers, a mini-radiator on the side of the regular radiator.

I am a little confused here. My car has a transmission oil cooler there for the automatic transmission. Are you saying there is an engine oil cooler on manual tranny cars?
1970/71 280SL Automatic
Sandy Beige
Parchment Leather
Power Steering
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Hardtop
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German specs
3rd owner

mrfatboy

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Re: Overheating and Remedy
« Reply #22 on: November 25, 2020, 23:34:47 »
I believe he is talking about the oil cooler on the left side of the radiator on 280sl’s. Both manual and auto.

See pic with blue arrow.
1969 280sl (Aug 1968 build)
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ja17

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Re: Overheating and Remedy
« Reply #23 on: November 27, 2020, 06:16:09 »
A lot of owners are upgrading the radiators by having them re-cored with a heavy "heavy duty" core which has an additional layer of cooling tubes. These have three layers of cooling tubes and fins instead of two, I believe?
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

dirkbalter

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Re: Overheating and Remedy
« Reply #24 on: November 27, 2020, 17:41:37 »
A lot of owners are upgrading the radiators by having them re-cored with a heavy "heavy duty" core which has an additional layer of cooling tubes. These have three layers of cooling tubes and fins instead of two, I believe?

Got it. Thank you
Dirk
66 230 SL
70 280 SEL
53 CHEVY 3100
18 C300 COUPE
05 HD FLSTNI

FGN59

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Re: Overheating and Remedy
« Reply #25 on: November 27, 2020, 17:48:11 »
Just to be a little bit contrarian, I (seem to) have the opposite issue: except in unusual circumstances (which would probably cause the overheating of a number of your cars, for those who have such a problem), the thermometer on my late 1968, 4-speed manual 280SL stays around 70ºC, sometimes reaching 80ºC after a good run if the car then idles for a bit, before returning to around 70º.

The engine has been completely overhauled after a high regime incident in which a piston and rod where damaged (block and head, including all parts thereof were checked and replaced if necessary, resurfacing, etc.), radiator recored, water pump and thermostat changed.

I have checked several times the temperature of the various accessible parts of the engine with an infrared gun (radiator in and out pipes, water pump in and out pipes, head and block in various locations (left and right side, top and bottom, at different cylinders), heater pipes, pipe to air intake box, etc.) during warmups and after runs, and always found it to be around 85-90ºC (depending on location and after warmup obviously), sometimes 95ºC at the entry to the water pump and near cylinder 6 after a good run. Should we conclude that the cooling system, when everything is in good working order, is almost flawless? No AC to interfere with the normal engine cooling in the engine bay. Where I live is never stifling hot (maybe 35ºC for a few days in late July at midday), very low humidity (continental Mediterranean climate, 500m altitude), and traffic jams are the subject of stories told to unruly children to make them behave or else... 

So, in a nutshell, nothing wrong (I think) except maybe for the display in the car. I nevertheless hate to think about this car being used in Poland, Germany, Canada...

Having said that, in case I wanted to fix the display, is the opinion of our distinguished experts on this forum that the problem (if there is a problem) is to be found in the gas/tube or in the gauge itself (I believe the two are inseparable?), is there a tweak (accessible to an amateur like me) on the gauge itself that is used to correct its reading?

Does anyone have a similar experience with the actual performance of the cooling system in their car?

For those who have yet more patience reading about this, I had a somewhat similar issue with my previous old timer, a 1962 JaguarMk2, after I had the original radiator replaced by a more efficient aluminum one, made by ... Mercedes, of all companies (or at least designed by them or for them). The engine would never get warm enough except in exceptional circumstances, which would probably cause other cars to overheat. In that case though, the gauge was displaying the correct temperature, which was really too low. I changed the thermostat twice, nothing would do. In the end I had to restrict the airflow through the radiator to make it less effective! The world on its head, as we say in French (Le monde à l’envers).

For those of you in the Northern hemisphere, keep warm (and safe), in spite of my stories. For all others, keep cool (and safe too)!
« Last Edit: November 27, 2020, 22:15:21 by FGN59 »
François

1994 Toyota Land Cruiser SW HDJ80 4.2L diesel
sold:
1969 280SL US specs, 4-speed manual, beige-grey (726H), parchment leather
1962 Jaguar MK2 3.8L (4.2L XJ6 engine), black, tan leather interior
1968 Peugeot 204 roadster, white, black interior
1955 Massey Ferguson TEF20 diesel tractor 😁

mauro12

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Re: Overheating and Remedy
« Reply #26 on: November 28, 2020, 10:43:21 »
Is it possible to find this document already in the technical manual ?
Mauro Pisani
250sl 1967 5speed zf manual

Benz Dr.

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Re: Overheating and Remedy
« Reply #27 on: November 29, 2020, 02:08:06 »
As I recall, Dan Caron (Dr. Benz) has always indicated that the ENGINE OIL carries a lot of the cooling load. I don't doubt him for one second.
Some, but not all of our cars have oil coolers, a mini-radiator on the side of the regular radiator.

I have said that which is why you should check your oil level in hot weather every time you go for a drive longer than an hour or more. I check my oil level almost every time I take my car out. A low oil level will defiantly increase cooling temp. 
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
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1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

wayne R

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Re: Overheating and Remedy
« Reply #28 on: December 10, 2020, 11:53:18 »
Hello all,sorry , have not been on forum for awhile,but when i seen this ,wanted to let owners know about
another wonderful coolant product, that has been used for years now,from owners of Buick Club Of America,
reason is on ,mainly 1936 to 1941,Buicks grill design on these particular models was fairly restricted,and because of
the long straight eight design  engine  ,with the narrower design radiator at front, could in really hot areas ,did cause
overheating alot.
So many use  a coolant  called ---Evans waterless engine coolant--,i have never used it ,but some of my best  friends in US
still use it today in there cars,and i dont have any association with the product, but i know it works.
I do know its expensive, but lasts life of the car, so best to go online and read about it ,better than me talking about it,
Just in case it helps owners here,. regards .

teahead

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