overheating or not? (1985 500SL)

[ianh]

Hi all. I have a 1985' 500SL, in the UK.
I had noticed that the temp gauge sat over the 80 mark (87 - 90?) in normal driving, periodically, going as far as 100 up a hill, or in traffic, but settling back down. Up and down as load dictated.
Thought - mmmm, is there a problem?
So, just had her sat at idle with heaters on (nice and warm) -
After 10 mins, gauge showed around 85 degrees with top radiator hose warm and lower one cold.
So, turned heating off -
gauge rose to 95 - 100 quite quickly, but then fell as i placed some load on the engine. I thought she would overheat, but she didn't.
Initially, top radiator hose warm, then hot,
lower hose cold, them warm, then hot.
temp gauge back to it's 87 - 90 state.
I was aware of how quickly the temp fell, so assume that that was the thermostat opening? Seems very late?
Can I assume all is ok?
Is this another case of replacement thermostats running nearer 100 degrees?
The radiator is a recent replacement from Mercedes. Is it feasible that, at idle, with heaters on, the engine does not get hot enough to circulate coolant to the radiator?
All and any advice welcome....

 

[television]

The Visco fan cuts in at 80C and your electric one (if fitted)at 100c as long a the temp does not go above 100C it should be OK

If Visco only do the carrot test at 80c and see if it chops it up

 

[jaymanek]

doesnt really explain it here, but in hot weather its normal for the guage to reach nearly 100...

sounds like you may have a lazy stat and or partially blocked rad?

 

[grober]

One problem with modern radiators altho efficient is that they have quite narrow coolant passages compared to the older designs. If there was a lot of crud floating in your cooling system when the radiator change was made it may have partially bocked the new rad. Did they change the thermostat when they changed the radiator. Its certainly worth doing this first as Jay suggests since its not too expensive. The other thing to check is for cooler sections in the radiator once its hot --these indicate poor coolant flow in the cool section. What you describe is classic poor engine cooling. Increase the engine load and the temp rises. This all depends on engine load versus speed. On a high speed top gear run with the engine fully warmed up where fans etc don't come into the equation with the airflow thro the radiator being the primary cooling, you will see the temperature begin to rise as the engine revs increase E.g it will sit happy at 65-70 but push it up to 80+ and the temperature begins to rise. Drop the speed back down and the temperature falls again. This effect is present in all engines to a minor extent but shouldn't really be evident in a well cooled engine.

 

[ianh]

thanks all.
Can anyone tell me the price of a thermostat from Mercedes?
Reckon I'll try that first.
The car hasn't driven a lot of miles in the last 2 years, so maybe it's become a little sticky.
My logic is that, instead of opening incrementally, it seems to get so hot, and then open all at once', so to speak....

Also, i tried changing the radiator cap, and got a part from GSF. The part no is different, and the cap says 140, whereas my old cap says 120. The new part fits, but could the different cap have an effect?

 

[grober]

thanks all.
Can anyone tell me the price of a thermostat from Mercedes?
Reckon I'll try that first.
The car hasn't driven a lot of miles in the last 2 years, so maybe it's become a little sticky.
My logic is that, instead of opening incrementally, it seems to get so hot, and then open all at once', so to speak....

Also, i tried changing the radiator cap, and got a part from GSF. The part no is different, and the cap says 140, whereas my old cap says 120. The new part fits, but could the different cap have an effect?

Possible but if the no on the cap refers to the opening pressure than 140 is going to be "tighter" than the 120 so shouldn't be a problem.

try this first to see which thermostat you need
http://www.detali.ru/cat/oem_mb2.as...&L=765.707&CT=M&cat=322&SID=20&SGR=015&SGN=01

part no A1162000315 is £14-27 +vat+postage from inchcape

 

[ianh]

thanks Grober.
My car is a pre 85 500SL.
that part number relates to 86 - 89 engines.

mailed a number of suppliers with my chassis number, so will, hopefully, have a result soon.....

 

[LastMinute]

You'll want either this page for a 117.960 engine, or this page for a 117.962 engine. Then enter the part number (with a leading 'A') into this page to get the price for a genuine part.

 

[Stephen T]

Cooling

Not sure if you ever sorted this out but it wasz while surfing the internet at work that I nioticed you post which required me to become a memeber to reply. Do you get commision.


What you describe has been normal behaviou for my 1983 500 SL since I aquired it 14 years ago, it stil does it and it has not caused any problems in over 200 000 Km which includes 2 journey to Athens and 1 to Rome form and numerous tours through France and Germany. I just accept it, there is always that moment each time I set off when I wonder is the temperature gauge going to fall back again but it alawys does.

When I lived in Germany I had a very good MB trained mechanic who looked after the car he said dont worry so I dont.

One other thing he tole me was never fill the auto gear box to the level indicated on the dipstick, only fill it to the bottom of the stick so it just covers the loop on the end. I have done over 150 000 Km since this advice and it is true that the chjanges are much smoother than others i know and economy is also better. I will post this elswhere.

Stephen T

500 SL
230 CLK

 

[television]

Hello Stephen and welcome to the forum with your info, and two nice cars

 

[Bazzle]

Not sure if you ever sorted this out but it wasz while surfing the internet at work that I nioticed you post which required me to become a memeber to reply. Do you get commision.


What you describe has been normal behaviou for my 1983 500 SL since I aquired it 14 years ago, it stil does it and it has not caused any problems in over 200 000 Km which includes 2 journey to Athens and 1 to Rome form and numerous tours through France and Germany. I just accept it, there is always that moment each time I set off when I wonder is the temperature gauge going to fall back again but it alawys does.

When I lived in Germany I had a very good MB trained mechanic who looked after the car he said dont worry so I dont.

One other thing he tole me was never fill the auto gear box to the level indicated on the dipstick, only fill it to the bottom of the stick so it just covers the loop on the end. I have done over 150 000 Km since this advice and it is true that the chjanges are much smoother than others i know and economy is also better. I will post this elswhere.

Stephen T

500 SL
230 CLK

That must be vehicle specific as MB had a bulletin here in Oz for the 722.6 box saying to ensure filled to the top line at op temp to keep changes smooth ...

Bazzle

 

[television]

That must be vehicle specific as MB had a bulletin here in Oz for the 722.6 box saying to ensure filled to the top line at op temp to keep changes smooth ...

Bazzle

This car uses the 722.305 box Bazzle