My 1982 380 SEL is overheating. The wierd thing is that it only overheats when I push the engine going up a long steep hill to my home. Othewise the temp gauge hovers just under the 100 degrees level.

So while driving around the city, the engine temp is fine. But when I go up the mountain to my home, the temp rises and the car over heats.

I changed the thermometer this weekend and it didn't make a difference. I don't lose any fluid unless it over heats. I checked the fan and it is running when the engine is at running temp.

Any suggestions?

Many thanks for your help....

did you change the thermoSTAT? if so what temp stat are you running? how big is the hill?

if you are running too high a stat, you may not have enough reserve cooling capacity available when encountering a hill.

hovering just under 100 seems too high for a normal op temp.

also your radiator may be marginal, either plugged internally or externally.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Thanks T:

I bought the thermostat directly from our MB dealer. So I really don't know what temp it runs at. Sorry for calling it a thermometer....work term....

The hill is about 3 KM and runs to an elevation of 1200 ft.

So your theory might be correct and the coolant might be too hot at the bottom of the hill. I guess the engine runs pretty hard getting the beast up the hill and the coolant boils.

The radiator was changed by MB a few years ago, so I assume it must be a good one.

So your suggestion is to change the thermostat to one that runs cooler? I've read about running without a thermostat, what do you think?

It was a VERY difficult project to change the thermostat as one hose on the housing was really difficult to work with.....

How would I find out what temp the thermostat runs at?

Many thanks T! and everyone else....

You definitely don't want to run the engine without a thermostat. The temperature should be stamped on the thermostat. Call your local MB dealer and verify that the thermostat you bought is the correct one for your engine. Assuming it's the correct thermostat, is it installed correctly and is your cooling system filled with a 50/50 coolant mix? You may need a new cap for the expansion tank.

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Fred Hoelzle

Hi Fred:

Thanks for your post.

I am looking at the MB box the thermostat came in, and it doesn't say what temp it runs at. I don't want to take the thermostat out if I don't have to. I've also looked at the old MB thermostat I took out and it doesn't have the temp on it.

I'm pretty sure I installed the new thermostat correctly. The car runs fine until I encounter THE HILL! I refilled the fluid with new 50/50 coolant.

Good point about the cap for the expansion tank. When the fluid boils, the cap appears to be fine, because the fluid leaks from the small valve on the side of the expansion tank.

Any other suggestions?

Thanks again Fred.

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Dr. Brad

2003 C320 4Matic Station Wagon
2002 C240 Elegance
1982 380 SEL Star Certified

100 is too high for normal running I think. Should be more like 85. Have you been using MB coolant? How often have you changed the coolant? Might want to try a bottle of Water Wetter. Although it is not designed to reduce normal operating temperatures, it may prevent the coolant from heating up as much as it does on the hills. Is your coolant level correct?

Len

My forgiveness...

Hats off to Hatty for recognizing that indeed it was the rad. Replaced as Hatty suggested....

Sorry...

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Dr. Brad

2003 C320 4Matic Station Wagon
2002 C240 Elegance
1982 380 SEL Star Certified

I'm just messing with you, I couldn't resist!

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

No need to forgive him...........I taught him everything that he knows..........

I was waiting for you to chime in.

I still beat you to it, post 17. You beat me like 500 other times, but I got you once!

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

You did.......and I'm proud of you.......