1987 300TD running hot - PeachParts Mercedes-Benz Forum

HGV · #1 03-18-2002, 02:05 PM

I have a 1987 300TD with 200K miles. About 15K miles ago the car over heated, into the red, because of low fluid level in the radiator that was leaking. Replaced the radiator, thermostat, hoses, and serpentine belt. Car contiued to run hot, at about 100deg C. with the temp fluctuating with load. This all began to happen after it over heated the first time.. Car gradually got worse and began to make lifter noise. Decided to remove head and do a vlave job and replace all the lifters. Also replaced water pump and visco fan clucth. Car ran much better but still runs hot with fluctuating temp. Oil cooler was swapped with another car. No change. Finalyl decided to change oil thermostat this weakend as a last ditch effort to solve problem. No change. Where is the next place to look? Also I changed the temp sending unit early on. It almost seems that the termostat opening point is off,but I have changed it twice. I have gotten so fed up that I feel like selling the car, but it runs well outside of this temp problem. Also ambiant temp has minimal effect on engine temp. It was 42deg F this moring and car still ran hot.

md21722 · #2 03-18-2002, 11:58 PM

my 1987 300DT runs hot too. regardless of ambient temperature. i don't think it ever overheated, but the previous owner went thru TWO radiators one month apart, two years ago each time with a tow charge.

why do I mention this? My RADIATOR is already CLOGGED! The passenger side is "ice" cold and the drivers side is HOT. Somebody elsewhere said it was the DEXCOOL introduced by the previous owner after the fact that turns into brown sewage. That describes what I see in my upper radiator connection at the head.

I am saying this, check your radiator even though it was just replaced, to make sure there are no hot/cold spots.

Dont' know if that will help, but its the best I can suggest. good luck,

Brian

HGV · #3 03-19-2002, 12:07 AM

Thanks, I already swapped a new radiator in for 2 days to see if it made a differance. No change what so ever. I have the barely used radiator that will one day be offered on ebay. If you are interested I will let it go for 20% of what I payed for it. It is a Behr OEM radiator. Anyway thanks for trying to help.
henry

the_good_fellow · #4 03-19-2002, 01:04 AM

You may have some air trap in your system. try to refill it with its nose up. Or else release some pressure while it is hot. I don't think other members will recommend this method because it is very dangerous. Cover the filler cap with a towel, push it down and turn it CC a little and realse the pressure slowly. Do not turn it all the way as the coolant will come out. hope this will help.

md21722 · #5 03-19-2002, 01:20 AM

HGV,

Please send me email md21722@yahoo.com about that radiator! I need a new one this week... I am hoping this cures my temperature problem. There are SEVERAL temp. sending units in the car. One for the guage, one for the ECM, one for the aux. fan, etc. What do you mean by FLUCUTATING? If it moves around constantly then there is probably something with the wiring flaking out or a LOOSE sensor. I have read of this happening to others.

Regards,
Brian

#6 03-19-2002, 07:49 AM

It sounds like you have got an air lock. You need to flush the system out totally. When you are doing this make sure the heater controls are set to hot...so the flush water goes through the heater matrix as well.

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