A year of running hot (Arrgh !)
 

I figured I'd throw this out at you guys because I don't know what next to try. My car has been running hot for over a year.

I've flushed the rad about 4 times, I've had a pinhole in the rad fixed, I've even (during the summer) hard wired my aux fan to run all the time, because it doesn't seem to come on when it's supposed to.

The only thing left that I haven't done, is replace a hose leading to my heater that should be an "S" hose and instead there is a straight hose on there that is slightly bent, but the coolant flows through fine. I was also thinking of replacing the thermostat, but it seems to be opening fine.

Is there anything I've overlooked ?

It's almost winter and I can't believe that the cold air hasn't helped.

Thanks,

AARON ROCHARD

1976 230 W115

you already went through everything else, you might as well replace the thermostat to eliminate that as the source of the problem. BTW if the cold air isn't helping then the radiator isn't cooling - maybe the thermostat is stuck or sticking!

Seeing that the model is a 1976 and the fact you have fixed a pinhole in the radiator the problem is likely to be the radiator itself. Only speaking from my own problem similar to yours, if you change the thermostat and it still is to warm to your liking that would be my guess. Not cheap but still better than warped heads and engine problems associated with excess long term temps.

Keith D

Sorry, I'm not too familiar with the clutch part of the fan. All I know is it works when grounded and the relay and tem sensor were replaced in the last 2 years. But I will replace the thermostat, hose and rad cap and see if this helps.

I just fixed my head gasket and I don't need it going again.

Aaron Rochard

1976 230 W115

running hot
 

3 things the water pump have you replaced this at all. They do wear out the vanes can cause cavitation and thus not move water they way it should this is especially common on no MB water pumps. The second is the fan not the auxilliary fan has a clutch on it to control its speed as itiis driven directly by the engine. If the clutch wears out it might not let the fan spin enough or to fast. thirdly you might want to get the radiator recored as this makes it like new and and will cool the water a great deal more efficiently.
hope this helps.
martin

running hot
 

3 things the water pump have you replaced this at all. They do wear out. The vanes can cause cavitation and thus, not move water they way it should this is especially common on non MB water pumps. The second is the fan, not the auxilliary fan, has a clutch on it to control its speed as iti is driven directly by the engine. If the clutch wears out it might not let the fan spin enough or too fast. Thirdly you might want to get the radiator recored as this makes it like new, and will cool the water a great deal more efficiently.
hope this helps.
martin

If I was a betting man (and I'm not), I'd put my money on a clogged radiator.

First, after driving the car to get it warm, shut it off and put your hand around the radiator. If it is clogged you should find cool spots.

Second thought, are you sure it is getting too hot? Maybe a strange question, but could it be a gauge error? Also, using the heater should show an almost immediate cooling effect on the temp since it is really an additional radiator of sorts.

I have to agree with Suginami. Bet you a dollar to a dime its time for a radiator. They don't last forever and on top of that the money you spend recoring that old one, your much better off with a new one. And when you look at the temp guage all you'll be able to do is smile.

Keith D

running hot
 

haasman is on the money--same thing happened to my 420.checked radiator,had cool spots. installed new radiator and problem solved.

over heat
 

A new radiator on your model MB is actually not easy to find and pretty expensive. I believe it is substatially cheaper to recore it. You have one of the old all metal radiators not newer the plastic and aluminium ones if I remember correctly. A good recore on these old ones is really almost as good as new. I have done it for an old 220D and 280SEL 4.5 with great success. Hope this helps.
Martin

Thanks all, I haven't yet tried all of the repairs that I've been planning, but I have had a new water pump installed about 3 years ago and the radiator was re-cored about 4 years ago.

However, there could very well be a gauge problem. On occasion, I've noticed the temp gauge bounce slightly up and down before settling on one temperature.

I've also had issues with the wires in that area, (choke, temperature sensor) as I've had to replace my water choke coil because it wasn't warming up fast enough on start up and running too rich. (I ordered a new one from England last year and it's been fine since)

Aaron Rochard

1976 230 W115

arochard, had the same problem in a 190D including bouncy temp gauge. The gauge bounces because of steam build-up in the cooling system. I believe you ARE running too hot. If it's overheating under load (highway speeds) and the faster you go the hotter it gets, then I would bet on a radiator. If you overheat while idling, try to rev it up. If temp goes down, it's a water pump. If it does not, it's a temp switch ( I replaced 2 in so many years, both in the spring). However, I tried the "cool spot" method on my old rad and did not feel any. After replacing the rad everything went back to normal. on a mechanic's advise I replaced the fan clutch only to be yelled at by the regular MB certified mech. He said in 25v years of working with the MB's he had to replace a total of 2 (TWO) fan clutches.
hope it helps

well, dogonit, I don't know how much credibility you have since you disagree with the moderator (these guys know EVERYTHING, right??? :rolleyes: )! Just a little sarcasm...:D
But, it all depends on when the car is overheating. Above 45 MPH you should not need ANY fan, with the airflow being sufficient for heat exchange (I believe no fan can spin fast enough to even match the air flow at that speed). So, if he is overheating at highway speeds, it cannot be a clutch, or anything related to the fans (well, maybe not only the fans...).

Just do the test and it will give us a little more info.

Good luck

Thanks Piotr, hope that it's not the rad because I just spent a wad fixing my rear brakes, the Ujoint and changing the head gasket. However, It's currently at the mechanic's getting the timing done, so I'll re-evaluate after that. I'll probably try replacing the sensor again before doing the rad (optimisitic)

Aaron Rochard

1976 230 W115