240d got hot
 

i just bought my first 240d day before yesterday. It is sweet! looks and rides beautiful! However, on the 250 mile trip home, the water pump/alternator belt broke and it got up to 120 or a little over. I shut her down before overheating and fixed it. It ran fine with temps where they should be the rest of the way home. Today my wife drove it on a 30 mile trip to work with no problems there and back. But, right before getting home, encountered some traffic and sat idleing for 10 min or so with the a/c on in 95 degree heat in Houston. It got to 120 again and got shut down before overheating and after cooling off drove the 3 miles home without a problem.

Is this normal for these? Or could the thermostat got locked when it got hot the first time? It has only 5k on a brand new water pump and radiator i was told from guy I bought it from.

I have a 240D, manual, with a new engine and live in Houston, when I replaced the engine I did not re-install the AC. This car is not designed and can not cope with the AC load in Houston traffic & heat, pure and simple. I drive a 210 E320 when I need AC, the 240D is my commuter car and I am used to driving without AC. I know, this sounds insane, but if you want cold air you bought the wrong car.

Vahe
240D 77 / 350K

A 240D in proper condition will handle Houston traffic on a 105 degree day and idle all day long while you have the windows rolled up and a sweater on. There is just something wrong with this particular car. I used to have an office in Houston and an office in Dallas and spent lots of time in Houston summer traffic in my 240D with no trouble whatsoever.

The thermostats are designed to fail open, so that is probably not your problem. There are several things that could indeed be your problem. These cars are not young any more. You could have a plugged up radiator, a hose sucking shut, an aftermarket water pump with improper impeller, a slipping belt, a bent up condensor covered with bugs preventing good air flow, a non operative aux fan, etc.

If the car is otherwise a nice car, I would start by going to a radiator shop and having them pressure test the cooling system.

Good luck,

Did you top the water off?
Not sure about the 240D, but my 300SD took a few times of topping off the bottel to get it all happy dandy.

There are air bubbles in the head that take time to get out.
Hows the fan doing?

If I remember correctly,,,
 

The 240D has a bolt on top of the thermostat that needs to be removed to bleed off any air in the cooling system. Well atleast my '76 had one, I think. (It's been tooo many years ago to remember something like that for me.

www.benzbonz.biz

Marty

thanks for all the quick replies! When my wife gets home with the car and it is not dark outside I will begin looking into the fan, coolant level, and possible slipping belt. I found somewhere that there is a bleeder screw above the water pump to let out possible air in the system? This was a qoute from someone with an 80 240d.

"If this is your problem, there's a bleeder screw, almost directly
above the water pump (as I recall) which will allow you to bleed the air out.
Loosen it a turn or two, until coolant seeps out and tighten it down again."

When should the fan cycle on? around 80 degrees C?

i dont think
 

mbs have a bleed. my old bmw did though.

i think you should check function on the aux fan. it should come on with the ac. and perhaps with high temp in coolant.

tom w

The aux fan does not run all the time that the ac is running. It only comes on when the high side pressure is high. It's purpose is to bring down high side pressure to prevent overpressure damage.

Good luck,

well my wife finally got home and after letting it coold down a bit I checked the first simple thing, the coolant level. It took about 1/2 gallon to get it up to par and let it idle for a good 25 min with heater on half that time. The belt was not slipping, the aux fan came on with a/c anyways. Not sure if the thermostat ever opened or not. Never got above 85 centegrade. It is though 8pm here now though and not near as hot as the middle of the day.

1/2 gallon is enough to leave a large pocket of air...

Keep checking that coolant for several days. Only pull the cap when the engine is dead cold.

Good luck,

along with topping off the radiator, keep the coolant reserve full. The natural expansion and contraction will tend to purge the air and suck coolant in out of that reservoir, so when you are at work or in the store and the engine cools a bit, the radiator will be helping you top it off.

I've never seen a 240D with an expansion tank. The only ones I can remember seeing only have an overflow hose neatly mounted along the fan shroud to drain on the ground.

Have a great day,

On my 300SD there is an expansion tank..
There is also a line on the tank...a max full line?

I only ask becuase I am having overheating problems...

There is not an expansion tank on mine that I am aware of anyhow. Looked everywhere thinking it had one since every other car I have owned did. Thanks for the help, going to check the level again this evening when it and the wife arrive home.

I had tried a few other boards before this one and never got a reply. Ya'll replied quickly and with many possible scenerios. Thanks again. We are enjoying the car immensely. This thing seems just as solid if not more than a 3/4 or 1 ton truck and rides much nicer!