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Discussion Starter #1
Hi,
My 240d mercedes started to overheat, the temperature gauge started to go all the way up to 220, and then down to about 190, and then up, then down, until it stood up at 220, as soon as that happened I pull to the side of the road, however as I was pulling to the side of the road there was some strange loud sound, then I let the car cool for about 3 minutes and moved the card to avoid a parking ticket, I start the car, and the car starts fine, then I drove 2 blocks and park the car to let it completely cool.

The oil level was fine, and it was using synthetic oil.
The water/antifreeze level was a little low, but it could be seen from looking by the radiator cap opening that it had water.

What I did notice was that the top radiator hose was very hot, and the lower one was only warm when the car was overheating.

After the car cools I remove the thermostat since I believe that the overheating could either be a stuck thermostat or a clogged radiator, then when I try to start the engine the engine rotates a little and it stops.

I have the car jump started and again the engine barely rotates, and at times it does not rotate, I then fully charge the battery and the engine rotates a little very slowly, when trying to start the car I can see the interior light dim a lot.

When I stopped the engine it was running fine, but overheated, after it cools it does not rotate and therefore does not start, it rotates but very little.

I checked the oil and it does not have any water.

The battery and starter are almost new, they have less than a year in use.

What can be causing this problem? I find this to be a very strange problem since the engine was running when it was stopped.
Could it be that the engine siezed when engine was off but still very hot?

Any suggestions will be highly appreciated.
thanks
 

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Interesting. Sorry for your misfortune! The starter is the first thing that popped into my mind while reading through your text. I had a Saab 9000 that the key would stick sometimes causing the starter to stay engaged... I had lent the car to my mother, she drove it with the starter engaging for a 15 mile drive... I couldn't get that car started again, voltage was fine, but it just wouldn't fire up!

Turned out the starter itself was burnt up, so it would turn a very little bit, but not fast enough to actually fire the motor. Does your key stick at all?

The temp issue really may be the real cause, and it may be a dead motor from overheating. When you turn off the car, there's no more heat being generated, but there sure is heatsoak that happens for the next few mins as the coolant stops moving, too.

Dave
 

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'73 450SL, '83 300CD, '01 E320 4matic
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Could be a blown head gasket. That will cause fluctuations in running temperature, and also if the cylinders are filling up with antifreeze, then certainly the engine will be tough to turn. Remove the injectors and crank the engine- you'll know right away if it starts puking coolant from one of the injector openings. Also, if it's been sitting, pull the dipstick and look for the presence of coolant. If the oil level seems excessively high... that'll be a clue too.
 

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If you over heat it bad enough to cause internal damage and obviously more friction then it will be difficult to get spinning. :(
 

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Discussion Starter #5
Update, today I took out the glow plugs, and there was no water in the cylinders.

Tried turning the engine with 12" long wrench from the power steering pump nut, and it turns easily without much effort, but turning it by hand without the wrench is difficult.
I did not have a 27mm socket.

When I tried to turn the engine without the glow plugs using the starter it turns a little more, but still it turns very little, it appears that the starter got damaged from the overheating.

I will try getting a new starter and then check the compression of the engine to make sure that the head
gasket , and cylinders are fine.

Thanks everyone for the suggestions.
 

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After you replace your starter, let us know if it worked for you. This is a pretty curious situation. Thanks.
 

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Discussion Starter #7
update,
Yes it was the starter.
After the 240d overheated, the total damaged was a thermostat, water pump, and starter.
The reason the engine was rotating very slow was that the 2 small nuts that hold the starter together fell off, it is a very strange coincidence that they fell off when the engine had overheated, even though the 2 small nuts had fallen off the started was complete, one thing I noticed is that in addition to turning the engine very slow, the starter would generate some sparks.

And due to the overheat the seal at the water pump broke, and the water pump started leaking a lot.
However the engine it is running fine, I drove the 240d today and it is working great.
Things I need to do now, add a thermostat, do a radiator cleaning at a radiator shop since it may need it,, and probably I should change the oil after the overheat.
Also as a safety measurement add an additional transmission cooler, since on heavy traffic on very hot days it has a tendency to overheat.
I guess that the fact that I had synthetic oil may have helped.

The good news is that the engine appears to be running fine.

I have been thinking on getting the following transmission radiator, the long Tru-cool LPD4588 since it has 24 plates, and its size is 5 3/5x11x1 1/2 with a gwv rating of 19000 , since I believe it would make a good fit to the left side of the auxiliary fan, any bigger and it would not fit, also it is my understanding that stacked plate provides more cooling surface than a tube and fin radiator, planing on adding it in series with the current radiator.

Guys what is you opinion on the transmission cooler LPD4588 for the 240d? any better recommendations for a transmission cooler for a 240d?

I am assuming that it will help with the cooling of the engine.

Thanks everyone for all the recommendations on troubleshooting the problem, it helped a lot.

One thing I do not know is what causes the strange sound when I was driving it, maybe it was when the water pump seal broke, but not sure.

I am very happy to have my 240d working again, and that the engine survived the very high temperature.
 
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