Hallo,
I own a Mercedes C220 from 93. No engine modifications. Just had a service with change of air inlet filter and spark plugs
(150' Km service)

The problem is as follows :

When the engine is hot (over 80 degrees Celsius, it seems) it will not start by using the starter motor. However if i roll it down a hill, it will start fairly easy (sometimes it takes 5 revs or so). The normal runnig temp for the engine is about 85-90 Degrees Celsius.

The start motor runs the engine sufficient fast to start it when cold (starts actually very easy, maybe after 1 or 2 revs) and dosn't seem slow, compared to other cars.

If I let the the engine cool down a little (about 20 mins), it starts immediately by using the start motor.

I would appreciate help from anyone who has an idea what causes the problem !

Thanks in advance !

pfgjerpe,

Do you mean the starter will not turn the engine over at all when the engine is hot, or do you mean you can crank it with the starter and the car will not start and run?

If it is the first case, the starter acts like it is dead when the car is hot, you may have a worn out starter. Seems a little odd for your car, but it is more common on Diesels as they can frequently be abused, cranking too long and getting the stator windings (electrical coils in the stator) hot enough to damage the insulation on the wires. This damage is more apparent at higher temperatures and so when the engine says it is 80 degrees C, the area near the starter (on a Diesel it is near the exhaust manifold/pipe) can be much hotter. Since starters are used very intermittently, for short periods of time, they cannot be operated at their rated capacity continuously or they will overheat. If they were sized to run continuously they would be huge and heavy, so the solution exercised by automakers is practical and usually gives good starter life.

So, it sounds like you may need a new or remanufactured starter. Be sure you get one rebuilt by Bosch, not a local guy unless you are sure he will test the winding resistance with the stator hot. It is typical for Bosch to rewind Diesel starters when they are remanufactured. Good luck, and I hope this helps, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

Thank you very much for your answer Jim.

I am sorry that I did not express myself clear enough.
The starter motor runs fine, regardless if the engine is hot or not.

What I tried to explain was that when the engine is hot it will not start by using the starter motor (even though it cranks fine), but the strange thing is that it it starts (after about (5-6 revs) when I push-start it downhill. The latter situation may cause the engine to be run faster then the start motor manages, but I dont think that is the reason.

Any idea as to what can cause this problem ?
Electronic or mechanic ?
Any idea what to try to narrow down the problem ?

I would be grateful for any answer !

Hi check your fuel preuusre reg just put off vacuum hose at reg see if you can see or smell gas at reg vacuum fitting if yes replace the reg next thing to check is you over load relay. hope this help

__________________
MB STARS Master Guild Technician,17 years MB tech
14 years independent shop owner

Yes, I'd say OVP.

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

Thank you very much for your answer.

I will try the things that you mentioned in your mail, as soon as I can find the fuel pressure regulator.

Thanks again !

Paul

Just thought that I should post the solution in case other people should encounter the problem :

After a while the engine refused to start by starter motor even when cold, however it still started easily when pushed downhill (hot or cold)
The solution was that overload voltage releay was busted. Even though this releay has a fuse. In addition they changed the fuel filter. Now the motor starts every time very easy.

Regards to everyone who helped me

Paul

I want to check this also but do not know where it is located. I have a 1993 190E 2.6 with similar problem. Before I go out to replace my OVP which is still stock, I want to check this also.

Thanks!