I bought the ml 270 cdi as a non runner.It looks like it had overheat as one of the pistons was shrunk.We got the piston,new main bearings and big ends and took the block and everthing to the engineers who put it together.The cylinder head was aslo checked and pressure tested.Now,when the car starts,it moves but has no power,when the temperature hits about 60 degrees the fan kicks in but as the temperature gets to about 90 degrees the engine cuts off and the water will be boiling.The top hose from where the thermostart is to the radiator will be very full and looks like it wil explode.The fan stays on at high speed until the engine cuts off.You try to start the car and it cranks only without starting.You leave the car long enough to cool down then it starts again and moves until it gets tyo 90 degress and cuts off engine again.I have checked for leaks and there is non,changed thermostat and temperature switch and replaced coolant twice.The expansion tank is new.Has anyone experienced this overheating as am now stuck and considering getting another engine.

 

Hello and welcome to the forum! I'm assuming that you checked all the electrical as well. Are there any codes that come up? It seems odd that you're experiencing an overheating issue with new components.

 

Yes,actually a lot of codes came up

P1636 Electric suction fan
-008 open circuit

P0100 B2/5 (Hot film MAF
-001 sensor) The signal voltage is too low

P1403 Exhaust gas
-008 recirculation open circuit

P1189 Inlet port shutoff
-008 open circuit

P0105 B28 (Pressure sensor
-001 the signal voltage is too low

P1482 N14/2(Glow output
-004 stage) Excess current

P0703 Brake signal
-128 Plausibility 2

P0115 Bll/4(Coolant
-002 temperature sensor) The signal voltage is too high.

P0190 B4/6(Rail pressure
-002 sensor) The signal voltage is too high.

I have changed the fuse at the positive terminal of battery as it was blown.

The coolant light stays on even though there is coolant in the expansion tank.

I have noticed that the fan kicks on as soon as the key turns on,that is at number 2 without even the engine running.


I think I need another engine.

 

Have you consulted with an independent MB shop or mechanic to get their thoughts?

 

Yes,they said I need new camshaft sensor and injectors.I dont know how they are related to overheating as I thought the camshaft sensor will be related to the engine cranking for long time.

 

That also seems a bit odd, as the camshaft deals with timing and fuel injection.

 

One thing I am noticing,every morning I am putting 2 or 3 litres of coolant but I dont see any leaks.Where could the coolant be going.Sometimes even during the day when I check,I find the coolant level very low and have to refill.I top the coolant and leave the car idling for about 10 mins without the expansion tank cap on.I used the water pump that came with the car so am not sure how to check if water pump is ok..

 

It seems that the coolant issue is one that is known with the MLs (from what I've heard) - most people have said that it had to do with the coolant sensor and that the fix was to replace the tank with an integrated sensor. Do some additional research on the issue before spending additional money on parts. I'm including an older thread where this is discussed, but I'm sure that you can find other references as well. Best of luck!

Coolant Level Light (2003 ML500) - Mercedes-Benz Forum

 

Thank you very much,this is helpful.Wil try it in the morning.

 

Could you possibly have a diagram that shows the flow of water in the car,that is the connection of all pipes from expansion tank to other parts of the car.