Help, E300 Diesel W210 Starting Problems

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Mercedes cozy

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LONDON (Near Heathrow Airport)
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Mercedes ML 320 CDI W164 KEYLESS GO / (NOW WITH STAR)
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I'm having a hard time at the moment, my mates E300 Diesel W210 non turbo is giving problems in starting.

Eventually it will start after turning the engine over so many times, Air seems to getting into the fuel pipes.

When I get it to start there are large air bubbles traveling through clear pipes.

When I stop the engine the return pipe fills up with air.

All the pipes were changed a year a go. I just changed the thermostatic return valve. No difference.

I cant see any leaks and all o rings seem to be fine.


Please help
 
If the pipe before the pre-filter is filling with air suspect either the fuel heater or the flexi to metal pipe connections at the rear of the engine bay.

It could be that the tank strainer is clogged which will put the whole system under high vacuum, thius sucking in air.
 
thanks for the advice, I will check tomorrow.

There is a bolt that screws through the fuel filter, how many seals is that supposed to have?

I found a green one and a black one, is that right?
 
There is normally only one O ring high up. That isn't it though as the air is being drawn before the main filter.
 
I had exactly this problem with mine last year. MB Cheltenham and Gloucester changed all the clear pipes and securing clips, but it also needed a new pre filter and seal, as there was a leak there as well.
 
I'd do all the o rings including shut off at the same time; £10 ish from MB plus a year later you won't forget which you didn't do.
Related to Dieselman's post...one of my C250Td's has had the fuel thermostat bypassed (presume it leaked)...is this wise or should i reinstate it, especially with a veg mix?
My p*ss poor Haynes seems to omit the tank strainer, is it just a case of taking out the sender?
Andy
 
The strainer is underneath the car, inside the tank.

Reconnecting the fuel heater is a good idea but it only warms the fuel a bit to stop waxing. For Veg use a seperate heater and remove the fan. The filter heats up significanlty more and quicker without it.
 
I always wondered about those big heavy fans, the viscous unit works ok on mine but the fan rotates almost as fast at start up as when warm -

Can it be removed altogether without problems?
 
Yes. It won't overheat unless there is a problem with the cooling system or you are towing a large caravan across the sahara.
 
Update,

This car is begining to be a nightmare now.

I have changed the small fuel pump on the side of the injection, which seems to reduced the amount of air bubble in the pipes now.
Also changed the termostatic fuel valve.

As per the link below:

http://www.detali.ru/cat/oem_mb2.as...GM=717.446&CT=M&cat=19T&SID=07&SGR=120&SGN=04

Pipe number 32 seems to be the return pipe.
Does it draw the diesel back to the tank when you stop cranking?

Engine cranks over but does not fire up and the glow plugs seem to be fine.

Any Ideas?
 
32 is the feed pipe so is under lift pump suction. When you stop cranking the suction will suck any air back down this pipe. A single bubble isn't a problem, but continuous streams are.

Crack one of the injector high pressure unions free and see if it squirts when cranking, also actually measure the voltage to the glowplugs. If it's not there the engine will struggle to start.
 
i'd change the delivery valve seals - i had starting problems like yours and the delivery valve seals were the culpret. There is a how to on here
 
A year a go I had changed all pipes and rubbers.

I have opened the injector pipes and there is sqirts of diesal coming through the pipe to the injectors. But I will measure the voltage to the plugs. Also is it worth getting some easy start to try and start it.
 
It may start with easystart, but it's very bad for the engine. Just sort the problem.
If it's delivering fuel there should be smoke, is there any?
 
It may start with easystart, but it's very bad for the engine. Just sort the problem.
If it's delivering fuel there should be smoke, is there any?


At the moment, I can't get it to start, so I will check the voltage going to the glow plugs.

Engine cranks over and battery goes flat after a bit, So I have to keep charging the battery.

Since changing the pump, its helped get rid of the air in the pipes.
 
Is the pump properly timed and has the engine got compression.?
 
Is the pump properly timed and has the engine got compression.?


I managed to get it started about a week ago after the turned turned over quiet a bit. So I suspect it could be something to do with the glow plugs.

So the timing should be ok.

I put 12v directly to the glow plugs with the wiring off and you can see that it sparks so it means that its working.

The yellow light inside the car goes off in 5 seconds, so not sure if the plugs work.
 
Meter the plugs at the connector, then stick 12v straight into the connector, count to 5 then turn the key but leave the power connected.
The GP light coming on, then extinguishing indicates the plugs are all ok.

Can you perform a compression test.?
How did you time the pump.?
Starting after a while normally indicates an air leak, just check again.
 
Meter the plugs at the connector, then stick 12v straight into the connector, count to 5 then turn the key but leave the power connected.
The GP light coming on, then extinguishing indicates the plugs are all ok.

Can you perform a compression test.?
How did you time the pump.?
Starting after a while normally indicates an air leak, just check again.


I only changed the small pump on the side of the injection system.
I didnt change the whole pump,

I don't have any means of performing a compression test.

I will have another look for air leak? But I cant see any more air bubbles apart from the fuel going back in picture item 32.
 
I only changed the small pump on the side of the injection system.
I don't have any means of performing a compression test.

I will have another look for air leak? But I cant see any more air bubbles apart from the fuel going back in picture item 32.

You did say just the small (lift) pump, I forgot.:eek:

Look for bubbles going up from the lift pump towards the main filter and down fromteh filter to the IP body. If there are no bubbles make sure fuel is actually flowing, then discount air.

Beg or borrow a compression tester from a diesel specialist or an engine rebuilder.

Did this engine suddenly stop running or was it just getting harder and harder to start, with more smoke.?
 

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