A question for Alex and the other guys that have overhauled an ML270cdi engine (2003)

[wvr]

Thank you all for your replies; this is really a great forum!!! The car is at a bosh agent / bosh service centre now (this is the same centre who diagnosed the low compression when I took it in because of the hard starting problem, at that stage it didn’t have a idling problem, still not sure if they were right or not but they the only guys around with all the expensive common rail testing machines);
I’m hoping they find the problem. Ill ask if they checked the MAF and try find out all the extra info that you guys have requested (like rail pressure as she cuts etc.) and also let you know what they find.

About the air bubbles in the pipes – the pipe between the fuel filter and first pump is stained inside. Pipes between the pumps are clear, they all have a covering over but as far as I can see (if I move the covering away) there didn’t seem to be any bubbles, not sure how noticeable the bubbles would be? (should I remove all the covering to get a proper look?)

Thx again.

 

[wvr]

Have you had an injector leak off test done?.........i'm wondering if one of the injectors is faulty and causing a drop in rail pressure at low revs.

Also, possibly a faulty pressure sensor which is located at the end of the common rail.?

They did a leak off test at MB and said it was normal. The valve at the end of the rail was checked for o ring damage and they put a frequency tester (or something on it) which tested ok. I think they also tested the pressure valve but will make sure, thanks

 

[kebo57]

Hi regarding the washer I make it 38mm O/D, 15mm I/D, 5.0mm thick, not many washers like this on a car, looks like end of cam shaft something internal that's going against a ground finish nice shinny ring round the outer edge face but you not going to miss that sort of washer, could be a spacer, maybe I got this all wrong

Kevin

 

[wvr]

Good evening all, I went past the bosch agents today as they were closing. They put a piece of clear pipe just before the fuel filter and they say it is sucking bubbles from the tank (I’m sure this has been the problem all the time (like many of you mentioned) but they diagnosed the problem as low compression). At this stage, I’m not sure what to believe anymore, I can’t understand how these guys (bosch agents), MB dealers (who also put it down to low compression) and another two different qualified merc mechanics, one being a previous MB workshop foreman (each having the car for over a week, the ex foreman had it 6 weeks) couldn’t find this problem. They all checked so many different components. It might be that the clear pipe they put in line today was not a tight enough seal and was sucking air from there (Only thought about it afterwards and I wouldn’t put it past these guys)
I know a lot of you have asked if there is air in the system and I said no, I thought these guys all checked for that and I know all the seals around the pumps and filter have been replaced.
Just to make sure anyhow, would air in the system make it hard to start or will it make the car cut out when idling? Or both?

Anyway, I really hope this is the problem after all, i'm sure it will be one of the cheaper problems to fix.

 

[panason1c]

"would air in the system make it hard to start or will it make the car cut out when idling? Or both?

Hi, air in the system would cause both as above.

Hope you get sorted soon.


ps, i meant to ask.........how many miles has it done?, i'm surprised at the low compression diagnosis....

 

[wvr]

Hi regarding the washer I make it 38mm O/D, 15mm I/D, 5.0mm thick, not many washers like this on a car, looks like end of cam shaft something internal that's going against a ground finish nice shinny ring round the outer edge face but you not going to miss that sort of washer, could be a spacer, maybe I got this all wrong

Kevin

Thx.
Well, We have started the car and it runs and sounds good, we took it for a drive and it really goes well, until you put your foot on the brake and then she cuts out because of this persistent problem (we had to crank it at every stop) the guy who did my engine still is 99% sure the part landed up amongst mine by mistake. I really hope he is right!

Just can't wait for tomorrow to see if there is a leak in the line or not.

 

[wvr]

"would air in the system make it hard to start or will it make the car cut out when idling? Or both?

Hi, air in the system would cause both as above.

Hope you get sorted soon.


ps, i meant to ask.........how many miles has it done?, i'm surprised at the low compression diagnosis....

The car has done 180 000km (aprox. 110 000miles)
Not sure if the hard starting I had previously (no cutting out at that stage) was just the beginning of this leak in the line. Alex patient was also one of the good guys that recommended I get a second opinion about the compression, I decided to deal with the hard starting issue for the time being but after a month it started cutting out at idle, I then took it to MB, they eventually told me it had low compression (I did plant a seed in their heads though by telling them that this was the previous diagnoses), this was also difficult for me to understand cause when running, the car still did perform well.
The car was unusable at this stage so I had no choice but to have the engine opened. (I first bought a second hand engine but that was a facelift and it didn’t fit so I luckily got a refund).
Re-doing the engine ended up not being very expensive, everything measured within spec, in fact, there were no visible signs of any wear inside. I asked him to make sure the cylinders weren’t oval inside and he did check that. So he honed lightly and replaced rings and bearings. Also skimmed head and re-seated valves. I am a little concerned about the fact that this can be referred to as a patch job. Will it be good for a long time now or not?

 

[panason1c]

".....I am a little concerned about the fact that this can be referred to as a patch job. Will it be good for a long time now or not?"...............


If the rebuild has been carried out to a high standard i see no reason why your engine shouldnt have a long and reliable life.

 

[panason1c]

"I first bought a second hand engine but that was a facelift and it didn’t fit "


Your 2003 ML is a 'facelift' so i'm confused why the engine you bought didnt fit?...............i thought all the ML diesel engines pre and post facelift are the same anyway?

 

[wvr]

"I first bought a second hand engine but that was a facelift and it didn’t fit "


Your 2003 ML is a 'facelift' so i'm confused why the engine you bought didnt fit?...............i thought all the ML diesel engines pre and post facelift are the same anyway?

You are right, that’s how I ended up with the wrong one, mine has a 611..... motor, and a facelift has a 614.... (Or something like that) motor. The harness is different with no vacuum pump, the facelift motor has also just got one pump in front but mine has a small and bigger one just underneath. My car is a 2003 and looks like a facelift, the MB guy said some of the first facelifts did have pre-facelift motors in ?#%????
You can refer to the photo of my license disc on the first post of this thread; it displays my chassis and engine numbers on it.

 

[wvr]

".....I am a little concerned about the fact that this can be referred to as a patch job. Will it be good for a long time now or not?"...............


If the rebuild has been carried out to a high standard i see no reason why your engine shouldnt have a long and reliable life.

After reading about cam chains breaking because of tensioning pulleys and things not being fastened correctly it does make me a little nervous when you think of all the things which could go wrong.

BUt maybe I shouldn’t be so negative...

 

[panason1c]

"mine has a 611..... motor"

Now i'm confused, your engine code is '612' according to the picture of the disc you posted, and and far as i know, all the pre and post facelift ML 270CDI engines are code '612'...........

The vacuum pump, etc you mention are bolted on ancillaries and anyway, all diesels have a vacuum pump.

 

[wvr]

The turbo is also controlled with a servo along with some other differences on the manifolds, and the harness is completely different so you need its computer box too.

....the scrap yard was spinning me a story then. They said that I told them I had a facelift and the motor they had kept for me was a facelift (it was actually out of an E class but they said it is the same as the ML facelift motor). I was upset because I drove far to get it so I think they tried to bul@&it me into thinking the fault was with me.

 

[wvr]

I went to the Bosch Agent/garage today, they connected the inlet and return line to a separate tank (to take the bubbles out of the equation) to no avail(car still cutting out), so it looks like that was not the problem after all. It was probably sucking the air from where they connected the clear pipe like I hinted to them (because I’d never seen the bubbles before that).
This is really depressing!

I think they getting a little agitated cause I guess I’m interfering, so I’m not sure if I should just leave them to do there thing or if I should just get my car back?

 

[wvr]

Concerning the crank position sensor and the teeth that run along the circumference of the flywheel, can anybody tell me if there is supposed to be a small gap in these teeth (about 4 teeth width) which the crank position sensor reads off? It’s just something I noticed when the engine was out and the mechanic was sure it was normal.

The other question is; is there any electronics which shouldn’t get wet just underneath the centre console (the one between the seats). A bottle of cooldrink leaked out in there a few days before the cutting out started.

Nothing more I can think of, I’ll just have to wait and hope for the best…

 

[panason1c]

Concerning the crank position sensor and the teeth that run along the circumference of the flywheel, can anybody tell me if there is supposed to be a small gap in these teeth (about 4 teeth width) which the crank position sensor reads off? It’s just something I noticed when the engine was out and the mechanic was sure it was normal.

The other question is; is there any electronics which shouldn’t get wet just underneath the centre console (the one between the seats). A bottle of cooldrink leaked out in there a few days before the cutting out started.

Nothing more I can think of, I’ll just have to wait and hope for the best…

I am not sure on this but i think the teeth should be continuous, perhaps they might have been damaged when the new cps was installed?...........did the engine cut out BEFORE the cps was fitted?

It is known that liquids spilt onto the gear selector can make their way into the tcu (trans control unit) and cause problems


Looks like the reluctor ring that the cps picks its signal from is attached to the starter ring gear, the teeth look to be continuous in the diagram below.....item #65

http://www.detali.ru/cat/oem_mb2.as...GM=716.644&CT=M&cat=21T&SID=03&SGR=015&SGN=01

 

[panason1c]

Just one example of spilling a drink onto the centre console..........

http://forums.mercedesclub.org.uk/showthread.php?t=47496&highlight=spilt+drink

 

[television]

Also if anything wrong with the teeth, the starter motor could not crank it

 

[Number_Cruncher]

>>about 4 teeth width

I take it you're talking about sensor ring teeth rather than starter ring gear teeth. If so;

It's these "missing" teeth that turn what would just be a crankshaft speed sensor into a position sensor. When you watch the output from the sensor on a scope, you get lots of small amplitude waves from the teeth, and then one big pulse at the missing section.

This big pulse gives the ECU the info it needs to implement the time delays from that known crank angle to all the cylinders' injection events. [you'll find the missing teeth line up some fair distance before TDC]

As a contrary example, there aren't any missing teeth on ABS sensor rings, because the absolute angular postion of the wheel isn't important, only its angular velocity and angular acceleration.

 

[Alex Crow]

^what he said.