C250 turbo faulty?

[CHRIS STARKEY]

Hi all,
C250 turbo diesel 1996, 195000 miles.
Lots of oil found in the pipe going over the engine (air intake) and intercooler slightly clogged, also apparently the turbo is tight to spin.
Has anyone had problems with these turbo's? as I can't seem to find any mention of them going wrong.
Doesn't seem to have much power until warm & very noisy when first started (rattling) but no smoke from exhaust at any time.

Sorry to be a bit vague but it isn't me working on it at the moment!
Any help appreciated.
cheers
Chris

 

[Dieselman]

Noise could be mechanical but more likely bad injection causing knock, low power could be the same and tight turbo, oil could be breathing heavily causing oil to pass into the breather or turbo bearings, but that doesn't fit with tight turbo and no smoke.
I'd recommend an oil flush and change, injector clean, check the turbo for lateral play and clean out the breather.

If possible have a listen with an engine stethoscope to eliminate mechanical noise.

 

[CHRIS STARKEY]

Thanks Dieselman,
it's having an oil change tomorrow - hopefully that will stop some of the noise at start up.
The mechanic who is looking at it thinks the engine is 'tired' & says all the airpipes and intercooler are full of oil. This oil is leaking from the EGR valve onto the exhaust.
I don't know how he knows the turbo is 'tight' but he thinks it is kaput ! Is there anything that can be done to a tight turbo or does it need replacing?

Any more ideas or things for him to look for?

cheers
Chris

 

[Dieselman]

If it starts well without smoke then the rings are Ok. Make sure he gives it an extended flush before refilling.

If the turbo was work one would expect it to be loose, not tight, although the thrust bearing could have broken or become displaced..but unlikely.
Is the oil from the breather or turbo.?

 

[CHRIS STARKEY]

Do you think a flush is a good idea with nearly 200K on the clock?
Several people say don't in case it upsets the engine & dislodges any muck?

It looks like the oil is leaking down onto the turbo from the air pipes.

 

[Dieselman]

I personally do think it's a good idea and have never had a problem when flushing.
If the engine has been run on a diesel specific oil it will have had extra detergency anyway, if not that's why it's clogged up.

 

[CHRIS STARKEY]

Update:

just come back from having oil changed & its rattling more!!
Sounds like the cam chain tensioner - it was rattling before but stopped after a while -now seems to rattle all the time - except when it's revved.
Has anyone got any pics or details on the tensioner - I believe it works hydraulicly so sounds like some muck has got stuck in the supply.
cheers
Chris

 

[Dieselman]

Half way down the right hand side of the timing case. ITEM 89.

To fit a new one you must fit the outer part first then push the centre part into it, otherwise it will be too tight.

 

[CHRIS STARKEY]

Thanks DM - can these be serviced or just replaced (is the assembly above it in the picture -128 - 107 the insides of the tensioner?) and is there any way to check if it is working OK?
Is it a common fault for the tensioner to fail or are there any other usual problems ie. item no 53 (sliding rail) breaking.
cheers
Chris

 

[Dieselman]

Replacement only.
Rails don't normally break, but if you fancy the extra work, especially if you need a chain.
Check the chain 'stretch' by rotating the crank until the cams line up with the timing marks then see how advanced the crank is. If more than 5 deg do the lot.

 

[CHRIS STARKEY]

Half way down the right hand side of the timing case. ITEM 89.

To fit a new one you must fit the outer part first then push the centre part into it, otherwise it will be too tight.

Does the engine have to be set at TDC to change the tensioner & does it have to be primed before fitting?

 

[Dieselman]

It does need to be at TDC and the inner tensioner section should be pressed back into the housing so it is retreated. It will expand as it is used.

 

[CHRIS STARKEY]

It does need to be at TDC and the inner tensioner section should be pressed back into the housing so it is retreated. It will expand as it is used.

Thanks. I was just thinking I would whip it out & see if it was knackered - does the cam cover has to come off to make sure its at TDC?

 

[Dieselman]

Just use the crank marker.

 

[CHRIS STARKEY]

Update but help still needed

Just to update the story-
the rattling I could hear was the shock absorber from the fanbet !!!! The bushes in both ends had worn & were rattling causing an amazing amount of noise.
That has now been replaced thanks to franny

The oil leak was a loose oil feed pipe to the turbo causing oil to leak out. A new washer has stopped that.

The last problem left is a lack of power.
I have checked the turbo & its working fine, but the vacuum operated wastegate isn't working. The vacuum side is OK as if I suck the pipe it actuates the rod.
Is there anyway to check the electrically operated pressure converter?

I have found the temperature sensor in the intercooler pipe was full of oil & wonder if there is any way of testing that & does it work the pressure converter?

thanks in advance
Chris

 

[Dieselman]

Oil on the AIT isn't an issue. The lack of power is probably lack of fuel, which in turn is controlled as a result of the pedal sensor and MAP sensor. The more boost there is, the more fuel is introduced.

Suspect faulty MAP sensor.

 

[CHRIS STARKEY]

Oil on the AIT isn't an issue. The lack of power is probably lack of fuel, which in turn is controlled as a result of the pedal sensor and MAP sensor. The more boost there is, the more fuel is introduced.

Suspect faulty MAP sensor.

There is plenty of boost when the wastegate is actuated. I suspect that the wastegate actuator isn't getting a signal. (Do you know if the AIT affects the wastegate pressure converter?)
I don't know if it's the AIT or the pressure converter at fault (or both?) or like DM says it could be the MAF as well - but I can't get the wastegate to move. (should it move just when revving the engine?)
PS where is the MAP sensor?

cheers again
Chris

 

[Dieselman]

The AIT is just one of the inputs into the ECU. The boost modulator is controlled as an ECU output dependant on the inputs from all the sensors and will be released if the ECU is in Limp Home mode.

The 250 turbo doesn't have a MAF sensor and relies on the MAP sensor and accelerator position for fuel quantity.

 

[CHRIS STARKEY]

Thanks DM, where is the MAP sensor?
Is it where the vacuum pipe goes into the inlet manifold? If so how is it removed.

 

[Dieselman]

It's a 1" square sensor mounted on the N/s inner wing and has a small pressure pipe leading to the intake manifold.