ML 270 2001 - Loss Of Power & Black Soot In Engine

[Intertav]

I have spent the last 3 hours going through posts on similar problems and I have to say I am none the wiser. My ML experienced loss of power today and whilst I continued down the motorway, I could hear a loud hissing noise coming from what I thought was under tha car. I assumed it was one of the cats however on opening the bonnet saw the engine compartment was covered in black soot around where the turbo is located. I am changing the back silencer as the first cat was done 2 months ago...
Any ideas what order I should start my diagnosis or who I could take the car to in the south east that is reliable?
Thanks much

 

[nuppy]

i assume no intake pipes have blown off?

 

[230K]

Hi

Identify the source of the soot (is it soot or just oily gunge?)and this will be your problem possibly a pipe blown off from pressure side of the turbo.

230K

 

[television]

You cant do any harm, just lousy to drive

 

[dieselman]

Sounds like the second Cat is blocked.

 

[Xtractorfan]

The loss of power and hissing would certainly point to a turbo intercooler pipe coming adrift or more likely splitting or bursting you can get someone to start the engine rev it and check from where the hissing noise is coming. and u should remember loose clothing, ties, hoodie strings etc near a running engine are a recipe for disaster..this is just incase u aint a techie..if u are... severe blushes

 

[Ellsy Tanners]

Thats right the second cat will be blocked and the pressure build up will be causing it to escape from the joints by the turbo.

you can remove the second cat and drive the car, should be problem solved then you know its the cat blocked.

 

[Intertav]

Thanks so much for the advice, I will check the second cat tomorrow. How many cats does this car have? When you say the second cat - does this mean the large box towards the tailpipe? or is there another between the first cat and the silencer. Is there a diagram of the exhaust system somewhere I can see?
Thanks again - this is my first posting anf all of you are very helpful. I am no techie by the way......
Can I do damage to the turbo if I drive it like this? albeit from home to the garage - 10 miles

 

[Intertav]

just need some clarification on cats if thats ok, are there two cats on this car and where are they situated? The cat in the middle of the car was changed 2 months ago so it cannot be that one. Is it lekely to be the rear silencer that is blocked? how can I diagnose if it is the cat and which one it may be? As you know these parts are not cheap so would like to get it right before I place an order for a part I do not need
Thanks much

 

[panason1c]

The primary cat is underneath the airbox where it connects to the turbo flange...


Cats on diesels are not compulsory for the mot test....you might want to consider 'de-gutting' the cat?!!!!

 

[Intertav]

As the secondary cat was replaced 2 months ago does this mean the primary cat is the likely culprit? Can I disconnect the primary cat so ascertain if it is this?
What do you mean by degutting? cutting open and removing the insides?
Can I not simply replace this part?
Should I rule out the silencer as being blocked?

any advice on how I can determine which cat is blocked would be greatly appreciated

Thanks

 

[panason1c]

As the secondary cat was replaced 2 months ago does this mean the primary cat is the likely culprit? Can I disconnect the primary cat so ascertain if it is this?
What do you mean by degutting? cutting open and removing the insides?
Can I not simply replace this part?
Should I rule out the silencer as being blocked?

any advice on how I can determine which cat is blocked would be greatly appreciated

Thanks

Its more likely that the primary cat would become clogged before the secondary cat.
Yes, you can release the clamp that seals the cat/downpipe to the turbo flange and then test drive to see if full power is restored.

You can replace the cat if you dont mind paying ££££ but if the cat(s) on my ML ever fails in any way i will open it up and remove the innards, a much cheaper 'repair'.

 

[230K]

Hi

Yes you have 2 cats, one right beside the turbo and one underneath the car well before the silencer.


Hope this helps

230K

 

[Intertav]

OK, so I have removed the primary cat and degutted it. Also changed air filter and fuel filter. Am about to change glow plugs however I still have a loud hissing noise from within the engine compartment when accelerating. Car does not seem to go into limp mode but I have not tried it for extended periods on the motorway. How can I find this hissing noise? Is it likely to be a loose pipe? This is driving me crazy.....
could it be a blocked silencer?
Pics would help on where to look for the noise?
Thanks all once again - you have been most helpful for me to get to this stage as I am not a mechanic but am not frightened to give anything a go

 

[panason1c]

Can you look under the bonnet whilst someone floors the throttle from idle ......you should see a puff of smoke from wherever the gasses are escaping.

 

[Intertav]

have tried this and I cannot seem to see any smoke, seems a bit black around the trubo outlet though. I will need to strip it down again and check all pipes....aaaarrghh. This car has doen 139,000 miles so cannot complain really.

 

[230K]

Intertav

139000 miles is nothing to a 270cdi.

230K

 

[panason1c]

have tried this and I cannot seem to see any smoke, seems a bit black around the trubo outlet though. I will need to strip it down again and check all pipes....aaaarrghh. This car has doen 139,000 miles so cannot complain really.

Check that all the turbo pipes connections are secure from the turbo through to the inlet manifold, particularly check the inlet and outlet pipes to the intercooler are secure, also, check that the intercooler (the upper smaller radiator in front of the main radiator) is not 'holed' anywhere (look for any damp 'oily' patches).

 

[Intertav]

Hi Thanks for the tips, looked at the inlet pipe - the one with a junction to the top of the head. The junction seemed very oily - thick black oil - cleaned and there does not seem to be any breaks in the pipe. The junction does seem quite loose - is this meant to be the case?
Will check pipes to intercooler too, is the intercooler the very small radiator below the main radiator?
What pipes do I need to check? Do you have any pics?
Thanks much

 

[panason1c]

The very small rad' that you described is the gearbox oil cooler, the intercooler is the larger rad' higher up above the oil cooler. The intercooler has two large pipes connected to it, check that they are tight and not allowing pressurised air to escape........follow these pipes to their respective destinations checking all connections along the way.

If you dont have any success you will need someone to look at the problem.