OM642 engine smoke.

[Tuningdrew]

Hi all, recently privately bought a 55 plate ML320. Bodywork and interior good, initial test drive threw up no issues and the car drove really nicely. Service history was there, a little sketchy but the previous owner had the car 8 years and had used a local MB ‘specialist’ for servicing. However, on the drive home after about 5 miles on the motorway I noticed blue/grey smoke pulling away or accelerating. Also noted the timing chain rattled on a cold start up next morning . The ‘minor oil leak’ on the fresh MOT should have read ‘excessive’ they also didn’t comment on the nearly illegal front tyres so you can see the pattern emerging and me a 30 years served mechanic and MOT tester feeling slightly annoyed with myself.
Cutting to the chase I carried out a service and found the air filters 6 years old and completely choked, 5 of the 6 glow plugs were u/s, the PCV breather diaphragm in two pieces, oil filter 3 years old, fuel filter 6years old and the turbo shaft has a significant amount of play. Obviously neglected. My feeling was that the choked filters and split oil separator was probably causing an excessive amount of old oil to be drawn into the inlet system coupled with possibly an oil leak round the turbo bearings filling the cat with oil. A good long engine flush and fresh oil has eliminated the noisy chain up on cold start but after a few miles I’m still getting the smoke once the engine is hot. Let it cool down for an hour or so then no smoke until it’s done a few miles.
I’m going to replace the turbo core, fit new seals to the oil cooler and timing chain cover, replace the injector seal, auxiliary belt then flush and change the engine oil again. Wash out the intercooler and inlet manifolds then run a cleaning foam through the cat.
Just need some feeling on how mechanically strong these engines are, whether they will tolerate some neglect or are they like the latest generation Peugeot engines used by JLR, Ford BMW etc which fall apart if they miss an oil change or two?
End of the day I’m debating whether to pull the engine and refresh it or cut my losses (not too much as the car was not expensive) and find a good secondhand engine.
Your thoughts would be most welcome.

 

[kid-jensen]

This engine is pretty robust, and capable of high mileages, but there are limits.
It could be that fixing the PCV diaphram will fix all your oil burning problems, but it's best to assume it won't be that simple. Certainly the first thing to fix before you go any further. About £90 IIRC..

Once that is eliminated, it's time to established if the oil is going past the rings or the valve seals. The cost of fixing the rings might well write the car off, but the valve seal replacement should fall into the "reasonable" price-point.

You could always vent the PCV it if it turns out that's where the oil is coming from. The Jeep forum (mainly USA) has loads of examples of using a catch-can for the breather, so it's obviously considered worth doing to keep the oil consumption down. Not to mention reduce the corrosive gasses being fed into the inlet.

 

[Tuningdrew]

Forgot to say I changed the breather during the service for the latest type.

 

[Tuningdrew]

Oil leaking past the stem seals would show up as a blue cloud on start up, my car starts smoking once I’ve done a few miles. Now I’ve fixed the glow plug issue it starts cleanly with no chain rattles and all you get is a little white steam from the exhausts which dissipates within a few inches of the tailpipes.

 

[Becosemsaida]

Well i might be of some help since i had a lot of problems with mine. Same problem, grey/blue smoke when hot, worse on "standing" acceleration..... Problem was that the PCV diaphram was leaking and the turbo sucked all the oil out of the engine.... This was about 1L/1000KM, too much. Changed it and checked the dpf and cat: FULLY clogged and beyond regeneration. So for now and until the new DPF/cat arrives i'm driving without. No more smoke or the sense of a "choked" engine. As soon as i confirm that the oil level isn't lowering, its in "test" mode, i will drive it with care. Check your dpf/cat its about an hour work....

 

[Tuningdrew]

Well i might be of some help since i had a lot of problems with mine. Same problem, grey/blue smoke when hot, worse on "standing" acceleration..... Problem was that the PCV diaphram was leaking and the turbo sucked all the oil out of the engine.... This was about 1L/1000KM, too much. Changed it and checked the dpf and cat: FULLY clogged and beyond regeneration. So for now and until the new DPF/cat arrives i'm driving without. No more smoke or the sense of a "choked" engine. As soon as i confirm that the oil level isn't lowering, its in "test" mode, i will drive it with care. Check your dpf/cat its about an hour work....

Certainly the original (2005) PCV valve had failed. The diaphragm was very stiff and had split all round the outside. It’s been replaced but until I’ve done the other jobs, turbo core, timing chain, crank oil seals and oil cooler I won’t be driving it much. I’m going to haul the engine out to do these jobs as I have a leaking injector to deal with as well. I’ll take the opportunity to flush out the transmission and intercooler while it is all off.
Thanks for your response, appreciated.

 

[Becosemsaida]

Well my problems are not sorted, still using too much oil and getting worse. Mechanic says it may be two things: Turbo or piston rings..... If its the Turbo i will replace it with a new one if it's the piston rings i will have to chase other options. It seems that there is no repair kit for these engines and all the parts need to be bougt on its own. Looking at a very pricy repair......... Decisions, decisions..

 

[Tuningdrew]

Thanks for your update. Due to pressure if work (and too many holidays) I’ve not touched the Merc other than to run it to keep everything loose and the battery charged. Certainly my turbo bearings are shot so hoping that’s it. Be grateful for any updates but I’m going to pull the engine week after next to deal with the issues I know about.

 

[Becosemsaida]

Well after taking out the DPF and the cat we did another test (maybe not fancy but it gives me some hope) we disconnected the new diaphragm and put the hose in a plastic bottle, similar to a catch can. After 1500km no significant oil in it, just some moisture but the oil level was lowered. Next step: new turbo.... This one is gonna hurt since where i live there are no original turbos available so i had to wait. Send the turbo to a tech to see if its salvable. Answer was: the exhaust part had been heated up so much that the bearing on that side was damaged as was the shaft and the impellers..... Reason: Did you drive with a clogged dpf. ??. I could repair it but i was advised to put a new one in, so bad was it!! No, the new turbo comes from another place so there are NO interests envolved. So new turbo on its way and lets hope that the engine itself survived all the trauma and that everything else handled the excess pressures that were build up during this stupid DPF crysis.

Hope that this will sort my problem, i really like this car alot and from a poor mans way of seeing it is better then a RR

Still pondering if i should install the new DPF and cat...... I know, I know it might be slightly "bending" the laws a bit....

Beco

 

[Tuningdrew]

Thanks for the update. Still not had time to pull the engine yet but your findings fill me with hope!

 

[Becosemsaida]

Well got my baby back today, new turbo fitted and no programming needed (seems that the electronics come "blank" and the car assumes old version) just checked for errors.

So my exhaust is full with soot so it will take some kms to clean it out BUT on preliminary testing only some black smoke on kickdown... Now next week i have some trips planned so i will be able to see if the problem is solved..... 1L/1000km is about 1/3 of the dipstick.

Will report back with something good or bad.

Beco

 

[Tuningdrew]

Well got my baby back today, new turbo fitted and no programming needed (seems that the electronics come "blank" and the car assumes old version) just checked for errors.

So my exhaust is full with soot so it will take some kms to clean it out BUT on preliminary testing only some black smoke on kickdown... Now next week i have some trips planned so i will be able to see if the problem is solved..... 1L/1000km is about 1/3 of the dipstick.

Will report back with something good or bad.

Beco

Any news Beco?

 

[Tuningdrew]

Sorry it’s been so long but everything else just gets in the way. Anyhow finally got round to stripping the front out of the car, very straightforward other than rusted fasteners but got the whole front off the car in about two hours. Instantly revealed the cause of the oil leak, the car had recently had a water pump replaced. As said before this vehicle has been “maintained” by a MB “specialist” in Bexleyheath and they had not replaced the rubber seal in the top of the sump that the dipstick goes through properly, nett result was oil sloshing out of the hole all over the front of the engine. They’d also never replaced the breather which was in several pieces allowing oil into the turbo and manifolds and all over the flap motor into the vee. I’ve got the leaking injector out,#3, and the offside cam cover off ready to change the chain and guides. I had to make up a tool to get the crankpulley/damper off ( if anyone needs to borrow it they are welcome) and next job is taking the chain cover off the front of the block. Unfortunately this means removing the sump, a messy job scheduled for tomorrow. Meantime I’ve got all the carbon out of the manifolds using Cif oven cleaner, the turbo has been refurbished by Midland Turbos and the oil cooler will have its new seals on tomorrow too. Other horrors we’ve found due to the care and attention of the specialist is an auxiliary belt so stretched it was rubbing on top of the sump, (why didn’t they change it when they did the water pump, they had to remove it anyway??)the guide rollers are shot, the air filters were choked solid and the oil and fuel filters were several years old. Not impressed.To be fair it may have been penny pinching by the previous owners but if I’d been doing the job there’s no way I’d have given it back in such a state.
Next up is to purchase the chain installation kit, I got a Febi chain kit and Reinz inlet manifold gaskets from AutoDoc. Need to order oil seal for the timing cover plus injector stretch bolts and clamps (they crack apparently) and figure out where to fit the engine breather oil separator tank I’ve recently bought. It condenses out the oil and sends it back to the sump, should keep the manifolds clean as I’m doing an egr delete at the same time as a remap.
Update with pics to follow.

 

[kid-jensen]

A lot of "interesting" jobs you have in front of you...

I'd particularly interested like to hear how the Oil separator turns out, I reckon the OM642 works the oil harder than most, and anything that can be done to reduce internal, pollution is well worth it. I've not seen many oil catch-can installations where the engine cover still fits....if you manage that, you'll be ahead of the game.

 

[rossy]

I've fitted a catch can and engine cover still fits.....may just be about to fit turbo due to similar issues....mine only smoke on long idle....over 15 mins. Just orcered another catch can..one with the little filter on too so as to iliminate over crack case pressure.....

 

[kid-jensen]

Keep us informed!

 

[rossy]

I will, taking Turbo off....then taking to local Refurb place...he'll give it a once over before I splash out the dosh...kinda hoping it is. As there is play in the shaft and if not it means its stem seals or rings maybe......unless I find somthing else when I go to remove the turbo...
On the 2nd catch can....DONT USE A BREATHER....I said I bought one with a filter and I have but will not be using it as the PCV valve closes once the turbo spools up on vacume....it may not with a filter on top.
Main reason I bought another is the 1st one does not have any baffles in it!!!

 

[rossy]

Please look at my other post.....:-
Please what is this and whats it for/do etc....or as I suspect not doing...

 

[Tuningdrew]

Hi All. Bit of an update. Absolutely positive now my oil burning was simply down to the split breather. By the time I’d got the offside cam cover off , the manifolds, the sump and timing cover I decided that I would take the heads off and have new valve stem seals fitted and the valves lapped in again. Man those head bolts are TIGHT! By now I was 9/10ths of the way to pulling the engine out anyway so out she came..... eventually.
Made a note to self at this point, if I ever need to do this job again and to anyone else contemplating it my advice would be take the engine and transmission out in one lump. With the offside head off you can get to the bolts holding the torque converter to the flex plate quite easily, otherwise it’s a very fiddly job. It was also apparent that with the engine out it would be prudent to have the alternator and starter refurbished as particularly the starter must be a nightmare to change in situ. To remove the transmission took a little over 30 minutes
I took the heads and short motor to my local specialist for inspection. he called to say that apart from the inlet ports almost 50% choked with carbon all was well with the heads, minimal lapping required and only .003” needed to be taken off the heads to get them perfect. The bores had absolutely no wear in them but were honed and the pistons re ringed. Main and big end bearings were in perfect condition with no measurable wear on the crank. Mileage is 118k.
So far then I have the engine back and the heads are back on. Everything that could possibly contribute to oil burning has been attended to and I’m quietly optimistic of a good outcome. Just as well as due to a change of circumstances I have lost the use ofmy company Navara as a towcar for the caravan.. This means the ML is going to be our replacement towing barge with many outings planned including a long stay in the south of France in June and July. As with our previous E Klasse Estate I shall fit an additional trans oil cooler.
I’ll keep you posted with the progress...........

 

[rossy]

Not sure OP if you took the time to read my post above but you certainly put me a little more at rest......
Did you have the Valve Stem seals replaced as a precautionary measure or where there signs of wear?
Good luck with the "put together" and yes, look forward to your updates!