Smell related to DPF Regeneration?

[mikecb1]

On two or 3 occasions over the past year or so I've noticed an odd smell in the car. Hard to describe smells, but it's rather like very hot oil. It also reminds me of the smell of Millers fuel additive(!). It's always happened when the car is stationary in traffic after driving fairly briskly for a while beforehand. It passes off after a minute or two. I can't see anything obvious under the bonnet like an oil leak. My car is a 2.0tdi sport which has a dpf, and my garage suggested the smell might be related to dpf regeneration. That doesnt really stack up though because I've had the car for 7+ years, and I've only had the smell over the past year or so.

Suggestions welcome.

Mike

[DMitch16]

A possible exhaust leak somewhere or oil leak from the turbo area. Burning oil smell is common when there's a small leak from the turbo or intake pipe (the plastic ones with the spring band don't seal so well and can leak the additional oil vapour vented from the crank through the cam cover into the air intake before the turbo).

[mikecb1]

Thanks Mitch. I'll check the areas you mention.

Interestingly, I had a service last week, and the garage replaced the "NSF turbo boost pipe seal" which they said was weeping oil. Maybe related, though I noticed the smell again when I got home from the garage.

Mike

[DMitch16]

On the BMR engine the intake pipe is just plastic, with no o seal, which fits on the hard pipe elbow of the turbo compressor side by a large retaining spring band. The turbo compressor exit pipe is a traditional push click with seal. I have replaced the spring band with a large jubilee clip which has improved the seal due to the more even pressure exerted around the pipe circumference.

Also the v clamp connecting the turbo and DPF can work itself looser causing exhaust gases to be forced out under high pressure so I'd check that for tightness and inspect to see if there is any tell tale sooty deposits around the clamp anywhere.

[gresty]

Hi. I have same issue and I have bmr engine but have had dpf removed. found out that the wastegate pivot bush on my turbo has worn and exhaust gasses are passing. I only get the whiff of fumes when stood stationary. Mine has 170k on the clock and need to get turbo reconditioned (at some point when car can be off the road). Might be a bit difficult to see turbo with dpf being at the back of the engine. Hope this helps.


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[mikecb1]

-just a thought. Would a leak on the inlet side of the turbo cause an escape of fumes? I would have expected a partial vacuum here, rather than any pressure, so a leak would cause air to be drawn in, rather than fumes coming out. Or am I missing something?

Mike

[mikecb1]

Latest update. I braved the elements yesterday and checked the areas mentioned by Mitch. The joint between the turbo outlet and the dpf definitely looked suspicious, with a layer of black soot on the clamp bolt. Access is not easy, but with some contortions and minor loss of skin I managed to tighten the bolt by 1 full turn. With the engine running there is now no apparent leak, but I've cleaned the soot off and I will check it again after a decent run.

Mike

[DMitch16]

Latest update. I braved the elements yesterday and checked the areas mentioned by Mitch. The joint between the turbo outlet and the dpf definitely looked suspicious, with a layer of black soot on the clamp bolt. Access is not easy, but with some contortions and minor loss of skin I managed to tighten the bolt by 1 full turn. With the engine running there is now no apparent leak, but I've cleaned the soot off and I will check it again after a decent run.

Mike

Sounds like this was your leak and tightening the band the immediate cure.

Mine was leaking badly from the same join and the cabin full of exhaust gas which over a period of a few months caused me minor heart arrhythmia (which has now almost gone fortunately). I had a few cable clips missing and the cabin intake under the bulkhead plastic cover on the NS was drawing in the leaking gases through the holes, along the bulkhead and into the cabin, via the fan. I have since replaced the clips and resealed the heat shielding so that no gases from the engine bay get anywhere near the cabin intake. I replaced the spring band with a new one from VW (£18) and also the thin metal gasket (£3) that fits between the turbo and DPF join (NO EXHAUST PASTE SHOULD BE USED). Aligning the two is a bit tricky as the DPF unit is heavy and the turbo is moulded to the exhaust manifold but by slackening the DPF bracket bolts I managed to get a very good seal and a well fitting V clamp as a result. No smells since and the car is no longer trying to kill me!

[mikecb1]

Thanks Mitch. I've noted all your comments for future reference. Until I've had a few fume-free runs I won't be sure that I've fixed the problem. I'd love to think it only needed a bolt nipping up, but experience tells me it is seldom that easy! Getting at the joint in question to replace the gasket looks to be really difficult, so if the problem is still there I may hand it over to the garage. At least I will be able to tell them exactly what needs doing.

Thanks again for your help

Mike