EGR should we all be more concerned

[stormshark]

Interesting update- i picked up my diesal after its 30k service., and the Service manager unprompted, suggested i get a Manifold flush/solution procedure or similar comment, next time i am in For $190. Interesting when i previously raised queries , there was no need or problems. Anyway, guess this is a positive pro active step.

[Greg Roles]

IMHO VW should be doing them for free given they are potentially going to be up for expensive part failure within the warranty period, and it's their design. The newer SUV diesels coming out of the USA are now running a second parallel EGR circuit with post DPF exhaust gas being fed directly back into the air filter area, so double the problem!

Still for everyone without a DPF it would be highly advisable.....but remember a Provent runs about $220 full RRP......

[Buller_Scott]

provent is on the cards for sure, but has anyone ever paid a garage to do a manifold clean? if so, what kinda $$$?

[tonymaroney]

It's been about 6 months since I put a Provent into my 103kW 2L TDI Golf V. I checked it once after the first month and didn't find any oil in it, but after 6 months there was about 100-150mls of dirty black oil that I drained out of it. (My car is fairly low mileage..it has only done about 15K in the 6 months when the Provent has been on. In the first month the oil separator itself was soaking up the small amount of oil). The first thing I thought when I looked at the black oil that was caught was "I don't think I would like that to go through my engine"...a certain percentage of this would be part of the crud that accumulates at the EGR valve if it wasn't caught in the Provent.
To those that have Provents...when you drain your Provent and/or inspect the filter do you just wipe it down and put it back in, or do you somehow clean the oil separator filter (eg soak it in detergent solution)? The Provent instructions indicate it just gets replaced at 1000hours, rather than being cleaned, so I think I know the "correct" answer, but just interested to know if a clean/soak has been tried.
Cheers,
Tony.

[Greg Roles]

Yep, I tried to degrease mine, but it quickly clogged up again, so I got a new one at a rather expensive $50 odd from memory. I'm still on that second one at 65k's and it's about due for a newie. In my opinion, once the filter is soaked through, the only way to keep the vent operating at it's best is to replace the filter. I'm seeing that as about every 20k or so. Still, it's a lot cheaper than the flushes, new EGR parts or DPF replacement, and most importantly, keeps the car running as it was designed to and not getting a bad case of sludge induced asthma!!

[Roaming Refuge]

Just a small clarification, when people refer to EGR are they indeed refering to "exhaust gas" or are they refering to the gases from the crankcase?

[gtimk5]

provent is on the cards for sure, but has anyone ever paid a garage to do a manifold clean? if so, what kinda $$$?

I charge $80 to do the clean.

[tonymaroney]

EGR is indeed referring to exhaust gas recirculation, where part of the exhaust gas (literally from the exhaust output, nothing to do with the crankcase) is coming back in to help lower the oxygen content of the overall air flow going into the cylinders for new combustion. The lower oxygen level will help to keep the combustion temperature lower, which in turn helps to keep the NOx production lower. The NOx level needs to be kept low to pass environmental standards etc. The reason why the crankcase vent gas (which is totally separate to the EGR gas) is getting involved in this story is that the crankcase gas (which has a certain proportion of oil in it) is vented into the air stream at a point which is "upstream" from where the EGR gas is coming in, and what happens is the oil from the crankcase gas combines with the soot in the EGR gas and you get oily sludge buildup at the point that the EGR is entering. That buildup can choke off the air flow that is going to the cylinders etc.
Does that make sense?
Cheers,
Tony

[Roaming Refuge]

Yep, cheers Tony, making a LOT more sense now!

I'm now wondering if VW intended the crankcase oil as some form of lube for the intake side of the turbo?

[gldgti]

oil laden crankcase vent gasses have long been utilized to lubricate various intake parts such as inlet valve seats. The turbocharger doesnt require any lubrication in the compressor housing. However, I am positive that the amount of oil in the vent gasses needed to lubricate inlet valve seats is far far far far far less than the amount that actually gets pumped through.