Audi 3.0tdi fumes coming through A/C

**Crasher** · 06-08-2021,08:46 AM

Originally Posted by swwalker

so you will know they leak out the side of the head

Like so

**swalker** · 06-08-2021,09:02 AM

thats messy, mine must be a bit like that.
I got worried when I started towing the caravan I could smell it burning off. Luckily it was only an hour drive and I made it with no flames.... tick tick tick all the way home lol
I have went to do them a few times but have talked myself out of it.
By the time i buy the pullers - socket for the fuel pipe and the cleaning kit i could get someone else to do it. what do you think?

sorry for the slight hi-jack.

**mhobson** · 07-08-2021,10:33 AM

I have wiped around the trapezium plates under the injectors, not easy to get to. The smell is definitely crankcase fumes, not neat diesel. Normally the exhaust does not smell very strong from behind, very different to the fumes entering the car, apart from gases exiting from a pressurised crankcase not able to discharge the fumes via the EGR system, the only other idea, and I have no idea if it is valid or not, is if the EGR system is dumping fumes on the overrun while I am slowing down, it may exit through the exhaust unburnt and with the engine twisting in the opposite direction to acceleration if there are splits in the short lengths of flexible exhaust pipe, the fumes could rise up to the plenum chamber. Realistically, I am just foxed, apart from this issue it is a really good, comfortable, well equipped car.

Originally Posted by swwalker

hmm clean up your plates and se if the oil comes back, you said you did the injector seals so you will know they leak out the side of the head, i wonder if the oil is diesel?

a smoke machine can be easily made :- FIND VACUUM LEAKS FAST with this $15 DIY SMOKE MACHINE - YouTube
you mention the drain pug in front, there is one on the bottom i pushed out on mine worth a look on 7 zap to see if there are more you dont know about which are not there?

**mhobson** · 28-08-2021,04:14 PM

As stewart suggested there are two problems, 1/. there are crankcase fumes coming from the engine, so there must be some problem with the normal way the crankcase fumes are sent back through the inlet system, the oil filler is oily again, only driven about 600km since I cleaned it. 2/. the fumes are getting into the A/C. I was under the car today with the undertray off and I noticed a large teardrop shaped hole about 30mm wide in the steel pressing between the bottom of the chamber where the plenum chamber is located and the underside of the car. Is that where the air for the A/C is supposed to come in? it is clean and no cables or pipes pass through it it is just behind one of the small rubber drains. It seems to be a likely site that engine fumes could enter. I have blocked it with duct tape and see if there is any change.

**swalker** · 30-08-2021,08:05 AM

bungs Audi A6/S6/Avant quattro (A6Q) 2007 year Audi EUROPA 803035

number 9 is what i poked out of mine to let the water out as the chamber filled with water. its hard to make out whats what there but are you talking about number 4?

**mhobson** · 30-08-2021,08:30 AM

Stewart man, you are on the money, the hole is where number 9 should be but nuffink! All this time, I thought that the water drain was the little rubber tube just in front of the hole, I cannot thank you enough Stewart, you have made a big change in my driving life. I suspect that when in time the rubber perishes or dirt builds up it may cause blockage, hopefully if I buy a new one it should work for a while, until then I will put up with the duct tape although I may cut a small cross hole in it to allow for water drainage. The car is up in the air because I am attempting to change the left side drive shaft, have disconnected both ends but it seems that I have to disconnect the bottom suspension arms and pivot the hub outwards to get the shaft out and I don't think that my balljoint splitter is up to the task. Again, thank you very much, regards, Michael

**swalker** · 30-08-2021,08:35 AM

Good stuff, you just need to make that smoke machine now to see where the fumes are coming from.

**mhobson** · 30-08-2021,09:14 AM

Oh, the challenges of life!

**Crasher** · 30-08-2021,11:21 AM

For years I have been telling people not to remove the drain bungs as they are a one way valve… not a good one but that’s the purpose.

**swalker** · 30-08-2021,11:30 AM

agreed, i never meant to loose mine but a no start one winter night when i wa sin a rush and found i swimming pool in there fumbling around in freezing water it was gone before i had fully figured it out. I really should get a replacement now the injectors are leaking a bit. and of course sort the injectors lol - which brings me to a post i want to start but i will not hijack this one