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Smoke at idle

Finder

Finder

Ready to race!
Location
Canada
Started experiencing this last winter and it would come and go which is the strangest thing. When the engine is fully warmed up after about 20 seconds of idling gray smoke starts to come out of the exhaust. Clearly the smell is of burnt oil, not coolant. It doesn't happen all the time but more recently is a lot often. There is no smoke when driving normally.

I've searched various forums and I've seen the PCV system, cracked valve cover, piston rings, valve stem seals or turbo seals as possible culprits.
I have installed an ECS baffled catch can a few months back and before that I ran an IE block-off plate for 2-3 years.
Valve cover was replaced at the beginning of this year.

I recently did a cylinder compression test on a warm engine and got 170 PSI for all 4. Next was a cylinder leakdown test where I got 7-8% on all 4, so very good.
What I've discovered recently: if it's smoking and I turn on the AC, the smoking will stop. I do see on my boost gauge that when AC is on there is slightly less engine vacuum.

I'm not sure how to proceed here, without throwing money on useless things (I've been through this recently chasing a lean condition) :iono:
 
Finder

Finder

Ready to race!
Location
Canada
Yes I know.
The question is: where does the vacuum suck oil from? And how can I know for sure.
I guess i can rule out the turbo cause afaik there's no vacuum there.
 
E

eiresgaus

Passed Driver's Ed
Location
Los Angeles
Also in for info on this one. Exact same issue and grey smoke. I can actually tell when it's going to happen when I have the windows down because I can start to smell a burnt oil smell and then as I take off the big cloud of grey smoke appears.

I started a thread the same as this, exactly the same with the A/C although it now sometimes puffs a bit of smoke with it on, much less than with it off though. I did valve cover, PCV etc etc and the turbo is new from earlier this year. I just don't know anymore.
 
ROH ECHT

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Vacuum smoke usually means valve stem guides and seals. Smoke at idle usually means the same. Your seals are likely allowing oil to seep down when cooling off...and when you start it again it smokes...does it clear up later after running a bit? If so, seals. You can just replace the seals for now, but consider the number of miles you have on it as well as the stem guide condition. You may be coming up on the need for those as well and may want to decide on a head rebuild now rather than in the not too far off future. New guides and seals and the head rebuild should run $500 but you have to remove and install the head. Decisions decisions....
 
Finder

Finder

Ready to race!
Location
Canada
My car doesn't smoke after a cold start. Only when the engine is at operating temp and at 24 in Hg vacuum. When I turn on the AC the vacuum goes to 20-22 in Hg and it instantly stops smoking.
Are there any other areas I can check for clogging or cracks?
I've pulled the turbo oil return line but it was clear.
I'm thinking of testing the valve cover PCV ports to rule out cracks event though it's been less than a year since the cover was replaced.
 
ROH ECHT

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Valve cover inner ports being cracked and allowing oil into the two channels for both evap and pcv would only smoke under full throttle unless you have an open recirculating pcv fix(non-oem stage 1 or CC kit)...do not know because only see brand names in your Sig. Perhaps the AC load has something to do with vac draw through the valve stems...but yes, odd that it's only seen when vac is bumped up from max. Perhaps all that's causing it is the change in load on the engine. Either way...the AC has nothing to do with exhaust smoke...but being warmed up is when it allows oil to be sucked into the combustion chamber creating smoke. It's only going to happen at the valve stem guides and seals. You can let it go for a bit..and address it when you are adding a quart every 1k miles.
 
Finder

Finder

Ready to race!
Location
Canada
As mentioned in the first post, I have the ECS catch can but I've only installed it this summer. Ran the IE blockoff plate before.
Smoking at idle started last winter actually but it only happened every now and then.
And now there are times when it doesn't smoke which makes troubleshooting this even more difficult.
However it does happen frequent enough so I have to address it..
 
ROH ECHT

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
I've read other's posts that the stem seals can be replaced without removing the heads, I did a full head rebuild. You can do just the seals or decide to go as long as you can and do both at a later date. Then, after pulling the head for its rebuild, drop the oil pan and add new rings and bearings to the pistons and rods at that time.
 
H

helldiver14

Passed Driver's Ed
Location
Ohio
Okay, so this is the identical symptoms my mk5 is making. Only when the motor is warm does it smoke and when I kick my AC on, no smoke. I have a turbo waiting to be put in, but I dont think its that. If I had to guess, it would be the rear PCV tube for us. I have yet to swap it, but thats the only thing left I think we could do. I originally thought it was my block off plate, but I highly doubt. LMK if you come up with a solution, because pulling away from a stop light and leaving a large cloud gets pretty annoying.
 
GTIAPRK04

GTIAPRK04

Cam Follower Replacer
Location
Maryland
The seals can definitely by changed with the head on. A bit more of a hassle, but there's nothing preventing you from doing it as long as you make sure the valve doesn't drop while you have the keeper/seat/spring assembly removed.
 
ROH ECHT

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Nitrous1024 said:
That doesn't sound right. What then prevents the seals from being dislodged under pressure?
Click to expand...
The seal caps are a press-fit into the head. You can do just the seals but the valve stem to guide clearance should be checked and not assumed it is tight still. If in need of seals...I would go on and rebuild all of the head with seals, guides and whatever else it needs. It's what I did when mine began smoking.
 
Finder

Finder

Ready to race!
Location
Canada
I would attempt to do this myself but based on what I've found online, it seems special tools are needed so it won't make sense to spend money on them and do this once.
I will have to find a shop who can do this for me.
The next question is what seals to go with? OEM, Supertech, others?
 
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