Our GMC Acadia blew out a pile of smoke from the tailpipes after I had done a brake job. Oil was about 3/4 quart low in 2000 miles. The dealer said that from having it jacked up while doing the brakes, oil drained into the intake manifold. This is the GM 3.6L V6.
I’m a little confused. What path is there for oil to the intake manifold that could be considered normal? PCV valve?
They also said the GM spec for normal oil consumption is 1 quart every 1000 miles.
factory PCV systems are known for sucking in oil
Here’s roughly the latest conversation I had with the dealer:
I called back and asked to clarify how the oil was draining into the intake manifold. They said it’s coming “through the port”.
Me: You mean from the cylinders past the oil rings?
Yelled over to someone else and they said it’s because it’s an overhead cam engine and it drains back.
Me: So it’s going past the valve stem seals? Aren’t the valve stem seals supposed to keep the oil out?
Them: Yes, but it was on an angle.
Me: The valves are pushing on the seals enough that they leak?
Them: Yes.
Me: So by jacking up one side of the car the cylinder heads twist enough to push the valves against the seals?
Them: Yes.
Me: So if I’m on the side of the road and I change my tire, smoke is going to come out of the tailpipes.
Them: 3/4 of a quart isn’t that much for 2000 miles.
Me: But 5000 miles ago it wasn’t using any.
Maybe tilting it for an extended period of time puddles enough oil around the valve stem seals that it seeps past. I don’t pretend to know everything there is about cars, so I could be misunderstanding something and maybe this is normal. They’re doing an oil consumption test and I have to take it back in 1000 miles.
3/4 in 2000 miles ?? On a fairly newer vehicle??? My POS 98 Hyundai burns 1 quart per 3500 miles (1.8liter 90k). Id be taking that thing back to the dealer.
1 quart in 2000 miles is common for the GMs today. their PCV system blows, pull the pcv line garrenty oil residue is in there
Wow I wouldnt be very happy with that. Sounds like a rather poor design.
it is thats why on the LS motors they have around 6 or so designs. best solution was remove all pcv and run breathers, problem solved
lol are you talking to Wright on this?
I’m using a catch can now between the pcv and intake. It’s was about $100 and takes 10 minutes to install.
Bowser
Could the PCV possibly pull in enough oil before turning it off to fill a 3-car garage with smoke? :dunno:
All PCV lines will have at least some oil residue as the air that passes through them is going to have oil vapor.
Did you pull the vehicle in running or did you start it up in the garage and get smoked out? Crappy valve seals could let oil drain into the combustion chambers if it was sitting fir a while and then fired up.
Pulled it in, turned it off for a few hours, jacked it up one side at a time to do the brakes, so it sat for a while with each side tilted before being started up. Valve seals seems to be the only thing that makes sense. And maybe it was tilted long enough to all run toward a seal and seep past.
yes it’s soundling like you need a catch can somewhere in there. problem with burning oil is it’s killing the life of the cat(s). i doubt valve seals would leak on an angle but no other time. my guess is oil got somewhere around the pcv outlet and once subjected to vac just sucked it into the intake
don’t expect anyone in service, other than an actual mechanic, to give you an answer that doesn’t sound like complete bullshit. management is so in tune to telling the cust what they want to hear they’re accustomed to spewing complete bullshit for 8hrs a day