Smoke on startup after longer trips

[chap3]

Recently purchased a ‘16 lr4 w 70k miles and have noticed a decent amount of smoke from the exhaust on startup but only after the car was driven a longer distance (like an hour or so) then sits for a while. If I am just taking short trips then there is no smoke. Even longer trips where the car doesn’t sit for multiple hours afterwards is fine on startup. Only the combo of long trip + long sit time before the next startup.
Already replaced the PCV valve but it’s still occurring. Smoke is not sweet smelling like coolant but rather smells like Burt oil/gas. Any recommendations on where to look next.

 

[ftillier]

vacuum pump maybe?

 

[powershift]

The color of the smoke is critical. If it is blue that would be from burning oil and the problem could be one or more worn valve stem seals.

 

[chap3]

vacuum pump maybe?

Interesting. How would a vacuum pump cause smoke?

 

[jlglr4]

That was my reaction when I first heard of the vacuum pump issue. I looked at some diagrams and this is my assumption: The pump receives lubrication from the block. Apparently, when the pump goes, it fails in a way that lets the oil into the vacuum tube. The vacuum tube is joined to another vacuum tube at the intake manifold (the vacuum assist uses pump vacuum and intake vacuum). When the pump goes it loses vacuum and the vacuum from the intake then sucks oil from the pump like a straw and dumps it into the intake manifold. At least that‘s the only thing I can figure out. I‘ve seen a couple of different reports of this same problem causing a lot of smoke out the tailpipes. However, those were the V8’s. Not sure if the V6 has the same setup.

 

[chap3]

That was my reaction when I first heard of the vacuum pump issue. I looked at some diagrams and this is my assumption: The pump receives lubrication from the block. Apparently, when the pump goes, it fails in a way that lets the oil into the vacuum tube. The vacuum tube is joined to another vacuum tube at the intake manifold (the vacuum assist uses pump vacuum and intake vacuum). When the pump goes it loses vacuum and the vacuum from the intake then sucks oil from the pump like a straw and dumps it into the intake manifold. At least that‘s the only thing I can figure out. I‘ve seen a couple of different reports of this same problem causing a lot of smoke out the tailpipes. However, those were the V8’s. Not sure if the V6 has the same setup.

Wow never would have thought of this, thanks for the detail. I have oil accumulation in the pcv breather hose having removed it a few times changing the pcv valve (hint: don’t buy the cheap ones off Amazon, they didn’t quite fit right in the groves so never properly sealed) so there is oil getting into the intake. I would think the leaky vacuum pump would also have symptoms with the breaking system. I guess maybe there is a way for it to leak oil but still pull a vacuum properly? Idk