Why oil burner only smoke on initial acceleration?

[StillLearning]

I was following an older oil burning Mitsubishi Montero in traffic through town, and I am curious if anyone can explain why it would only send "puffs" of blue smoke on initial acceleration after a period of no throttle?

If the person was cruising or let off the gas for a brief stop and then started accelerating again right away, no smoke. If they were stopped for a while, or were coasting for a bit and then hit the gas there would be a cloud of blue smoke. The longer they were stopped or were coasting, the bigger the cloud of smoke would be.

If the engine was running the whole time I don't understand how oil could collect anywhere only to be burned off when they hit the gas. Wouldn't it be burning off any oil that was making its way into the combustion chamber while idling as well?

 

[BrendanC]

maybe a PCV issue.

 

[Rand]

idling, the engine has high vacuum might have something to do with it if its valve stem seal related.

Which then burns off when you accelerate?

 

[ripcord]

Plus one on worn valve stem guides/seals.

On deceleration there is high vacuum which pulls oil from the top of the head past the valve stems into the combination chamber. Then when the engine is loaded down under acceleration, cylinder pressures rise and the oil is burned more rapidly causing visible smoke.

 

[dbias]

Worn valve stem seals

 

[Passport1]

Could be valve seals/guides or maybe just positive karma. The vehicle just doesn't want to embarrass the driver.

 

[4WD]

Small block Mopar’s were famous for this …

 

[Nick1994]

Mitsubishi things. 9/10 times I'm sitting at a light and a car takes off with a puff of smoke, it's a Mitsubishi.

 

[dumkid]

All the Monteros have leaky valve stem seals after like 150,000 miles. They're not super hard to replace, but most people wait a couple months until the oil burning gets really bad or they don't care and never fix it. Some people get lucky and never have to do valve stem seals, but most people end up having to fix it between 2 and 300,000 miles.

 

[Gus_Mahn]

Seen the same thing on several Crown Vic’s. Another vote for valve guides. Didn’t Motero’s have a 2.6 with those goofy auxiliary valves?

 

[dumkid]

Seen the same thing on several Crown Vic’s. Another vote for valve guides. Didn’t Motero’s have a 2.6 with those goofy auxiliary valves?

The last Monteros that came with a 2.6 were made in 91 or 92 i think. Since then it's all the 6g72 (or 4 or 5) v6.

 

[eljefino]

^ Is the 6G72 the same 3.0 they put in all those early 90s dodge minivans? Those were all smokers, too, every one.

 

[malibuguy79]

^ Is the 6G72 the same 3.0 they put in all those early 90s dodge minivans? Those were all smokers, too, every one.

3.0mitsu caravans were **** near guaranteed to smoke after about 35k but they were generally good running motors.

 

[dumkid]

^ Is the 6G72 the same 3.0 they put in all those early 90s dodge minivans? Those were all smokers, too, every one.

yep same engine. I think they got better valve seals in the late 90's but they still smoke eventually.