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Discussion Starter #1
Dudes it drives me nuts this problem and I don t know what the reason is.
When I am stoped to the light more than 30 sec when I take of a cloud of blue smoke comes out from the exhaust and is not happening allways even if I stay more than 30 sec, it hapends more in the summer than the winter.
When I start the car in the morning theres no smoke so I suppose that is no leakage overnight of oil during the night.
The PCV valve is new and in working order, I cleaned a few times the throtle body and always it was oily like the oil is geting thru the PCV valve inside the throtle body.
The spark plugs were changed 2 weeks ago no oil deposits on them ( gray/brownish color electrode) and the top of pistons were silvery with some carbon deposits spots on them no oily deposits.
No check engine light, oh and the car is a 2000 Intrepid 2.7 with 133.000 miles.
Now my question is from where the oil gets inside the pistons and what it can cause that ? Some vacuum created by the PCV valve sucks oil in the throtle body? Leaky valve seals ? I have no clue and how long can I drive like this before it gets out of hand?
Thanx alot for replys in advance.
 

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If I remember right there is a thread about leaking valve seals. I would do a search, and if all else fails. Use some seafoam to clean the motor out :)
 

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Discussion Starter #3
Yes I read the posts about leaky valves but what causes my symptoms leaky valve, vacuum created by the PCV valve, blowby, worn rings?
 

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spy1309 said:
Yes I read the posts about leaky valves but what causes my symptoms leaky valve, vacuum created by the PCV valve, blowby, worn rings?
Bad exhaust valve stem seals for sure.
the seals get very hard and brittle because they are on the exaust side of the head and the catalytic converter mounted next to that side of the head makes that side of the engine run unusually hot. Oil also pools around the exhaust valve stems on its way to the drainback holes in the head. when you take off, especiaaly after idling on a slight uphill, some oil is drawn into the exhaust stream and burnt out the exhaust( Smoke). It doesn't get into the cylinders(so usually the plugs look fine) it goes strait from the top of the head through the exhaust valve guides and into the exhaust stream where it collects while you idle and goes out the tailpipe when you take off.

don't use any engine flush type products it only makes it worse, once the seals get brittle they aren't going to soften again and seal.
The link in UNREAL's thread above gives a very detailed fix for replacing seals.
 

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Chevy's are known for bad exhaust valve guides and seals. However, when bad valve guides and seals are suspeted, typically you'll see smoke on start up when the engine has sat overnight. The oil on the heads will leak down into the cylinders past the guides and you get this blue puff first thing in the morning. I think Spy's issue might be rings. Pull the hose off the pcv valve with the engine running and see if there's any smoke coming out of it. If there's a lot of blow-by (from bad rings) you'll start seeing more coming out the pcv hose.

*Edit-I re-read Lextrep's post, and actually sounds very logical. I hadn't thought about it like that, how the exhaust pressure can pull the oil out. One way to find out for sure is to get a compression test done.
 

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froggy81500 said:
Chevy's are known for bad exhaust valve guides and seals. However, when bad valve guides and seals are suspeted, typically you'll see smoke on start up when the engine has sat overnight. The oil on the heads will leak down into the cylinders past the guides and you get this blue puff first thing in the morning. I think Spy's issue might be rings. Pull the hose off the pcv valve with the engine running and see if there's any smoke coming out of it. If there's a lot of blow-by (from bad rings) you'll start seeing more coming out the pcv hose.

*Edit-I re-read Lextrep's post, and actually sounds very logical. I hadn't thought about it like that, how the exhaust pressure can pull the oil out. One way to find out for sure is to get a compression test done.
He mentioned that when he changed plugs a little while ago they looked normal so I ruled out rings. Bad exhaust seals are a pretty common problem for 2.7s. And if the timing chain is original then the small bit of stretch in the chain makes the problem worse because the exhast valves stay open just a little bit too long and let the cylinder create a little more suction in the exhaust port than usual which helps draw oil through the valve guides and into the cat., where the next cylinder's exhaust stoke pushes it on out the exhast system after the hot cat. converter has burned the oil into smoke.
Old Ford V8s also were bad for valve seal problems and usually smoked on start-up also. If he looks real close it probably actually smokes just a little all the time it is just a lot more noticable after idling when you take off and the volume of air going in and out of the engine quickly increases. And I've seen them use up to 1 qt of oil every 500 miles in stop and go driving just through the valve seals. Also changing to a thicker oil or some oil additives will help for a little while(like when someone is trying to sell it to you) BUT thicker oil will cause a whole new set of problems down the road so I would not go that route.
 
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