Engine smoke

[86Nick]

Having trouble with my 86T. After running for a while at idle the car starts to smoke pretty good out of exhaust. This problem has been going on for quite sometime with two different turbos on the car and different size injectors. So, think it's oil burning. What is a good way to tell if it's a valve seal problem or a ring problem? I Have removed plug a couple of time and did not see any signs of oil on them.

 

[Pronto]

I assume the smoke is blue? You could be sucking oil up from the pcv line too. Check under the vacuum block for a puddle. You can do a leak down test too.

 

[fastlikeanascar]

just did this check because I was having the same problem. is it suppose to be completely dry ?

 

[86Nick]

I assume the smoke is blue? You could be sucking oil up from the pcv line too. Check under the vacuum block for a puddle. You can do a leak down test too.

I have a RJC check valve on PCV. Where else could it suck oil from

 

[DailyDrifter]

I assume the smoke is blue? You could be sucking oil up from the pcv line too. Check under the vacuum block for a puddle. You can do a leak down test too.

+1 Leak Down test. Listen for air comming out of intake, exhaust ports, and beathers. Could be valve seals also.

 

[dank GN]

white smoke what does that mean?

 

["Turbo-T"]

White smoke means water in the combustion chamber.

 

[RmvBfrFlght]

I have a RJC check valve on PCV. Where else could it suck oil from

The check valve is used to keep boost out of the crankcase. Oil can still be pulled through it into the intake.

Check the outlet of the turbo on both the cold & hot sides. It may be leaking out a turbo seal.

RemoveBeforeFlight

 

[Turbo1dr]

Leaking valve stem seals will start to smoke after the engine idles for a long time. Replace the seals and your car will stop smoking.

 

[Steve V]

If your heads have been milled a LOT the intake may need to be milled to match. Just saw a thread on here about this last week and the intake was the issue.

 

[turbofabricator]

Might be a blown head gasket, valve seals, PCV valvesucking oil. Valve stem seals are a serious problem with ported heads. If the head porter cut the valve stems for valve seals, and used the stock exhaust valves then that is your problem. Stock exhaust valves NEED the valve guide un touched because there is a oil pump groove cut into the stock exhasut valve and NO seal is used. Alot of machine shops cut the guides for seals, thinking that they are doing the right thing, but in fact, they are completely killing any sort of oil control on the exhasut valves. The seal will end up riding on the under-cut stem (oil pump) of the valve, and not even make contact with this thin section of the valve. If the guides have been machined, then you MUST replace the exhaust valves with a smooth stem aftermarket stainless valve. No way around it. IF this is your condition, you should talk the machinist into machining/fitting the new valves for free. He made a mistake.

Plug your PCV valve for a week and see if it clears up. (leave the PCV valve in the manifold base, and plug the hose.)

 

[Pronto]

Ken, do you have any pictures of what is right and wrong with the valves and seals for us that haven't seen them to understand better? I'm sure many people have had heads done and would like to check on that issue...

 

[Turbo1dr]

Ken, do you have any pictures of what is right and wrong with the valves and seals for us that haven't seen them to understand better? I'm sure many people have had heads done and would like to check on that issue...

Stock exhaust valves can't be used in a head that has had the exhaust guide cut down for push-on (positive type) seals.

 

[turbofabricator]

Good pic. Notice the valve on the left (stock) the lower groove is tapered at the top of the groove, but has a sharp edge at the bottom. This sharp edge grabs the oil and pushes it up and out of the guide, while the taper at the top prevents the groove from dragging oil down the guide. This ONLY works if the valve guide is left un touched, meanig that the machinist ddin't cut the top of the guide down. You can cut it down about .060" max. for additional retainer to guide clearance. But if you machine it down more, then the lower groove stays un covered, and you loose the oil metering function of the valve, and oil will flow down the guide, causing smoke. If you run a cam with more than .515" lift, you will have to replace the exhaust valves with an aftermarket SS smooth stem valve and have the guides machined down for positive seals, and retainer to guide clearance. You can use stock TTA exhaust valves, too. They have a smooth stem and use a positive seal from the factory. (different heads)

 

[Pronto]

Ah, very good pictures. I see the the issue that would happen with stock valves and the guide cut down. May I ask what is the stock height of the guide is so I can tell if the guides have been machined down?
What is the diffence between the stock style seal and a positive seal?

 

[Esasky's85GN]

Same thing!

Guys,

I am getting this same thing. The car blows blue smoke from mufflers after I throttle it. No smoke @ idle though. I also have a check valve tied into my vacuum block. Should I just try to plug the PCV hose and leave the PCV valve in the manifold, open to atmosphere? My plugs show no signs of oil either. Only difference on mine was that my fuel pressure was @ like 65 PSI for a little while. Possible cylinder washout?

Chris