Eshaust Smoke

[ThikStik]

EricS,

It sounds like your problem has been diagnosed per Turbofbricter, u just need to remove a valve spring and look at your exh valve boss and see if it has been cut. Im hoping this is my cars problem. I have so much smoke that I wont drive it at this point. I also have the mysterious starter oil leak with no known wetness starting point. Might as well be some tiny hole in block around the starter!!! I think its possible that the rear main can leak , and the oil blows or slings toward the starter....may never know. Been doing this too long for such madness. Do u have a wet breather after hard runs? That would indicate tired ring sealing and would help blow out oil pan gasket. U have to be careful not to overtighten the blue gasket, but i cant see why your cork is also leaking. Is your pcv working well? if not , pressure in crankcase will be too hi all the time, pushing oil out in many places. Good luck.

 

[ThikStik]

An experiment is in order here. I believe that Turbofab is correct in nailing this problem. So I have a possible experiment to try. It is to put orings on the exh valves. That'd keep oil from migrating down stem leaving only splash oil to go into guide. Buick just ran the oring. I reckon it could cut the smoke in half. Guess ill find out...gonna try it. These cars are TOOLS.

 

[Eric Stauch]

yours is my cars twin

wow crazy to find another car doing the same thing as mine. what do i look for on the valve boss. i was actually the one that cut them under the close eye of my machinists. i cut where the valve springs sit so i could get my spring pressure right and you know how the boss is wider at the bottom than at the top? well mine got trimmed a little when i was cutting the seats for the valve springs. mine have no orings. and when i had my tranny out i took the flywheel off to and my rear main is dry as a bone. and yea my breathers drool everywhere no matter what. not very bad but you can always see "smoke" coming out of them. i ran my PCV to its own breather but it is very hard for me to believe that with 2 breathers and a PCV that this thing is building up THAT much crank case pressure.

 

[turbofabricator]

wow crazy to find another car doing the same thing as mine. what do i look for on the valve boss. i was actually the one that cut them under the close eye of my machinists. i cut where the valve springs sit so i could get my spring pressure right and you know how the boss is wider at the bottom than at the top? well mine got trimmed a little when i was cutting the seats for the valve springs. mine have no orings. and when i had my tranny out i took the flywheel off to and my rear main is dry as a bone. and yea my breathers drool everywhere no matter what. not very bad but you can always see "smoke" coming out of them. i ran my PCV to its own breather but it is very hard for me to believe that with 2 breathers and a PCV that this thing is building up THAT much crank case pressure.

With a trimmed exhaust valve guide, you completely eliminate the "oil pump" feature of the stock set-up. (if you trimmed over .10" and use stock valves) If you are smoking out the brathers, then you have a bad ring seal, or bad head gasket. It has nothing to do with valve guides or seals. If you have more than .500" net lift, then guide to retainer clearance MUST be verified. The factory did NOT use o-ring seals on the exhaust valves (Tubo Buick's anyway). There are NO seals on the factory produced exhaust valves. The Turbo Trans Am DID, however, use positive seals on both the intake and the exhaust.

 

[ThikStik]

ErickS,

Dont know if you actually cut the top of the boss to cause the scenario that Turbofab describes. Rather , you may have just cut spring seats...can u say? My car must have this. Its smoke is light grey at idle. Valves are stock, and bosses were cut, valve seals put on, and bronze guides put in. (Ive heard on this board that bronze guides are bad for the street). Smokee got worse when putting in a new roller cam with more lift. I tried putting on orings last night, no help at all.
Re your blowby-How many miles are on your motor? Did rebuilder over lube cylinders on rebuild? Did u use synthetic oil soon after build? Any of these things could point to rings that are not seated , in which case, drive it alot, and i bet theyll seat. Re PCV, I dont know what you mean that u ran it to its own breather. Gotta have suction on crnkcase, altho a worn motor will always cause weepy breathers.
Re valve issue,I guess ill have to educate another machine shop at my own expense . Thanks TFab, I cant believe this info was so obscure.

 

[turbofabricator]

The reason the valve seals won't work on the stock exhaust valves, is they have a big under-cut stem just below the valve keepers. Valve seals do NOTHING on a stock GN exhaust valve. They control oil by pumping it out of the guide, via the under-cut. If the top of the guide is cut down, then it will be too low for the under-cut to do it's job. Then add to it high lift, and it drags even more oil down the guide. If you replace just the exhaust valves, with stainless aftermerket, you can use a PC seal and cure the oil leaking problem. With a roller cam, it is a good idea to replace the exhaust valves and use a machined valve guide and seal.

 

[ThikStik]

Turbofab,

Thanks again for the explanation....Ill say again, I dont know why this isnt widely known. Maybe it just escaped me. I had heard of bronze guides being unsuitable for street duty. Are u suggesting running iron guides on both exh&int? Thanks.
PS-I wonder how well my machine shop will "work" with me on this one.
PS-As for the oil showing up all the way into intake, maybe it is valve overlap allowing it to be sucked into those areas. Pistons even look altittle wet.

 

[Eric Stauch]

I did not cut the top of the boss only the diameter at the bottom. my motor has about 7000 miles on it and as for a bad ring seal, if the haven't sealed after 7000 miles then what does it take to seal these things? and i do have stock valves in it but you say they are doing nothing. then why did it not have this problem before? or is it because of the positive style seals?

 

[turbofabricator]

Eric,
If the top of the guides were not cut, then you are OK. Just don't install a seal. No seal will help a bad guide, though. Did your shop install K-line bronze liners? If so, they work great, if installed correctly, on a street motor. It sounds like you have a leaking PCV valve or bad intake seals or guides. Leaking exhaust seals/guides will smoke, but will not oil a piston. Check your turbo. If the compressor seal is leaking, it will send oil everywhere. You can PM me for my number if you want to talk about it.

 

[ThikStik]

Well, the scenario TFab described should be my problem. I pulled a head , and oil was all in the exh ports. With only the center of the valve dry, the rest oily. Pistons were semi wet...keep in mind, i idled it along time just before disassembling. Header was wet with tarry oil on each port. Intakes were clean and dry.
I think my machine shop should really do something for me. So TFab, you recommend i get rid of the bronze guides.? Ive not heard of K-line liners.