Eshaust Smoke

[Eric Stauch]

I've had my 87 gn for a little over a year and lost two lobes of the cam one night so i pulled the motor and did a rebuild on it with a new crank new bearings and rings i reused the pistons and the cylinders were fine so i just honed it i checked the clearance on the pistons and it was at the factory limit according to my book so i let it go. along with the rebuild stock heads ported new roller .495 lift cam new timing set and springs. valve guides felt fine so i put new seals on them. it mainly stock other than a 59mm turbo. every sensor is new. stock computer. now my problem is mainly when its hot and sitting still it will smoke blue. never while going down the road. and some days it wont do it and others it will. the first to things that came to mind was blow by and valve guides. but if it was either one would it not do it all the time and be getting worse? this is my first time to this site so any help would be greatly appropriated.

 

[mikestertwo]

Could be a lot of things. Valve guides, leaky intake manifold gasket, PCV sucking oil out of the lifter valley, too much piston to wall clearance, ect. Pull the dog house off the intake manifold and see if there is oil in the manifold.

 

[GSX-PKV]

Try taking out the pcv valve and plugging the vacuum hose with a spark plug to rule the pcv valve out as a cause of the smoke. Paul

 

[vacuum 6]

Does the engine use oil? Check both the compressor and exhaust side of turbo for oil.

 

[Eric Stauch]

yes the motor does use oil. about a quart every week and a half to 2 weeks depending on how much you drive it. im going to check the turbo for oil and try pluging the pcv valve. when i plug the line do i just leave the unpluged pcv in the intake? i wont have a chance to try this till around wensday so i will get back and tell ya'll the results. thanks again for you help.

 

[vacuum 6]

One quart per how many miles?

Plug at the vacuum block and yes you can leave the PCV with hose plugged into the intake. I guess a spark plug works too...someone else said that.

 

[chris718]

Sitting and idling is when you have the highest intake vaccuum present.It seems you are sucking oil into the combustion chamber from a leaky intake gasket or valve guide that is worn or not sealed due to a bad oring or floating valve stem seal depending on what was used when the head was assembled..If the engine smoked on start up i would say the valve seals is the likely cause,however it is wise to understand that blue smoke is burnt oil that has past thru the combustion chamber and whitish grey oil smoke has been introduced into the exhaust via a leaky exhaust valve guide.Ihad a gn do that to me with a valve seal(the ones you machine the head for)that wasnt retained to its boss on the head.

 

[turbofabricator]

What valve seals did you use? The retainer to guide clearnce on the stock exhaust guide is usually close with .500" lift. Did you install larger stainless valves? If so, you will NEED to cut the guides for a positive seal. If your valves are stock, then the exhaust does not need a seal. The stock exh. valves have an "oil pump" machined into them. I would think that the turbine seal may be your problem, though.

 

[Eric Stauch]

they are the stock valves and i did cut down the valve bosses because my machinist said it would be a good idea with the bigger lift cam. i used the positive style seals, the kind with the metal band around them, but i don't remember any oring. is there and oring that goes under them? and no the car did not smoke when we first cranked it. the car idles high sometime when you put in in park kinda like a vac leak and i couldnt find one so maybe intake gaskets? and would that explain where my oils going? oh and speaking of idling is the factory tach accurate? mine says it idles at 1400. and by the sound of the motor i know its not. and at 70mph with stock gears it says 4000rpm.

 

[turbofabricator]

Your exhaust valve oil control provisions have been completely eliminated, now. The stock exhaust valve have a oil pump groove on the stem just below the valve keeper groove. This groove has to be located precisely in the correct location in relation to the valve guide to meter the correct amount of oil in and out of the guide. By cutting the guide down, the groove will be completely exposed rendering it useless. Any valve seal used will now just ride loosely on this necked down section of the valve and not even seal at all. The solution is to replace the exhaust valves with smooth stem aftermarket SS valves. (Or the stock TTA exhaust valves can be used) and then use a good positive seal that snaps over the valve guide. Don't feel bad, I've seen this many times over the years.........and how do you think "I" learned it? I just went through this on a friends car. He went to a roller cam and I felt the retainer to guide clearance was insufficient, so instead of using SS valves, I used the TTA valves and good seals. (after machining the guides down and cutting for positive seals. Good luck.

 

[Eric Stauch]

well not looking forward to that job but at least now i know what it is. since im gonna have the heads off would you just go ahead and put intake valves in it to? and you say tta valves, is that turbo trans am valves? and would you put them in it? just the stock tta valves can i get them at like a parts store? thanks again for everyones help!

 

[hybridgnwagon]

What valve seals did you use? The retainer to guide clearnce on the stock exhaust guide is usually close with .500" lift. Did you install larger stainless valves? If so, you will NEED to cut the guides for a positive seal. If your valves are stock, then the exhaust does not need a seal. The stock exh. valves have an "oil pump" machined into them. I would think that the turbine seal may be your problem, though.

X2 I was going to say valve seals or turbine seal....

 

[Kibster]

Similar Problem

I was going to start a thread/post of my own - until I read this post...

I'm having a similar problem with a freshly rebuilt engine in my 87 GN...rebuilt after losing a head gasket (and because of a leaky rear seal).

The engine was built (disassembled, cleaned, machined, reassembled w/all clearances checked/recorded) professionally by a recommended Buick machinist (although w/more V-8 than V-6 experience).

The engine remains standard bore/pistons/rods/crank - as all were in good shape and within tolerances. Cylinders were honed and the crank polished.

Both the block (.015") and heads (.010") were resurfaced to insure a flat mating surface.

The engine builder replaced the pushrods with custom length pushrods (non-adjustable) - the cam is a Bullet Hyd w/Crower Cam Saver lifters.

The heads were machined for "K-liners" - and for PC seals. The valves were also "back cut" and received a "5-Angle" valvejob...

After breaking in the cam - changed oil and took it out for its maiden voyage... While the valve train was noisy/ticky - the engine ran smooth and w/good oil pressure (both at idle and at speed). However, after letting the car idle (showing it off to a buddy) - we noticed blue smoke appearing in the exhaust. A quick rev - and we had a cloud.

Drove it home - and pulled the plugs - finding #1 & #6 wet w/oil. Did a compression test - all cylinders were good and with a couple % of each other.

The engine builder was concerned that the intake might not be sealing - so I pulled the intake (off my freshly painted engine) and replaced the GM gasket with a Fel-Pro gasket - putting sealant around all the ports and water jackets - both sides. Unfortunately - the problem persisted - with oil now on 3 plugs...

Pulled the dog house and it appeared that the intake might be riding high (a possible byproduct of the decking of the block and milling of the heads)

So...off came the intake and out went the pushrods (the later replaced with T/A adjustables). The engine builder machined the intake - in an attempt to improve it's seating/sealing...

The intake was replaced - again with a new Fel-Pro gasket - with liberal use of RTV sealant - carefully aligned & torqued in place.

Disappointedly - the oil smoke re-appeared and I now have oil on 5 of 6 plugs - 3 being seriously wet and two lesser so...

Naturally - the valve train noise remains as well...

Any thoughts?

 

[turbofabricator]

Sounds like the vavle guides are your problem. Did the machinist relace the valves with aftermarket stainless valves? If NOT, then that is the problem. Remove the engine, and have him/her repair the heads. You can not cut the exhaust guides for a PC seal IF you retain the stock valves. (OK on the intake valves) The stock exhaust valves have an undercut below the valve keeper that will ride were the PC seal will sit, causing oil to drip down the guide. The intake seals may also be compromised, too, but not for the same reason. Also you need to check the retainer to guide clearance when using a high lift cam. Is this a flat tappet cam or a roller? It sounds like your guy just over looked a few things. Not the first time this has happened.

 

[Kibster]

No...he re-used the stock valves...

The cam is a hydraulic flat tappet - Intake 214/490 - Exhaust 210/470 - 110 seperation...Bullet Racing Cams - BUE6 266/260-10H

 

[87NAT]

I was going to start a thread/post of my own - until I read this post...

I'm having a similar problem with a freshly rebuilt engine in my 87 GN...rebuilt after losing a head gasket (and because of a leaky rear seal).

The engine was built (disassembled, cleaned, machined, reassembled w/all clearances checked/recorded) professionally by a recommended Buick machinist (although w/more V-8 than V-6 experience).

The engine remains standard bore/pistons/rods/crank - as all were in good shape and within tolerances. Cylinders were honed and the crank polished.

Both the block (.015") and heads (.010") were resurfaced to insure a flat mating surface.

The engine builder replaced the pushrods with custom length pushrods (non-adjustable) - the cam is a Bullet Hyd w/Crower Cam Saver lifters.

The heads were machined for "K-liners" - and for PC seals. The valves were also "back cut" and received a "5-Angle" valvejob...

After breaking in the cam - changed oil and took it out for its maiden voyage... While the valve train was noisy/ticky - the engine ran smooth and w/good oil pressure (both at idle and at speed). However, after letting the car idle (showing it off to a buddy) - we noticed blue smoke appearing in the exhaust. A quick rev - and we had a cloud.

Drove it home - and pulled the plugs - finding #1 & #6 wet w/oil. Did a compression test - all cylinders were good and with a couple % of each other.

The engine builder was concerned that the intake might not be sealing - so I pulled the intake (off my freshly painted engine) and replaced the GM gasket with a Fel-Pro gasket - putting sealant around all the ports and water jackets - both sides. Unfortunately - the problem persisted - with oil now on 3 plugs...

Pulled the dog house and it appeared that the intake might be riding high (a possible byproduct of the decking of the block and milling of the heads)

So...off came the intake and out went the pushrods (the later replaced with T/A adjustables). The engine builder machined the intake - in an attempt to improve it's seating/sealing...

The intake was replaced - again with a new Fel-Pro gasket - with liberal use of RTV sealant - carefully aligned & torqued in place.

Disappointedly - the oil smoke re-appeared and I now have oil on 5 of 6 plugs - 3 being seriously wet and two lesser so...

Naturally - the valve train noise remains as well...

Any thoughts?

I have 100 or so miles on my new engine and had oil smoke as well. My PCV was sucking oil back into the TB and inatke. I put a catch can and check valve inline. See if you can blow thru your PCV. You might be sending boost back into the engine stirring everything up in there.

 

[Kibster]

Well - I took the dog house off again last night (after the 5 of 6 wet plugs) - and the plenum of the intake remains clean and dry (I would have expected to find some oil residue/discoloration if the PCV valve was sucking oil).

The intake ports on the heads looked moist - but I couldn't see any puddled oil nor could I pickup much oil when I put a shop towel (paper) down the intake ports.

The port alignment looked "OK" - although it's hard to see the top of the ports - even with a small mirror and a flashlight.

 

[Kibster]

Spoke w/my engine builder - and we're (Ok, I am) going to pull the engine to get a better look...

I know...sounds like fun...

Thanks for the feedback and guidance...

 

[ThikStik]

I dont understandwhy Kibster has to pull his motor if he has same problem (and cause of that problem) as EricStauch. The problem that Turbogfabricator explained, that is. It would seem that only "half" a valve job is needed....only replacing the exh valves.
Anyway, I hope thats whats wrong with my 10,000 mile rebuiild. I have the same issue of whitish smoke at idle. Thing is, behind my throttle body and all inside my intake, it is oily. Also very oily in combustion chambers, I can see wet piston tops.

 

[Eric Stauch]

I am not alone

Havent posted on this in awhile, i guess cause im trying to forget because mine STILL smokes although not as bad anymore....but who wants any smoke?. turbo seals are good, had the valve covers off and all the valve seals are in place. PCV has been hooked to its own breather. so it has to be ex. valves or piston clearance. but it is with in the factory limit, so the factor would have said let it go cant imagine it being that, although lots of blow by would explain why i cant keep an oil pan gasket on the thing. went through 3 rubber ones, kept blowing them out. but i went to a cork one it stays in place jus leaks. is it law that every Buick must leak? haha. also off the subject of smoke. i have a oil leak it comes off the starter and falls on the cross over pipe. VC's are dry and so is the head gasket on the back side. im puttin a stall in it and got the tranny out so i can see very well but i cant figure out where its coming from. anyone got any ideas?