Anyone have blue smoke upon first startup?

[peppy]

Anyone else also have blue smoke come out tailpipe after the van has been sitting for a while?

I have 1991 Astro AWD.

Peppy!

[mikedamech]

Valve Stem seals, Most engines don't have exhaust ones from factory.

[peppy]

Where are they? Why not on exhaust? Are they difficult to replace/insert? How is it done?

Isnt the smoke bad for the catalytic converter?

peppy

[safariobsession]

I have a 91 and mine did that until I replaced the said valve guide seals. You might have seals on the exhaust side too because i did. It'll take some knowledge to do the seals but its sworth attempting. If it only gives you the "blue salute" when you start it up, the convertor should be fine.

[peppy]

So, are the seals currently installed somehow defective, or is this because of age?

Did you change them yourself?

Peppy

[Kidhauler]

This is due to age. You can try running some 10w40 oil that will help reduce the asmount of smoke. If you take the heads off you can have them rebuilt at nearly any engine shop for around $100 each. The good thing about having a shop do the heads is they will do new seals, valve guides, and a valve grind. It is a bit of a job to get the heads off with the engine in the van but you can do it in a afternoon if you are motivated and the shop will take a couple of days to rebuild the heads.

And despite what the other post said both intake and exhaust valves have seals and guides if they didn't very bad things would happen you would blow blue smoke all the time. Also your oil would crud up from exhaust leaking past the stem on the exhaust valve and going right into the oil which would cause massive blow by and huge crank case pressure thus causing your pcv system to malfunction. Also with out valve guides your valves would be floating around smashing into the sides of the tubes they are in and also they wouldn't seat right causing a drop in power.

[crash]

two 93's one a Z and one a W motor... both would always have a puff a blue on startup since nearly new. both still pass emissions testing no problems when warmed up so to me, wasn't worth the cost or effort to resolve and they never got any worse.

[peppy]

So, from the looks of it, a poor design... since the post above me says "since nearly new".

How difficult is it to change the seals? Anyone do it themselves?

Peppy

[WVKayaker]

two 93's one a Z and one a W motor... both would always have a puff a blue on startup since nearly new. both still pass emissions testing no problems when warmed up so to me, wasn't worth the cost or effort to resolve and they never got any worse.

my 1990 did it for 120k+ miles...no issues with emissions or performance

[Jim in Indy]

Yeah, I've done it. If you are a good wrench, (I'm a retired aircraft mechanic), plan on about 8 hours... start - to - finish.

Simplified;

pull the rocker covers & pull the rocker arms (keeping them in order).

Pull the spark plugs, and knock the center out of one of them & install an air chuck.

screw in the modified spark plug & pressurize the cylinder with about 50psig air pressure

With a clamp-style valve spring compressor, remove the keepers - retainers - springs for the intake & exhaust valve for that pressurized cylinder.

replace each seal carefully, using several drops of oil to lube it.

reinstall valve springs, retainers & keepers. use a dab of grease on the keepers to make sure they stay in place.

so the other 5 cylinders the same way. you may have to bump the engine a bit to make sure the valves are on the base circle of the cam (fully closed).

after completing all 12 valves, look at your work a couple extra times as sometimes the keepers can look fully seated but in fact, be ready to drop/pop.

reinstall rockers, torque stud nuts.

reinstall rocker covers with fresh gaskets.

Now, don't forget.... there's always a bracket to remove & reinstall, plug the oil drain-back holes with shop cloths to prevent stuff from falling into the lifter galley... things always take longer than you planned, especially if you have never done them before.

Alternative solution; Don't sweat the General Motors Salute, just think about the fine engineering that provided that little idiocycracy for you, the consumer.

[Rebel]

Now, don't forget.... there's always a bracket to remove & reinstall, plug the oil drain-back holes with shop cloths to prevent stuff from falling into the lifter galley...

=D> =D>
Good un.

Something I could never get my son to do. Guess that's why he's riding around with half of my 1/4" drive sockets in his motor. #-o

[Smiliesafari]

Now, don't forget.... there's always a bracket to remove & reinstall, plug the oil drain-back holes with shop cloths to prevent stuff from falling into the lifter galley...

=D> =D>
Good un.

Something I could never get my son to do. Guess that's why he's riding around with half of my 1/4" drive sockets in his motor. #-o

Funny, Larry.

[peppy]

Could GM repair the seals?

[mikedamech]

As hard as it is the Dealer will cost 1500.00 to 2000.00. Jim in Indy's got it right but I might add, Doesn't matter where the cam is your removing the rocker arm. One of the best ways I've done is shove a 3/8 or 1/4 inch rope into the spark plug hole, run the piston up till the rope is pushing against the valves then brace the breaker bar so the piston wont go down. If you use the air method, run the piston all the way to the top and brace the breaker bar so the piston wont move down so that if the air supply or tool you made fails the valves wont fall into the cylinder.

[Jim in Indy]

Never have done the rope trick, someday I gotta try it.

Peppy, unless you are killing the neighbors rose bushes with the Chevy 'Good Morning', just remember there are 900,000+ of these 4.3L V-6's that do the same thing everyday.... and if you do the job, it'll be back in about a year or so anyway.