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Topic: Valve guide seals

in Forum: C4 Engines


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Valve guide seals (1/8)
 10/18/10 4:07pm
Lenny_WV
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Princeton, WV - USA

Vette(s):
A 1986 coupe currently with 60,000 miles, purchased in August of 2010. G44 - Rear axle 3.07 ratio, Z51 - Performance handling package, FE7 - High performance suspension, FG3 - Preloaded gas shock absorbers, to name a few.


Joined: 9/29/2010
Posts: 17

Just wondering... has anyone else had trouble with valve guide seals?  It's an '86 that is totally stock with 59,000 miles.  It smokes for about 10 seconds when started up after sitting for a while.  Are they a big deal to have replaced? 

Thanks


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Valve guide seals (2/8)
 10/18/10 6:33pm
eddie20890
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lanoka harbor, NJ - USA

Vette(s):
1990 L-98 white/ red/black leather interior targa top auto 1975 L48 blue/black leather interior t tops auto


Joined: 3/22/2009
Posts: 1363

is it oil that is smoking? just another question...does it smoke at all when it shifts or when you pull your foot off the gas? these are other signs of worn valve seals. i would imagine they are just like any other seals to change.

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Valve guide seals (3/8)
 10/18/10 7:48pm
Lenny_WV
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Princeton, WV - USA

Vette(s):
A 1986 coupe currently with 60,000 miles, purchased in August of 2010. G44 - Rear axle 3.07 ratio, Z51 - Performance handling package, FE7 - High performance suspension, FG3 - Preloaded gas shock absorbers, to name a few.


Joined: 9/29/2010
Posts: 17

To be honest I haven't really looked when it shifts or I lift off the gas.  I'll have to pay attention next time I drive it.  The smoke on start-up is blue and definitely looks like oil smoke.  Thanks for the answer, everyone seems nice here and I look forward to learning a lot about my new toy.

Cheers,
Lenny
Valve guide seals (4/8)
 10/18/10 10:33pm
Adams' Apple
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Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2230

Smoking on startup, especially after idling for a few minute, definitely points to valve seals. As Dave(eddie20890) says, you need to look and see if it smokes on coastdown when you let up off the pedal. That's a sure sign of seal failure, and possible guide wear.
Teh seals are not that hard to change, but it requires a special tool to remove the valve springs, and an compressed air to hold the valves up in the head while changing the seals. Changing the seals can certainly be done on a lazy Saturday.
 You may also want to have a look at your PCV valve. If it is stuck, or gummy, it can allow too much oil vapor into the intake tract, which can puddle after shutting the engine off, and create a whiff of smoke on startup.


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Re: Valve guide seals (5/8)
 12/29/12 6:57pm
The Car Whisperer
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Andover, MA - USA

Vette(s):
1986 Coupe


Joined: 3/22/2009
Posts: 50

I had the same problem, drove my 86 Vette like that for years with the smoking at startup.  Performance was not impacted so I drove it that way.  Smoke went away after a few seconds.  I did replace the valve seals over last winter.  Not a difficult job, just had to take it step by step. I will tell you that the factory seals were no longer even remotely tight to the valve stems.  They were very loose and of course the oil was getting right by them.   New seals are tight to the stems and sealed tightly to the valve stem guides.  If you do it yourself it's not an expensive job, just takes time.  The results were worth it, no more smoke at all, added zero oil over the 3000 miles too!!!!  My motor has only 59,000 miles on it, but the valve seals were totally cooked
I attached a really good guide to replacing valve stem seals I found on the internet.  Follow this and you won't go wrong.


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1986 "Bright Red" COUPE - Aluminum Heads,
Sport Seats, Bose, Ultra-Flo Exhaust,

Automatic, Bilsteins - "Mostly Original" otherwise.

Re: Valve guide seals (6/8)
 1/1/13 11:50am
eddie20890
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lanoka harbor, NJ - USA

Vette(s):
1990 L-98 white/ red/black leather interior targa top auto 1975 L48 blue/black leather interior t tops auto


Joined: 3/22/2009
Posts: 1363

thanks for the link. always good to get as much info as you can.

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the dynamic duo


c3vr life member #97
Re: Valve guide seals (7/8)
 1/4/13 6:01pm
jonneyone
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galion, OH - USA

Vette(s):
1984 base coupe 17,000 miles all original. very low production number.red on red 3853. pro num.


Joined: 5/31/2012
Posts: 413

Does the motor rattle on acceleration? does it only smoke at first start up after sitting for a day or over night? what causes this, is the valve seal could be dried up from heat.  oil runs down the valve guild and sits on top of the piston.thats why when you start it up after sitting for a day or over night the oil sitting on the piston burns with the fuel mixture.  you can change out the seals with out removing the heads. makes me wounder if the valve guides are worn out to. when you go to change out your seals once the valve spring and seal is off check for play in the valve stem and guide. if its only the seals, make sure you adjust the valves correctly after assembly of the seals.look at the web sight that was suggested on the other post. if you have the tools and knowledge its not a hard job to do.shouldn't take more than 7 to 9 hours. of course this depends on your mechanical expertise .



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Re: Valve guide seals (8/8)
 1/4/13 6:57pm
The Car Whisperer
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Andover, MA - USA

Vette(s):
1986 Coupe


Joined: 3/22/2009
Posts: 50

I found the most difficult part of the job was threading the air hose into the spark plug hole. Because I have the Aluminum heads on my engine I was worried about cross threading, and with the tight quarters and the stiffness of the air hose when trying to bend it out of the way it was nearly impossible to get the feel need to start the hose with your fingers.  What I did was purchase a spark plug anti-fouler and threaded that into the spark plug hole first.  It was easy to thread in compared to the hose, then I threaded the hose into the anti-fouler without any worries about cross-threading.  Made the job real easy.  Other than that, as stated previously, it's a rather easy mechanical job.  In my case the seals were just worn out from age and heat, no excessive play in the guides that I could detect, but then it's difficult to check that when you have the cylinder full of compressed air and the valve is firmly seated against the valve seat.  As I may have said in a previous post, the motor didn't burn any oil over the summer after doing this job. No more smoke when I start up when leaving car shows and cruise nights!!!!!!!

______________
1986 "Bright Red" COUPE - Aluminum Heads,
Sport Seats, Bose, Ultra-Flo Exhaust,

Automatic, Bilsteins - "Mostly Original" otherwise.

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