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I have that age old problem in my L-82. When you start the engine, you get a cloud of oil smoke for a second, then disipates with a few throttle revvs. I've been told there are 'umbrella' style valve stem seals out there that are relatively easy to install, and work quite well in eliminating the oil draindown. Which seals have been used as replacements with the heads remaining on the block, and is it a relatively easy repair?
Thanks,
Mike
From: Fairview Heights Illinois, near Saint Louis MO, STL C3 Shark
I used them once and they worked for about 3 months, then the smoke came back. but I think mine had REALLY worn valve guides. If yours smokes at first, then goes away, it would be worth a try. I think I had to get a spring compressor, or the air compressor in the cylinder to keep the valve from falling in the cylinder.
Basically, you do it 1 cylinder at a time. Remove the spark plug, Bring the piston to TDC, and use an air compressor adapter or a piece of rope in the cylinder to keep the valves from falling in the cylinder. Remove the rockers, valve keepers and springs. Replace the seals. Replace the rockers. Do the next cylinder. When all are done, do a valve adjustment. Put the valve covers back on.
Personally, however, I viewed bad valve seals as a good excuse to do a cylinder head swap!
As already mentioned. Bring the cylinder you work on to top dead center. This will be your last chance to stop a vavle from falling down. The air should keep it up, but some of the vavle stem locks where so tight that I cracked the valves open when trying to release the spring.
You can see the cracked umbrella seal(s)
You see the air hose going to the spark plug hole. I used a old spar plug, broke off the ceramic and drilled a hole through. Welded a quick disconnect air fitting to it. ( you may also buy a adaptor )
I have that age old problem in my L-82. When you start the engine, you get a cloud of oil smoke for a second, then disipates with a few throttle revvs. I've been told there are 'umbrella' style valve stem seals out there that are relatively easy to install, and work quite well in eliminating the oil draindown. Which seals have been used as replacements with the heads remaining on the block, and is it a relatively easy repair?
Thanks,
Mike
Do you know how many miles are on the engine?
Original heads?
If it's high mileage, chances are you need valve/guide work.
With worn valves stems and/or guides, seals will help for a short while but will fail.
For the money, one of the best seals out there for this purpose are the Vega valve seals. Baring serious valve guide wear issues, they work well, last a long time and are pretty easy to install.
Thank you all for the insight. I'll go the replacement route right now and see what happens. Don't be surprised that in a year from now you see a thread..."What kinds of aftermarket heads flow best".
Mike
I believe the actual seals you are asking about were designed for the small block Ford. The factory seals you have are just like a flat "O" ring that fits in a groove in the valve stem. Fel pro sells the seals. When You buy a full gasket set for small chev engine they give you both type seals. This is an old machine shop trick that was adopted as standard fare. And you can do it yourself. You can check with a local auto supply such as Auto zone ,they might even lend you the valve spring compressor.
I have that age old problem in my L-82. When you start the engine, you get a cloud of oil smoke for a second, then disipates with a few throttle revvs. I've been told there are 'umbrella' style valve stem seals out there that are relatively easy to install, and work quite well in eliminating the oil draindown. Which seals have been used as replacements with the heads remaining on the block, and is it a relatively easy repair?
Thanks,
Mike
Mine puffs blue on a cold start and when down shifting. Bought from original owner. Came with dealership bill of sale and a stack of maintenance receipts from dealership for annual spring checkup. At 38k on the odometer I'm hoping its the 45 year old seals.
2020 Corvette of the Year Finalist (performance mods)
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Viton valve seals are what the Head companies use. They have to machine the stem to accept them as they are press on. I think its $70 a head at my machinist. They can check you seals and seats while they have them. I lapped my seats when i got them back
Last edited by Rescue Rogers; Feb 9, 2023 at 11:43 AM.
if it smokes on downshift it is bad guides. engine vacuum sucking in the oil. the exhaust just about don't need seals. no vacuum there. boat guys don't even run seals on the exhaust valves. wiggle the valves. a tiny tiny bit of movement sideways is barely acceptable. if they wobble, accept the fact that your new head thread will be posted soon.
The small rubber o-rings were used by the factory to seal the stem to the metal umbrella. The rubber falls apart after the years and allows the oil to drain down the stem and leak past the (now worn) intake valve guides. They make an aftermarket larger rubber umbrella seal that rides on the valve stem under the retainer. They will work for a while. If I wanted the cheap band aid fix for oil burning I would add the aftermarket rubber unbrellas and also replace the factory o-ring at the top of the stem. The rope in the spark plug hole trick is what I use. The screw top valve spring compressor works great for stock valvetrains.
4th owner who knows right ? you can throw some new umbrella's on there and see what happens, or if you pulled the heads off the machine shop can machine the top of the guide to fit the Viton seals and correct loose valve guides if there is a problem and really be done. My 80 L82 does the same thing , I haven't pulled mine apart yet but I already have some 80 L82 heads from my other 80 L82 that I had freshened up with Viton valve seals ready to bolt on
if you have to pay somebody to do the guides, toss the heads and buy aluminum. along with guides they need valves and seats cut at the very minimum. and that is to have an OE head that is, let's say suboptimal... skip white starts with decent chinese castings and builds a good head with good parts. the ebay complete heads are 50 bucks more than the bare castings. i don't mind chinese heads. not so fond of chinese valves and springs, etc.
Thanks for all the feedback, appreciated. Last time I did valve guide seals was in the early '80s on a camero. I still have the tool Stingr69 posted. Now I need to remember how I did it. I think I'll pull the valve covers and check the stems for play. If I remember correctly there shouldn't be any. If there is I'll replace the heads and then no more issues.I'd much rather drive my car than work on it!
if there is more than a couple thousandths play, throw the seals on anyway. then it is a running car while you decide what you want for heads...
Good advice for sure derekderek. Before I bought my car I looked at quite a few of them. I didn't want a project, I wanted something I could drive and enjoy. I paid the original owner exactly what he paid when he bought it new. No regrets. I've had faster cars but NOTHING that handles like a corvette. I can only imagine what the new ones must be like. .
Valve stem seals??
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