My 87, 90,000 miles smokes briefly at start up. I know it needs valve seals. Slight leak, few drops of oil underneath. Hoping to what until next spring to do valve seals. Would adding a stop leak to oil help for a short term fix or is this a bad idea. Not a daily driver, only 4,000 or so miles per year. Thanks

 

I'm only a shadetree,but I've always been told that stop leak is a BAD idea because it may stop up areas that can be harmful to your engine.

 

Having had the same symptoms on my 85, I changed the valve seals myself this spring. Just took my time; it's not too difficult. This is a good opportunity to inspect valve springs/dampeners, valve guide clearance, etc. Based on the condition and hardness of the o-rings and valve stem seals (some of the o-rings were even cracked), there is no way that a 'mechanic in a bottle' would have done anything to soften these seals as the products suggest they will. I'm not a believer in these kinds of 'fix-it' additives, and would be concerned more about what other problems might arise by using them. Just my .02...

 

Yes, I kinda doubted the claims made by these products, just thought I would get opinions to back it up.
Thanks

 

Most of the Stop leak products (for engine oil seals) wont plug anything, they have stuff in them that reactes with rubber. The idea is it will slightly swell the rubber seals to make them "seal" again.. I have used it in some junker cars to mixed results. I had a rear seal in a Mazda that leaked bad, and i didnt want to pull a couple hundred dollar car apart. I ran som stop leak through it, took 2X and suprisingly the car has pretty much stopped leaking. This car also puffed a little on start up and now doesnt do it. How long this will last, I have no idea? My 87 (hmm two 87 smokeing, mine is 93,000) also smokes a little at start and I have also been thinking about it. I must admit, I have had good luck in cars I care little about (done it 3X and it did iprove each time, but the Mazda story is the best, the others where not so pronounced). I dont think its going to seal up anything (the radiator stop leaks of yesteryear used to do that and cuase all sorts of problems, hence most stop leaks have a bad name). But I cant say one way or another, anything is possible, and you have to decide if its worth risking.. I dont think its going to harm my car, but even so, I'm still sitting on the fence and havent done it yet. Most miracle cures are to good to be true. but I honesly have had some luck with the stuff.

 

This link might be of some help, www.vettenet.org/vlvseals.html

 

Sounds to me like the symptoms are easily ignored until you're ready to do the big job. Quit looking out the rearview on startup and keep an eye on the dipstick. Don't forget it's an old Chevy and this is what they do.

 

Not a bad write up but one important piece of information is missing. When re-installing the compressed valve spring and retainer, the new o-ring should not yet be installed on the valve stem. The retainer has to be positioned below the o-ring seal so if the seal is already there, you'll be forcing the retainer over the o-ring, most likely damaging it. Once the compressed valve spring and retainer are placed over the valve stem, then install the new o-ring and the keepers and slowly release the compressed valve spring which will press the retainer up underneath the o-ring - creating the seal.

 

My 87 had the same puff on start up at 35000 miles. I lived with it for years. At around 85000 miles it was my excuse to do heads, cam and intake mods.

 

Now, will this valve seal leak lead to plug fouling?

 

not likely