Valve Stem Seals

I pulled the valve covers on my 302 (car had been sitting for close to 10yrs and when I fired it up it was smoking pretty bad). I read on a previous thread that sometimes the oil drains will be become clogged and that could cause some smoking. Anyway, when I pulled the valve covers I found small chunks of plastic underneath. Another thread indicated that this was most likely the valve guides/seals. I came across several tutorials on how to replace the stem seals and I "believe" that it seems pretty straight forward.

My questions for you guys is:
Which Valve Stem Seals do I need? (Stock heads 1971 302)
Should I pull each spark plug first and see if they have any oil on them? Replace the seals for the ones that do or do them all?
Does anyone have a part# for the air compressor adapter I would use to screw in to the spark plug hole?


I know it is a lot of questions... I'm trying to do as much as I can myself without depleting my bank account to much. Thanks for the help!

 

pull the heads get a valve job done while you are at it you will not regret it later

 

I would perform a dry then wet compression check first. If all looks good then do like Old Goose said and perform a complete valve job.

If you want to tackle just the seals you will need an air hold fitting (Jegs 555-80522 KD Tools #901) or some use a piece of rope and feed it into the cylinder then gently turn the crank by hand to hold the valves in position. You will also need a air compressor, spring compressor, small screw driver and a magnet to remove the valve keepers. Use the stock style umbrella seals as the newer style will require machining to install.

 

Thanks for the suggestion. Pulling the motor and valve work just isn't in the budget yet....

 

Hi mikal. Not trying to squash your enthusiasm for a low budget fix here because we've all been there at one time or another.. but those factory umbrella seals didn't/don't do a very good job on a fresh engine.. much less one that is heavily used one with worn guides and valves/seats. They're a low budget seal that got phased out for very good reason.

Now, obviously it will be better than not having any seals at all, especially on the intake valves, but I believe you'll find that the gains will be minimal for the amount of time invested into replacing them. It will likely slow the major leaks.. but that's about it.

When/if you do have the seals done when the heads are removed?.. make sure you go to a positive type seal that stays permanently attached to the top of the guide rather than these types that move up and down on the stem. They're basically a plunger which pushes oil down the guide.

The rope method works best for a low budget time sensitive approach such as you're trying to achieve here. Good luck with it all.

 

Thanks! I realize that it probably won't be a long term solution (the long term will be a complete rebuild/crate). Is there a o-ring type gasket that should go on before the spring retainers?

 

no. The better style umbrella seals are made of rubber instead of plastic though.

IIRC.. there are some Viton styles with small ridges that act as wipers to get you closer to the positive style seals efficiency levels. I don't use them any more these days and would be worth searching around rather than just ordering the cheaper stuff. Might help the final outcome and buy you more time before they start leaking again. I wouldn't expect much more than around 20-30k mile lifespans from them.

PS. you also need to be very careful as they are slid over the stems because the valves key notching will slice and tear away the seals bore and result in poor sealing. They make a cheap plastic "seal guide" that slips over the top of the valve to protect the seals during installation. Kind of like a straw with a rounded end and some gasket/seal kits likely come with them.

 

Thanks! You've been very helpful!

 

I don't think anyone mentioned it yet, so here goes.

Drop the oil pan and remove all the chunks of rotten seal that have worked their way down there, and clean the oil pickup tube screen.

That is where all those broken chunks of plastic end up.

 

That man.. ^.. makes a very good point.

 

The other problem you have is if the guides are badly worn every time the intake valve opens the piston acts like a vacuum cleaner sucking oil down into the cylinder.No seal will stop it,a temporary fix at best,hope you have good luck w/ whatever you decide to do.