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Discussion Starter #1
I know this is an easy thing to do but I havent ever changed valve seals so if you guys have any tips I would appreciate it. I have the spark plug adapter and need to rent a compressor and some hose.I'll buy a compressor tool at a parts store. Is there any thing i should know before starting this job. I figure the pistons need to be below the plug hole..Anything else?
 

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If nobody out of the thousands of members answers your question right away there's a reason so don't be impatient with the "anybody? anybody?" bumping posts.

Why do you want to replace the seals? Stock chevy seals are O-rings that fit in a groove in the valve under the retainer. They don't seal the guide.
If you are burning oil past the guides, your guides are probably worn also. You may get some temporary relief with special guide seals but they will restrict oil to the guide and accelerate wear.
More than likely you heads need to come off for rebuilding.

btw, pistons don't (and can't) go above the spark plugs. Piston should be at TDC compression and a socket on breaker bar put on the crank bolt to hold the piston up. If you don't, the piston will be forced down and more air will escape out past the skirt. Also, if the piston drops down far enough, the valves (probably) could drop into the cylinder.
 

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valve seals..

Using the umbrella type seals is a common fix...but it won't last long as Paul said. Best thing to do is get a professional opinion on the engine condition eg; compression test and leak down...that way you will know what you have and can make informed decisions.

measure twice...cut once :rolleyes:

wilma
 

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If nobody out of the thousands of members answers your question right away there's a reason so don't be impatient with the "anybody? anybody?" bumping posts.

Why do you want to replace the seals? Stock chevy seals are O-rings that fit in a groove in the valve under the retainer. They don't seal the guide.
If you are burning oil past the guides, your guides are probably worn also. You may get some temporary relief with special guide seals but they will restrict oil to the guide and accelerate wear.
More than likely you heads need to come off for rebuilding.

btw, pistons don't (and can't) go above the spark plugs. Piston should be at TDC compression and a socket on breaker bar put on the crank bolt to hold the piston up. If you don't, the piston will be forced down and the air will escape out the exhaust. If that happens the valves (probably) will drop into the cylinder.
Typically Paul, I'd agree with you 99% of the time........However. If you're replacing the seals or springs, the rockers will be pulled off so the exhaust valve won't open when the engine rotates.:no: Yes, the compressed air will push the piston down but with no rockers, NONE of the valves will open. If they do, then there's REAL problems at hand!!:D

I do recommend to anyone with a standard transmission to make SURE it's in neutral!!! Or it WILL lunge forward or backward a bit every time the air hose is connected to a different cylinder!!!!:yes:
 

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Ah...you got me on that! Yep, my brain was visualizing the similar process of leak-down testing done with the rockers on. Yes, for the spring change the rockers would be off, (unless you are just replacing intake seals). I stand corrected... however... if the piston goes down the cylinder might not seal as well at the bottom and excessive air would still leak out.

(Quickly changing the subject of my screw up)
Here's a cool, 'on engine' spring compressor from Buxton engineering ($375!):


 

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I wonder who had the idea first???


Same principal...
 

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Discussion Starter #7
So....is that yea ot nay on the umbrella style? What would be the down side of using them?
 

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Using the umbrella type seals is a common fix...but it won't last long as Paul said. Best thing to do is get a professional opinion on the engine condition eg; compression test and leak down...that way you will know what you have and can make informed decisions.

measure twice...cut once :rolleyes:

wilma
some people cant afford a pro mechanic who charges 45 to 60 dollars an hour, and what better way to learn than jumping in and doioing it yourself
 

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So....is that yea ot nay on the umbrella style? What would be the down side of using them?
You haven't said why you want to change your seals? The reason I say this is because you may be opening up a can of worms that will cost more money and trouble than you think.

I presume it's because you are burning oil and someone told you replacing the seals will "fix it". On a Chevy engine the seals are little O-rings that fit on the valve stem. They seal the retainer which on a stock engine also has an oil shield. That set up acts like an umbrella preventing excess oil from dripping down the stem and flooding the guide. The stem to guide needs a little bit of oil to stay lubricated. If the guide is worn, too much oil will get past the guide and get into the ports.

Sealing it off to stop the oil burning starves the guide of oil and aggravates wear. It's a very temporary solution. Not worth the effort and risk IMO.

More than likely if you are burning oil past the guides it's not because of the O-rings. Guide wear on old engines is common. Once the guides wear the valves don't sit square then the seats wear.

I still don't know why you are asking this question, but if you are thinking of buying a car that's burning oil and the guy who's selling it says "all it needs is new seals", walk away from the deal.

some people cant afford a pro mechanic who charges 45 to 60 dollars an hour, and what better way to learn than jumping in and doioing it yourself
I just gave him $65 worth of advice for free and potentially saved him money and trouble.

I've been answering questions here since last century and I can tell you that time and again, novices that jump in and tear things apart without knowing what they are doing do learn lessons. Very expensive lessons.
 

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Just for argument sake, I will add that there are cases where the valve springs have been replaced and no longer use the factory oil shields and an umbrella seal is warranted.

There's also times when the factory umbrella seals get hard and crumble over time warranting replacement...


But the fact remains that if it's BURNING oil......It needs more work than just a seal replacement.:yes:
 

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Discussion Starter #11
The car is not using oil in any noticeable way,when driving,it doesnt smoke. However, after driving some,and letting the car sit then restarting,it pushes some smoke mostly on the right side.Then after a couple seconds its smoke free.This is why I was thinking seals.
 

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The car is not using oil in any noticeable way,when driving,it doesnt smoke. However, after driving some,and letting the car sit then restarting,it pushes some smoke mostly on the right side.Then after a couple seconds its smoke free.This is why I was thinking seals.
Sounds like it but like Paul said....it's usually a sign on something more.... Like worn guides.

The real question is...Do you want to band-aide the problem or FIX it?
 

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Discussion Starter #13
Eventually my plan is to change the motor.A bandaid I guess would work for now.I dont want to tear it down in the middle of the driving season either.
 

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The car is not using oil in any noticeable way,when driving,it doesnt smoke. However, after driving some,and letting the car sit then restarting,it pushes some smoke mostly on the right side.Then after a couple seconds its smoke free.This is why I was thinking seals.
Smoke on hot soak startup indicates worn exhaust guides. The exhaust guides expand when they get hot. When you shut down the engine, oil drips past the guides and onto the backs of the exhaust valves. When you start it back up, the oil burns off.

If you are planning on keeping the car, you really need to fix the problem instead of the symptom.

Adding positive seals to the guide boss will cut off the oil path to the guides, but guide wear will be accelerated. You will have spent time and money to make it worse sooner. An extra quart of oil every 3,000 miles is only $3.
Save the band aid money for new heads or fixing your old ones if they are even worth fixing.
 
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