changing valve seals

[Creisol]

What is the best way to hold the valves up with the piston at TDC while changing valve seals? I've heard of some feeding a rope into the spark plug hole and others using a compression tester. If a compression tester is used, how much psi should be applied? Its a 90 chev halfton with 5.7.

Thanks!

[GM-Tech]

Nothing has to be at TDC. Once you've removed the rockers, the valves will be fully closed no matter where the piston is.

 

In the shop, we use compressed air. Whatever the pressure happens to be... I don't know 120-130 psi or so? There's gonna be some air leakage, so you need a source that will keep up with that. It shouldn't be much leakage unless your rings/valves are in bad shape.

 

The rope trick works. Obviously, make sure you only turn the motor over by hand to bring the piston up and jam the rope against the valves.

[C & A s Dad]

Marc, several companies like Lisle and KD make "air hold kits", which allow you to screw shop air into the fitting, which screws into the plug hole.

[Creisol]

Ok, I removed both rockers from the #1 cylinder valves, the intake had only the flat o-ring type seal but the exhaust had that as well as the umbrella type. Should the intake valve have the umbrella type seal as well?

[C & A s Dad]

I am no Tech but I can tell you that there are two opinions on this. I have seen some of the older Techs insist that both intake and exhaust need the Umbrella style or even the more expensive positive type seals. I have also seen some Techs simply use the small flat o' ring style on both intake and exhaust.

[Festus611]

I know this is an old post and I hope someone will read it. I'm new here and cant start my own treads yet. What would it could me , about, to have somone change the seals for me. I have always worked on my own vehicle, but unfortunatly now I live in an apartment complex. I dont have the space or time to do it myself. Also, they dont allow it. When I changed my radiator it was done under the cover of darkness and by flashlight. Any help woul dbe greatly appreciated. Thanks

[Westlotorn]

Suburban 350 Engine, I suspect you can get both valve covers off without removing any accessories, like the AC compressor.

I had a 95 and the Valve covers came off easy.

If that is the case I am guessing 3 hours labor to replace your valve stem seals. Call around and see what prices to expect.

Even at 3 hours you are looking at $300.00 shop time plus parts. Valve cover gaskets and Valve Stem Seals.

 

Good Luck.