Valve Stem Seals Differences

[pkufeldt]

So looking at replacing my valve stem seals and notice a couple big differences between FelPro (SS72861) and GM Genuine (10212810,12564852) seals. First is that the GM Genuine exhaust and intake are separate product numbers and look different, while the FelPro set supposedly has both but they look the same in the pictures. And then there is the price, the FelPro price is way cheaper at $12 vs GM Genuine at $60+. Anyone have any opinions on these differences and if they matter?

 

[GoToGuy]

Are you sure the photos are the actual part, not a generic stem seal ? As in doing a wide google search or going to manufacturers Web site for actual photos. When I'm doing a parts basket at Summit, or Rock Auto, wherever, I often will cross check the parts I've chosen with the manufacturers web site , catalogs to sure I'm getting what I need.
I really, really hate wasting time returning stuff , it just creates this chain reaction of grief, irration, loss of productive time, scheduling headaches. Good luck!

 

[Erik the Awful]

The 12564852 and SS72861 are positive seals while the 10212810 are umbrella seals.

Some years GM used positive seals on the intakes and umbrella seals on the exhaust. Later Vortecs used positive seals on all the valves. Way back in the day, everything was umbrella seals.

The big difference I found between the two was seal to retainer clearance with a big cam. I used all umbrella seals on WCJr's engine because the positive seals were too thick on top.

I'd feel fine using the Fel-Pro SS72861 seals. I'd even be okay with using all 10212810 on an engine.

 

[pkufeldt]

Thanks for your recommendations, was worried there was some material/temperature differences between exhaust and intake. Didn't even notice the difference in seal type. Appreciate your pointers.

However, looking around at the differences between positive and umbrella seals I am seeing a frequent discussion around valve stems that originally come with umbrella seals, like my intake valves on my 99 Vortec, that the tolerances between positive and umbrella seals may be different requiring machining to accept positive seals. So, I took a closer look at the inner diameter specs (had to go to both rockauto and summit racing to find them). I do see on RockAuto that the GM Genuine parts have a small difference in the inside diameter 0.326" (exhaust - positive) vs 0.327" (intake - umbrella), but the FelPro (summit racing) is bigger at 0.344" (intake/exhaust - positive). Is that 0.018/9" difference gonna be a problem?

Also I assume that if I can switch the intakes to positive seals, I will no longer need the O-rings on the stems.

 

[pkufeldt]

An update.

Groveling through the service manual, I found the valve stem specs, looks like GM parts would need to stretch around the stem (0.3410 > 0.3270), but the FelPro would loosely fit onto the stem (0.3410 < 0.3440). Would the FelPro's even seal?

And I see from the service manual there are no O-rings.

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[Erik the Awful]

Keep in mind it's a rubber seal. A while back I discovered that marine engines often have .371" stem exhaust valves. A couple weeks ago I assembled those heads, and I used a set of umbrella valve seals. I forgot that the valve stems are different sizes and threw the same seals on all the valves. I didn't even realize that until now. With as well as they fit I'm sure it'll run fine.

 

[Welderdad]

Quick question regarding valve seals. I'm replacing mine this week . My engine is currently torn down to the lower intake manifold. While it was out I saw a pool of oil on number 1 exhaust valve. I'm going to go ahead and swap them all out.

My question: should I swap the valve springs, retainers, etc While I'm there? I found some cheap on rock auto and read that the L29 engine has a history with bad valve springs do to compression.

I know " if it's not broke don't fix it" . But would it be a good idea? Thanks!

1998 k3500 454 L29

 

[Schurkey]

Are you sure the oil on the exhaust valve is from the seal leaking oil down the guide?

Could just as easily be from a failed lower intake gasket drawing oil up from the lifter valley; or from oil coming into the intake manifold via crappy valve covers having no PCV oil baffles (or good baffles, and heaps of combustion blow-by, and a failed or incorrect PCV valve.)

As for replacing the springs/retainers...how many miles are on this engine? MAYBE you need to consider wiped-out valve guides are going to destroy new seals in short order. How confident are you that you won't drop a valve into the cylinder when the keepers are removed? And..."cheap" valve springs may not be as good as the ones you have doin' their job already.

 

[NMNorsse]

I just did this job on my '88 5.7. There were no exhaust seals left, just some rubber goo. The intake seals were hardened and several were crumbling. No more puffs of smoke when it starts up and oil consumption is gone.

There are 2 different part numbers for the felpro intake and exhaust seals. I think they were about $18 per set at Autozone, so under $40 in parts. Both were high temp plastic bodies with positive seals. The OEMS were rubber positive on the intakes and umbrella on the exhaust.

I bought a valve spring compressor for Harbor Freight and it worked great for $15.

I "rented" the compression tester from Autozone. Didn't use the gauge, just the hose and spark plug adapter. Removed the valve core (like a tire valve core). Hooked up my compressor to the air hose to pressurize the cylinders and that kept the valves in place while I did the work. You'll have to rotate the engine using the crank bolt until the cylinder you are working on has both valves closed. If air is leaking, a valve isn't closed. Remove all sparkplugs first so it is easier to rotate the engine. Pressurize the cylinder first, then remove the intake and exhuast valve springs. It helps a lot to have a magnet to snag the valve keepers. I'd plug all the holes in your head with rags, newspaper or paper towel before you start doing this because you don't want a drop a keeper and have to tear down your engine to get it back. Do one cylinder and one valve at a time.

This is an easy job but it is time consuming. Don't be surprised if it takes 4+ hours. Not sure what the book calls for.

After I got it running I went back and redid the valve lash with the engine running at full temp. Loosen until it clacks. Tighten until it just stops and then 1 full turn or 3/4 or 1/2 depending on what the FSM says for your year engine.

Watch a youtube video or two on valve seals and valve adjustment before you get started.

Good time to regap or replace your plugs and/or wires. The newer 'spiral wound' wires supposedly don't develop resistance as quickly so work better and last longer.

I painted the valve covers while I had them off with VHT rattle can chevy satin black.

 

[Schurkey]

...Hooked up my compressor to the air hose to pressurize the cylinders and that kept the valves in place while I did the work. You'll have to rotate the engine using the crank bolt until the cylinder you are working on has both valves closed.

If the rocker arms are removed...the valves are closed. Nothin' to push them open with no rockers in place.

BEWARE. You STILL want the piston to be at TDC of the cylinder you're working on, so that if you bump a valve and pop it open...you don't lose your cylinder pressure and both valves fall to the bottom of the cylinder. They may fall against the piston, but you stand a chance of having enough of the stem sticking up that you can pull 'em back into place and re-seal the cylinder.