I put together an LS1 engine, and bought a set of 799 casting heads that were off a 5.3L truck/SUV motor. The heads were complete cores, which I sent to an auto machine shop. The shop replaced a couple bent valves and valve guides, did a valve job, and installed new "performance" seals. I installed the heads and ran the car for about 500 miles. After a 100 miles or so, the engine started burning oil upon startup and under heavy throttle. It kept getting worse. The last 100 miles I drove, it used about 1.5 quarts of oil.

I pulled the springs off and here is what I saw:



The tops of the seals separated from the bottom of the seal's metal base. I found a total of 5 or 6 seals like this. There were another 4 or 5 where the seal was starting to separate. The rest of the seals were okay. It happened on both intake and exhaust valves. I have a stock 1999 Camaro cam, stock lifters, stock rockers, stock springs, stock locks and keepers, and stock-length Comp Cams pushrods.

I replaced the seals with the revised OEM style Fel-Pro seals:





I did NOT install the seals that failed.

Any idea what caused these seals to fail?? My only theory is that they were forced over the ridges at the top of the valve stems, tearing the seals and causing them to separate.

Any thoughts?

 

Which ones failed, only the ones with the new guides? If the distance from the top of the guide to the machined surface of the head was increased, than the valve spring forces pushing the bottom of the seal in contact with the head surface would have pulled apart the valve seals.

What type of springs? The one piece seal/seat can't be used with dual springs. Can't tell from the photos whether you have duals or not.

 

Stock springs and hi rpm can cause float. The bottom of the retainers are beating up on the seals.......

 

I think I only had two valves and guides replaced, and six seals totally failed, so the math says that at least a few of the seals failed on valves and guides that weren't touched by the machinist.

That's a good thought. However, the pics show the failed seals that I took out did not have an integral spring seat. They were little barrels that were pressed on, so the spring could not put any pressure down on the seal. The new ones that I put on have an integral seat (the look like little hats.)

Everything's stock except for the pushrods, and they're stock length. The springs are stock with the blue stripe.

I have a stock cam and a 6k RPM redline. I don't think contact between the top of the valve and the seal would be possible without more cam? The cam should not open the valves far enough for the retainers to hit the seals. I measured the seals I took off vs. the new seals I put on, and the installed height seems to be about the same.

 

The OEM type seals are best to use with oem springs since it guarantees the seal sits all the way down as it is integrated into the seat. It looks like they didnt tap the seals down over the guide far enough, and they rode up and got destroyed by the spring. It's the only thing that will tear a seal up like that. If you look at the seats they installed, there is no inner retainer to kepe the springs from walking side to side (compare to oe seat). This could also cause contact. Poor head assembly and parts choice imo.

 

I had 14 of 16 seals lift up off and they showed no signs of damage on the top. Bottoms were beat up from being forced into the guide though. Looks like the ones in the pic were torn during install unless the aren't the correct size for the valve stem. Do the affected stems show and galling?

 

incorrect valvetrain geometry or from valve float will be the two things to cause that.

 

Thanks for all the suggestions guys. Got some good ideas here that I did not think of.

Interesting theory - so maybe they were installed too shallow and the tops of the valves fully seated the seal assemblies (pushed them down) and while doing that, beat up the Viton part of the seals. Very possible.

Another interesting theory - maybe they were pushed down too deep onto the guide, and the guide tore up the Viton part of the seals.

The stems and the OD of the guides both looked fine - nothing caught my eye. I wiped the stems down with oil and I did not see anything unusual.

With all stock parts, stock cam, etc?

 

Its almost impossible to tap them down 'too far'. The seal will literally bottom out on the head (of the guide) before the viton comes close.

 

I have had aftermarket seals come off the guides on several cars, including imports. For some reason the OEM seals don't do this.

Looks like the original installer beat on them too hard and thinned out the top so they tore out once the motor was running.

 

did you check your pushrods? Are any of them bend?

 

Well the OEM style are in now, so hopefully I'll be good to go.

I had all of the pushrods out and they seemed fine. I didn't inspect them but they tried to roll away when I set them down, so I think they're still straight.

 

The machine shop setup my install height incorrectly and I had bad valve float. The inner spring spins as it bounces pulling the seal up.

I think it was previously mentioned not enough retainer to valve guide clearance will do the same thing.