Valve seals ???
Thread Starter
Drifting
Joined: Jun 2001
Posts: 1,625
Likes: 1
From: Zagreb, Croatia
Valve seals ???
I allready asked this question but it still isn't clear to me.
What is the purpose of little o-rings that are on valves?
I believe that they won't protect from oil geting into
chambers.
And why are real seals ( with metal ring on it ) only
on intake valves?
What is the purpose of little o-rings that are on valves?
I believe that they won't protect from oil geting into
chambers.
And why are real seals ( with metal ring on it ) only
on intake valves?
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Valve seals ??? (Sliding)
Hmm, that's a little different from my '88 L98.
My L98 has the lower oil seals (fit over the valve guides with a metal band around them) and the upper oil seals (O-rings) on intake & exhaust valves. My valve springs also have the tin "oil shedders" on top of the valve springs.
I'm not sure what purpose the O-rings serve; maybe to help seal under the oil shedders.
Anyway, I tossed the oil shedders and replaced both the lower oil seals and the upper O-rings with OEM parts from my local Chevy dealer.
Do you have a GM Shop Manual, as it will show the valve spring details for your year L98?
My L98 has the lower oil seals (fit over the valve guides with a metal band around them) and the upper oil seals (O-rings) on intake & exhaust valves. My valve springs also have the tin "oil shedders" on top of the valve springs.
I'm not sure what purpose the O-rings serve; maybe to help seal under the oil shedders.
Anyway, I tossed the oil shedders and replaced both the lower oil seals and the upper O-rings with OEM parts from my local Chevy dealer.
Do you have a GM Shop Manual, as it will show the valve spring details for your year L98?
Thread Starter
Drifting
Joined: Jun 2001
Posts: 1,625
Likes: 1
From: Zagreb, Croatia
Re: Valve seals ??? (65Z01)
I don't have the manual. :(
But I'm sure that it came like that from the factory, with seals
only on intake valves.
And I never had any smoke from exhaust and no oil consumption.
:confused:
Maybe somebody with '90 Vette had the same confusion!!
But I'm sure that it came like that from the factory, with seals
only on intake valves.
And I never had any smoke from exhaust and no oil consumption.
:confused:
Maybe somebody with '90 Vette had the same confusion!!
Drifting
Joined: Feb 2003
Posts: 1,976
Likes: 2
From: San Antonio Texas
Re: Valve seals ??? (Sliding)
The seals are on intakes because the valve guides are exposed to vaccum, where as, the exhaust are not. Any oil trying to pass down the exhaust valve guides, gets pushed back up, by the exhaust pressure. The o-rings do stop oil from leaking through the guides, and should be used.
:chevy
:chevy
Drifting
Joined: Feb 2003
Posts: 1,976
Likes: 2
From: San Antonio Texas
Re: Valve seals ??? (Sliding)
Correct...If they are good, and working correctly, they will allow only enough oil past to lube the stems. Of course when they're worn out, you get smoke. An ole' timers saying was...smoke on acceleration-rings....smoke on deceleration-seals or guides. Smoke on start up is usually seals or guides too.
:chevy
:chevy
Drifting
Joined: May 1999
Posts: 1,697
Likes: 1
From: Joliet IL
Re: Valve seals ??? (Sliding)
When I was doing the cam on my car, I replaced the springs and seals also. The intake and exhaust seals were different part numbers. Can't remember which, but one set was red and the other were black. These were directly from GM.
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Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Valve seals ??? (Sliding)
So unbrella seals likely fit most L98s but till '90 the L98 (like my '88) had lower seals on both intake & exhaust.
Anyway a GM dealer should be able to sell you the correct set of seals for your L98.
Anyway a GM dealer should be able to sell you the correct set of seals for your L98.
Advanced
Joined: Mar 2003
Posts: 86
Likes: 0
From: lakeland fl
Re: Valve seals ??? (65Z01)
the umbrella seals are the OEM setup; I installed a Fel-Pro set, with Viton seals, so both the intake and exhaust has the positive seals instead of just the intake. No real difference in performance, but I figure the Viton should last longer, and it just seemed less crude than the umbrellas.
Instructor
Joined: May 2001
Posts: 136
Likes: 0
From: Raleigh NC
Re: Why 16 umbrella seals
Some good reading...... http://www.automotiverebuilder.com/ar/ar79842.htm http://www.federal-mogul.com/cda/con...6_7501,00.html
and a cut/paste from the 2nd link
A common misconception is that exhaust valve stem seals aren't as important as those on the intake side because they don't operate under a vacuum. On the contrary, exhaust gasses rushing past the valve create a low-pressure area near the lower end of the valve guide, which tends to draw oil into the combustion chamber.
and a cut/paste from the 2nd link
A common misconception is that exhaust valve stem seals aren't as important as those on the intake side because they don't operate under a vacuum. On the contrary, exhaust gasses rushing past the valve create a low-pressure area near the lower end of the valve guide, which tends to draw oil into the combustion chamber.
