Jump to content

Improved L6 Valve Stem Seals

Recommended Posts

Does anyone have any pictures of how these "improved" seals should look installed? I've already installed them and I'm not sure if I pushed them on too far or not far enough. Thanks.



95 impreza

81 zx turbo (brother's new toy)

02 kawi

Link to post
Share on other sites
  • Replies 69
  • Created
  • Last Reply

Top Posters In This Topic

I purchased these seals and right now I'm not to sure letting some one else install them when I get my valves done. So I've got a ford valve guide on order and will see how these things go on the right style of guide. I plan on machining what ever ford has on there guide into my new z guides to insure proper seating. Just my 2 cents.








Link to post
Share on other sites
  • 3 weeks later...
  • 9 months later...

No pictures...I didn't even think about it when I got around to installing mine. I installed mine and you'll get a good idea of how far they need to go on. if you go too far you'll know it and the seal will pucker just a bit. Pull it back up just a hair and all will be fine. I don't have a lot of miles on my car since the new seals, but have had zero problems as of right now

Link to post
Share on other sites

I began tearing into my engine in the first place because I had very heavy carbon deposits on top of the valves. I've been told this happens because of leaking valve stem seals but not sure so I 'upgraded' to these ford seals. I now have about 800 miles on the complete rebuild. I pulled the intake off the other day and noticed the carbon deposits were coming back. I even took the effort to polish the valves to help deter this from happening again. So if leaking valve stem seals causes this then the Ford seals have failed. Now this could obviously be a variety of reasons from user error to worn valves to seal fit to ??? but thought I would relay my experience.



Link to post
Share on other sites
  • 2 years later...
  • Administrators



Some issues regarding the “installation” of these seals has been noticed…


The Felpro VITON stem seals were not designed for the L-series, but for Ford V-6 engines. They will work on the L-series and are desirable as they are shorter allowing more retainer to seal clearance, the Viton material is much more resilient and a longer lasting material vs the OE specified seals which generally a Poly Carbonate that becomes brittle over time. When installing the Viton seals, extreme patience and care is required. I’ve installed literally hundreds of those stem seal on L-series heads and learned the hardway, i.e. more than few sets of stem seals trashed during the learning curve. Here is my current procedure for installing these seals.



1) Always use the stem seal condoms over the valve stem to protect the seal from being cut as it passes over the keeper groove. For the L-series, I always cut those stem condoms down to half their length.


2) The top of the guide AND the inside of the stem seal need a thin film of oil.


3) “Carefully and gently” ease the seal down the valve stem till it contacts the valve guide. Now with even more care and precision, and bare hands, grab the metal perimeter of the seal and spin it while pushing against the guide. This will help just start the seal over the guide. This is not a 100% guarantee it will go one without any issues but it does reduce the tendency of the inner rubber to tear and bunch up on top of the guide as it is being installed. Trust me on this!!!


4) Now that you have the seal started on the guide, using your seal installer, (bare hands will NOT push these seals on all the way) the normal tendency is to push them on all the way! Resist that temptation with all your might as the Datsun guides will bulge the top of these seals out, sometimes off to one side leaving a gaping hole between the seal and the valve stem for oil to drain down the guide an into the port and this is also when those springs pop off.


5) Some of these seals are green, some are black, (no idea why the difference, its just what I’ve seen in all the ones I’ve installed, all the same part number). If you notice that the green or black portion has been overly stretched, evidenced by the white stretch marks near the metal shield surrounding the seal, the seal is no longer any good and needs to be replaced.


6) When installing these seals, it is imperative you have an extra set on hand as it is inevitable one or two will get boogered up during install. Some times I can build 5 heads with not one issue, then I can build up 2 heads in a row and end up trashing a couple seals per head.


7) Again, scrutinize the installation of these seals very carefully as they are very finicky and easy to screw up.



For mild lift cams on engines that wont see more than 100,000 miles, the poly carbonate seals are a no brainer choice, in my opinion.




Here are a couple pics of this seal improperly installed, spring has popped off…


This pic below shows the bulging of the green rubber from being installed to far;





This pic below shows the gap surrounding the valve stem as a result of the bulging from being installed to far down, i.e. there is more clearance between the valve stem and seal than there is between the valve stem and the valve guide itself!!! You can make out the top of the guide through that gap!!! Oil burner for sure!!!





This pic is of the condoms and also shows a normal Viton seal, i.e. NO bulge and spring is intact…





This pic shows the FelPro Poly Carbonate and the Viton seal side by side. You can clearly see the height difference.



Link to post
Share on other sites
  • 2 weeks later...
  • Administrators
BRAPP, you say these seals are very easy to mess up. For those of us rebuilding a motor and not using a high lift cam, are the O.E. style seals that much easier to install? That is, enough to warrant using the older, perhaps not quite as good, stock set in favor of a bit more user friendliness?


Absolutely. If you don't need the shorter stem seal and 100,000-150,000 miles between overhauls is acceptable, I prefer the OE style seals. How many of us that "drive" our cars spiritedly actually put more than 100,000 miles on the engine before it gets torn down again for rebuild/upgrades?

Link to post
Share on other sites

just thought i'd mention that most FelPro nissan exhaust seals are Poly Acrylite and not Viton like their intake valve seals. Says so on their packaging bags!


The Ford seals look like intake valve seals, but Viton usually doesn't have a problem with the heat that is transfered through the valves/guides upto the seal, so they will work good for that application.


I found a neat way to resist damaging a seal while installing is to take your old seal and turn it upside down and put it over-top the new seal and hit that with a socket. also, cut a straw and feed it over the valve stem before putting the socket on it. the squareness and the rough casting of some shitty sockets will mar the stem and that's not a desirable thing. the seal against seal contact will prevent damage to the tightening springs and will allow the top of the new seal to slide down evenly and concentrically around the valve guide and valve stem. carefully move the valve down first, and then slightly pop it up like a millimeter to see if the valve will bulge itself. if it does, you went too far (too late, anyways!) and if it doesn't bulge up, then give the valve some action over and over again to make sure it stays that way.


I've never had a problem with nissan valve seals doing it this way and it's the method I used the first time on a friends 1.2L Micra engine and it worked out fine.


It may take an extra 20 minutes to do an entire head, but hey... works for me since I'm slow already!


sucks that the cars rings are leaky though :-( sweet little car.

Link to post
Share on other sites
  • 3 months later...
One question. Would you guys recommend the Ford Felpro seals for an '83 L28ET that is driven fairly frequently with stock cam? If it is an upgrade then it is a no-brainer, but you speak of the stock being fine in some cases.

I have no love for the stock seals. I'd put these in any motor I built now that I know about them.

Link to post
Share on other sites
  • 2 months later...

  • Create New...