Exhaust Valve Stem Seal

tiemeyj · 09-11-2022, 05:03 PM

I have my engine out to replace a snapped tunnel brake line. While it's out I'm chasing a few leaks and other issues. I noticed a pool of oil on my #6 intake valve a few hundred miles back and swapped the existing teflon seal with a viton version which seems to have stopped that issue...the teflon seal was worn down enough to see the spring's shadow through the plastic. I think I have an oil control issue in this cylinder after a quick inspection with a borescope so I'm trying to eliminate the easy stuff before digging into piston rings / cylinder.

So now that the engine is out and on a stand, I thought I would replace the #6 exhaust valve stem seal for good measure. After pulling the spring retainers, I discovered the outer spring was impossible to remove. Seems to be too much material around the cam box stud bosses. Has anyone experienced this and figured out a solution? It's a an original 1974 2.7

Thanks for any ideas

Justin

john walker's workshop · 09-11-2022, 06:21 PM

Try harder. Some sort of grabber helps.

smadsen · 09-11-2022, 09:37 PM

Do you really need valve stem seals on the exhaust side? It's pressure, not vacuum, so oil has trouble getting down the stem anyway (unlike the intakes). Maybe a little oil down the stem is a good thing for heat dissipation & lubrication. Anything that dares to drip get blowtorched down the exhaust pipe. This is all assuming good, tight clearances in the guide/stem.

And just another thought, the exhaust valves are almost upside down anyway (or way past 90 degrees. Oil would have trouble running down the stem into the exhaust stream. Even Mobil 1 can't run uphill.

If your engine is worn, exhaust stem seals will only postpone the obvious necessity.

stownsen914 · 09-12-2022, 04:09 AM

Am I reading correctly that you can't remove the valve spring? That seems like a strange problem to have, especially if you've gotten the retainers out.

tiemeyj · 09-12-2022, 07:29 AM

Thanks for the replies. I thought it was a strange problem too and wanted to ask before the BFH came out. Smadsen - I completely agree on your point about seals. The exhaust port had significantly more carbon build up than it's neighbors. I figured it couldn't hurt to swap the seal while I'm this far in. I'm pretty certain the oil control issues is with the rings or cylinder. I was hoping to get lucky at least once. I'll leave it alone for now.