Replacing valve seals without removing cylinder heads

["Cadillac Kid" Greg Surfas 15364]

A while back someone was asking about replacing valve seals without removing the cylinder heads.  At that time I mentioned the recommended factory tool to compress the springs so that keepers and retainers could be removed and the seal replaced.  I finally got around to taking a couple of shots of this tool and here it is.
Greg Surfas

[Jay Friedman]

When you do that, don't you have to have air pressure in the cylinder through the spark plug hole so that the valve doesn't just descend into the head as you compress the spring. 

If I remember correctly, when I had a seal replacement job done on my '49 many years ago, the mechanic screwed a special fixture (one way valve) into each spark plug hole in turn, connected an air hose to the fixture, and only then compressed the spring.

["Cadillac Kid" Greg Surfas 15364]

Jay
That’s correct. There was a thread on this subject a while back and this tool was mentioned. I finally got around to posting a picture.
Greg Surfas

[chrisntam]

Must be nice to be in Hi-Wy-ya for so long!



When will the Texas summer end?  It's 101 in Dallas today...

["Cadillac Kid" Greg Surfas 15364]

A cool 100 here in San Antonio. I’ve been getting a couple of “car”
Hours in, in the AM so I’m easing on down that road.
Greg Surfas

[Scot Minesinger]

Greg,

Thanks for posting, is there a place to buy this? 

[savemy67]

Hello all,

The photos below show my adapter for getting compressed air into a cylinder, and the hose attached to the adapter in the engine.

The adapter is a spark plug.  I drove out the electrode/porcelain, and threaded in a 3/8 NPT x 1/4 NPT reducing bushing.  Into the bushing I threaded a 1/4 NPT male quick connect plug.

Don't use too much air pressure.  You don't want to drive the piston down in the cylinder.  You just want enough pressure to keep the valves in place when compressing the spring.  30 to 40 PSI should work.  Adjust as needed to suit your springs.

Christopher Winter

["Cadillac Kid" Greg Surfas 15364]

Scott,
Bought mine from Kent Moore.
Using this tool and the "heads on" method is great for say one valve spring or seal, but I have found that usually for more than one or possibly two, pulling the heads and doing a complete valve/spring/seal and possible valve guide job pays off in the not too long run.
Greg Surfas

[The Tassie Devil(le)]

My tool is a bit more aggressive.  I silver-soldered the air line fitting into the spark plug.

Bruce.

[chrisntam]

Here's my tool.

["Cadillac Kid" Greg Surfas 15364]

The heat getting to you Chris?
LOL. Actually in the long run, pulling the heads is no more costly than trying to do individual valves.
Greg Surfas

[Big Fins]

Actually in the long run, pulling the heads is no more costly than trying to do individual valves.

Till an exhaust manifold bolt snaps off....Then it's, 

[klinebau]

I used this valve spring compressor with a double-ended stud.
Compressor:  https://www.jegs.com/i/JEGS/555/80521/10002/-1
Stud:  coarse ( 7/16-14, UNC ) on the bottom and fine ( 7/16-20, UNF ) on the top

Here is the procedure I used and it was surprisingly easy:
1.  Make sure both valves are closed and introduce compressed air into cylinder.  Piston at bottom of travel worked best for me.  Unless piston is exactly at TDC, the compressed air tends to rotate the crank.
2.  Remove T-pedestal bolt and remove pedestal, rockers, push rods (keep track of the locations of the rockers and push-rods so that they can be re-installed in same position)
3.  Thread in double-ended stud into T-pedestal bolt hole
4.  Thread spring compressor on stud and compress spring.  Use a magnet to remove keepers.
5.  Remove spring and replace valve seal
6.  Reinstall spring and keeper. Then reinstall push rods, T-pedestal and rockers
7.  Move to next cylinder in firing order and repeat above steps

["Cadillac Kid" Greg Surfas 15364]

Kurt,
If I am not mistaken that tool is for use for stud mounted rocker motors such as Chevrolet's. As far as the procedures, pulling the "T" pedestals will of course close the valves regardless of the engine's rotary position.
John,
Not to be argumentative (as I know you hate to be)-Ha) but IF you break off any exhaust manifold bolts in the process of removing the heads they are much easier to remove with the heads off.  If I am not mistaken I believe my machine shop has charged me something like $25.00 per bolt extraction.
This thread was not intended as a discussion of the task, just an update of the tool mentioned in the previous post concerning valve seal replacement.
Greg Surfas

[klinebau]

If I am not mistaken that tool is for use for stud mounted rocker motors such as Chevrolet's. As far as the procedures, pulling the "T" pedestals will of course close the valves regardless of the engine's rotary position.

You are correct on both accounts.  I threaded a stud into the T-pedestal hole in order to to use the tool.  It worked great.  I think it is easier to remove the T-pedestal with the rocker not loaded on the spring.

[TJ Hopland]

Many compression and or leakdown kits have quick connect air fittings on them so they can be used for this purpose.   They often do have a one way valve which is basically a tire valve stem that has to be removed to use them this way but that is easy to do just don't loose it.

Ideally you do want to try and find a way to lock the engine while you are working.  If you let the piston go down and something sticks while you are working on the valve and it opens you could end up with the valve falling all the way down in some engines.   If you work with the piston up it can't fall but the engine suddenly turning could decompress the cylinder enough that the valve will then fall.   Don't ask how I know this.