Hunting stuck valve

[RatLabGuy]

Hunting an internal air leak on #4 cyl on 88 22RE 4cyl.
If I push shop air through the spark plug hole and run through the cycle it never closes off.

Having a brain fart.... How can I find TDC where both valves should be closed on #4 cyl? Where would that be relative to #1 at TDC, as indicated by the cam pulley mark?

 

[RatLabGuy]

OK *think* I figured it out, the normal cycle of manually adjusting the valves is to set the #1 at TDC, as indicated via the mark straight up and rank notch at 12:00, do the #1 and half the #2 and 3 valves, then turn teh crank 360 - which is cam 180 - then do #4 and remaining of 2 & 3. To me that means they should be loose and closed.

Well the intake side is still very tight, can't wiggle it, and blowing shop air comes right out the intake, so this makes me think #4 intake is my culprit...

 

[Blkvoodoo]

1 and 4 are TDC at same time, 1 @ compression, 4 @ end of exhaust stroke over lapping into intake, feel the rockers for loose if 1 is on compression, both rockers will be loose if 4 is on compression


It’s not unheard of for a valve seat to drop out of position which would cause you to have an open valve situation. If you can wiggle the rockers and the valve tips on the same cyl aren’t even on believed compression stroke, you have a seat issue or a valve issue.

If the head happens to have been reman’d at some point it’s even more likely for a seat to drop especially where any welding repairs may have been done.

All lash adjusters appear to have same thread exposed above cinch nut ?

If you’re able to fit feeler gauge between rocker tip and stem after adjustment at that cyl and you still hear air when blowing thru spark plug hole, you have a seat or valve face issue. If you cannot then you’re still too tight you should be measuring at rocker tip on valve tip, and visually check that rocker follower on cam is on base circle of lobe not on ramp up or down

Turn engine and watch all rocker movement, be sure everything is actually moving, broken cam isn’t that far fetched either.

 

[RatLabGuy]

1 and 4 are TDC at same time, 1 @ compression, 4 @ end of exhaust stroke over lapping into intake, feel the rockers for loose if 1 is on compression, both rockers will be loose if 4 is on compression


It’s not unheard of for a valve seat to drop out of position which would cause you to have an open valve situation. If you can wiggle the rockers and the valve tips on the same cyl aren’t even on believed compression stroke, you have a seat issue or a valve issue.

If the head happens to have been reman’d at some point it’s even more likely for a seat to drop especially where any welding repairs may have been done.

All lash adjusters appear to have same thread exposed above cinch nut ?

If you’re able to fit feeler gauge between rocker tip and stem after adjustment at that cyl and you still hear air when blowing thru spark plug hole, you have a seat or valve face issue. If you cannot then you’re still too tight you should be measuring at rocker tip on valve tip, and visually check that rocker follower on cam is on base circle of lobe not on ramp up or down

Turn engine and watch all rocker movement, be sure everything is actually moving, broken cam isn’t that far fetched either.

Running the crank through the whole cycle and getting up and checking the intake rocker every quarter turn or so, there is never a case in the cycle where the rocker has any play. I was noticing last night that it looks like there's a little bit more screw adjuster head sticking above the cunch nut on that one rocker than on all of the others, which also makes me suspicious.
Unfortunately because I have to be under the truck to turn the crank I can't watch the rockers at the same time . Gonna have to employ a helper set of eyes.

I'm definitely suspicious of a valve seating issue.

 

[Mac5005]

A few times on an engine sitting for a while, it got rust on the back of the valve and seat, and enough to keep compression low enough to not run.

To fix, I made sure valve is not open according to cam, and tap on valve stem with hammer to get it to quickly open and snap shut to knock the rust off both valve and seat.

 

[RatLabGuy]

A few times on an engine sitting for a while, it got rust on the back of the valve and seat, and enough to keep compression low enough to not run.

To fix, I made sure valve is not open according to cam, and tap on valve stem with hammer to get it to quickly open and snap shut to knock the rust off both valve and seat.

Yep I gave it a couple love taps.
I went through and checked and set the valve lash, the exhaust side was tight on three of the cylinders. On the one in question I had to back it way off, but now it's in spec,, or at least close, given I'm adjusting cold.
Had wife watch the valve train while I ran through the sequence several times and she says everything on that one seems to be at least moving in a similar fashion to all the others. So I'm hoping at this point it's a matter of having a little carbon built up or at worst the stem is ever so slightly bent preventing it from closing but not from generally doing it's cycle.

I can't quite wrap my head around why it would tighten. Loosening I can see. But is it possible that if the clearance is so tight it actually never is able to come all the way up to close?

At this point I think the only thing left to do is run a little cleaner through it and see if that helps. Anything that is useful to pour in or do while I have the valve cover off?