: Valve keepers fell off! But valve still in there!



YueIBM
01-13-10, 01:03 AM
Hi everyone!

I took the cam off and found a valve keeper floating with no sign of the valve stem! (no wonder I had no compression)

Somehow the valve is still hanging in there and didn't fall inside the cylinder.

Should I just stuff some rope in the cylinder (or use compressed air) to keep the valve in place while I reattach the spring and valve keeper?

I've never seen anything like this before and don't know how it didn't just fall inside. Could it be jammed stuck? I'm afraid to try and push it in before I stuff the cylinder with rope or get an air adapter for the spark plug hole.

Thanks for looking!

-Yue

Ranger
01-13-10, 11:38 AM
It didn't fall in because it is resting on the piston head. Pull it out with pliers or a magnet and then use compressed air to hold it closed while you reattach the keepers.

YueIBM
01-13-10, 01:51 PM
Thanks Ranger!

But, I had driven it with that cylinder dead (no compression) for about 50 miles thinking it wasn't a mechanical issue until I pulled the cam to discover the valve keeper had fallen off.

Would it have stayed in there for that long without falling in?

A blurry borescope picture of the cylinder showed all 4 valves still in place.

In any case, I'll be stuff the cylinder with rope tonight (intakes slightly open, already took cam sprocket off so compressed air is out) and treaking it with tweezers to see what's up.

The Northstar TDC to valve clearance isn't enough to let hang in one position without being hit, is it?

Have a good day! -Yue

Ranger
01-13-10, 03:34 PM
Perhaps it was riding up and down on the piston head. Scary thought.

Mark C
01-13-10, 04:44 PM
A N* stroke is 3.8", think the stem of the valve is that long?

Ranger
01-13-10, 08:35 PM
I don't know. I'm grasping at straws. I suspect even if that was the case, it would have made one hell of a racket bouncing off of the valve seat and the piston head. Probably not a very likely scenario the more I think about it.

YueIBM
01-14-10, 12:25 AM
The exhaust valve is stuck in place. I thought I could hammer it free but now there's just less of it sticking out and no amount of pulling could get it to start coming back out.

I looked at the service manual and it seems like there's a tool that can take out the valve stem seal which I'm guessing is where the valve's getting stuck.

Knowing about the possibility of a porous block, would it be a good idea to try to tie the valve with floss and knock it all the way in, and then try to replace the valve stem seal without taking off the head?

This engine just keeps throwing surprises!

Thanks for your help Ranger and Mark C! Have a good evening!

-Yue

Submariner409
01-14-10, 08:42 AM
Dollars to doughnuts that, if that valve is now stuck at some point in its travel, the stem is bent. The head has to come off: you have more problems than just a stuck valve, and judging from the other cam follower (lifter, tappet) still in place in your picture, you need a whole new set, so all 4 cams have to come off, and at least the cam that came off that bad follower is toast, too.

If you drop the piston to its lowest point (BDC) and knock that valve into the cylinder, there's no way on earth to get it back into the guide. Dental floss (even one fiber of floss) will not, ever, go through the guide while tied into the keeper groove. Physically impossible.

YueIBM
01-14-10, 04:37 PM
Dollars to doughnuts that, if that valve is now stuck at some point in its travel, the stem is bent. The head has to come off: you have more problems than just a stuck valve, and judging from the other cam follower (lifter, tappet) still in place in your picture, you need a whole new set, so all 4 cams have to come off, and at least the cam that came off that bad follower is toast, too.

If you drop the piston to its lowest point (BDC) and knock that valve into the cylinder, there's no way on earth to get it back into the guide. Dental floss (even one fiber of floss) will not, ever, go through the guide while tied into the keeper groove. Physically impossible.

Yeah, floss won't fit. The Lycoming aircraft engine forum suggested that but their valves are quite a big larger and have more clearance.

I've ordered a valve seal removal tool and will try to have the piston hold it in place while I put a new valve seal in, that is, if valve isn't damaged enough to prevent the new one from going in.

I've also ordered a used head (missing an intake cam, but mine's fine, just need the exhaust) in pretty good condition.

Will update when the parts get here. Thanks again!

Yue

YueIBM
01-14-10, 04:38 PM
Oh, I thought I'd ask you experts this:

What are the chances that I'll have to time/Norm-sert my block if I take the head bolts off?

Thanks!!!

STSS
01-14-10, 04:40 PM
Oh, I thought I'd ask you experts this:

What are the chances that I'll have to time/Norm-sert my block if I take the head bolts off?

Thanks!!!

The chances that you SHOULD are 100%

Submariner409
01-14-10, 04:44 PM
Yeah that ^^^

If you don't disassemble the top end and do the Norm's Inserts, you'll be back in there in May - guaranteed.

And replace ALL the cam followers (lifters).

Ranger
01-14-10, 09:05 PM
I'll third that. Insert ALL the bolt holes once the head is removed.