Loose Valve guides

B_man_Al

B_man_Al

Senior Member
Has any one ever seen the valve guides coming loose on an 8BA engine before? The engine has less than 10 hrs (none on the road, except around the neighborhood) and two of the exhaust valves have come loose ( 7 & 4). I thought it was sticking valves at first, but looking at it closer, the entire assembly is moving up and down ( valve, spring and guide). I haven't taken off the intake yet but I can see them moving through the fuel pump hole.

I can't imagine the C clips coming loose, considering how difficult they are to get in in the first place.

Anything that can go wrong does!

Al
 
The valve springs usually hold sufficient pressure on the clip to keep it from coming out. I have seen the cast iron guides crack and chip bits of the groove edge that holds the horse shoe clip in place though. Maybe the edge broke off of them for some reason. Maybe they got accidentaly dropped and hit there causing cracks that gave way. Sh!t does happen.
 
It turns out that the problem is indeed stuck valves in the guides on both. While it looked like the C clips had come loose, after taking the intake off, they hadn't. They are still holding the valves, springs and keepers together, but because the springs are compressed and jammed there, the guide is now free to move up and down in the block, appearing as though the whole thing had come apart. Good news as far as fixing, but now to find out how to prevent more of them from seizing on the valve stems. Some kind of top lube I guess until they get a little wear on the guides.
 
I have one motor where the horseshoe clips were inserted between the end of the spring and the guide. Heaven knows what would have happened if it had been fired and ran.

Mart.
 
More than once I thought I had the horseshoe clip in place, but had it under over the spring and not in the grove..
 
Stainless steel stem valves sometimes gall in the cast iron causing problems. If it's just carbon, the guides can be polished. If the valves are all stainless and galled, a phosphor bronze sleeve in the guides would keep any further galling from happening. So many of the new repro parts are stainless now but I don't know if the stems are or not. A magnet would tell for sure.

Could still just be the clip not properly in the groove.
 
rotorwrench said:
Stainless steel stem valves sometimes gall in the cast iron causing problems. If it's just carbon, the guides can be polished. If the valves are all stainless and galled, a phosphor bronze sleeve in the guides would keep any further galling from happening. So many of the new repro parts are stainless now but I don't know if the stems are or not. A magnet would tell for sure.

Could still just be the clip not properly in the groove.
Click to expand...

Not all stainless is non-magnetic. No idea exactly who is using what grade to make valves.

Anyone know?

As far as helping the valves out. Marvel Mystery Oil and SeaFoam.
 
This is true but the ones that are are generally the type that have to have some cold work done on them to get the magnetic properties back slightly like cold rolled types 301, 302, & 304 but all are non magnetic in their annealed states.
 

It turns out that the problem is indeed stuck valves in the guides on both. While it looked like the C clips had come loose, after taking the intake off, they hadn't. They are still holding the valves, springs and keepers together, but because the springs are compressed and jammed there, the guide is now free to move up and down in the block, appearing as though the whole thing had come apart. Good news as far as fixing, but now to find out how to prevent more of them from seizing on the valve stems. Some kind of top lube I guess until they get a little wear on the guides

So what happened to the horseshoe clips??
 
The only way it can come loose in the bore is if it shears edges of the clips out. If it did, that would be preferable to a broken camshaft or a messed up hollow cam follower. I've seen the valve stems go right through the OEM non-adjustable followers before. The valve guide bores might be a bit loose now. Might have to glue them in.
 
I knurl new guides, then clean them out real well with solvent and a brush on a drill motor.
Knurling puts a threaded-like finish on the inside of the guide. Makes it a lot less likely to seize. This also resizes the guide to fit the valve stem.
Years ago I bought some copper plated (on the outside) guides from Reds Headers. This was to make up for a loose fit guide to block. If you decide to use a glue like product, be aware that one of the things exhaust guides need to do- transfer heat. And, I would put in the valve assembly with the guide to make sure that the valve is centering the guide where it needs to so the valve will seat.
Karl
 
I had an engine where two valves froze in the guides and broke the bottom out of the retainer slot in the guide the bits of which were in the bottom of the valley. The C clips were still in place but the guide was going up and down with the valve. Must have been big stress on timing gears etc.
 
Oldfor2 ...

The C clips are still there, but can be easily removed by hand as the guide and valve assembly is now "shorter" since the spring is seized in the compressed state.

Rotorwrench ...

Similarly,as the springs and valves are stuck compressed, the guide is free to move up and down in the bore.

This raises an interesting point, though, about measuring the gap. In order to get an accurate gap setting, the guide must be fully pushed up against the C clip and recessed in the block. When the cam pushes the assembly upwards, the guide will bottom on the clip, but if it is loose in the guide bore, it could slide down by the amount of the gap when the cam is rotated by 180 degrees from the max lift position, appearing as though there is no gap. Under this condition, the C clips will be loose, but cannot come out because of the recess in the block.
 
Let me put this up here again, it won't help "already-built" units but it may help on future builds.

Install bronze liners in the guides, we started this program/procedure many years ago and to this day haven't had one single "stuck" valve!!

There are numerous reasons for this happening, the valves hanging, but most times it is moisture inside that doesn't "burn" off. It accumulates in the system especially after driving short trips and shutting down. Having owned numerous Flatheads over the years and driven miminal numbers daily (under 1 mile to the shop) this was always an issue with the exhaust systems also. Constantly replaced pipes and mufflers.

For the cost of the bronze installation, which initially may be somewhere around 8.00/9.00 per guide, it's really good insurance in the long run, just in the price of gaskets alone, not mentioning the labor involved. If your original guides are OK you just "line" and reuse them.

While knurling guides is OK, it doesn't "change" the materials involved. There is more "resistance" with the bronze liners to moisture collecting on the stems than with the cast iron guides/steel valves. You can also run slightly tighter valve-to-guide clearance in there. We do not "ream" bronze liners, they are ball-broached for sizing. Some get finished with a Sunnen valve guide hone also, not to be confused with the silicon ball-type hones, it uses actual stones and guides get I.D. measured with a bore gauge. About 99% are fine with the ball-broach setup.

Thanks, Gary in N.Y.

P.S. We would never reuse the original guide retainers (horseshoe clips) anymore, always use new pieces. I would also use some Viton stem-seals on the guides.
 
Just to clarify my stuck valve problem, 2 pictures showing the movement in the valve assembly with the stuck spring. Note how far out of thebore the guide will come in the down position.
 

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Since this is a new build is it possible the valves hit the head, bent the stems and jammed in the guides?

Lonnie
 
Binx ...

I hope not but I don't think so as the exhaust valve would have hit the plug before the head I think. The plugs are OK
 
I suppose this is an odd situation because the engine is low miles. From my experience, this would not happen on an older motor because the guide is tight enough in the bore to not move. Most of my problems have been from guides not wanting to move in the bore. I've never had them moving when I didn't want them to!

If you can free them off and use something to add lube to the fuel as you say it will probably be all right once it gets some miles on it.

Mart.
 
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