Valve Stuck Open

You are right about the cylinder number. Have you ever seen this engine running?

Negative

I would not assume that the valve is stuck open, but that the valve spring is being held in a compressed position. I would assume there is damage at the other end of the valve; one of two possible problems:

the valve head is partially broken off the stem, hanging to the stem at an angle that holds the valve spring compressed.

the valve head is broken completely off the stem, and while in the process of breaking off the valve stem was bent, which is holding the spring in a compressed position.

The next step is to pull the intake manifold, drain the coolant, and pull that cylinder head to determine the extent of the damage to the engine.

Would your assessment change if I told you that I fully trust the former owner and his description of the circumstances around the car being parked is that he drove it until the gas tank started leaking and parked it?

There was no mechanical malfunction.

I got it. Popped right up.

glad I was wrong.



Still, it is unusual for a valve to stick open. You have to ask why or how did that happen. Might it be a sign of something; a warning. According to many people the factory valves in the Cleveland engine have a history of cracking and dropping their heads.

I had a car do this after it had set for years after backfiring through the carb for several minutes it quit and is still running fine maybe I was just lucky.

Jack, was that car powered by a 351C?

Perry H;
Now that the valve has popped up, have you been able to determine if the valve stem was possibly rusted or seized in the guide from the length of time the vehicle was sitting?
Wouldn't want the valve to hang up again in the spot where it may have been seized and cause any further damage.
Is the valve stem smooth and free?
If not, it may be worth your time to pull the push rod just to make sure it isn't bent.

yes 351c

The pushrods are straight. I took all of the rockers off and checked.

I can’t inspect the valve stems without either pulling the head or doing the rope trick and taking the springs off.

I did a compression test and got a lot of fun wacky numbers. High of 170 and a low of 40 - with everything in between. The low ones could be sticky valve stems/rusty valve seats.

I was hoping to get it running with this motor so I could putt around in it while restoring other things - saving the engine rebuild for last.

Def a job for the rope trick to see if vales are freely moving/rotating. Is a bit of a mess with the motor in the chassis.

Matthias

Perry H; Have you also performed a vacuum test?
You may be able to isolate why the various high and low compression readings from the test (sticky valves, weak springs, etc., etc.)

I have not checked vacuum.

I think I am just going to bite the bullet and pull the heads off to look at the valves and directly into the cylinders.

My dad (long time Mustang/Windsor guy) seems to think that's crossing some point of no return - we might as well pull the motor and rebuild, but it looks like a few easy to get to bolts to me (and buying some new gaskets).

Someone has been in this motor before - at least the top end. One of the push rods has been replaced and some of the rockers have a different stamping (some are smoother around the edges that others) and two of them have been ground on the outside of the pushrod end for some reason. The only reason I can think of doing that is for valve cover clearance - and the valve cover is not even close. Mass reduction also came to mind, but it's not enough material for that and why only two? (unless these just came out of someone's box of spare stock rockers and they did not notice or care about the grinding marks).

quote:

Originally posted by Perry H:
I have not checked vacuum.

I think I am just going to bite the bullet and pull the heads off to look at the valves and directly into the cylinders.

good idea, if it's crusty enough to stick valves, that crust will be fouling the cylinders getting into the rings and scoring the walls doing more damage than necessary

as far as the rockers, there are several variations, some have a bulge that causes interference between the rocker body and the pushrod. then there are the 'lugged' rockers that look quite different around the top edge

Other than the coffee colored oil I have pumped up through the pushrods with my electric drill, the thing looks like someone just rebuilt it - or at least freshened it up.

There is nothing rusty or goopy looking.

The differences are subtle, but follow the top edge of the rockers and compare these two.

Here are the two that someone put a grinder on...

hard to make any sense out of that not seeing what it looked like before they hit it?

it does look like Folgers though, i thought you said the valves & seats are crusty?

No - not crusty (at least not the part I can see with the head still on), but one was stuck open.

There was one other that would stick open and then pop loose.

I found 2-3 plugs that had some rust one them, but it wasn't terrible.

The engine was initially stuck too. It would not turn with a breaking bar on the crank. I got it moving after a good 3-4 days of marvel mystery oil soaking.