Stuck valves - advice please

cederholm

cederholm

Senior Member
After two years in storage my ‘30 is running poorly and if my POS compression test kit is to be believed, #1 & #2 have stuck valves.

Short of pulling the head, is the anything I can do?

…and what brand of compression gauge would you recommend for the hobbyist?

Thank you!!
 
Had the same problem. Shot some Marvel Mystery Oil directly into the carb at elevated rpm and the engine settled down to a smooth idle. My problem was sluggish valves rather than stuck valves. The MMO approach would be a good first step before a more serious tear down. Good Luck.
 
Mulletwagon said:
Had the same problem. Shot some Marvel Mystery Oil directly into the carb at elevated rpm and the engine settled down to a smooth idle. My problem was sluggish valves rather than stuck valves. The MMO approach would be a good first step before a more serious tear down. Good Luck.
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Thank you, I’ll try it. How do you identify sluggish valves vs stuck valves?
 
Stuck valves don’t move any, sluggish ones will move some but perhaps not all the way to the seat.
I recently had a car given to me by a neighbor, it had sat without manifolds for many years under a porch roof, I removed the starter and with a pry bar it broke free, loosened up and had one stuck up valve, I used a brake adjusting spoon through the spark plug hole to pry against the stuck valve and it popped down, after it opened again it stuck, lever it down with the brake spoon and it seated, the engine has compression in all 4 now, as soon as I scrounge a manifold stud,some nuts and washers I will try starting it.
 
Kurt in NJ said:
Stuck valves don’t move any, sluggish ones will move some but perhaps not all the way to the seat.
I recently had a car given to me by a neighbor, it had sat without manifolds for many years under a porch roof, I removed the starter and with a pry bar it broke free, loosened up and had one stuck up valve, I used a brake adjusting spoon through the spark plug hole to pry against the stuck valve and it popped down, after it opened again it stuck, lever it down with the brake spoon and it seated, the engine has compression in all 4 now, as soon as I scrounge a manifold stud,some nuts and washers I will try starting it.
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Interesting. Is it advisable to try to squirt MMO into the spark plug holes at the valves?
 
I pull the side cover off, shoot in some PB Blaster and work the valves up and down with long nosed pliers.
 
I agree with Neil, pull the head. Even if you free up the 2 stuck valves they more than likely will never properly seat due to carbon build up or maybe they are partially burned.
 
I run MMO all the time because my tractor stuck a valve a few years back, and tractors can be a pain to work on. I believe it was caused by the modern gasolines, they run very dry.
 
I too would spray the valves as good as you can thru the sparkler holes. If that doesn't work then pull the side cover and free up the valves.
 
Before you start taking things apart. Try the MMO in you gas, in the spark plug holes.

Give it some time to work. Then try running your engine. It might take a few minutes running for the valves to start working properly.

Are you using High Detergent oil?

Good luck.
 
What’s wrong with pulling the head?

That’s my last resort, after I’ve tried other cures. If I break a head stud, I don’t have the equipment or skill to extract it, especially if it breaks below the block surface. At that point, I have to haul the engine, or the whole car, to a more skilled and better equipped person to pull my chestnuts out of the fire.

I’m certainly not a machinist!

W. Michael
 
W,

Very unlikely you will break a stud by pulling the head. If you do, I have the tool to remove it and am willing to drive down to help you. It can be done with the engine in the car. Don't be afraid of making mistakes. We all do. I have a list several pages long.
 
nkaminar said:
W,

Very unlikely you will break a stud by pulling the head. If you do, I have the tool to remove it and am willing to drive down to help you. It can be done with the engine in the car. Don't be afraid of making mistakes. We all do. I have a list several pages long.
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To some owners these cars are for working on. For others, there for just having fun and driving. Not everyone has the skills or desire to take an engine apart.

If it isn’t broken, don’t try to fit it.

I have broken a stud and anyone else could break a head stud removing the head. It is not easy to fix that problem. Do you at that point replace “ALL” the other studs? What other things now require fixing?

Try the simple things first.

I’ve been a Model A owner for over 60 years. MMO and some time could be your problem solver.

Enjoy.
 
WHN, You are right. I love driving my car but also love working on it and think nothing of pulling the engine and taking it apart. I also have been a Model A owner for 60 years and have always wrenched on them. But not everyone, as you say, enjoys that part of the hobby.

Regarding the studs, the recommendation is to replace all of them when rebuilding the engine. Not necessary when just replacing the head gasket or other work with the head off like fixing a stuck valve. If you do replace studs use an anti seize compound and don't over tighten them. I think if one breaks it would be good to replace all the studs.

I would be interested in learning how you broke a stud by pulling the head. Were you removing the stud? Was a nut frozen?
 
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