Bent push rod or stuck valve?

Geo-TH,In · Sep 21, 2023

My Jubilee has been retired for 3 years.
I would start it every time I go in the garage where it's parked.
It started just fine about a month ago.
Today it is missing on #4 which has zero compression. Grrrr

I wish it were my Farmall. It a piece of cake to get to the valve cover.

It is going to take some time to drain the full gas tank and then remove the gas tank to get the valve cover off.
Place your bet, stuck valve?
Bent push rod or both??

Janicholson · Sep 21, 2023

A stuck valve will cause a bent pushrod if the valve was closed when the engine was turned. If the valve was open, the pushrod has a much better chance of survival. Good luck. If solid rod it can be straightened with a hammer on some end grain wooden block. Jim

Steve Metcalfe · Sep 21, 2023

If I remember correctly a Jubilee has the overhead valve engine. If that's the case you can remove the valve cover without removing the gas tank.

John T · Sep 21, 2023

Bent push rod or stuck valve?

My best guess not being there is IM STARTING WITH A VALVE WAS STUCK

NEXT

If the valve was stuck badly CLOSED,, NOW YOU HAVE A BENT PUSHROD and valve is still closed

If the valve was stuck badly OPEN pushrod may have come out of place and got bent or might be okay ???

Betting you will find a stuck valve and perhaps a pushrod also LET US KNOW It will be fun to see other bets and guesses

John T NOT any professional mechanic see what they bet ??

Geo-TH,In · Sep 21, 2023

If that's the case you can remove the valve cover without removing the gas tank.

I wish you were right, but you are not.

DanielW · Sep 21, 2023

No compression, valve might be stuck open and thus not have bent a push rod. My brother hauled home a Cockshutt with a sticking valve on #1 a few months ago. Because I didn't want to put too much time into one of his projects, I just pulled the plug for that cylinder, sprayed all around as best as I could in there with a good penetrating oil (I'm a fan of the Delco stuff you get at GM), then prodded around through the plug hole with a hardened pick to try and get the valve moving a little. To my surprise it unseized pretty easily, and came back with good compression after running for a couple of hours and burning some carbon out. Might be worth trying before you pull the tank off.

Geo-TH,In · Sep 21, 2023

JohnT
My best guess not being there is IM STARTING WITH A VALVE WAS STUCK!

You guessed right.
Now is there a simple way to un-stick the valve or did the piston bend the valve?

I smacked it a few times with a hammer, no luck.

I hope I don't have to remove the head and take it to a machine shop.

If I do, I may be looking for an exhaust manifold. Mine has a fracture crack. No place critical, but a crack just the same.

John T · Sep 21, 2023

I dont know if you can get to things ??? but in cases where I was able to I sprayed a lot of knocker loose and gently tap tap tap tap the valve in center to avoid any more damage.. Did piston bend the valve ??? (or damage piston) I dont know Im unfamiliar with your engine?? I bet some Ford mechanics might know

John T

Robin Hood · Sep 21, 2023

George, isn't that a 172 cu in? Lots of them around. Tough as nails. I wonder if the valve wouldn't come loose when the engine gets hot?

Hobo,NC · Sep 21, 2023

Soak, tap, walk away from it repeat till it moves. I doubt it bent the valve are will bend the valve. The last one I did it took about a week of off and on it had me worried.

Geo-TH,In · Sep 21, 2023

Soak it with What?
Would using large channel locks and try to turn
the valve spring help? I think the valve stem is
covered in rust.

This picture says it all.
The jubilee has sat around almost 4 years, not
worked hard, not warmed up and condensation is
obvious, rust.

I wouldn't have thought letting an engine sit in
a garage would cause this mess.

old-9 · Sep 21, 2023

Not a 172, the NAA's had their own engine several things different from the other 134's or 172's. I replaced my original 132 in my jubilee to a 172 from a sprayer. Was an exact fit. joe

geok · Sep 21, 2023

This post was edited by geok on 09/22/2023 at 05:34 pm.

ss55 · Sep 21, 2023

A leak down test can pinpoint where a cylinder is loosing compression.

T.R.K. · Sep 21, 2023

If it wasn't hot when you shut it down last time, my bet would be on carbon holding a valve open.

Geo-TH,In · Sep 21, 2023

Look at my pic below HoBo post.
Zero compression on #4 tells me what cylinder.
No need for a leak down test.

Hobo,NC · Sep 21, 2023

That looks worst than condensation but it probabley is. June a year ago I brought a ford 2000 it had set in a un-insulated metal building for several years. I knew it ran good before that I never would have thought it would have stuck the valves. A pix is in this post it has some rust bit no water.

https://forums.yesterdaystractors.com/viewtopic.php?p=10612857&highlight=dist#10612857

What to soak it with, I used every penetrate in the shop, ATF mixed with diesel and acetone etc so take yer pick : ) penetrate is a hope and a prayer so pray.

I have a un-insulated metal metal building I keep tractors in I use to get a stuck clutch every now and again. I put two Wind-Driven Turbine Exhaust Ventilators in it that eliminated moisture issues.

onefarmer · Sep 21, 2023

My super M was stuck when I got it and it had a couple stuck valves like that. I just pried up on the spring and it popped loose. One I had to drive open a bit further to break it loose then pry back up. Then I bounced them a bit with a hammer on the retainer.

To break the engine loose I took the rocker shaft off added some atf to the pistons and put air pressure to it with a compression tester hose. I had it lose in about an hour.

ss55 · Sep 21, 2023

A leak down test helps determine if:
rings;
intake valve;
exhaust valve;
or head gasket, cracked head, sleeve
are the leak in #4 cylinder.

MarkB_MI · Sep 22, 2023

George, you probably didn't do the motor any favors by regularly starting it up and running it for a few minutes. If it doesn't get hot enough to vaporize the water inside, condensation will just build up from blow-by gases.

It sounds like there's rust on the valve stem. You can remove the manifold and shoot some oil directly on the valve stem.

One trick to free a stuck valve is to get the problem cylinder on its compression stroke, then stuff rope into the spark plug hole. Rocking the crankshaft will cause the piston to bump up the stuck valve.

I used to add Marvel Mystery Oil to my gasoline to prevent valves from sticking, but I quit because I suspected it was causing rubber fuel lines to rot out prematurely.

Bent push rod or stuck valve?

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