The Stovebolt Site Forums The Shop Area Engine Shop No compression in cylinder #4. :(

So just bought a battery for my 59 Apache (235) and did some cold cranks to check compression.

1- 100
2 - 95
3 - 90
4 - 0
5 - 80
6 - 40

Pretty devasted and confused on what to do next. Anyone want to offer some advice on what I should check and in what order? I'm somewhat mechanically inclined but have never taken on a project of this scale before. Any help would be appreciated.

Pull the valve cover and see if the rockers are moving on that cylinder.

The possibilities are:
A. stuck valves, B. broken rings, C. blown headgasket, D. hole in piston, listed in order of likelyhood IMO.

Remove the valve cover and have someone crank it & watch to see if all the valves are moving an equal amount or at all. Then pull the plugs and see if they are covered in oil. If it will start you can check for the head gasket leak and also discolored paint stains on the head around that cylinder. You'll likely end up pulling the head for a thorough inspection and repair.

You didn't say how it was running before these problems and that is a huge clue.

The truck had been sitting at my dads house for about the past 4 years not running at all. Before that he used it rarely and it ran great about 10-12 years ago. When I picked the truck up he thought it would only need a new fuel pump.

Before I dropped some cash on new brake components and fuel lines/pump I thought I would see if the motor even turned and check compression.

So picked up the battery today and that's where I'm at. Fuel lines are not even connected (no idea why not).

I'd vote that you have a stuck valve. As mentioned above, remove the valve cover and take a look. If things look intact slowly turn engine over by hand and take a peek.

Get the #4 cylinder to the top of its compression stroke and put some compressed air into the spark plug hole. Listen at the intake, exhaust, and crankcase for air escaping. That should pinpoint the source of the compression loss. Then you can decide how to deal with it. I'm going to predict you've got a stuck or burned valve. Be sure all the rocker arms have at least some clearance at TDC compression.
Jerry

I've just been through this exact experience— even the same cylinder, #4! I ran air through the plug hole, as Jerry mentioned, and had air coming through the carb which told me the problem was on the intake valve, not the exhaust valve. It also meant that I didn't have a hole in the piston.

My valves moved fine, no sticking, and no bent pushrod to prevent the valve closing properly. So I tried soaking in Marvel mystery Oil for several days, but no luck and no compression still.

I pulled the head and found a broken valve guide on the #4 intake valve. I had planned on swapping this head onto my 261 eventually so this kind of sped things up, but means it will need a rebuild.

Hopefully yours is just a stuck valve that will loosen up with some MMO.

Good luck and keep us posted!

my money is on a valve....It takes an aweful big hole to read "0",
Scott

Thanks for all the advice guys. Going to start start running through these processes on Saturday morning. I will let you know what I find.

Well I had got the valve cover off and immediately noticed two push rods that were bent. The one that was bent the worst was the intake on cylinder #4. I also have some air leaking out of the carb.

Pic #1

Pic #2

So I think I'm just going to go ahead and move forward with a complete engine rebuild instead of fixing one thing and then another breaking.

Unless you just want to do a rebuild, I would try freeing the stuck valves with something like Marvel Mystery Oil. What you picture is something that is very common when an engine is started with stale gas. I would put something like Marvel in each cylinder and let some run down each stem and let it set a few days. Put in some straight push rods or straighten these the best you can and turn the engine over by hand with no plugs in it to see of the Marvel has done its job. If you hit a hard spot, the valve is still stuck. You may have to remove the rockers and tap on the stems of the valves that are stuck until they are free. If everything is free, DRAIN EVERY DROP OF THE OLD GAS OUT OF YOUR SYSTEM. If you try starting it with stale gas, it will do it again.

Hmmm, maybe I'll try that out this week.

OK, so just order a new fuel pump, new push rods, oil change stuff, new spark plugs, valve cover gasket, push rod cover gasket, and a single lug nut I was missing.

Going to stop by and pick up the Marvel Mystery Oil tonight and put that in there and then follow your suggestion this weekend.

It doesn't take much convincing to change my mind huh? LOL

Doused everything in the Mystery Oil last night. I should be getting my parts in today and will probably not work on it until Sunday to let that oil soak in.

Mystery Oil

Replaced the pushrods and put everything back together minus the valve cover. Compression on #4 is up to 110. Woohoo.

But #6 is still at 40 lbs. So hooked the compressor up to it and could hear and feel air coming out of the exhaust. So I'm going to put the fuel pump on and everything else and try to start it to troubleshoot some more.

It's looking more and more like I have to pull the head unless someone has any more suggestions.

Make sure the valves on #6 have some clearance. It's possible the #6 exhaust valve is still stuck a little, or there might not be enough clearance to let it close fully. For now, don't get concerned with exact clearances- - - -just make sure there's some slack in the rocker arm with the cylinder at the top of the compression stroke.

The longer you let the penetrating oil soak, the less likely you'll stick some valves on startup. Working the valves up and down with a pry bar on the rocker arms is a good idea, as long as you don't get rowdy and break a rocker! I've also been known to thump the top of a valve with a dead-blow hammer a few times to dislodge carbon deposits on the valves and/or stems.
Jerry

Thanks I'll try more oil and try prying them a little. Then bangin em.

I still have to put in the new fuel lines so won't be trying to start it until the weekend or next.

I went to replace the fuel pump today because the one that was on was an electric wiper pump and I have vacuum wipers. Come to find out the bolts are different per pump. So the ones I have are too short for the correct pump. I can't find the size of those anywhere or where to order them? Any help on that?

The fuel pump bolts are 5/16"-18, plain old standard-thread grade 5 bolts. Any hardware store or home improvement center should have all sorts of lengths of them in stock. Just take your pump in to the store, and find a bolt that will allow about 1/2" of thread or a little more to stick uot the back of the mounting flange. It's also a good idea to use split-type lockwashers between the bolt head and the pump housing. Just be careful that the bolts don't stick through the block far enough to be hit by the camshaft as it rotates.
Jerry

So finally got the motor started:

Movie of motor starting


Compression on #6 is up to 75 lbs.

I never get sick of watching engine running videos!

What were you doing with the line 1/2 way through the video? Looks like you were blowing through it!

That was actually my step dad. He had it up to his ear to see if he could hear an exhaust leak (which he didn't). A trick he learned from being a mechanic for 28 years I guess?

This week I am going to take the gas tank out mainly to clean the interior out but also to see if it's still usable. Then I am replacing the rest of the fuel lines, rebuilding the carb, and replacing the brake master cylinder.

edit: We had a hose going to a gas can to run it this time since I haven't checked the tank yet.

I like those startup videos too and that one is great! It is a very nice follow up to your initial post. Oh, and now I know the true meaning of "manual choke"!