compression??

[leed]

How much "suck" and "blow" should i feel with my finger placed over the plug holes while turning the crank? Will it be obvious? I think I'm not getting compression...although the tappets are working fine. Any ideas??

LeeD

[Lurker Carl]

How much air moves depends on how fast you're turning the engine, but you will feel it sucking in and blowing out past your finger. A valve can hang open just a tiny little amount (either stuck within the valve guide or carbon on the seat) and it will not have compression at that cylinder.

[leed]

well i definitely have stuck valves in #1, #3, and #4. I tried to work with them tonight a little but no luck. Any suggestions?

LeeD

[Lurker Carl]

LeeD,

You might want to take readings with a compression gauge. I'm assuming you are dealing with an engine that hasn't run for a while. Here is a quick way to try and determine what is going on.

If a valve is leaking due to carbon on the seat, you'll hear the air hissing thru the exhaust manifold. Unless your hearing is as lousy as mine. If the valve is sticking open, there will be a gap bigger than the required lash measured at the lifter and you won't hear hissing because of the larger gap. The tappets will still go up and down with the cam as you rotate the engine, however the valve will not completely close. Hopefully someone hasn't tried adjusting the valve lash with the sticking valves.

Every time I've dealt with leaky or sticky valve issues, the head had to come off. Typically the valve and seat had a crusting of carbon that needed cleaning and lapping or the valve stem is coated with carbon that holds it open at the guide. You can access the valve from the top to tap it closed or remove it to clean carbon off the stem to stop it from sticking.

If your compression loss is due to worn or stuck rings; add a tablespoon of engine oil thru the sparkplug hole. Then take another compression reading. If the compression reading is higher after adding oil - valves are not the problem.

Keep us informed with your progress.

[leed]

Carl,

It's true...my tractor has been in my garage for three years...I was scared to tackle it.

With the sparks out, I can see that several of the valves are indeed stuck up. I can also see that there is what looks like a good bit of carbon build-up as well. I do hear hissing in #2, I i suppose there is some trouble there, too?

I strongly suspect that noone has tried adjusting the valves. I am the third generation to own this little baby, and besides that, she was running a few years ago.

I was really afraid that you were gonna say "take the head off." You see I'm a chemist, not a mechanic...the very reason my little jewel is in the condition that she's in is because I'm scared...well i guess it's time to overcome my fears and dive in "head" first. I guess I should go ahead and order an overhaul kit or at least a head gasket. I'm going to have to take the valves to a machine shop to have the cleaning done I suppose? After all, I consider lapping that which my dog does to drink water!

Is the tablespoon of oil a test for whether the problem is rings or valves? Should I do this first (before I take the head off)? What if it is the rings? What then? I don't know how to fix that.

Thanks so much for your help. I need so much more!!

LeeD

[Bigdog]

Lee - several members of this board recommend using Sea Foam to help dissolve carbon deposits. You could try dumping some in through the plug holes and let it soak. But it sure sounds like you are going to need to pull the head anyway. It's not that big a deal and replacement head gaskets are readily available and reasonably priced.

[beaconlight]

There is no problem with stuck rings either. A cub is basic basic technology from over 50 years ago. Tey are designed so that any one with a 6th grade or less education can work on them. Fear is your only enemy. If you are looking down the spark plug holes I have to assume that you have the gas tank-hood offalready. You could put some penetrating oil or diesel fuel into the spark plug holes let it set a day or two, putting a little more a couple of times. Take the side plate off the engine and you will see the valves and springs spray some penetratng oil on them too. You can clean out the years of sludge while in there too. Try turning the engine over with the plugs out abit it may be enough. Patience is the key word here. If you have a magnito ground the wire from the mag to the distributor. This is a safety to protect the mag. After a week or more of this if it doesn't help it is time to bite the bullet and remove the head. to make it easier you should be penetrating oil the head bolts while doing the valve tricks. You will need a new radiator hose and valve cover gasket as well as anew head gasket when you reassemble. When the head is off if you are lucky penetrating oil around the valve stems and tapping on the valve heads may be sufficient. Use a wooden block so that you don't have steel on steel.
Lapping is just spinning a valve gently back and forth on its seat with a fine grinding compound between them.
When you get this far let us know and we will jump in to help.
Look over the links and info on the home page of the forum. You will find much helpful info. Use the search feature too. You will encounter mqny others with the same problems as you encounter and how the cured them.

Bill

[leed]

I've taken the head off and whoa! it's really in bad shape. Lots of carbon build-up on the valves and on the pistons. I dare say that none of the valves were getting a proper seat. I need to get a tool in order to take out the spings. How should I clean the block surface and pistons? I've been spraying Kroil on my valves to try to loosen them up a little. so far so good...any other suggestions?

[beaconlight]

Did you take the side plate off? Its about 3 or4 inches tall and 12 long above the starter. on a valve that shows space between the end of the valve stem and the lifter you could tap on the valve wih a hammer using a block of wood as a cushion. Also seafoam the bottom of the velve stem.

Bill

[johnbron]

Did you take the side plate off? Its about 3 or4 inches tall and 12 long above the starter.

Bill

? "HUH!! ?

[leed]

I think my valve cover or my starter must be on the other sidefrom yours , Bill, but yes I have been tapping on the top of the stuck valves with a wooden dowel.

I've used a straight edge razor blade to scrape a lot of the carbon deposit off the top of the block. That's just what is lose. Much is burnt on...how to remove??

[beaconlight]

The penetrating oils take a lot of time to work. Time is your best friend on a job like this.

Bill

[Lurker Carl]

Scrape, heat, try some penetrants. Repeat, repeat, repeat. If you have that much carbon on top, I'd think the rings are clogged as well.