LUC low compression

[fpappal]

I picked up an LUC just for fun, took a chance on it. Previous owner bought it from an auction, it has been sitting for years. Initial compression check showed 0 psi in both cylinders. When I removed the tappet cover I noticed the valve on the far left stuck open, the other three seemed to be fine. I was able to free up the valve with little effort and now all four valves move up and down like they should. Now my compression test is showing 10 psi in each cylinder. I poured some marvel mystery oil in each cylinder and after two days the compression is still at 10 psi.

A new head gasket is $80 so I hate to pull the head if I do not have to. Any suggestions other than removing the head? Maybe stuck rings? Thanks.

 

[Wisconsin Cowman]

With compression that low no snake oil is going to fix that. You will have to take the engine a part to inspect to find the reason why the compression is low.

 

[rustred]

just because the valves are free now dont mean they are seating. i would use another engine to spin it over and blow the rust and do that for 15 minutes at least so it gets oil pressure and things lubed up , out then check it again. doing a compression test on an old sticky engine is not accurate . need to run it then check it.

 

[wore out]

(quoted from post at 08:12:27 04/18/22) I picked up an LUC just for fun, took a chance on it. Previous owner bought it from an auction, it has been sitting for years. Initial compression check showed 0 psi in both cylinders. When I removed the tappet cover I noticed the valve on the far left stuck open, the other three seemed to be fine. I was able to free up the valve with little effort and now all four valves move up and down like they should. Now my compression test is showing 10 psi in each cylinder. I poured some marvel mystery oil in each cylinder and after two days the compression is still at 10 psi.

A new head gasket is $80 so I hate to pull the head if I do not have to. Any suggestions other than removing the head? Maybe stuck rings? Thanks.

I would suspect there's crud on the valves and seats preventing them from sealing.

If you have access to a cylinder leakdown tester or even a simple fitting to blow compressed air into each cylinder you can determine which valves are leaking and note if there's a large volume of air coming out of the crankcase breather.

That might even blow some junk out of the valve seating area if you turn it over so the valves lift off of the seats/crud.

If this was an old tractor or vehicle it's POSSIBLE it might gain some compression and even start while being pull-started, a little more difficult with your power unit, though, unless you could "belt it up" safely to a tractor or electric motor.

 

[fpappal]

That makes sense,thanks. I am not sure how to use a different engine to spin this stationary engine over. It does not have a belt pulley attachment on it.

 

[rustred]

those were a combine engine also and they had a clutch on them with a pully. get it mounted on something solid and use a belt off the pulley from another tractor. a v belt will work on the flat tractor pully. but you dont say what your engine has. post a pic. another idea... is u can bolt a plate to the flywheel with a drive shaft attached and use the pto. all this takes some doing.

 

[fpappal]

Here are a few pics. No belt pulley on this one. I might be able to rig up a big drill to turn the PTO end.

 

[Loosehandle]

There should be a good sized v belt pulley on the shaft with nut.

 

[rustred]

you need to find the pulley from the end , then you can get a belt rigged up. there is no drill that will turn that. plus leave the plugs out so it turns easier. cause you are turning from the rear of the transmission. no mechanical advantage that way.

 

[rustred]

the other way is to rig up something from the front of the engine be a lot easier to turn it. and another way is to remove that transmission and go from there.

 

[jdal]

It also may be the rings are stuck, I've had them loosen up using snake oil and cranking the engine. It is surprising on how these little engines will start with low compression. If you can get a good spark and enough compression to get gas or starting fluid into the cylinder you may have a chance.

 

[JIM MN]

Automatic transmission fluid and Lacquer thinner--50/50-- shake up and fill the cylinders.. Let soak a week or more.. Clean magneto; get spark.. Figure out how to spin over the engine.. What does the carburetor look like?? Clean out cylinders; get spark; squirt a little gas into the cylinders; new spark plugs; see if it will fire.. Give it a chance???

 

[J.Wondergem]

I seen a guy at the tractor show start his with a battery powered drill motor. He had something chucked into the drill to fit the crank adapter on the motor.

 

[buickanddeere]

Nothing wrong with taking it apart , then cleaning, inspecting and measuring everything .

 

[fpappal]

I hooked my air compressor up to the front cylinder. The valves are definitely not seating. As I turned the engine over with the crank I could hear air coming out of the exhaust and then intake. Now to try and get the cylinder head off. I have the bolts soaking in penetrating oil.