Rebuilt engine hard to turn over, but then loosens up?

U

unioncreek

Active Member
I have a JD D140 lawn tractor with a B&S 22 hp V Twin engine. I just over hauled then engine and replace the rings because of oil loss. I reinstalled the engine and cranked it over a number of time trying to start it. Wouldn't start got that figured out and started it and ran for a while at varying speeds to break it in. I tried to start it yesterday and it wouldn't turn over. Thought the battery was low on charge. Put a booster battery on and it would crank over. To the top off so I could get to the flywheel. I put a socket on it and it was hard to turn over for a couple of revolutions then got easy. Cranked it over and it started right up. Today it did the same thing. Runs good once I get it started. Any suggestions on what I should do? The first thing I thought was I got the wrong rings, but the end gap was within specs and it cranks over easy after a couple of revolutions. Is it just that tight and will loosen up over time?

Bob
 
Remove the belts and a clutch if it has it and the spark plugs. Then try to turn engine over by hand. If it is still tight for a couple revolutions you have a problem in the engine.
 
Checked out my mower this morning. Turned the key and it spun right over and started. Took the plugs out to look at them and it wouldn't crank over (plugs we're out). I started it off and on during the morning and it started right up. After lunch it wouldn't crank, turned it over with a ratchet a couple of times and it loosened up and started right away.
It's not hydrolock there's no gas in the cylinders when it won't crank.

I don't know what to think. When I first started it after the overhaul it cranked over right away.

If I pull the engine what should I look for. The only thing I can think of is the connecting rods are torqued too much. Pistons slid in the cylinder with ease.

Bob
 
Most engines stop in exactly the same position no matter the revs they are stopped at. This is usually with the exhaust valve open, as many will know, as the valve can stick open if left for a long time.

Maybe the tighter piston rings has changed that stop position, and the valves are closed, so your engine maybe trying to start under immediate compression ?

My take on it would be to continue for now, and see if they wear in slightly and return to the original stop position.
 
First make sure nothing attached ti the PTO if the engine is causing the binding. If engine still is tight with the plugs removed then you probably either have a rod on crank problem or a top or bottom crank bearing issue. Assuming everything else in the motor is correct.
 
I decided to pull the bottom on it next week and check that everything is correct. I removed the belts and pulleys off the pto end, it was still hard to turn.

Bob
 
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