LTX1050 Kohler 22hp starter can't overcome compression and stops rotating
 

2009 LTX1050 22hp Kohler.

The starter tries to rotate the engine but stops on one cylinder's compression stroke. The engine also seems very hard to turn past this point by hand.

Turning past the hang point by hand and engaging the choke seems to help it a bit, but on one of the cylinder's compression strokes it will still try to stop even after the engine gets some rotational momentum. The closest thing I can think of that seems similar to my symptoms is "hydro-lock"

The battery is 5 days old, the charging system is working and it looks like the starter itself is new. All electrical connections have been cleaned, connectors removed and contacts cleaned well, battery connections checked and contact cleaner spray for electronics has been worked in to the ignition switch. This was the reason I took the gas tank out, so I could get to the connectors and get the stuff out of the dash to work it all over.

Are there any known pattern failures that match these symptoms, or maybe someone has a diagnostic chart?

Thanks

I am reading on the net about several people having this same issue. Am I seeing it right there is a gear driven compression release of some kind on this engine?

Also is this 22hp Kohler known for valve train issues like backed out rocker studs, rocker arm, bent push rods or stuck valves?

I can see any of these causing the symptoms.

Was it doing this before you had fuel tank out? We need some back history on this tractor. Start with the last time you heard it run please

1. Determine which cylinder is causing the issue.
2. Remove valve cover on that cylinder.
3. Inspect rocker arms and push rods.

What Ironman said....

Getting ready to do that shortly.

I removed each plug individually, re-installing it after cranking the engine over. The problem exist on both cylinders, but #2 I significantly worse than #1 which will roll over past the compression stop point. The following actions were then taken:

Inspect push rods: I spun all 4 push rods while installed and they were not bent or wobbly.

Inspect valve clearance: Intake #1: .005 Exhaust #1: .009/ Intake #2: .008 Exhaust #2 .011

Adjust valve clearance: All 4 set to .005

Compare total valve installed height on all 4 valves: all identical

Check spring clearance: All at least .010

Re-install valve covers and re-test: When cold the engine will push past the compression stop point but it taxes the starter and battery pretty good. Once it has run for a while the starter will not overcome the compression stop point.

Attach jumper pack to battery: Does not help overcome compression stop

Attach charger to battery: Does not help overcome compression stop

Attach charger to battery with boost: Does not help overcome compression stop.

Otherwise when it runs, it appears to run good, maybe slightly better after adjusting valve clearances.

I talked to a local small engine parts house. They tell me the automatic compression release is part of the camshaft. Looking at pictures online I can't see anything on the cam that looks like a compression release, unless there's a hump on the opposite side of the cam lobe I can't see?

Maybe I'm missing something? Maybe someone can explain to me how the compression release works on this engine?

EDIT/ADD: It looks like the starter has been superseded by one with more torque? Starter issue?

It certainly could be. Does it only have trouble cranking when hot?

Hot and cold both.

Further diagnostic steps taken:

Check for voltage drop at starter: Remove starter activation wire (solenoid is rear mounted in tractor) activate starter with key/ignition switch and check voltage at activation wire. Battery voltage found

Remove starter and bench test: Activate starter with jumper pack. Starter has very noticeable roughness/catches as it spins. Voltage drop on activation: 1.7 volts.

Disassemble starter and inspect: Brushes are fractured and have significant wear. One ground brush was stuck and mis-shapen. Part of a fractured brush found inside on the rear plate. Armature contacts have deposits.

I cleaned the brush holders and rear plate, cleaned the brush case ground tab and corresponding areas on the rear plate, cleaned the armature contact points, test fit the brushes and all were moving freely. The mis-shapen brush was re-shaped with an emery board. I compressed the brushes then used 4 toothpicks to hold them in their withdrawn position then inserted the spacer plate that rests on the rear armature bushing to hold them in place and removed the toothpicks. Starter re-assembled and bench tested. There was a much smoother feel to the starter's rotation and less of a voltage drop on activation, this time 1.4 volts. By my view the starter does appear to lack the torque I'd expect for a high compression engine.

Re-install starter and re-test: Problem still exist even with a boosted battery.

Check starter solenoid external connections: all check OK, base studs slightly loose, tightened, wires re-installed and re-test. Problem still exists even with a boosted battery.

The next things I suspect are lousy internal connections in the solenoid cutting the cranking amps, a bad battery (jan/19, sold 5/5/19), the starter is still weak even with the "freshen up"....or the compression release is not working.

I'll be taking the battery up to the parts store shortly to have it tested. It does seem to drain quickly, but then again a non-turning starter is essentially a dead short which would drain it pretty fast considering its capacity.

Does anyone know how many cranking amps are required in a battery for this model/engine?

Check this link. Someone else had about the same problem.

https://www.lawnmowerforum.com/showt...finally-solved

The service manual for the engine should be available from the Kohler Engines site.