More problems on the 425 Kohler CH25

[Modrob]

In my last post, it was about getting in “tow mode” and about the engine quitting on bad gas, etc.
So I was able to get it moved with the Bypass Hose installed. Got it home and ordered a new push rod for the bent one. Changed the oil and filter.
Took the lifter out and bled it (it was solid as a rock) and installed the new rod. I went ahead and pulled the intake side Lifter and same thing. Put it back together last night and no start. It backfired once with a little starter fluid and choke, but never tried to start. I pulled the cover back off and all looked fine. Decided to take some compression measurements and found ZERO movement on either cylinder. Placing a finger at the plug hole no pressure coming out but could feel some suction. Took cover off other side and all look fine—all four rockers are moving when cranking…I’m lost again…

 

[Modrob]

I still have the bypass hose in place—surely that doesn’t have any effect?

 

[ponytug]

In my last post, it was about getting in “tow mode” and about the engine quitting on bad gas, etc.
So I was able to get it moved with the Bypass Hose installed. Got it home and ordered a new push rod for the bent one. Changed the oil and filter.
Took the lifter out and bled it (it was solid as a rock) and installed the new rod. I went ahead and pulled the intake side Lifter and same thing. Put it back together last night and no start. It backfired once with a little starter fluid and choke, but never tried to start. I pulled the cover back off and all looked fine. Decided to take some compression measurements and found ZERO movement on either cylinder. Placing a finger at the plug hole no pressure coming out but could feel some suction. Took cover off other side and all look fine—all four rockers are moving when cranking…I’m lost again…

Sorry for all of your troubles! My apologies if the questions sound basic.

Did you check the valve clearances? Sometimes more than one push rod is bent.

Did you look into the cylinder from the spark plug or measure the depth with a dowel? And then crank and retest? (A check for crankshaft movement.)

All the best,

Peter

 

[MossRoad]

I still have the bypass hose in place—surely that doesn’t have any effect?

No, that shouldn't have any effect on the engine. However, I'm not sure you should run the engine with the bypass in place. The pump may need to build pressure to stay lubed, etc.

As I said, I'm not sure.

The tram pump is 'in neutral' when the pedal is not pressed, so it shouldn't drag on the engine too much. It's the two sections of the PTO pumps that I think cause most of the drag. But again, that's just a guess.

 

[MossRoad]

Did you check the opposite side for bent push rods?

 

[ponytug]

No, that shouldn't have any effect on the engine. However, I'm not sure you should run the engine with the bypass in place. The pump may need to build pressure to stay lubed, etc.

As I said, I'm not sure.

The tram pump is 'in neutral' when the pedal is not pressed, so it shouldn't drag on the engine too much. It's the two sections of the PTO pumps that I think cause most of the drag. But again, that's just a guess.

You make a good point about it probably not being a great idea to run the pump in bypass mode. IIRC, I think that it just bypasses output to input, which is to say that the charge pump should still be functioning. Without the bypass, towing the tractor, the wheel motors deliver full pressure to the locked pump, where the oil is forced into a high flow bypass through the pump generating heat.

All the best,

Peter

 

[Modrob]

Sorry for all of your troubles! My apologies if the questions sound basic.

Did you check the valve clearances? Sometimes more than one push rod is bent.

Did you look into the cylinder from the spark plug or measure the depth with a dowel? And then crank and retest? (A check for crankshaft movement.)

All the best,

Peter

No problem at all with the “basic” questions. Many times I’ve found, I can overlook the simplest of things.
Let’s see: All four push rods look fine and are working. Looking into the cylinder I can see the piston moving when starter is bumped…

 

[Modrob]

No, that shouldn't have any effect on the engine. However, I'm not sure you should run the engine with the bypass in place. The pump may need to build pressure to stay lubed, etc.

As I said, I'm not sure.

The tram pump is 'in neutral' when the pedal is not pressed, so it shouldn't drag on the engine too much. It's the two sections of the PTO pumps that I think cause most of the drag. But again, that's just a guess.

I went ahead and took off the bypass hose, just in case.

 

[Modrob]

Did you check the opposite side for bent push rods?

Yes sir, both sides checked, and again just a little bit ago. All look fine. I’m gonna rig up a remote start button so I can position myself to observe better going forward.
This afternoon though, I am concerned about the right side bank (looking from rear of the tractor)…the springs look to be a little less space between them compared to the other side. Last night I just bled off the lifters, put in the new rod, and ensured there was movement in the springs and valve stem when I pushed down on the rocker with my thumbs. Earlier I was reading many articles about TDC, so maybe that’s a factor?

 

[m5040]

I would look for a timing issue. Make sure as the piston come up with the valves closed you get a spark at the top of the stroke, then watch what the valves are doing in relation to the piston position (the 4 strokes). Easy to do and no cost. Then go from there.

 

[woodlandfarms]

Did you check to make sure the pistons are moving. Kohler is notorious for breaking rods.

 

[Modrob]

Yes, both pistons are moving.

 

[ponytug]

Yes, both pistons are moving.

Ok, so both pistons move, all the valves move, but you have no compression, which leaves either perhaps timing, or perhaps lack of oil in the top of the pistons due the fuel / oil issue and wear, or no fuel, or no spark.

You could try a teaspoon or two of oil in each spark plug hole, then crank briefly with no plugs, put the plugs in after checking the spark, and see where you are. If that doesn't work, then I think you are on to timing or a lack of fuel, but the starting fluid failure suggests no spark or poor timing to me, if the oil in the pistons isn't effective.

All the best,

Peter

 

[oldnslo]

Does this engine have a timing belt? I don’t remember what models had the timing belt. If belt could timing have jumped a tooth?

 

[RandyT]

Does this engine have a timing belt? I don’t remember what models had the timing belt. If belt could timing have jumped a tooth?

That was the Triad TH engine family. Good engines until their weren't

 

[Modrob]

Ok, so both pistons move, all the valves move, but you have no compression, which leaves either perhaps timing, or perhaps lack of oil in the top of the pistons due the fuel / oil issue and wear, or no fuel, or no spark.

You could try a teaspoon or two of oil in each spark plug hole, then crank briefly with no plugs, put the plugs in after checking the spark, and see where you are. If that doesn't work, then I think you are on to timing or a lack of fuel, but the starting fluid failure suggests no spark or poor timing to me, if the oil in the pistons isn't effective.

All the best,

Peter

Good thinking Peter…I had wondered before I found the bent push rod, and just after I found gas in the oil, about compression. I had spark on both sides. So when I did the compression test about that time, I thought maybe the mixture had stripped all the years of “use and bad oils” away from the rings. But then I thought, wouldn’t that be both sides? I read about 90psi on the other bank at that point.
I had thought about the oil in the plug port today to see if it made a difference, but didn’t get to it. (I was thinking that after pouring a little in, to try another compression reading. Probably not good for a real result, and I can see where your suggestion would likely give a more positive element.)

 

[MossRoad]

I you have good compression on the one side, the engine should still start and cough, run rough, etc, but it should still start.

So compression test on both cylinders would be the start.

Spark: you see it, but is it strong? Could be coil issues.

If spark is strong, you have good compression, you give it a squirt of starting fluid, and no pop, then it's timing. If it pops on starting fluid, but won't run, it's fuel issue.

One more thing. As I recall, there's some sort of seat or saddle thing under the rockers. Someone once mentioned finding that out of place and it caused a similar issue. So it might be worth pulling each rocker and making sure that little thing is installed correctly. I saw a video and/or pictures of it somewhere but cannot recall.

 

[Modrob]

I you have good compression on the one side, the engine should still start and cough, run rough, etc, but it should still start.

So compression test on both cylinders would be the start.

Spark: you see it, but is it strong? Could be coil issues.

If spark is strong, you have good compression, you give it a squirt of starting fluid, and no pop, then it's timing. If it pops on starting fluid, but won't run, it's fuel issue.

One more thing. As I recall, there's some sort of seat or saddle thing under the rockers. Someone once mentioned finding that out of place and it caused a similar issue. So it might be worth pulling each rocker and making sure that little thing is installed correctly. I saw a video and/or pictures of it somewhere but cannot recall.

The latest has been: no compression at all—zero—on both cylinders, about three days ago.I haven’t had much time to go into it very much since then with so many other fixes that have popped up.
I’m curious to try Peter’s suggestion with the oil in the cylinder and see if any different result. Maybe then a leak down test?..
My last start attempt was after I’d replaced the pushrod and before the last compression test, starting fluid didn’t do much if anything. Adding a little choke as well didn’t help and got that terribly loud backfire—this one sounded like a gunshot! (Scared the crap out of me, and I was ready for it)
The spark tester is inline and appears to be bright. But, this is that ignition system that I believe or calls for the conversion kit of flywheel and new coils. It has that little electronic box mounted over off one of the valve covers…Smart Advance maybe? Wouldn’t it be kind of odd for that system to suddenly go haywire at this point?
I’ll relook at those rockers and see about any seat or saddle…

 

[ponytug]

The latest has been: no compression at all—zero—on both cylinders, about three days ago.I haven’t had much time to go into it very much since then with so many other fixes that have popped up.
I’m curious to try Peter’s suggestion with the oil in the cylinder and see if any different result. Maybe then a leak down test?..
My last start attempt was after I’d replaced the pushrod and before the last compression test, starting fluid didn’t do much if anything. Adding a little choke as well didn’t help and got that terribly loud backfire—this one sounded like a gunshot! (Scared the crap out of me, and I was ready for it)
The spark tester is inline and appears to be bright. But, this is that ignition system that I believe or calls for the conversion kit of flywheel and new coils. It has that little electronic box mounted over off one of the valve covers…Smart Advance maybe? Wouldn’t it be kind of odd for that system to suddenly go haywire at this point?
I’ll relook at those rockers and see about any seat or saddle…

Do you have the service manual?

https://resources.kohler.com/power/kohler/enginesUS/pdf/24_690_06_EN.pdf

Here is Kohler's list;
Engine Cranks But Will Not Start

● Battery connected backwards.​

● Blown fuse.​

● Carburetor solenoid malfunction.​

● Choke not closing.​

● Clogged fuel line or fuel filter.​

● Diode in wiring harness failed in open circuit mode.​

● DSAI or DSAM malfunction.​

● Empty fuel tank.​

● Faulty electronic control unit.​

● Faulty ignition coil(s).​

● Faulty spark plug(s).​

● Fuel pump malfunction-vacuum hose clogged or leaking.​

● Fuel shut-off valve closed.​

● Ignition module(s) faulty or improperly gapped.​

● Insufficient voltage to electronic control unit.​

● Interlock switch is engaged or faulty.​

● Key switch or kill switch in OFF position.​

● Low oil level.​

● Quality of fuel (dirt, water, stale, mixture).​

● SMART-SPARKTM malfunction.​

● Spark plug lead(s) disconnected.​

I would certainly consider the low oil sensor as being possibly bad.

A large backfire certainly makes me think of timing issues. As your engine is a gear driven camshaft, a bent push rod could have done some damage. Did you find any metal when you drained the oil?

All the best,

Peter

 

[Modrob]

Do you have the service manual?

https://resources.kohler.com/power/kohler/enginesUS/pdf/24_690_06_EN.pdf

Here is Kohler's list;
Engine Cranks But Will Not Start

● Battery connected backwards.​

● Blown fuse.​

● Carburetor solenoid malfunction.​

● Choke not closing.​

● Clogged fuel line or fuel filter.​

● Diode in wiring harness failed in open circuit mode.​

● DSAI or DSAM malfunction.​

● Empty fuel tank.​

● Faulty electronic control unit.​

● Faulty ignition coil(s).​

● Faulty spark plug(s).​

● Fuel pump malfunction-vacuum hose clogged or leaking.​

● Fuel shut-off valve closed.​

● Ignition module(s) faulty or improperly gapped.​

● Insufficient voltage to electronic control unit.​

● Interlock switch is engaged or faulty.​

● Key switch or kill switch in OFF position.​

● Low oil level.​

● Quality of fuel (dirt, water, stale, mixture).​

● SMART-SPARKTM malfunction.​

● Spark plug lead(s) disconnected.​

I would certainly consider the low oil sensor as being possibly bad.

A large backfire certainly makes me think of timing issues. As your engine is a gear driven camshaft, a bent push rod could have done some damage. Did you find any metal when you drained the oil?
View attachment 846301

All the best,

Peter

Thanks for that link…
I’m just baffled by the sudden loss of compression on both sides. My warped sense of “thinking” can’t get unwrapped on that. Seems like it should be so simple to find but yet I’m fumbling my way around. (I think my biggest problem is I have too many problem projects that need fixed immediately and I keep getting distracted—even my therapist agrees LOL)