More problems on the 425 Kohler CH25

[Modrob]

Right or you have no compression on that side. Suggest pulling plug, attaching plug wire, clamping spark plug flat (where wrench goes) to convenient ground, and cranking starter. Look for strong and consistent spark. If none, troubleshoot your ignition system -if looks good/strong, check compression

Forgot to mention, earlier I had done a compression test—between 150 and 160 on both cylinders…

 

[Modrob]

I am going in circles here…earlier, thinking the coil had gone bad, (I had pulled the plug wire off that side and no change) I decided to look again. First, I pulled the white wire off the coil and went to crank on it. The motor sounded very odd while cranking (can’t think of a way to describe it, and battery seemed a little weak as temps here got colder) but after about 6 seconds it fired up but no change in the missing. Put the wire back on the coil, and then pulled the plug and found it wet. Then, found my spark tester and put it on and fired it up. Immediately saw plenty of spark, and then noticed an arc bouncing all around the tester boot surface to the surrounding metal cover. Grabbed hold of it with some insulated needle nose pliers (still got a good bite—ouch!) but no difference.
So…I’m getting spark but nothing is happening at the end of the spark plug, revealing I have an issue going on with an exhaust lifter (this is the side I found a new lifter solid so I replaced it with one of the old ones I had rebuilt,) push rod, or valve issue?

Evidently I’m missing the basics and chasing my tail. Today I’m going to pull the cover and head and see if there’s anything there…

 

[Modrob]

This morning while studying videos, I found one particularly interesting…(this was on a Briggs twin)
Using a spark tester like mine, he had a good spark showing in it, but noted still a problem with missing. Ended up finding a diode bad in the kill wire to that cylinder. Maybe a possibility here?

 

[2manyrocks]

I haven't priced the aftermarket ignition parts, but wonder if it would be that expensive to replace them in case you have some intermittent issue going on that would make anyone chase their tail?

 

[MTGreen]

Did you replace the plug wire?
Could be arcing/shorting.
If there is a lifter/valve/pushrod/valve seat issue it will show in the compression. Suggest retesting
Other possibility is your cam lobe is worn down. Did you measure when you had it apart?

 

[MossRoad]

On that engine, I don't think you can replace the plug wire(s) without changing the entire coil(s).

 

[ponytug]

Can you swap the coils/wires to rule out a bad wire/plug on these engines?

@Modrob- I like the idea of a bad/flakey ground on the kill switch. Can it be disabled / disconnected?

All the best, Peter

 

[Modrob]

I haven't priced the aftermarket ignition parts, but wonder if it would be that expensive to replace them in case you have some intermittent issue going on that would make anyone chase their tail?

I found a set of two cheap coils on eBay and ordered a few days ago…we shall see…

 

[Modrob]

Did you replace the plug wire?
Could be arcing/shorting.
If there is a lifter/valve/pushrod/valve seat issue it will show in the compression. Suggest retesting
Other possibility is your cam lobe is worn down. Did you measure when you had it apart?

The arcing was around the boot of the nearly new spark tester. Inspection of it didn’t show any cracks that my eyes could see…
Yes a deeper inspection is warranted—but between snow squalls and high winds today I just don’t have the energy…(so far)
I will retest after I start looking deeper…

 

[Modrob]

Can you swap the coils/wires to rule out a bad wire/plug on these engines?

@Modrob- I like the idea of a bad/flakey ground on the kill switch. Can it be disabled / disconnected?

All the best, Peter

Last night, I did pull the kill wire off the affected side coil—no change. But now I believe I need to verify that if there are diodes in this kill wire circuit I need to test them…see a couple more videos on that….