C160 auto engine cutting off

[manant 57]

Well. I am still not happy.

I now have:

1. a new battery - needed

2. new points. condenser, coil, plug, and plug wire.

3.new rectifier - needed

4. dedicated ground wires from the battery negative terminal to rectifier, solenoid, and head lights.

 

Yesterday, I started the tractor and adjusted the idle and power screws on the carb.  I cut the lights on (the brightest they have ever been due to the dedicated ground).  I noticed that when I cut the lights on the Ammeter jumped to the far side of positive.  When I cut the lights off, there was a slight hesitation before the needle came back to the neutral position.  I then ran the tractor and mowed about 200" and it quit. Dead as a hammer electrically.

 

For all you Ammeter haters I figured that I was not getting battery power across the ammeter to the coil so I by-passed the ammeter today and it started right up and ran it under mower load for about 200" again and the engine started a bad knock and I thought it might blow so I shut it down. BUT I still had electrical power - like to the lights. It seems like the engine is getting very hot, It even smells hot. I always check the oil level before I start out and it's level was between the full and add marks.  I did add some oil and it started right up and I was able to get it back to my shed for more work.  I thought I might have a mouse nest under the cowling that restricted air flow across the fins.  I removed the metal shield on top of the engine and was going to remove the entire cowling but I could see down to the flywheel and everything looked clean and unobstructed.

 

Running under load seems to be when the engine labors and cuts out.

Any thoughts on the laboring under load problem?

Thanks for the interest and suggestions.

 

 

[Gasaholic 224]

I would start with a DVOM handy , and/or connect the meter to monitor voltage at the coil positive and see if the voltage cuts out at coil when the engine dies. that lets you confirm or eliminate an electrical issue causing the cut-out (bad switch? seat swicth cutting out? bad ammeter?)  The ammeter jumping to pegged when lights are turned on just indicates a heavy load , and if lights are off when tractor cuts out, I wouldn't concern myself with that until the cutting out is solved.  I would also want to know if this tractor has the engine mounted on vibration isolators - if they are, I would want to verify that the ground strap is actually connected properly (Original had a small ground jumper bolted to the engine mounting plate and then to one of the vibration isolator through-bolts.. that little jumper cable often was the cause of a number of weird electrical problems including throttle or choke cables getting hot because engine was grounding THROUGH those unreliable "ground paths")  Rather than dedicated ground as you did, I would instead run a jumper cable from engine bare ground to battery negative which also would temporarily solve that ground continuity problem. 

 

If you can confirm your problem is not electrical as I mention above, then I would start thinking about ignition timing - Have seen some engines that had cracked camshafts that caused timing to jump around... (I'd call it a pretty rare/unusual problem and rather unlikely.) Cracked cam can also affect valve timing if it cracks at the fuel pump lifter area... and when you replaced the points, i would have also taken note of the push rod for the points - The old ones were aluminum and had problems, Kohler replaced them with steel push rods.. so we'd often keep breaker pushrods in stock too. 

 

[manant 57]

My engine does not have vibration isolators.  It is bolted directly to the frame and the ground wire from the battery (-) is attached to one of those bolts.  I have a good ground.

Regarding timing, I just replaced the points and static timed it. At th ewidest gap I have .020".  It still may be a timing issue.

[953 nut 55,264]

Sounds like you have multiple problems that need to be corrected. I would begin by cleaning and tightening ALL electrical connections including grounds. The cutting out issue has been there before and after the repairs you have done.

Was the engine running hot before? The overheating issue could be the carburetor setting being too lean. Running too lean could also contribute to the laboring under load issue. Check your engine timing to be sure it is correct, use a timing light or the static timing method as covered in the Kohler service manual.

 

[Gasaholic 224]

11 minutes ago, manant said:

 I have a good ground.

 

Are you sure? (Voltage drop test under load, usually while starting, is the best test) - Have seen brand new OEM ground cables that were nice and tight on a brand new tractor, but the cable itself was improperly attached/crimped to the terminal, causing very hard cranking due to high resistance under load (not enough contact to carry the amp load) - as well as cables that were not tightly crimped and engine vibrations were causing intermittent ground drop-out. One of the very first things I learned as a pro tech was:  NEW is not the same thing as GOOD. Especially when it comes to electrical stuff. (Like fuel lines, wiring, etc.. Might look beautifully pristine on the outside, but to use another cliche` , you can't judge a book by its cover!)   

 

Voltage drop test by the way: DVOM on DC Volts connect one test lead to Battery Negative, connect other test lead to bare engine ground, key on should see 0 volts, then crank engine over and watch the meter, if you see more than 0.2 volts or so, you have a voltage drop. - The higher the resistance of the drop, the bigger the voltage drop.  Here's a good guide on it from Fluke: Diagnosing Voltage Drops Electrical Automotive Troubleshooting | Fluke

 

Your symptoms being so mysterious and hard to solve is what makes me think of voltage drops - especially in conjunction with your seemingly un-related amps jump when you turn lights on.. It is likely NOT a cause of your problem, but may be a CLUE to an overall system problem that COULD be casusing your issues. (Hence my suggestion to watch voltage at coil + when engine cuts out.) 

[manant 57]

Here is the latest.

I figured that my no electrical power issue had to be in the key switch to battery circuit.  All that is in that circuit are two connections (to battery and to solenoid), a 25 amp fuse, the ammeter, and the switch itself. The fuse was good, the connections were good and the switch tested good..  I by passed the ammeter and everything seems OK electrically.

 

After some reading of the Kohler manual and following 953 NUT's suggestion I looked at the carb settings.  I mentioned earlier that I had taken the carb off to clean all the ports and vents. When I reinstalled it I incorrectly set the fuel needle screws.  I was thinking 2 1/2 turns for the main jet and 1 1/2 turns for the idle.  Should have been 3 1/2 for the main jet and 2 1/2 for the idle, so I was running a very lean mixture.

Today, I backed the needles off the proper number of turns and started the engine.  I heard a ticking noise at idle but otherwise the engine seemed to run fine. I set the low idle to 1200 RPMs.  Unfortunately at higher RPMs I got a loud valve clatter noise.  I wonder if I have a bad exhaust valve that is sticking or bent. Last Tuesday when the engine failed under load I had a lot of clatter before I switched off the engine.  I might also mention the the engine was rebuilt about two years ago. Had the crank reground and cylinder over bored.

Thanks for any help /suggestions you may have.

[peter lena 8,631]

@manant  not exact , but similar , had an eractic , engine dying / cut off , traced it back to the fuse holder area , there was , stress cracking , along with a powdery  crack tracking  fuses ,  agree with the increased grounding / corrosion issues . that rectifier mount bolt / screw , to the battery ground bolt , is the deal , you can try / test that , with an alligator clip test wire .  those engine cooling tins are counting on related ground , very often , rust / corrosion / paint , stops the flow . pays to go over all your wiring , renew / re route , cable / wire wrap , verify as you go , check at every change . make the electrical  set up a strong point , we have all been there , pete 

[peter lena 8,631]

@manant  https://www.amazon.com/uxcell-Flexible-Spiral-Computer-Manage/dp/B01MT81WNF/ref=asc_df_B01MT81WNF/?  use a lot of this , hunt around for pricing availability , also use the stick on  / screw mount  , in the same area , for a wire run. make a point of doing a remount / reroute  , eliminate tight , stressed , chafing wires , like a light smear of dielectric grease , to enhance /  and eliminate corrosion .  test / verify as you go , look at every connection , good luck , pete

[ebinmaine 67,540]

I've been offline for a few days. 

Good to hear you're making progress in some ways.  

 

With a known lean mix and the clattering noise at hand I'd be prone to removing the head and valve cover to verify conditions in there. 

 

 

[manant 57]

I checked the valve/lifter clearances the other day and the gaps were spot on.

 

I removed the head today and while there was some carbon build-up on the piston and the head I did not see any obvious damage or discoloration of the cylinder. The valves looked OK - black carbon on the intake and pinkish color on the exhaust valve.  I did not feel any slop in the  piston at TDC.  There were a few vertical wear scratches in the cylinder but I could still see the cross hatching on most of the cylinder.

 

I am going to see if a local engine guy will listen to the engine and see if he can provide insight.  He builds racing engines and helped me rebuild the kohler three years ago.

 

I am wondering if incorrect point gap and timing could be par of the problem.

Again I thank you for the input

[ebinmaine 67,540]

On 8/24/2023 at 5:46 PM, manant said:

I had a lot of clatter before I switched off the engine

 

Do you still have the balance gears in?

 

Those are increasingly well known to fail. 

 

[manant 57]

A few years back my k341 had a major failure - shattered piston, bent valves etc.  When I tore the engine down one of the balance gear shafts had broken off.  I thought the engine was toast, but I was able to rebuild it without the balance gears.  The fellow I plan to take it to next week advised me that we could rebuild it and he helped with re-boring the cylinder,  plugging the balance gear shaft hole in the block, and getting the rings and piston in place.  The engine has had more vibration without the balance gears, but otherwise has run very well.  Three years ago I tore the engine down again and had the crankshaft reground and put in a new oversize piston.

Today I pulled the head and cleaned the carbon off of the piston, valves, and the head.  I hope to get it back together later today and use some Sea Foam in the crankcase, in the fuel tank, and run Sea Foam spray through the throttle body.

[manant 57]

I am mowing again!

On reflection, I believe my problems came from a faulty rectifier connection and a faulty ammeter connection.

I was puzzled that I had no electrical power after the engine stalled (no soleniod click, no lights...) The more I thought about it it seem logical the I had a problem in the circuit between the battery and the key switch. I believe the engine was not starving for fuel it was starving for spark.  Since there are only a few connections, a 25 amp fuse and the ammeter in the circuit.  I bypassed the ammeter and I have electric power when I need it,  I just twisted the wires together and put a wire nut on the connection.  I have ordered a volt gauge to put in where the ammeter was.

 

My stalling-out problem was operator error.  In my search for problems, I removed the carb and cleaned it and remounted it.  Unfortunately I had set the main fuel and idle needles too lean so I was running the engine very hot.

I had set the points at 0.020" and static timed them but I must have done something wrong because when I checked the points again I noticed that the old points had a wider gap. - so I also had an ignitation problem as well.

I got everything back together and took it to my mechanic friend who said he thought it was running well.

 

So far new points, new condenser, new coil, new plug, new plug wire, new battery, new rectifier, cleaned carb, proper valve clearance,  dedicated ground wires to the rectifier, solenoid, and head lights,

 

I mowed some fairly heavy grass for a few minutes this afternoon and everything seemed to be OK.

 

I appreciate all of you who provided suggestions and input on my problems.