plug reading-K181S

[Mr. 856 170]

I made the very bad mistake of not torqing the nut for the flywheel after a rebuild. Engine ran awesome up until it started knocking and just quit. Flywheel nur came loose, flywheel hub broke leaving me dead in the water. Thankfully crank is fine and I have acquired a new flywheel. I invested in a torque wrench as to not make that fatal mistaje again. So I'm just going through the engine again before I bolt it back into the tractor. Pulled the plug and was wondering what you all think of this? Carbon build up not oil. Engine started easily, didn't smoke, seemed to be spit on minus the flywheel issue. I'm guessing 15 hours of run time on rebuild with a lot of those hours being at lower RPMS. Mostly putting around with the boy and runs out to the pile. How concerned should I be? Should I dig a bit deeper? Put a new plug in and check after five hours? I spent a good chunk getting this motor redone. I hate to be running it if this plug is telling me something isn't set up right. Thoughts from the engine experts?

[gregg'shorses 77]

If a lot of the 15hrs at low revs a little fouling can be expected , how clean is the air filter?

[Mr. 856 170]

Filter is clean as a whistle as is carb. Engine runsruns fine at all speeds. It just gets run at low rpm's more tHan not. I need to get some fresh oil so I'll grab a new plug while I'm out. See what happens after a few hours of run time after its bolted back in. What would be the cause of a hair of soot and oil in the air cleaner? I really mean just a tad. 

[ACman 7,655]

Anyone try E3 spark plugs , they were made for small engines in their beginnings.

[elcamino/wheelhorse 9,362]

I use E 3 plugs in my 5 hp Briggs ( on a leaf blower ) and my 5 hp leaf vac motor. I tried to find one for my 12hp Kohler on my C-120 , but could not find a cross to the recommended Champion plug. I like the E 3 plugs.

[slammer302 2,156]

I would try to keep it around half throttle or more being a fresh engine and that small kohlers are splash lubricated so your are not getting full lubrication at low idling speeds. I would put a new plug in it and run it for a few hours and check again. I have a old commando 8 that smokes very badly and when i pull the plug it looks like urs. Something doesn't seem right about it hopefully it just from oil getting by the rings while it was breaking in and maybe the fuel is a little on the rich side. Good Luck     

[WH nut 553]

15 hours the rings havent seated and the motor isn't broke in yet. Run it hard to seat the rings and the oil fouling will go away as long as the rebuild was within specs.

[AMC RULES 37,196]

Aren't these engines were supposed to be operated at full throttle?  

[WH nut 553]

5 minutes ago, AMC RULES said:

Aren't these engines were supposed to be operated at full throttle?  

When you are working them

 

5 minutes ago, AMC RULES said:

Aren't these engines were supposed to be operated at full throttle?  

When you are working them

 

[AMC RULES 37,196]

So...lubrication isn't an issue at low RPM?  

[Shynon 7,482]

Yes lubrication is a huge issue when running a new engine at low speed, not enough oil splash to lubricate surfaces when engine is tight. When I rebuild a kohler I will run it for one hour at full throttle (3600 rpm) then change oil. Then use it for the next 5 hrs at full throttle. Then I am confident it will be good to go. Been kicking around the idea of something I can hook up to put the motor under load for 1 to 5 hours to break in motors.

[WH nut 553]

13 hours ago, AMC RULES said:

So...lubrication isn't an issue at low RPM?  

It is a problem under load. The oil not only lubs, but helps with cooling. if you are just putzing around the yard picking up sticks or leaves part throttle wont hurt a thing.

[Racinbob 11,978]

Lower RPM isn't a problem. In the 60's and 70's I don't recall it even being mentioned. Between myself and my Dad we put many, many hundreds of hours pulling a trailer load of big and little kids through the paths just above idle with our K-series motors. There's a lot of splashing going on even at idle. Full throttle using a PTO driven attachment is more for the efficient operation of the attachment. Breaking in a motor is a different beast though. I like Shynons idea of a load.

[Mr. 856 170]

I haven't used the tractor for much more then putting around. Hasn't been put to work yet. Was hoping to do that this winter but not so much. When I get it back together I'll keep the rpms up.

Thanks for the advise.

[tbarnhart 240]

Lubrication in splash motors isn't a problem even at idle. Normal idle specs are around 1200 RPM. It may vary a bit for different models. At 1200, the dipper on the rod is splashing in the oil 20 times a second. Take a shallow pan of oil and dip your finger in it as fast as you can. You won't be anywhere close to 20 times a second and you'll still make the biggest oil slick since the Valdez. There's plenty of oil splashing around in these engines. Also, most reciprocating air compressors are splash lubed and run at low speeds (600-1000 RPM) and they often last for 10,000 or more hours.

[prondzy 3,889]

On 1/7/2016 at 7:46 AM, Mr. 856 said:

I made the very bad mistake of not torqing the nut for the flywheel after a rebuild. Engine ran awesome up until it started knocking and just quit. Flywheel nur came loose, flywheel hub broke leaving me dead in the water. Thankfully crank is fine and I have acquired a new flywheel. I invested in a torque wrench as to not make that fatal mistaje again. So I'm just going through the engine again before I bolt it back into the tractor. Pulled the plug and was wondering what you all think of this? Carbon build up not oil. Engine started easily, didn't smoke, seemed to be spit on minus the flywheel issue. I'm guessing 15 hours of run time on rebuild with a lot of those hours being at lower RPMS. Mostly putting around with the boy and runs out to the pile. How concerned should I be? Should I dig a bit deeper? Put a new plug in and check after five hours? I spent a good chunk getting this motor redone. I hate to be running it if this plug is telling me something isn't set up right. Thoughts from the engine experts?

Mr. 856, aside from the lubrication debate had above it looks like you are burning oil from blow-by. I and Shynon have built many k series engines successfully. If the motor was built by you or a reputable shop,that caused this problem i don't belive is the issue. When you build these kohler the first hour of break in should be at full throttle/3600 rpm. Dump the oil and install fresh. Wait til the next day after the heat cycle has been completed retorque the headbolts when cool. Then run the engine at full throttle for the next 5 hours (doesn't have to be all at once, but try to shoot for at least an hour at a time) under load by mowing or plowing to generate as much heat in the motor as possible to seat the piston rings. I beleive the lack of heat generated by putting around has caused the issue in question. At this point you could try to seat them with heat and see what happens or install new rings maybe hone the cylinder and break in as I stated above. Hope this helps and pm me if you have any questions.

Edited January 13, 2016 by prondzy