Identifying Kohler Pistons A, C And D

[dunoon2]

I need help telling which piston I have. And which direction it goes. What is the difference between a,c and d pistons?

[Skywatcher]

Hi Dunoon

Can't help you with identifying pistons as tech manual is out in the shop. However, most pistons have a right way and a wrong way round for installation. If the piston has a notch in the top edge or an arrow stamped into the crown, the notch or arrow always goes towards the flywheel. If the piston has no markings, then it can go either way round. I had a customer bring in a Kohler KT17 engine that was knocking. I figured it was probably the timing or the valves.

Timing was within spec, so had to be the valves. When I pulled the heads off to access the valves, I found that the pistons had been installed with the arrows pointing away from the flywheel. I also found that the wrong crankshaft seal had been installed leaving a 1/8" gap between the crank and the seal. The crankcase has to be split to change this seal. The customer was pretty irate when I pointed these out to him as he had just had the engine rebuilt a couple of years previously. The engine is still sitting in my back shed with the wrong seal, but with the pistons the right way round now. All the best,

Sky

[bgsengine]

Need a model number. Older K series? Magnum? Command? Can depend on the model series as to what the letters may mean. There were some K series cast iron singles that had letters identifying factory oversize, Others had specific marks or notches as sky said, because piston pins were slightly offset to one side , they had to match up with connecting rods and installed only one direction... So, a lot of that may depend on the model (or model series) of the engine. K series, KT series, M series, and then later command, command pro, courage, etc models may all have had different build specs and identifying marks.. Sometimes the letters were important, sometimes they were just batch stamps and only mattered to the factory at time of assembly.

[dunoon2]

I forgot to tell ya it's a K 241 there is no mark on the top of the piston, does the rod go in with the hole on top of the journal facing the cam?

[Skywatcher]

Hi Again Dunoon

The hole in the connecting rod needs to be positioned so that is scoops oil up into the bearing as the dipper goes through the oil bath. Hope this helps,

Sky

[bgsengine]

Like Sky said, think on it - normal engine rotation (from Flywheel side which is the closure plate side) would be clockwise , So given the cam is on the left side (again from flywheel side) you'll see that the dipper dips into oil pan and then throws oil (splash lube) towards cam and gears, etc, and as it comes up, oil is splashing back, so the oil hole in the rod and/or cap should be towards the cam side.

As for the pistons for a K241, no difference in pistons, as I recall (I presume you mean the cast letters, which would just identify the casting molds, etc for factory production and quality control use, techs don't need to worry about it) - If there's anything stamped in top of piston, it'll typically be bore size (STD, .003, .010, .020, .030) The piston itself, as they are not offset, can go in either way (those with a notch cast into them are offset pistons, notch side would face front/flywheel, so those, you do need to pay attention to mating up the rod and piston) Me, I liked to be consistent when I was doing rebuilds, so when I'd be assembling "either way" pistons , I'd tend to see if there was a single lubricating notch in the piston pin lands next to the rod, and set that lubricating notch towards the PTO side (thinking that side would be hotter, so needed as much cooling as it could get, via oiling)