[1031d]

I have a late 1968 195 with a K301 in it. I can run it for 15-20 minutes, then it dies. Full choke and it's up and running, full choke only and not anything past half throttle. It still has the original fuel pump on it with the steel plate on top, and a Carter N carb. Let it sit for 20 minutes and it runs fine again, then same thing. :headscratcher: I have a stock replacement muffler on it from Steve to replace the guys erector set of plumbing on it, but missing the heat shroud for the pipe on the back of the engine. Seeing as it runs with the choke on I'm ruling out the coil, condenser and points.

 

[Hydriv]

I would rule those out too. At least for the moment.


When diagnosing an elusive problem like this, it's wise to begin by getting back to the basics.


1. Remove the shrouding and make sure that all the fins are clean and nothing is blocking the cooling air for the engine. Check the flywheel fan to make sure all the blades are intact.

2. Make sure that the valves are set properly

3. Make sure that the points are set properly.

4. Make sure that the carb to block gasket is in good condition and that the carb is bolted tightly to the block. This is about air leaks that can get caused by the engine heating up.

5. Make sure that the engine is not starving for gas.. blocked vent hole in the fuel tank. Dirt in the float bowl. Fuel line that has hardened up from age and is no longer sealing properly at the places where it's clamped to the carb or pump....allowing air to get sucked in. Make sure that the needle and seat are not sticking, that they are clean and that the float level is set properly.


Your problem does sound temperature related and it also sounds like either fuel starvation or air getting into the intake on the other side of the throttle plate, thus throwing out the mixture ratio.

Do not overlook the wrong spark plug. Heat range is important. Vapour lock is a possibility depending upon what you are running for fuel. Of course, a weak pump might be an issue but if it runs well for 20 minutes then that is unlikely.

 

[1031d]

Hydriv, thanks for the input. It did it when I bought it. I replaced all the fuel line with new 1/4" rubber hose and put in an inline fuel filter(didn't have one). I replaced the float valve and bowl gasket. Float is brass and in good condition. I also installed one of those plastic spacers between the carb and block. I didn't remove the tin work from around the engine as it has a good blast of air blowing out of it when running. His erector set of exhaust was cooking my foot so I took that off too. I bought a new coil, points, and condenser but I think it's a fuel problem. It doesn't behave any different with the gas cap off. I put in a brand new Auto-Lite spark plug as it had a fouled out champion in it. It was also missing the tin from the sides of the grill in front so I bought new ones because I didn't know if the hydro fan helped push air over that way too? I know some of the Wheel Horse tractors have the same engine turned so the fuel pump and carb are all inside the tin of the tractor, so heat must not be a big bother. When it runs it has all the balls it should, pulled a large Agri-Fab cart filled with stones and bricks up the hill along side my house, didn't miss a beat, ran it around the yard a little at almost wide open, shut it down, then started acting up after I restarted. Usually it does it while cutting grass. :headscratcher: :facepalm:

 

[Hydriv]

Whether you have a metal fan or plastic fan on the front of the PTO clutch....that fan plays no part in cooling the engine. It is there just for moving air over the oil cooler.

Cutting grass means that you are asking the engine to work harder than if it is just moving the tractor along the ground and work means more heat. Just for the sake of experimentation, why not hang a heat shield made out of a piece of tin, between the exhaust pipe and the fuel pump. You can use coat-hanger wire or mechanics wire through some holes punched in the tin and wrap the wire around the head. Let's see if vapour lock is what's plaguing you here. Now....you did not mention checking the valve lash in your report above and I suggest that you delve into the Kohler manual in the Service Manual/Engines section to make sure the clearances are correct. Also.... are you 100 percent sure that the Autolite plug is the correct heat range equivalent to the specified Champion? It never hurts to double check.

As for not removing the tinwork....maybe you are OK and maybe not. Excess heat seems to be the problem. Mice love to build nests inside the flywheel shrouds. For an engine to be properly cooled, it must receive 100 percent of the air flow, not 75% and ALL of the fin area must be CLEAN. You cannot see all of the fin area so that issue is still in doubt. Yes, I know..... it's a PITA to pull the flywheel shroud but the purpose of diagnosis is to totally remove each suspect area one by one so that you narrow the problem down bit by bit to the true issue. Sometimes, overheating is not just ONE problem. It's a combination of several that are working hand in hand.

 

[Billygoat]

May want to check torque on head bolts also.