Kohler 7 3E

[Carverlvr2]

I’m back to tackling the genny again. Hoping someone here can shed some light. Kohler 7.3e, 2004 with 900 hours. The genny was hard starting last season (the few times I got to run it) and found the electric choke adjustment and new plugs and that seemed to help reduce the cranking time but then I noticed it would run great until I put the soundshield back on. It would shut down within a few min of closing it up. Didn’t do that the previous season. I don’t know if it’s shutting down for high temp or lack of air or some other cause so I pulled the entire soundshield off, pulled the spark arrestor and carb for cleaning/rebuild, and pulled the heat exchanger to back flush just incase that was causing an over heat. Replacing the thermostat too just for good measure. I noticed two things when dissembling:
1. The foam in the soundshield was clearly imprinted with the choke, carb connections, and coolant cap. In the top sitting too far down?
2. There’s a chamber that sits between the flame arrestor and the carb. There are two hoses coming off either side but the one on the left was not connected and had oil everywhere. What does this do? This could also be the source of the oil I’m finding in the pan and all over the back and side.
I appreciate any help you can provide.

[Carverlvr2]

Ok. I figured out the larger hose that was sitting disconnected is the crankcase vent tube and can certainly explain some or all of the oil I keep seeing but I’m now wondering if that got knocked off accidentally at some point or can it build up enough positive pressure to blow off? I would love to learn more about how all this works.

[Carverlvr2]

Finally got to put everything back together. Cleaned the carb (was actually rather clean), new gaskets, replaced the auto choke and noticed the new version is considerably beefier on the internal coil/spring, lubed the rest. Heat exchanger got new o rings, thermostat, and pressure cap and coolant. Won’t know if any of this fixed the issue for a few more weeks..still have another freeze or two on the way.

[km1125]

Source of the post Ok. I figured out the larger hose that was sitting disconnected is the crankcase vent tube and can certainly explain some or all of the oil I keep seeing but I’m now wondering if that got knocked off accidentally at some point or can it build up enough positive pressure to blow off? I would love to learn more about how all this works.

If it's the vent hose I'm thinking of, there really shouldn't be any pressure at all in that hose. Any pressure would come from the crankcase but the other end of the hose is vented into the intake of the motor ahead of the carb, with no restrictions, so any pressure from the crankcase still shouldn't develop pressure in the hose. Likely got knocked off or vibrated off. You could run this vent hose though a catch can before it hits the carb to catch any oil before it has a chance to leak into the bilge.