Kohler Command CV491S dumping fuel out exhaust

[mikenj]

Remove key from shaft, put some lapping compount on flywheel end of crank.
Gently put flywheel onto shaft and spin around. Back anf forth in both direction.
Remove flywheel, clean both shaft and flywheel of a compound.

This method will match up the tappers on shaft to flywheel and made for a good fit.

Ok I'll check this out. I imagine this has the change to score the tapers if you do it too much then you won't have a smooth surface (which will cause more slip).

I'll proceed with caution. Thanks.

[Mek-a-nik]

Also be sure there's no oil on the taper. That will prevent the taper from doing it's job, allowing the key to shear.

[mikenj]

I spent a couple of hours doing some troubleshooting. I did hook up a gravity feed for fuel and at first it started and ran fine. Sat for a little bit and started flooding out again. I purged the extra fuel from the intake and combustion chamber and started again with the gravity feed. Engine stayed running. So immediately I thought carburetor float/needle/seat.

What is interesting is while I had the engine running the last time with the gravity feed if I moved the fuel line a tad, the engine would go to stall and start smoking black. Granted there was some air bubbles in the fuel line but I need to check to make sure there's not an electrical problem with loosing spark. I did take apart the carb and inspected the float (no holes), needle and seat with very low air pressure. Working the float open and closed sometimes it would seat (no air escaping) and other times I'd hear air passing. The seat does have some corrosion inside and I've already replaced the needle and gaskets.

So my fuel issue is down to carb, but I'm going to rule out any electrical issue with me moving the fuel line. Looks like the seats are replaceable (12 521 04-S, list price of $30). I can get a whole new carb on ebay for $98 with free shipping. Are the seats easy to replace? I do have one walbro carb tool kit so I'm guessing I'd need a special punch to install and tap to remove.

I also changed the oil with a blend of 10W-30 and 5W-30 along with the filter (which looks like it was never replaced). Engine seemed to run a lot smoother; better yet, no valve train noise . Did a leak down test also and have a compression loss of about 20% so I know the engine is good and valves are OK. I'm giving this tractor to my father-in-law so I don't want it coming back to me haha

[kingnewf]

I'm hoping someone here may be able to help with a problem I'm having with this engine. Engine has about ~ 170 hours on it and about 8-10 yrs old.

The problem I'm having right now is when I try to start the engine the carb throat fills up with gas and fuel comes out the muffler. I also noticed gas being spit back through the carb, but not with enough force to blow up. I've had a long history with repairs on the engine, but for a while it did run fine. Here's the repair history roughly in this order from what I can recall:

* Replaced flywheel key (was sheared when I bought it)
* Cleaned and checked carb since mower sat for a while
* Mower ran fine for a while before stopping. However, the valve train (lifters) were noisy for a while and went away when warm)
* After running for several hours across several days, it stopped. Engine started dumping fuel out exhaust
* Took carb apart again, cleaned and checked bowl for gas and height (again) Needle valve appeared fine.
* Did compression check, OK given ACR on these engines. Did a leak down test and did notice air leakage through both valves and crankcase at TDC.
* Checked, cleaned and lapped valves. Installed new head gasket. I did note that clearance between rockers and valve stems was practically non-existent. Not sure if this is normal (engine has hydraulic lifters)
* At some point the engine wound up shearing another flywheel key. I have not cut any grass with the mower so nothing was hit.
* Mower sat 3-4 months before trying to start yesterday.

What I *think* might be wrong is either the ACR sticking, hydraulic lifter problems or some other carb issue. I'm not sure what to do next....

I had same issue with mine ended up hydro-locking engine as fuel got into my oil after it sat for a long time. I ordered re-build carb kit for my engine and the kit did not have a replacement needle seat for the walbro carb. After investigating further i found a kohler engine tech post a reply that the same carb after 2009 was fitted with stainless seat not brass whic is what i have. I ordered that kit and installed new seat and needle and fuel issue passing stopped. Now though when i try to start it backfires and looks like timing is out? Broken key now caused from hydro lock. hope hydron lock never damaged lifters or valves it ran like a top before this issue with fuel..