ACR problem or not?
 

Ok all working on a kohler 15.5 cv15s engine. Motor was running good, all at once starting backfiring through carbuator. Pulled valve cover, exuast valve not closing all the way. Loosend the rocker arm, valve then closed all the way. Pulled the lifter out, it's ok. Pulled bottom of motor apart, acr working ok. Checked the valves, they are seating properly. Carbuator checked ok. Put motor back together, still backfiring through carbuator. What do i need to look for???????:bash2::bash2: Also pulled the flywheel, sheer key was ok.

Walter,
Check the key in the flywheel. It may be sheared enough to to throw the timing off. If my memory is working right this motor should have the flywheel triggered ingition system.

I was always told it is an timing problem if it backfires through the carb.

Normally I would agree with Merk about this but didn't you say the exhaust valve wasn't closing?

If that is the case the valve stem or guide could be full of crud, the stem could be warped, bent... or the tolerances could be too close and the guide may need to be reamed.

Check the key like Merk said, if it has even a slight mark on it, replace it. If that doesn't do it, I would look into a problem with the valve or guide.

I have the CV15S on my non-cub tractor. On mine, one lifter quit and started clacking horribly. I ended up with two new lifters, two pushrods, and a head gasket. Fixed it. Odd thing was the new pushrods were solid, not hollow like the originals. And, the lifters "looked" different. Maybe you have a lifter that's pumping up and not bleeding down like it should and holding full height? If you look around on the 'net, the parts can be found quite reasonably. There are also people who want a lot more. Good Luck finding it.

Another thought: did you pull the carb and look in the plenum for any pieces of carbon or other nuts/bolts/junk that probably shouldn't be there? Might be a good place to check...

acr
 

Carb ok. Where did you get your lifters and push rods from.

thanks

pesnet.com

I had to run out to the shop since I remembered seeing this packing list yesterday.

I bought the following:
12 041 01-S Gasket, Carb
12 041 03-S Gasket, Exhaust Man
12 041 10-S Gasket, Cyl Head
12 411 04-S Rod, Push (Qty2)
25 351 04-S Kit, Hyd Valve Lifter (Qty2), came with special grease for breakin.

I don't recall the final cost, but I do know I shopped around a bit for the best price.

Hope this helps you on yours. I guess bad lifters was a known issue back in the late 90s, and mine never ran long enough to expose the problem. Honestly, my JD looked like it had maybe 20 hours on it, and it was 10 years old! 10 hours of me running it exposed the lifter issue.

I see Tulsa Engine Warehouse also. For some reason, pesnet.com doesn't sound familiar, but that's what's on the packing list.

Acr
 

Roderman

Thanks for the information. After the information you gave me i think it is probley the exaust lifter.:bigthink:


Thanks

I don't see how an ex lifter would cause it to backfire through the carb.

Also, when my lifter failed, it wouldn't pump up. It sounds like maybe yours won't let down, which, while possible doesn't seem logical.

When you said "backfire through the carb", is that when Idling? WOT? Under Load? Shutting it down? Opening from idle?

A misadjusted, malnourished or overfed carb will cause it to backfire, sputter and pop. I'd hate to see you waste cash on lifters and parts that aren't necessary.

How's the air filter on that engine? It may not run right with no air filter if you're trying it that way.

Acr
 

Rhoderman

It backfires through the carburator when you try to start the engine. When i first took the valve cover off the exaust valve stayed open all the time. You could remover the rocker arm and the valve would close. Both of the valves are ok and the seats are ok. The valves do not stick, and they are not warped. I took the lifters apart and cleaned them, no trash, no abnormal wear. The exaust lifter could have been sticking causing it to stay pumped and not closing the valve. It will be tuesday before i can check it out again.
Thanks for the help. I will let you know the outcome.

Thanks