1998 Gas Ezgo Engine Won't Fully Rotate

[oldsfan442]

I have a 98 Ezgo with the 4 cycle Robins engine. I am trying to adjust the valves but can't fully rotate the engine. I have the plugs removed and the engine will rotate smoothly almost a full 360 degrees before stopping. You can rotate the engine back the other way and will be nice and smooth but just before one complete revolution, it just stops. Both pistons ore moving freely as well. Nothing sounds bad and the oil is really clean. I'm not sure which valves are which but it is basically just rotating enough to complete an intake stroke or exhaust stroke.

Any help is greatly appreciated and will gladly talk to someone on the phone if that helps as well. Thanks for your time.

Bryan

[nobuckbuild]

loosen or remove the rockers and then turn the engine over by hand if it goes freely then its a valve clearence problem if it still binds you may have a bad rod also check the valve height across the bank they should all be about the same height you may have an exhaust valve stuck open due to carbon buildup and of course your timing belt may be worn and jumped a tooth requiring replacement

[oldsfan442]

Thank you so much for taking the time to reply. I was hoping for some trouble shooting pointers before I just started tearing things apart and this is a great start. I will post progress reports as I go.

One question though. If it turns out to be a valve clearance problem, what are some possible fixes for that? Or would that be related to the timing belt issue? Thanks in advance.

Bryan

[oldsfan442]

One other thing I wanted to help better explain is that the motor is stopping right before it gets to top dead center. Won't rotate past that point. Seems strange that something may be bent or broken since it does rotate smoothly.

Heading to garage now to check the valve clearance.

Bryan

[oldsfan442]

Quick update. It doesn't appear to be a valve clearance issue since I completely removed the valve adjusters so the rockers wouldn't open the valves. Also the valves all measure the same height so it would appear that they are fully closed. So with all that checked I would assume that even if the timing belt jumped time that it wouldn't be the culprit since the valves aren't even opening now.

Nobuckbuild had also mentioned a bent rod which is what I would guess at this point. Soooo, it would appear that the next move is to pull the motor. Any good tips for getting that done easily? Thanks in advance.

Bryan

[DOOmsman]

Get a small pea light and look in the spark plug holes.

[GreyGoose]

Pulling the motor is fairly easy. I take the cradle and all out the bottom after of course disconnecting battery wiring fuel hoses throttle and choke linkages and setting the cart up of the ground and supporting the engine with a jack.

[icyveins]

or you can unhook everything from the engine and grab the head like a case of beer and pull it right out of there.....

[oldsfan442]

Well I am working on this cart for the local cart shop who is currently buried with work. The owner of the cart doesn't want to mess with rebuilding so he is ordering a new motor and the bad one needs to go back as a core. Sadly I won't be able to look inside to see what the root cause was.

I sure hope the exhaust comes off without much hassle. It looks gnarly.

Bryan

[oldsfan442]

Well I got the replacement motor. I started to remove a few things to get the old motor ready to pull. As I started to remove the first exhaust bolt, that's when I noticed there was a problem. I have attached pics to better show the problem. The head from the new motor is different than the old and wont allow the old exhaust to mount correctly. It seems that the exhaust ports are formed into one port where the old head leaves them separate and an exhaust manifold bolts to that then goes to the muffler.

The old motor is model EH29C and the new motor is EH292C. Is there a production change or is this motor for a different style cart? I don't think the owner of this cart is going to be pleased.

Bryan