oil/gas leak

[dodgepa]

I noticed drips on garage floor and crawled under cart and leak appears left of exhaust where motor is bolted together. any fixes for this short of pulling motor and replacing seal. that job is probably beyound my capabilities. Cart is an '86 marathon with Robbins engine.

[LiL' rascal]

That should be a 2 stroke motor with no oil in it other than in the gas. Is it flooding and dripping down the carb? Might be as simple as giving the carb a good cleaning. Or do you still have the auto oiler on? That could also have a cracked hose or something.

[suffolklou]

My 88 had the same oil underneath it, and I was wondering the same thing. Carb is clean.

[Dave Box]

Dodgepa,

Is it possible that the leak is from the exhaust port but trickling down to appear as it it is from the join in the crankcase halves? If so this is what has happened.

The diaphragm in your fuel pump has split and fuel in the top of the pump can now get into the lower section. Here it migrated down through the pressure passage into the crankcase and it continues to migrate as you now have a siphon. The crankcase fills and the fuel reaches the bottom of the cylinder, it now pushes past your rings and dribbles out of the exhaust port.

Now a word of warning. Your crankcase is full of gas/oil and if you try to start it, it will hydrolock and maybe even do some damage. Remove the spark plug and rotate the engine by hand using the clutch. If it gets stuck turn it the other way. Once it is free replace the spark plug and start it up. If my hypothesis then the solution is to replace to fuel pump which should set you back ~ $33.

Dave

[suffolklou]

Thanks for the quick reply. I am running an electric fuel pump, the mechanical pump only covers the hole in the crank case. In my case it seems to happen after riding for a while. The oil is definitely two stroke oil, or some kind of heavy grease. Maybe grime cooking off of the motor, but I think it is coming from inside. Also the cart will backfire after I coast and then start again, sometimes. Can't seem to fix this either.

[Dave Box]

Suffolklou,
If you replaced the pump because the mechanical one failed you need to block the input and output on the pump. If you didn't and the pump has a cracked diaphragm you will have an issue with crankcase pressure and the engine sucking air as the piston rises. This will affect the transfer of fuel from the crankcase to the cylinder and will also lean out your mixture. If you didn't cap the old pump it is possible that it is splitting fuel/oil which is running down the engine.

With regard to your backfire this is an issue that plagues 2 stroke but the first question is do you have a spring on the throttle cable as it routes through the carburetor arm?

Dave

[suffolklou]

I do have the spring and have given the Carb attention to ensure it shuts all the way. would putting a hose between the fuel pump inlet and outlet be sufficient for blocking it?

[Dave Box]

Sure, as short as you can fit would do it or if the pump is dead fill each side with mastic.

Dave

[dodgepa]

Thanks for all the info, I'll do more checking. Im running a mix by the way.

[dodgepa]

Apparently leak was from crank seal so decided todive in and change seal. I thought clutch would come right off because it was new but not so. Had to use the bolt trick ahain to get it off. Got the seal changed and everything put back together and lo and behold this also solved my backfire problem. woowoo!