Author Topic: need help. air leak in bottom end (Read 4011 times)

sanddad21 · « **on:** July 26, 2014, 03:35:29 PM »

Ok guys and gal's. I'm rebuilding my motor top and bottom. I have all new seals and gaskets in it, I but three bond on all my gasket surfaces when I put it together.I have my drain plug installed and spark plug, exhaust is plugged and intake has my preasure Guage in it. I have a breather tube on my case vent and that is were I getting the leaking air from. My air loss is about 2 lb in 6 min. We're are the places it could be coming ?

Rupp250 · « **Reply #1 on:** July 26, 2014, 05:13:56 PM »

Spray all the seals with soapy water, you will find it fairly quick.

sanddad21 · « **Reply #2 on:** July 26, 2014, 05:22:46 PM »

I found the air leak it's coming out of my crank seal on the clutch side of the motor. Seal part number 91201-ka4-004 #21 an the parts diagram. How deep does that seal need to be sunk in. I have it installed pretty much flush now.

Pumashine · « **Reply #3 on:** July 26, 2014, 06:01:41 PM »

The seal on the ignition side goes in 6mm. The clutch side flush is fine. It seals on the collar. You should see about a 1/16" of the collar coming out from the seal. Is the collar dirty or worn?

sanddad21 · « **Reply #4 on:** July 26, 2014, 07:22:13 PM »

The collar has a slight wear ring in it but it seals fine there. The leak that I am getting it's coming out the center part of the collar were the splines of the crank come through it. Is there supposed to be a seal inside that collar that I'm missing?

udontknowme · « **Reply #5 on:** July 26, 2014, 08:54:27 PM »

when you tighten the crank gear bolt the bushing gets pushed against something im sure. probly either a step on the crank snout or the bearing race. for what ever reason its probly not sitting flat. assuming youve assembled and torqed all parts correct

sanddad21 · « **Reply #6 on:** July 26, 2014, 11:21:03 PM »

Ya it get goes up tight to the race of the bearing, the best I can tell. I will try sanding that surface maybe it has a nick in the face of the collar.

Pumashine · « **Reply #7 on:** July 26, 2014, 11:49:34 PM »

I really think you have nothing to worry about. Worst case is you pull a little tranny fluid in the crankcase. I forgot to put the collar in once and ran a whole season without a problem. It was a little rich at times :lol:

sanddad21 · « **Reply #8 on:** July 27, 2014, 12:36:40 AM »

I was just worried about the top end loosing the air preasure during the leak down test. Is 2 lb of preasure loss in 6min acceptable?

udontknowme · « **Reply #9 on:** July 27, 2014, 12:44:52 AM »

ive never done a air test but if you put in 4 or 5 psi i would think a loss of 2 in a few min is quit a bit. something isnt allowing the bushing to sit flat against the bearing. never had that problem so i dont know what else to suggest. if the ID of the bushing is fairly tight on the OD of the crank then maybe thats the problem. prehaps try to sand half a thousand off the ID of the bushing and maybe it will allow enough movement for it to sit flat