400ex Problems, PLEASE HELP!!!

[nofear911]

I have had trouble keeping oil in my 400ex for years now.

It just pumps it out the breather into the airbox and floods the motor. It also fills the starter up and ruins the brushes.

Here is what have:
-440 11:1
-Thick sleeve
-Hot Cams Stage 1
-New Valves, Guides, And Seals
-New Rings
-Dirt Digger Clutch Discs
-New Oil Pump

Everything looks great, I have blown through all of the oil ports, and I've tore it down completely twice looking for the problem.
This came on after about 50 hours or so after I jumped from 425 to 440. If you run the breather out on the ground or only run 1 quart of oil it runs perfect, pulls hard. It just fills the block up with oil.

The first time we tore it down we found one of the tranny gears starting to flake and we replaced it and its match. And we put the oil pump in then too. Also, it won't start no without a little push start, but fires almost every time on the first rev. when you push start it.

I am a diesel mechanic by trade and my buddy is a small engine mechanic so we are experienced, but we just can't figure it out.

Does anyone have a clue or have run across this before?

[hornetgod13]

My first guess is you're over servicing it when you change the oil. It takes roughly 1.95 quarts of oil with the filter change, oil tank and crankcase drained. Are you draining ther crankcase? If your not than the motor is pumping the excess oil out the crankcase breather tube. Another common mistake is you must run the motor atleast 5 minutes prior to checking the oil level. If you're not than the oil dipstick will read low and you might be over servicing that way too.

If you have been changing and servicing your oil correctly than most likely the piston rings are shot. have you done a compression check recently?

[nofear911]

I put new rings in it, didn't seem to help at all. And we just tore it down friday and they were perfect, with no burn marks on the cylinder or piston.

As for oil, after 5 minutes there is no oil in the tank. If you put more than one quart in it, it will pump it out. This was actually my first thought also, so we tore the motor out of the frame to make sure we were getting it all out.

Thank you for your input, do you have any more ideas?

[LeGrandeMS]

complete rebuild, or ou may have busted the inside of the tranny casing...

[lorenjr83]

is your return line plug up with something. thats the only reason i could think of why it wouldnt pump oil back to the tank. or maybe even your oil cooler is plugged up. take the return line and start it for a few seconds and see of the oil is circulating.

[the Z Man]

Does it make a difference if your oil lines are backwards?

[nofear911]

I'm going to check the lines a little closer, I blew through them with shop air with no problem, but i'll try less air. And I'll also try starting it and watching for oil.

Thanks for the info.

[nofear911]

We tore the side cases off tonight and found a leak in the clutch lube port. It was leaking into the breather cavity. So we split the cases and found the gasket had dropped just enough to weaken the seal enough to open the port into the cavity.

I also checked the oil lines and they were all clear.

After understand the oil flow, it is impossible for the oil not go through the oil cooler before going into the engine lube system.

Here's how it works:
1-Sucks oil from crankcase into oil pump #1
2-Pumps up line through cooler into tank
3-Sucks oil from tank into oil pump #2
4-Pumps oil through filter into head, clutch, trans., and rod.
5-Oil returns to crackcase

I will let you all know next week if this fixes the problem.
I expect it will.

Thank You All