My 91 flhtc has about 9k miles on a factory rebuilt motor. Beginning last summer I had a problem with the extremely high oil pressure. The pressure gauge would be buried until the oil warmed up then it would return to normal pressure. The pressure was so high that it started leaking from the jug gaskets and rocker covers. I put the bike away this last August with the intention of working on it during the winter. I finally started working on it this week and found that it had wet sumped. It puked at least a 1/2 quart of oil from the crankcase breather tube (I have the tube vented under the bike) when I tried to start the bike. I just removed the check valve and didn’t find anything unusual. The spring and ball bearing were not stuck in the bore. Looking at the oil feed system from the shop manual I don’t really see another path for the oil to flow from the tank to the crankcase. Any ideas, please!

Art

 

Sounds like you might have a problem with your return oil line or something in the filter.

As for the puking 1/2 quart of oil after sitting for a while that is normal.

 

First thing to check is the oil pressure gauge, it is probably giving you a high reading. Install a mechanical test gauge and check the pressure.

If the pressure is actually high, it would probably be caused by a stuck pressure relief valve in the pump.

The leaks in the rocker boxes/ base gaskets have nothing to do with oil pressure.

Oil coming out the breather is not abnormal on an engine that has been inactive for some time.

 

I just ran the bike, no more oil from the vent pipe. Are you saying that I may have some kind of restriction in the return oil line that would cause high oil pressure?

Thanks
Art

 

If the oil stopped coming out of the breather, it is good, no worries.

A restriction in the return hose could cause oil to accumulate in the crankcases (it will not affect oil pressure), causing the oil to blow out the breather, but that does not seem to be the case with your bike. Probably just leaked some oil down into the cases as it was sitting.

 

Thanks for your help. If I thought about it longer I'd see that there would be no connection between high oil pressure and high crankcase pressure? I've had this bike for over 10 years, this is the first time this has happened. Also last year is the first time I went with synthetic oil. Any connection?
Thanks again.

Art

 

A lot of people report leaky base gaskets, and leaky rocker box gaskets from synthetic oil. It is not any thinner than dino oil, it's just that due to the additive package, it flows better and can find places that are already leaky to begin with. Dino oil can kind of "gum up" and keep you from seeing leaks. Stick with Dino oil in these old evo's... no need for the high priced stuff.

 

The ball and spring on the inside screw is not the pressure relief valve the out side screw is ans having 100 PSI oil pressure is a normal thing and it returns to 15 hot is also normal

 

Think it has already been said but the ball check is the vent side back to the tank (thru the filter since that is how the EVO was designed) The long sleeve taller tower spring loaded sleeve is the relief valve. (or bypass valve) Be sure you run the open 10 micron filter. ( I THINK)

 

Just because! Check the oil lines and make sure they are properly connected.

Oil tank out to oil pump inlet, engine out to oil tank in, and the third line to oil tank return/vent. When you open the breather line to atmosphere it will leak oil because the oil vapors will eventually condense enough in that line to leak.

Puking oil after sitting all winter is normal, and hopefully you didn't "top off" the oil tank before starting for the first time.

And I agree should be using Dino 20w50 in an Evo above 40deg. F.