Thanks, man. I'm planning on pulling the oil lines at a minimum and I'll probably pull the oil pump. If for no other reason than to check all passages and make sure that the scavenger gears are still in good shape. I also thought it might help to check the bypass valve to see that it's functioning correctly and I'm not getting too much oil pumping into the engine.

 

Honestly, I'd pull the tank vent (at the engine case) and see if there's oil in it. Normal for some because it's just a vent to the tank and hot oil vapor will get in and thru there. But, with the oil cap off and blowing into the hose, if you hear gurgling in the oil tank then that's definitely the culprit. I hope that's it because you've checked about everything else it should be.

If you decide to pull the pump, pull the nose cone too and see if by some slim chance there's an old piece of gasket or anything restricting the hole where the pump picks up return oil. Also check/replace the shaft seal in the pump housing between the pressure and return gears. They seldom give trouble but if it's messed up, it could push pressure thru the return side causing the return gears to cavitate more than normal and that would make it foam excessively as well as keep too much in the cases.

You've really been run thru the mill with this problem so best of luck in pinning it down...

 

What is the gurgling in the tank a sign of? What's the fix?

 

That would mean the hose is connected to a pipe in the oil tank that is below the oil level - and that would be enough to keep the whole system from breathing and venting sufficiently...

 

Terry,
I've been following this thread for a while and finally decided to jump in. As I don't know you , I do not know how much knowledge you have with the V-Twin engine, so let's start with education/facts and please do not take offense. First the EVO is a dry sump engine and meant to run with very little oil in the crankcase. If oil gets down there because the scavange side of the pump cannot keep up with the feed side you will get oil puking out of it. "Wet sumping" will also cause this. Wet sumping is caused by the check valve not stopping the flow of oil coming from the tank when the engine is not running, sometimes this can cause oil to come out for a period of time and usually stops before too long.
Your oil tank has three lines going into it, One is the feed line that goes from the tank to the pump under a vacuum, supplies oil to the pump and comes from the bottom of the tank. The second is a return line and returns scavanged oil to the tank under pressure. This line usuall goes either to the bottom of the tank or to a tube that is partway up in the tank. Either way it is away from the feed/supply line so that it does not wash oil away from it and to let the oil cool slightly. The third is the vent line that goes from the crankcase to the tank up high and can be under pressure or vacuum depending wether the pistons are going up or down. Now that we've covered the basics let's move on. If the return/scavange line is kinked or obstructed in any way oil will sump in the crankcase and cause your problem. If the vent line is plugged or obstructed it will cause your problem. you should be able to take your vent line of and oil should not come out of it. You should be able to take the filler cap off and blow through the vent line and not hear any gurgling. If you hear it the oil is above the vent and that is bad. You then need to lower the oil level until you no longer hear it. Sometimes the tube that extends from the bottom of the tank can fail causing your broblem. Whet we do is cut the vent line install a "tee" and run a vent to atmosphere with a breather on it, This also helps with ring seal. You may also want to clean the check valve to give it the best chance of sealing and this may help to mitigate the situation. Don't forget to check out the rocker boxes to ensure that all was put together properly, we all make mistakes unless we do nothing. Hope this helps.

 

Thank you for your thoughtful response. I'm going to check all of these things tonight.

 

Dan, you may have nailed it. I checked the diagram in the manual to make sure my lines were hooked up correctly. The manual diagram, see below, is kind of hard to interpret. Since the lines have been hooked up in this order since I got the bike I figured they must be right.



Since you and a couple other people suggested there must be a vent problem I did a little deeper research online. I found the picture below of a cutaway oil tank and that showed me that my vent line and return lines were reversed. That explains why I have seen oil blow out of the tank before and why my breather re-routing caused oil to spew from the tank as well.



I haven’t had a chance to ride on the interstate yet; it’s supposed to rain today. But, I’ll be putting about 100 miles on it tomorrow and I’ll let you know how it turns out. If this doesn’t correct the oil leak then I’ll assume the bike’s possessed.

Thanks again for your help!

 

This is a great learning thread. I wish there were more like this, not that I want others to go thru TerryFXST's pain -- but others could learn from this thread -- I did.

 

Terry, That's why I went into such detail there are a couple of bikes we see each year like that. My cousin bought a 1982 lowrider really cheap ($2,500) last year after the PO had the engine done and it puked oil. We looked it over and changed the oil lines around and viola it was fixed!! Obviously the owner before you had the same problem., he probably ran it with a low oil level to cure the problem. Glad to see you found the problem, enjoy your ride now.

 

Thanks, John!