'75 FXE that has been sitting since '85. Started it up after putting back together, and it is backing up oil out of the top of the oil tank.

Otherwise it is starting strong, oil pump seems to be doing it's job and although I haven't done any compression or leak-down testing, it is running awesome. No fouling of the plugs after multiple start ups, and one 5 minute warm-up.

When I bought the bike, the piston rings on the rear cylinder had a little rust on them but cleaned up and moved freely with a little soak.

It is acting like a blow-by scenario but it could just be over filled? I put 3 quarts in the empty oil tank but didn't drain the case.

If it isn't blow-by from bad rings, could it be:

1. Oil filter inside tank is worse than it looks and not letting oil through fast enough?

2. The case holds more oil than I thought and it is just overfilled?

3. Bad check valve allowing too much oil into return?

4. Rings aren't seated anymore and I just need to revv those suckers into place?

Thanks for any and all input, just looking for some things to explore before I pull the top end apart.

 

the engine was sumped its a 3 and some quart system and you had almost 5 quarts in it - happens to all of them if left to long with out running

 

So you’re saying there is/was probably a couple quarts already sitting in the bottom of the case, so When it started moving around with the 3 quarts I poured in it overfilled?

 

its called sumping and some machines do it all the time some only when they sit for weeks / months kind of thing

 

As John said most likely sumping. Suck some of that oil out get it down to a normal level. Ride it a while and you'll see. Just don't let it sit for a long time again without running it....

 

I drained the tank put just 1 quart in to see if i could get the oil to calm down. Started back up and got the same thing. i popped the oil tank cap off while running to see how it looked, and it appears like the oil is coming in too fast for the oil filter as well. It was backed up to the lip and the oil appeared a little aerated, not super foamy but definitely bubbly. Please tell me if that part is normal.

Anyway, I removed the oil filter and put the cap back on. It stopped leaking immediately. It even stopped leaking out if the braided crossover tube between the rocker boxes, which it was doing before.

 

Different filter then and a new gasket for the oil cap, or run an external oil filter.

 

I picked up a new filter element for the stock cup-style filter assembly, and will test it out tomorrow.

The filter that has been giving me problems is an aftermarket canister style filter, with a spring on top. It doesn’t seem to flow oil at all. I can fill it up in the center and it barely creeps out the paper element. Maybe it’s just too old and clogged up?

 

You have a 75 that has been sitting since 85 and you didn't replace the oil filter right away? I do t mean to hate on you but after 30 years it would be reasonable to expect a filter to be corroded or otherwise clogged. As a matter or practice when I buy any used vehicle, the first thing I do is replace the fluids and filters. For a bike this old I would recommend also replacing anything made of rubber, too.

I'm betting you will see big improvements with a new filter (and maybe new lines). Let us know!

 

No, you are right to question it. I guess my thinking was to get it out of sump with an older filter before dropping a good new one in and ruining it right off tge bat.

Unfortunately even with a nee filter and less oil it is still backing up at the top of the tank.