I have rebuilt a 74 xlh and started it for the forst time today. My problem is that I loose my oil from the gearcase vent. I filled oil last week and run the starter to let the oil come down to the pump and let it rest in my shop until today. The bike started after two-three revs, but oil leaked out in large quantities ( 0,5 liter) and the oil lamp continued to be red. Oil returned to oiltank at the same time as the oil poured from the gearcase vent. What happened? someone who can help?

 

It is called wet sumping. It is very common. Oil leaks past the check ball in the oil pump when the bike sits unused for some time. Length of time varies. One prevention is to start the bike once a week. The solution may be to install a new check ball. More info ...

Engine breather 101 / Crankcase Vent 101

 

Yes, I know of Wet sumping from my early Indians, but I have never had a bike that have lost over 0,5 liter from standing still for a little over 1 week. I have filled it up with 10-40 synthetic oil. Is this oil the reason (together with a worn preasure ball/spring) for the lare quantity of oil. If its loosing 0,5 liter a week its going to be a expensive bike to own I think.
oil is returning to the oiltank but the oil lamp is still bright red, is this because of airlock in oil pressure switch? I have rebuild the engine with all new parts but haven't dimanteled the ball valve etc.

 

Most guys use straight 50, 60 or 70 weight oil, not synthetic, in IronHeads - 50 is most typical, 60 or 70 in very hot climates. I use 20W50 in the very cold winter weather [+10`C to -10`C].

To prime the oil pump i remove the oil pressure switch. Then i either just let it sit for a while, maybe half hour or whatever, until oil starts to drip out, or crank or run the engine until it starts to come out.

I have no direct experience with the wet sumping as neither of my two IronHeads have done that. The second half of that thread that i gave the link for has more info.

 

Oil lines reversed?

 

You can check for wet sumping by checking the oil level right after a ride. Check it again a few days later before starting it and compare the oil levels. They should be the same. Otherwise, the check ball is leaking.

I always check the oil on my bike right after a ride when it's hot.

 

The oil returning to the tank shows it has pressure. The light staying on says either the wire is shorted to ground or the pressure switch is bad.

Mine is loosing oil to the primary. Either the transfer valve or the crank seal, don't know yet. Mine doesn't seem to wet sump that much as it never blows out the tube. I added a lenght of rubber hose to keep oil off the bike. Now that I think about it, I better check and make sure that hose ain't blocked.