I have a 1988 Softail that I purchased of a young woman who inherited it. The bike sat for several years. At the advice of some forum members I purchased a Harley factory service manual. It helped me tremendously with correcting some wiring gremlins left by the prior owner. I however have located some oil system gremlins once I fired the old bike up...

I started the bike which sounded great and idled well. Much to my surprise it shot the oil tank dipstick out and across my garage. I discovered that it was building a significant amount of pressure inside the tank causing the dipstick to shoot across the room.

The manual shows the crank case vent as being located at the bottom of the oil pump (actually to the side of the pump on the case). This line was spliced in to a line which (according to the manual) should have been a vent to the oil tank. This led me to believe that the crank case pressure was being vented to the oil tank causing the subsequent forced ejection of the dipstick. I purchased a crankcase filter and replaced the line from the pump to the tank. I attached the filter to what I thought was the crankcase vent and started the bike up. Now instead of it venting the pressure from the crank case, it instead vented the oil from the engine. I also noted my oil pressure light came on.

In my online ventures to attempt to discover the problem I found one diagram which noted the bottom line (crank case vent) as being a return for the oil tank. The top line (vent to oil tank) was said to be the crank case vent. Is this possible? Was there a different configuration that this bike may be set up for? Please help guide me in the right direction...again.

Travis

 

Ok, So I have an update. My oil pressure light was not going off (just excessive glow from the neutral light). I do believe that I have oil pressure because of the fact it is running out of the breather while the engine is running. I pulled the oil filter to see if it was getting oil and it is NOT... Any suggestions guys?

 

There are two fittings on the crankcase:

The fitting just above the oil pump is the vent to the oil tank, the hose must be connected to the oil tank.

The fitting that is inboard of the oil pump is the crankcase breather, the breather hose that is connected to this fitting was originally connected to the carburetor backing plate, but most have routed the hose down to a lower part of the frame and let the oil mist go overboard rather than into the intake.

Put a drain pan under the breather hose (the hose connected to the fitting on the crankcase that is just inboard of the oil pump), start the engine and let it run for a bit so that it can scavenge all the oil that has accumulated in the crankcase.

Once you have done this you can service the oil tank to the correct level, about 1 inch below the bottom of the oil tank filler neck (bike level, not on stand).

 

Thanks for the heads up, I believe the lines are correct however still am not getting oil to the oil filter. What would prevent oil from reaching the filter? Am I wrong in thinking that it wouldn't be forcing oil out of the crankcase breather if the pump was shot? I let it run for a few minutes with no sign of it letting up.

 

The oil coming out of the breather is the oil that has accumulated in the crankcase, it is being pushed out by the pressure in the crankcase, not the oil pump.

Look into the oil tank while the engine is running, can you see if oil is returning to the tank? If so, you have oil circulation.

If you do not have oil pressure, the engine will tell you by a loud clattering of the lifters.


Here is what I suggest for a bike that has been sitting a long time:

Drain the oil tank and flush it out with kerosene or mineral spirits.

Remove and replace all the oil hoses, they are probably old and could be deteriorated, possibly kinked or obstructed (use hose made for automatic transmission fluid).

Install a new oil filter (make sure it is a filter designed for Evo: Harley 63805-80A, Wix 51215, K&N KN-170 are just a few that are specifically designed for the Evo).

After you get the new hoses and filter installed, put about 1 quart into the tank.

Make sure that the oil pump is primed, do this by removing the cap on the top of the oil pump, inboard side.

Underneath this cap is a spring and a steel check ball. Just leave the cap off and wait for the oil to run down through the oil feed hose, it will eventually start coming out the opening, when it does, reinstall the cap. The pump is primed.

Put 1 quart of oil in the oil tank. Don`t fill it at this point.

Start the engine, with a drain pan underneath the breather hose and let the engine puke all the oil that is in the crankcase out, it may take a minute or so.

Make sure the lifters are not clattering (this is an indication of low or no oil pressure), and look into the tank to verify that oil is returning to the tank, this is how you can verify that the oil system is circulating oil.

Once the engine has puked all the oil out of the crankcase, you can service the tank.

The proper oil level will be about 1 to 1-1/2 inch below the bottom of the filler neck, with the bike upright (not on the stand).

 

First off, let me say thank you for your help. This bike is driving me even further nuts... At least I have my other bike to ride while I am working on this. I do have several years mechanical experience however minimal on motorcycles (mostly muscle cars). I know things are a bit different on a bike and this is what is presumably throwing me for a loop. Now for where I am at...

Most if not all of the rubber lines have been replaced.

There are no obstructions that I can find in any of the lines.

I removed the inboard screw and primed the pump. It built up pressure and forced oil out of the top of the screw hole quickly.

I removed the return line from the pump and turned the engine over (I did not run it). There was no oil coming out of the return line. I confirmed there was oil coming from the tank to the pump.

I would like to note that I ran it for about 5 minutes last night. It continued to pump oil from the crankcase breather the entire time. Even when just cranking it over tonight it puked out some oil from the breather.

I removed the outer portion of the oil pump and verified there were no obstructions preventing oil from traveling out of the return line.

I again turned over the engine and confirmed both gears were turning on the pump. I do not believe that it has a sheared key and did not find any debris in the pump.

Any suggestions from this point? I am calling it a night on the bike... for now anyways.

Thanks again,
Travis

 

It sounds like the pressure side of the pump is working, but the scavenge side is not returning oil to the tank.

It may be a sheared key on the scavenge gear, on the inner side of the pump body.

You will need to remove the oil pump body to check the scavenge side of the pump.

Be careful when removing the pump body, make sure you do not push in on the shaft, or the key under the drive gear can fall out into the cam chest.

 

Something crossed my mind regarding my problem. I know many Evo's suffer from very low oil pressure at idle. Is there a possibility that I'm not getting enough RPM's just by turning the engine over to cause it to produce any pressure?

Thanks
Travis

 

Start the engine, if the pressure is low you will get a low pressure light (as long as the indicator system is working properly), and you will hear the lifters clattering.

If you don`t get a low pressure light and the lifters are quiet, you have oil pressure. Now look into the oil tank and see if the oil is returning to the tank.

If oil keeps blowing out the breather it may mean you have a scavenge problem, that is why you look into the tank while the engine is running; to see if the scavenge system is working.

 

Ok, now we are cooking with fire....

So I think we are on the right track. I put a mechanical gauge on it and at cold start idle I have 40+ PSI of oil pressure. That seems a bit high to me cosidering I have maybe 20 -25 on my Ultra at cold start...

There is no oil retruning to the tank or out of the oil pump return for that matter. That is why Im not getting any oil to the filter either I presume. I also suspect you are correct and thats why its dumping so much oil out of the breather.

That being said, any idea what would cause this? Where should I be looking to correct the problem? I have read somewhere about a plastic "breather gear" that often strips. Could that be the problem or is it still oil pump related.

I truly appreciate all of the help you have given. If you didnt live on the other side of the country from me I would deifnately buy you a few cold drinks of choice....