You know that joke about oil leaking from ANYWHERE?
 

I'm trying to track down an oil leak. Thought it was coming from the OMP, so I pulled it and rebuilt it. Still have a leak. Put the car up in the air (have access to a lift) and had one of my co-workers run through the RPM range because it seems that it leaks worse, and smokes worse at high RPM. OMP is clean and dry, no problems there. I start poking around the general area and I found when he revved it higher, I can see oil bubbling and hissing from the leak!.

It's coming from the back of the air pump. The backing plate of the air pump housing is leaking air and oil where the backing plate meets the body of the pump.

Now, this doesn't make any sense to me. There's no engine oil going to the air pump is there? I ran UV dye through the engine oil so I could trace my leak down and I'm definitely have engine oil coming from the air pump. Is there anywhere above the air pump that engine oil can leak from and run down the back of the pump? The pump needs to be replaced because it's leaking air, but what about the oil? Where do I look next?

air pump shouldnt be able to leak oil...

Are you sure the front cover gasket has not squeezed out near hte top or side??
and its running down near there??
i had the same kind of problem oil leaking near the omp and airpump... couldnt figure it ouit.... then i noticed it was running down the side of the front cover!!. i removed my water pump housing and saw that the gasket between the front iron and front cover had pushed out near the top... resulting in this nasty oil leak when rpms would increase.

I think oil is running down the back or side of the air pump, and then bubbling where theres an air leak on the pump housing. I FOR SURE saw oil bubbling on the pump. It looks oil is coming from the pump. It must be coming down from somewhere else. There's no way engine oil can be coming from inside the air pump.

I need to replace the pump any ways, but I guess the front cover is coming off too.

IF this is a t2, there is an oil line fitting right behind the airpump. If it were loose, it would likely drip straight down, but I guess I could see some getting on the pump.

Sometimes air pumps tend to get noisy or might lock up if not used for a while, so I can see someone putting some oil inside it. There are a couple vent holes that the oil could then get thrown out of.

Sorry, should have said what type of car.

It's an 88 Vert, no swap done.

Also, if someone just "put oil" in the air pump, why would the trace dye from the engine be in there?

remove the air pump and drive it around see if u can see where oil is coming from... did u check if the front cover of the engine was leaking??

its a front cover leak.

You think this is bad, I have a 99 buell motorcycle which I only bought because the deal was too good to pass up.

it uses a 99 Harley sportster engine and has 15K miles.

To sum it up I have fixed 6 oil leaks so far and oil is still leaking from 3 places. one of them is the cylinder base gaskets which require a top end rebuild to repair.

Every gasket used in its construction is made out of what can only be described as recycled newspaper