48 panhead oil leak by rear spark plug

[bobphd]

A friend recently bought a very nice 48 FL. He is a rider and rides his bikes a lot. There is oil seeping/leaking by the rear spark plug and it is not coming from the valve cover. The bike runs good and does not smoke or use oil.The picture is after about a 300 mile ride. I know almost nothing about panheads but assume that the head is cracked or porous somehow and the oil is coming from the oil return pasage in the head. There are no visible cracks that I can see. Anybody ever see this or have any ideas?

Thanks
Bob Patza
AMCA 13275




pan.jpg

[Grumpa]

Is that rear left hand head bolt loose? A lot of people don't get that one bolt torqued fully.

[bobphd]

Is that rear left hand head bolt loose? A lot of people don't get that one bolt torqued fully.

I dont think it is but will check. We are going for a ride today on this beautiful fall Wisconsin day. It does appear that the oil is originating from the plug hole area. Thankspan 1.jpg

[50Panhead]

How many miles did it take to produce that?

If it were mine I'd clean it off and run it for a few miles and look it over. This is kind of messy but if you can't see anything try using baby powder and dusting the suspected area. That will help reveal the source.

My panhead has leaks and I just wash it when I get tired of looking at the oil mess. I found that Super Clean in the purple gallon jugs works really well to remove oil stains on the motors. Just be careful using it full strength on polished aluminum. It will dull the finish real fast.

[Grumpa]

It does appear that the oil is originating from the plug hole area. [ATTACH=CONFIG]15926[/ATTACH]

I know I was just hoping for something that was an easy fix. Have access to a dye pen kit? You could check externally fairly easily.

[1970 XLCH]

I have the same problem on my '49 . I got tired of trying to figure it out , so I put teflon tape on the threads . It works & mine runs fine . Good luck

[bobphd]

Thanks for the responses. He cleaned it up yesterday and took a good close look after running it a while and found the oil seeping from the area where the cast in spark plug thread insert meets the aluminum casting. I assume that somehow the oil return passage is compromised to this area where the steel insert is cast into the aluminum. Not sure how this could be fixed.a.jpg

Bob Patza

[48hdbob1]

Pull the spark plug and get the rear piston on TDC and shine a pen light on the top of the piston, I bet it's wet. You have oil getting by the intake guide into the cylinder and weeping out around the spark plug.

[bobphd]

He pulled the head off and all is clean and burning good inside. He is going to send it to Advanced in Superior and see what they can do.

[50Panhead]

I'm following this with interest. Let us know want they find.