Hi guys. I’m riding a 1992 FXDC with everything fairly standard. She had an oil problem from the oil pump which left her without oil and messed up the pistons and cylinders so I had her rebored/sleeved (kept the same sizes) and new pistons put in at my best HD mechanic in southern Spain.

Since it was all put back together she’s been leaking around the bottom of the crankcase – not enough to stop me riding but just a PITA! The mechanic and I thought it was a leak from the crankcase seam. He said that it didn't leak before because no oil was flowing. He knows his stuff but I think my bike wasn't “interesting enough” for him. That may be a little unfair on him.

After cleaning, riding, cleaning, riding and tightening a couple of oil pipes (why is it always the hard ones to reach for!) it seemed to get a lot better.

On Saturday I took her for a long hard ride and I’m pretty sure after reviewing her stains it’s coming from the Tappet Guides at the top of the crankcase and flowing down and not the crankcase seal.

I’ve attached photos with a little comment on how I think the oil is flowing from the Tappet Guides backwards and down the back of the crankcase and also forwards down the front of the crankcase, passed the oil filter and along the bottom of the crankcase to the back left (drivers left) of the case.

There may also be a case where the inside connector to the oil filter is also leaking (you can see quite a stain down the side but not 100% clear where its coming from).

I’ve cleaned and ridden but when I look she looks like this so hard to pinpoint exactly. Someone somewhere had placed a cam pointing at the engine while riding to see the leak start…might try something like this if I can rig it up.

My questions are:
1. Any thoughts on where it might be starting from, anyone had similar “markings” on the engine. Could it be the Tappets and go backwards and forwards (against the flow of the wind?)
2. If it is the Tappet Guides can I tighten them or seal with externally rather than open up the top end to fix…at least to see if that is the problem?

Thanks

 

Oil is sneaky stuff and once hot can travel a long way from where it leaked. Clean your engine down to remove all traces, then keep an eye on it as you continue to ride, to see if you can locate where it is coming from. Simply stop briefly at frequent intervals, to see if you can catch it out! Then you/we can decide on a course of action. It's an Evo, it won't come to any harm with that low level of leak, so take a little time to button down where it is coming from. It could even be a cylinder base gasket.

 

Thanks grbrown. Yup it sure is funny every time i have a look after riding her I get a slightly different idea of where its coming from. I don't want to tear into her unless Im 100% sure of where its coming from. I'm just keeping my fingers crossed its something I can fix without tearing into the engine which at the moment is a little out of my expertise.
Thanks. Will keep updating.

 

Definitely take some brake kleene and spray it down and then blow it out with shop air. It'll return so you shouldn't have any issues locating it... But clean it real good... From the pics you posted it looks like the lifter blocks are your leak... Lots of oil specifically at the inner bolts. You can try to tighten after cleaning and go from there...

 

Oil can fool you on where it is really coming from. Clean the motor really well, then spray all suspect areas with a powdered deodorant like arrid extra dry.


It will leave white powder stuck to the motor...makes it really easy to see where the oil originates.

When your all done it washes off very easily .

 

It's a 92 Evo, and that's pretty "normal seepage/leak." Unless it's a major oil leak, leaving quarter size puddles on the floor, you would be all right. I know it's a PITA. What is the mileage of your bike? For those gasket type seepage, you could use a light flowable permatex type of gasket sealer and that might help without really opening anything up.

Those are funky tappet bolts you have on the lifters.

 

I had a bad leak and I thought I somehow cracked the cases. After a lot of cleaning and then just letting the bike sit and idle at home I was able to locate the leak, lifter block gasket was squirting all over the place. Not something you would usually be happy to see, but way better then cracked cases. Of course that lead to new cams etc, etc, but your results may vary. Good luck.

 

Thanks for thew feedback guys, I will keep cleaning it and stop ate regular intervals to see where she starts from (its a busy neighbourhood here so hard to leave her idling). I did try some baby powder but again by the end of the ride it was all over the place! Tom84FXST I love the idea of a dry deodorant, excellent, much more precise than what i did.

Daven9113, she has around 50,000 miles on her and yes shes old but i think its a bad connection that can be fixed rather than being "ageist"!! The weird tappet bolts are to be able to screw onto them a chrome tappet guide cover which the PO had on it but I dont have it on while Im looking for the leak.

Architect, I would love it to be lifter block gasket! ITs one of those annoying things you just want to isolate. If i can fix it myself all the better but i just want to know!

Thanks guys, will keep coming back with images or updates.

 

Good quality 12pt, 1/4" socket on a wobble extension for that rear bolt on lifter block( check all of them) and the oil filter fitting is a compression fitting, try tightening that also.

 

Here's a story about oil migration. A few years back I was convinced the cases on my Evo were leaking from the rear center seam. The entire rear motor mount was wet with oil. Turned out to be a leaking fork seal on the right front fork. The wind was blowing the oil from the fork under the motor and up the rear side of the cases!