Looking for oil leaks

I’m back on the hunt for this mysterious oil leak.  While I do think that I have a bad oil seal on the slave clutch cylinder, I suspect that I might also be leaking oil from the gear shift lever and the neutral indicator wire pass-through.  There also could be oil sneaking down from somewhere further up the engine but I’m not convinced one way or the other on that point.  The photos below are what I found when I took the plastics off my bike earlier today.  Please feel free to chime in if you have any thoughts on what I should be replacing or repairing to stop the oil bleeding.

Once again I am working outside my apartment.  The tupperwear came off MUCH easier this time than the first time I had to figure out how to take it off.

Oil oil everywhere!  It looks like the oil is either coming from further up the engine or is being blown around a bunch from the wind while I ride.  The only things I can think of above are the wire for the neutral sensor, large gaskets on the engine that I really don’t want to mess with, and that’s about it.  The cam plugs (see below) are solidly sealed now.

There was oil pooled in a little drip below the gear shifter hole.  I wonder if that seal is bad or if it is getting blown there from somewhere else.  Oil drips were also pooled on the bottom of the water pump.  I replaced the water pump seals back in December when I did the cam plug job.

Under the bike looking from the front rearward.  The oil leak is on the right side of this photo.  The oil stain in the rear left side is from where I spilled some oil doing a field oil fill-up after having problems in the redwoods of Northern California last weekend.

Looking back toward where the oil gets blown.  It’s interesting that there really isn’t any oil residue beyond where the kick stand attaches to the spring.  The center stand doesn’t have any oil on it nor do any of the components back by the rear tire.

That little screw I found wedged between the drain lines coming down from the carbs and the gas cap area to where they empty out under the bike.  As the note says (so I wouldn’t forget while doing other things), that screw is one of two that hold the throttle cables to the carbs.  It was VERY lucky that this little screw didn’t fall off the bike but instead migrated to somewhere I was able to find it.  And it was even more lucky that I right away figured out where it belonged.  Back in December when I did the cam plug job, I took off the throttle cables.  Evidently my tightening down that screw wasn’t enough to keep it in place.  I put it back in with a little dab of blue loctite.  It should stay put for a long time to come.

I’m pointing to where that screw belongs.  It didn’t affect the performance of the bike noticeably but eventually if it had been left like that, I think the throttle cables would have worn through faster.

When I put the bike back together after the cam plug job, I didn’t bother re-securing the rubber boot that attaches to the fiberglass (?) engine cover and protects the carbs.  It still seems to do its job just fine but now it’s much easier for me to look in at the engine and figure out if the cam plugs are leaking.  So far all four look just fine!

Any thoughts anyone might have on what seals I should replace would be much appreciated.  Thanks for looking!

15 Replies to “Looking for oil leaks”

  1. Hey Doug – thanks again for the tip on the carb hoses.

    I would suggest cleaning off all the existing oil and gunk and then taking it for a short ride to see if you can find where the leak(s)? are coming from. There’s too much there now to really give you a good look.

    Best of luck

    1. Hi Phil,

      Glad I could help with the carb hoses! Us PC riders have to stick together 🙂

      Cleaning off the oil and gunk and riding it to look for leaks is exactly my plan. I should be able to do that and hopefully pinpoint the source(s) today if the weather clears up enough.


  2. Hi everybody,
    I have the same oil leaking problem. I took the engine off the frame and I found the origin fo the leakage:
    from the gasket of the rear cylinder. It seems a common problem on pcs. Nothing to worry about.
    Another place where to look is the head cover. On other similar engines (shadows series – transalps), honda placed a rubber gasket between the head cover and the head, but not on the pc. Probably because the engine is completely covered by the fairing.

  3. Was that the gasket between the rear cylinder and the crankcase?

    This weekend I am going to put in new gaskets on the water pump, the clutch slave cylinder, and the gear shift lever. I already put in new cam plugs and applied new gasket material to the cylinder heads. Those gaskets are holding well. The only seals left that won’t have been replaced will be the gaskets between the cylinders and the crank case, and the neutral indicator wire gasket. Oh, and also the gasket around the crank case cover.

    My problem appears to be coming from either the clutch slave cylinder, water pump, or gear shift lever now. I think you’re right that sometimes the gaskets between the cylinders and crankcase leak but if mine is leaking, it is a very slow leak.

    Thanks for the info on your experiences! Every bit of information helps us PC riders keep our wonderful machines on the road. 🙂

  4. Hi,
    the gasket I’m talking about is the one placed between the head and the cylinder. Is made of metal and the oil was coming from there. I` have some picture of it on my computer at home….
    It is not the cranckcase cover gasket.

  5. Douglas,

    After scratching my head for weeks I found where my PC was dripping from-the airbox. The PCV line was burping oil into the box and was leaking out a crack near the drain tube nipple. A little cleaning, some RTV, and everything was OK. Now if I can just figure out why so much oil is being burped I’ll be fine (not excessive amounts!).


    1. Interesting! That’s a new one to me. It’s good you found the crack. Otherwise eventually it could have led to poor performance (bad air/fuel ratio) and you’d have had a devil of a time finding the true cause.

      Do you have too much oil in your crank case? An old filter? To get excessive oil out of the crank case and into the air box that’d indicate to me that there is either too much oil or too much pressure forcing the oil up. Have you seen a noticeable drop in the amount of oil in the crank case?


  6. A drop in performance? How would you tell on a PC? 🙂 Seriously, it wasn’t that bad, just annoying. The bike’s done this oil-burp off-and-on since I’ve had it. I’ve never over-filled it, and everything gets changed every 3000 miles. I just passed 77k and I’m starting to burn a very little between changes, but the level stays pretty constant. A couple of ounces is all.

  7. Haha okay you’ve got me there, Jared.

    I was thinking more along the lines of how the engine runs (horribly) when you have the air cleaner box completely removed from the carbs.

    Mine is getting close to 50k. Right now I’m chasing down a problem of losing power when going above 60mph up 6% or steeper grades. My suspects are vacuum issues, bad petcock, partially clogged fuel filter, or weak fuel pump. I’m guessing it’ll be a combo of several of those items. Maybe I shouldn’t go so fast 🙂

  8. Hi Doug,

    Did you ever track down source of oil leak? I recently picked up 1998 PC800 with about 42k on it and it has drips of oil on the crankcase below the water pump. I cleaned the engine and I don’t see a source above the water pump. Also mine seems to drip more when it’s on the side stand rather than the center stand. Any information would be helpful and thanks in advance.

    1. Hi Manuel,

      It might be the seals behind the water pump. They’re easy to replace. Also could be the clutch slave cylinder seals. Also easy to replace.



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