Strange oil leak?

Recently when I park my 1982 KZ750H3 after riding, I notice that there is fresh oil leaking down the left side of the engine in front of the alternator cover. Here....

(the image is just one I grabbed off the web as my camera bats are dead)

It doesn't appear to be coming from the cam cover above or to be under any pressure. It seems to be coming from the junction of the bottom of that cylinder and the case. I plan to rebuild the engine next summer, but I am wondering of I can put some kind of sealant (maybe hi-temp silicon) in there as a temporary fix?

Any ideas?

KZ650/750 are full of rubber orings. There's rubber orings that seal the cylinder to the block where the oil passages go up each side. My guess is the rubber rings have hardened and started leaking. You can use silicon possibly. I've done it and it's kind of a mess, but does the trick for a while at least.

RonKZ650 wrote:

KZ650/750 are full of rubber orings. There's rubber orings that seal the cylinder to the block where the oil passages go up each side. My guess is the rubber rings have hardened and started leaking. You can use silicon possibly. I've done it and it's kind of a mess, but does the trick for a while at least.

Use some brake clean (evaporates) and clean it real nice, go for a short ride and when you get back you should see exactly where it's coming from. Clean again and apply with your finger some good (usually "black" silicon is oil resistant) quality silicon along seam line 1-2 inches on either side of leak. Remove excess and let sit overnight and it should hold for quite a while. Can easily be reapplied if necessary to hold until re build.

Could it possibly be coming from the grommet at the bottom of the cover where the wires for the stator exit the cover? I have found that an aerosol foot powder works great to find leaking gaskets. Clean the motor and spray it on suspect areas, then take a short ride, it will highlight the leak.

Kawickrice wrote:

Could it possibly be coming from the grommet at the bottom of the cover where the wires for the stator exit the cover? ...

The grommet is on the lower rearward side. I don't believe the 750H should have oil behind the that cover.

No, it's not coming from the bottom grommet, it's where I indicated in the pic. But it's not flowing out from there but from somewhere above. That's why I assume it's coming from the junction of the cylinders and case. I've had the alternator cover off before and it's dry inside is JMKZHI thought. I'll try the cleaning/silicon idea.

Ever the optomist, By all means, clean & dry before searching further. If cam cover is dry, possible culprets are base gsk/head gsk, BUT! another is possible and should be checked before bumming.... Cam chain tensioner/gsk. could be source. the air passages thru head can allow weeps from this area to flow down, run along fins & drip to this area. after clean/dry, re-inspect, in cases where source is hard to find, ARID EXTRA DRY deoderant is a handy tool. spray liberally, It leaves a dry powdery residual. well everywhere! but cleans up easily, & will at least help find source..Luck G

Yes, the cylinder fins are oily on that side, but I don't see any flow there while the engine is running. I only actually see it flowing where I mentioned. It's not a leak under pressure but rather a slow flow.

Would also assure that an exhaust header clamp nut hasn't loosened. And if applicable that there's no loose oil cooler hose fitting.

I prefer the foot spray because it seems to contain more power residue.

While at it, after cleaning engine and allowing to dry, would also spray around all usual suspects (cam plugs, valve cover gasket, head gasket, tach drive, exhaust clamps, base gasket).

Then crank and run the clean freshly powdered engine for a few moments to detect the seepage areas.

Good Luck!

Does that bike have the tach drive on the head above the exhaust? Mine leaked and would blow to the sides from the wind and then drip. Clean the area then spray an aerosol foot powder in the area then start it up. The white foot powder will highlight the leak.

OK, have to ask the stupid qiuestion of the day...
Actually 2.... :blush:

Torques on the cylinder stud nuts and in this case, the side bolt in the image between the 2 cylinder studs have been checked/tightened/confirmed?

Is the oil leak coming for that side bolt... Clean oil is hard to detect. I had similar in my new engine build... Once I got some miles on the engine, Dyno oil at the time darkened and this is where is was coming from...

NOTE: On new builds, this is somehwat expected where bolts loosen... As provided to me... 50-500-1000 mile checks, torque every single bolt on the engine and frame to torque specs....

Just a thought....

OMR