I have a hissing sound and a clear fluid leaking from the end of one of the valve covers on my xj750. Is this bad?

It isn't good... and it's also strange.

What is your oil level? Check it in the window as well as open the top filler opening. Have you been mysteriously missing gas?

Perhaps you've gotten a lot of gas slip into the crank case? bad petcock?

more info please.

+1?

Something is strange.

My initial reaction is that your gasket/seal needs replacing. Not at all sure what the fluid is that's leaking, but does it matter? You've got a LEAK.

A leak means lower compression, misdirected fluids and vapors, and the possibliity that flammalble liquid is being sprayed on your or your bike.

That can't be good.

The liquid matters because the leak could be caused by over preasure - created by extra liquid in the crank case... ie it could be that the petcock is screwed and the floats have stuck - the gas tank slowly drains into the crank case.

When the oil/gas gets pumped about there is too much of it - heat plus pumping force it against the seals and out. Voila - leaking clear liquid.

Also - it is possible that it is water - however that tends to make oil look like milk. Gas on the other hand would sit on top of the oil and remain clear.

Still doesn't make sense - woot.

I will check the oil level in the morning ( I am at work right now ), I know there is an oil leak at the bottom of the engine, I think it is one of the switches, and may need need o-rings or gaskets. As for the liquid at the top end, I didn't detect a smell of gas, however the machine was flooded a few times when the old owner was trying to start it for me. He ended up spraying gas into the carbs to get it to start.

It didn't want to idle when I first got it started, but then starting it everyday made it work much better. Now it starts as soon as you hit the button and idles fine....I haven't had a chance to take it for a ride to see if there are any problems under load.

Well, I've done some investigating. It is definitely building pressure up inside the valve cover. This pressure then pushes the rubber end plugs of the cams out until it escapes. Causing an oil leak in the process. Anybody want to venture some opinions as to what needs to be corrected here?

What is the oil level?

When was the last oil change?

If you have too much oil in the crankcase this will happen. How do you check your oil level?

To get preasure you need fluid (ait compresses so much that you don't really get much preasure form that volume - besides it would just go out the crankcase breather hose - which wouldn't be a bad thing to check into either... you should get fluid going out that before it blows the seals - have you looked at your air filter lately?

I guess the other possibility is that the gasket is just worn out - and that it isn't so much the preasure that makes it fail, but that it has failed...

woot

I guess you could do a leak down test to see if you're getting blow by.

I would just change the oil and filter. Don't do it on the side stand. Might fill it to much.

Check your petcock.

Replace the valve cover with new gasket and plugs. (be sure to install new rubber plugs on the clean and dry surface)
NO gasket sealer on the new rubber plugs.

Check your vent hose.

Check and make sure your needles and seats aren't leaking.

It should be just fine after this.

Thanks for the advice, after poking around today I found the vent hose elbow that enters the air intake box was plugged solid. It had some white powder caked hard all the way from one end of the elbow to the other. This obviously caused pressure to build until a weak point ( the valve cover gasket and end plugs ) gave out and vented, taking oil with it.

As soon as I pulled the vent tube off the problem stopped immediately. I have cleaned the elbow and am now doing the contortionist routine to re-install it in the air box.

My next problem is an oil leak directly at the bottom of the engine, I'm thinking either or both the neutral switch ( which doesn't work anyways) and the oil level sensor need new gaskets/O-rings.


The good news is the XJ starts like a dream, I can't believe it. My old KZ440 used to crank over, even when warm. This machine fires on the 1st or 2nd rev every time!!

That makes more sense... :) I wonder what the white stuff was???

Air expands as it heats - as you engine was warming up it was creating the extra preasure...

It's good that you found a cheap fix! :)