Base Gasket STILL $%#@%!#@% leaking.

Yep, my base gasket is still leaking.

First time:

Vesrah base gasket, wiseco head gasket, new copper washers for the end stud, permatex #2 sealant on the base gasket, copper spray on the stud tops and washers.

Leaked oil at the base gasket at the front near the cam chain tunnel, and at the base gasket at the left front stud.

Rode 80 miles, re-torque to 38 ft-lb (have APE studs and top nuts). Still leaks. Rode another 100, re-torque to 40 ft-lbs. Still leaks.


Second time:

OEM Kawasaki base gasket, Cometic head gasket with copper spray, new copper washers, etc...

Shaved the idler sprocket dampers for use w/one piece head gasket, filled o-ring tunnel w/permatex ultra black.

Threebond Semi-Hardening case sealant on the base gasket.

Same re-torque procedure.

Now no leaks from the head gasket. Base gasket leaks at the front and rear near the cam chain tunnel again, and at the front studs.



Now what?

The cylinder has obviously been off many many times by god knows how many previous owners. Maybe the sealing surfaces and the bottom of the block and the top of the case are no longer flat enough to seal?

Is my only real option to take the motor apart, get the case surfaced, push the sleeves out, and get the cylinder base surfaced, and get new sleeves? Seems drastic.

Please somebody make it stop!

Bike runs great, by the way.

-Dave

What did you do around the base area where it is leaking? Silicone? Or?
Did you check for some places where some PO may have used a screw driver/ pry bar and buggered it? I use a 6" knife sharping stone on mating surfaces to make sure they are flat. Permatex red aviation sealant is my choice, but everyone has their fav.
Ever used low pressure air, <5psi on a regulator to pressurize the crank case, then soapy water in a spray bottle to pinpoint leaks? Maybe you are over looking a hair crack or something?
A straight edge and feeler gauge for a bow or low spot?

I hate to say it but you might be able to stop the leak from the outside, with a JB Weld epoxy. This until the season is over and you get around to pulling it down again, and think how cold the beer will be if you stock up now.

Hard to believe anything is getting by three bond sealer.

I can think of only three possible reasons:

1) There is a crack down there or some kind of deep groove or gouge so bad sealer can't fill it but that hardly seems likely.

2) A surface is so warped it can't seal. Doesn't seem likely.

3) Sealer not applied well. It's not that easy to apply it to a base gasket. You have to:

a) clean both flanges dead clean with acetone.
b) apply base gasket dry
c) install cylinder over jugs and rings
d) hold cylinder up as far as feasible with small clamps on the studs.
e) raise the base gasket and hold it up apply 3-bond bead on bottom flange.
f) drop base gasket.
g) apply bead of 3-bond to top of gasket.
h) drop the cylinder.
i) install head temporarily
j) use four head bolts to pull down slightly, enough to even the pressure on the base gasket and push some of the sealer out (not all)
k) wait about an hour and apply a little more down pressure (a socket finger tightening)
l) LET DRY OVER NIGHT
m) install head and torque down

Does this have the locating dowels around the studs or elsewhere? Maybe the height vrs the depth is a problem holding the cylinder up? Not torquing down because of interference?

Good idea. If there was gunk in the holes the dowels might not be able to seat.

The dowels are new, the cylinder was bead blasted and washed.

I applied the threebond very similar to suggested - put cylinder on pistons, apply threebond to case, drop base gasket, apply threebond to gasket, drop cylinders.

However, I went to a a torque of about 30 ft-lbs immediately upon dropping the cylinders.

Interestingly, where the oil leaks out of the base gasket, it actually seems to be pushing the threebond out - there are little bubbles of sealant that when squashed are full of oil!

Maybe the semi-hardening sealant is not what I need - it's too soft, esp. at high temps. Perhaps RTV is the way to go on this.

I am hesitant to blame the sealant, b/c even with out a sealant, it still shouldn't leak this bad.

-Dave

There shouldn't be enough gap for any bubbles. You say the dowels are "NEW", maybe there to tall? Really if the fit is correct it should seal with the bare minimum, like a anarobic 3m 518.

Motorhead hit it. I bet it's the dowels. Take them out, seriously. I had this exact same problem and I was told it's common. I took them out (at the drag strip btw lol) and haven't had a problem since.

beefsquasher wrote:

The dowels are new, the cylinder was bead blasted and washed.

I applied the threebond very similar to suggested - put cylinder on pistons, apply threebond to case, drop base gasket, apply threebond to gasket, drop cylinders.

However, I went to a a torque of about 30 ft-lbs immediately upon dropping the cylinders.

That is specifically warned against on the tubes of the stuff I use. That forces all the sealer out of the joint. The trick is to apply a small amount of pressure to get the excess to flow out but not oversqueeze it while it's wet. That's why I set the head on temporarily and used four head nuts at the corner and a socket in my fingers to apply even down force. I twisted and watched to not overdo it. You let it set an hour or two and it sets up mostly and you apply a little more force. That leaves a film of sealer in the joint and you let that fully dry overnight.

I learned the hard way too. I put the sealer stuff on my cam end plugs and top cover gasket and torqued everything down wet. Next day I fired it up and it sucked the cam plugs into the cam ends (the seals did not hold).

That said, I sill have trouble believing that's what is keeping yours from sealing. Unless there is something majorly wrong on one of the flange surfaces, the gasket should have sealed even with the sealer mostly squeezed out. If I had to bet, I would be thinking something else is holding it up. I had trouble with one of those goofy "locator pin" things on mine when I put it back together and had to file it a bit.

beefsquasher wrote:

Interestingly, where the oil leaks out of the base gasket, it actually seems to be pushing the threebond out - there are little bubbles of sealant that when squashed are full of oil!

The only way I could picture that is if the gasket failed (disnitegrated under pressure) which one of mine did but I don't think yours did because you would see it coming out. If oil can push the 3-bond out, there is no down force on it. The flanges are not coming together.

As I said, I had to file one of those knock pins to get mine to sit down right.

You don't have a hose on your crankcase breather that's kinked by any chance ?

Take a .0015" feeler guage to the base of the block where you see the leak. That will tell you a lot right there.

The cylinder dowels should be there. Without them, there's nothing to properly locate the block to the case. I definitely would not remove them.

Also, every dowel in the motor should slip fit into it's locating holes. Preparation before assembly is key.