Author Topic: Head gasket Leak (Read 5235 times)

CBGhia · « **on:** June 21, 2009, 06:44:58 PM »

So, I put a new (to me) head on my bike. I did not have it machined (I know, I will). But my main question...

Can you put anything on the head gasket?

I made sure the surfaces were clean when I installed it, and I just re-torqued the head and I think it actually leaks worse now.

I hate buying new gaskets when I just put new gaskets on there, and I really don't want to do it again. BTW I used the Vesrah kit if it makes a difference.

jmckinne · « **Reply #1 on:** June 21, 2009, 07:04:09 PM »

Are you doing a compression check to determine you have a leak and if so, are you sure it's not a bad valve or seat that is leaking?

In general using anything on a head gasket is not good.

If it isn't a valve have both mating surfaces looked over by a machinist.

Sorry, no good news.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #2 on:** June 21, 2009, 07:08:08 PM »

Use heavy duty studs next time rather than your stock ones that have been stretched 2 or 3 times already.

MCRider · « **Reply #3 on:** June 21, 2009, 07:14:27 PM »

My guess is he's talking about an oil leak, not a compression leak. Please confirm.

If so, If you can get the head off without wrecking the gasket. You can put 3bond or similar elephant snot on it (I have) and if you're a real cheapskate... you may be lucky.

Did you get the Orings and knock pins (dowels) in properly?

Certainly the HD studs as JRG suggests helps.

But your in the oil zone now.

Are the threads on the holes that hold down the cam towers in good shape. Some of them are open ended holes and if they are fatigued or stripped or helicoiled, oil will wick its way down them and exit the head at about the middle fins in the front. Not at the head gasket level but above, and drip down. Can be a g-- awful mess.

CBGhia · « **Reply #4 on:** June 21, 2009, 09:11:35 PM »

Yea, Oil leak, not a compression leak. The damn thing runs like a champ. I think I hit 106 today on a ride to breakfast with some friends.

I think I am going to pull the head and have it machined flat and get a new top end gasket kit. It leaks a little to much for a long ride. I think a lot of it is coming from the little o rings for the oil passages on the sides.

Little buggers.

MCRider · « **Reply #5 on:** June 21, 2009, 09:19:02 PM »

Quote from: CBGhia on June 21, 2009, 09:11:35 PM

Yea, Oil leak, not a compression leak. The damn thing runs like a champ. I think I hit 106 today on a ride to breakfast with some friends.

I think I am going to pull the head and have it machined flat and get a new top end gasket kit. It leaks a little to much for a long ride. I think a lot of it is coming from the little o rings for the oil passages on the sides.

Little buggers.

That's good, new gaskets are always best. I've heard of peple doing everything from Permatex Head Gasket stuff to dry, and everyone of them thinks its the right thing. personally, if the heads flat (and the cylinder too) and all the orings and knock pins are in, dry is best. Take your torque to the high end of the range. Once you get to 75%, go in 5% increments till you get to the max. At least 10 rotations/iterations with the torque wrench, following the pattern in your manual.

Too bad you don't have the HD studs. Issue is over forever.

andy750 · « **Reply #6 on:** June 21, 2009, 09:59:48 PM »

Quote from: MCRider on June 21, 2009, 09:19:02 PM

Too bad you don't have the HD studs. Issue is over forever.

Thats what I thought on my 750K4...engine rebuilt - head gasket leaked...engine pulled again...HD studs installed....head gasket leaked again $:-\$

There are no guarantees with 35 year old bikes....engine is coming out again in the Fall

cheers
Andy

MCRider · « **Reply #7 on:** June 22, 2009, 05:28:38 AM »

Quote from: andy750 on June 21, 2009, 09:59:48 PM

Quote from: MCRider on June 21, 2009, 09:19:02 PM

Too bad you don't have the HD studs. Issue is over forever.

Thats what I thought on my 750K4...engine rebuilt - head gasket leaked...engine pulled again...HD studs installed....head gasket leaked again $:-\$

There are no guarantees with 35 year old bikes....engine is coming out again in the Fall

cheers
Andy

I'll have to reconsider. That's a rare case, so let us know what you find.

HondanutRider · « **Reply #8 on:** June 22, 2009, 05:47:38 AM »

After I got my CB350F cleaned and running again (when I got it, it had been idle for about 20 years), it had the all-too-common weep of oil from the head. It would run a bit of oil on the left side and after a long run was most noticeable. However, after having put on a few hundred miles, the leaking seems to have completely stopped. I suspect that those old gaskets and o-rings got cooked, softened, and expanded in the right places.

bryanj · « **Reply #9 on:** June 22, 2009, 06:18:03 AM »

There are many places to leak except the gasket itself:-

Pucks
studs screwed into head with through holes
tacho seal
etc

before condeming the gasket and or "O" rings/Knock pin seals you need to find exactly where it is comming from

tlbranth · « **Reply #10 on:** June 22, 2009, 09:13:03 AM »

My CB750K0 used to have a gasket leak and it seems to me Honda came out with a sticky head gasket somewhere in the mid-70's. It didn't seem reasonable to me but it stopped the leak.

Johnny5 · « **Reply #11 on:** June 22, 2009, 09:45:27 AM »

I sprayed a thin coating of copper on my head gasket (used Emgo brand gaskets). Didnt think it would hurt anything. Stock studs and about 600 miles later, it's leak free. And I havent necessarily baby'd the bike either.

Fingers still crossed.

CBGhia · « **Reply #12 on:** June 22, 2009, 04:21:26 PM »

I have been thinking on this today.

I replaced the head because I bent a valve when a rubber band broke during the valve cover installation. It seemed easier to just buy a used head. I bet if I replace the bent valve and put the old head back on, I will have better luck. If it is warped a bit, I think it is warped the same as the cylinder because it never leaked.

So I guess I will just swap heads back to the old one after pulling one of the exhaust valves from the "new' one and put it on the old one. Sound like a plan?

andy750 · « **Reply #13 on:** June 22, 2009, 04:25:34 PM »

Sorry I should have specified....6000 miles after replacing stock studs with HD studs and riding it hard and often 2-up a small leak started from between 2 and 3 - so most likely cam pucks.....its getting progressively worse but still rideable of course....

Cheers
Andy

NitroHunter · « **Reply #14 on:** June 22, 2009, 04:34:29 PM »

Where EXACTALLY is the oil leak???

CBGhia · « **Reply #15 on:** June 22, 2009, 04:37:01 PM »

As far as i can tell, it is leaking on the right side (near where the o ring is) and it is leaking somewhere behind the carbs. i have tried to locate that leak but even a short ride gets oil everywhere and idling doesn't show much.

MCRider · « **Reply #16 on:** June 22, 2009, 05:21:07 PM »

Quote from: andy750 on June 22, 2009, 04:25:34 PM

Sorry I should have specified....6000 miles after replacing stock studs with HD studs and riding it hard and often 2-up a small leak started from between 2 and 3 - so most likely cam pucks.....its getting progressively worse but still rideable of course....

Cheers
Andy

Yes that's a bit different. The HD studs would have no effect on the leaks from under the cam blocks.

Since helicoils are problematical in that area, I'm going to be using a reinforced cam cover which will exert tremendous down pressure on those cam blocks, hopefully to keep it from ever leaking.

And the original poster threw us a curve ball in that he has a 550 or a 650. I jumped to assumption it was a 750. I don't think HD studs are available for a 550 or 650.

andy750 · « **Reply #17 on:** June 22, 2009, 05:28:49 PM »

Good luck Ron!

cheers
Andy

CBGhia · « **Reply #18 on:** June 22, 2009, 05:38:07 PM »

Sorry, it is on my 550.

Johnny5 · « **Reply #19 on:** June 22, 2009, 07:11:56 PM »

Did you replace the large oring underneath the piston sleeves?

bryanj · « **Reply #20 on:** June 22, 2009, 08:01:01 PM »

Did you get the correct washers in the right places on the steel brackets that hold the cam cover end caps, if not it leaks there

MCRider · « **Reply #21 on:** June 22, 2009, 08:06:36 PM »

Quote from: Johnny5 on June 22, 2009, 07:11:56 PM

Did you replace the large oring underneath the piston sleeves?

I'm not sure how important those really are. On big bore CB750s we throw them away. They've never been identified as a source of a leak, positively.

At some point some engineer did think it was possible for oil to wick up the seam between the sleeve and the block, turn the corner at the top and ooze out into the head gasket. But in reality I don't think so.

But if its apart and one has them I guess why not?

CBGhia · « **Reply #22 on:** June 22, 2009, 08:07:14 PM »

yep, I even replaced them again this weekend. It is not leaking from there. (referring to the end cap o rings)

bryanj · « **Reply #23 on:** June 23, 2009, 04:53:04 AM »

NO NOT the "O" rings on the end cap, there are two washers, one either side of the small right angled bracket that the screw holding the end cap goes into, One is a soft one and needs to be there and in the right place or oil will leak up the bolt and out. Similarly the bolt holding the top of the camchain tensioner has a sealing washer to stop oil

CBGhia · « **Reply #24 on:** June 23, 2009, 06:35:24 AM »

you know, i don't have one on that bolt, it doesn't leak from there, but I will put one on it to be safe.

I know there is not one on the cam chain tensioner. Perhaps that is where a lot of the oil is coming from. Thanks. I will look at that this week. Thanks!

tlbranth · « **Reply #25 on:** June 23, 2009, 09:26:56 AM »

With a chunk of granite or thick (1/2" or better) plate glass and some stick-down abrasive paper and some patience, you can true up the head and block yourself.

WFO · « **Reply #26 on:** June 23, 2009, 12:17:04 PM »

I re-used as suggested, torqued to 22lbs using Two Tired's torque pattern and Honda gaskets:

5lbs in sequence
10
15
20
22

let it sit overnight then loosen in opposite sequence:

20 (may already be loose)
15
10
5

Then tighten again:

5
10
15
20
22

No oil whatsoever. Perfect.

CBGhia · « **Reply #27 on:** June 24, 2009, 02:40:34 PM »

Well, tonight i am going to roll it out, clean it off and try the athletes foot spray to try to locate the exact source of the leaks. If work wasn't taking up so much of my time, I could get things done on this bike

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Author Topic: Head gasket Leak (Read 5235 times)