Head gasket weeping

Emlupi

Emlupi

Veteran Member
Joined
Sep 9, 2024
Total Posts
687
Total likes
1,079
Location
CT
Good afternoon all,
So I was going over the bike after a couple of practice sessions and I noticed that there was oil on the fronts of the carb bowls. So I poked around with a flashlight and it appears that there is some weeping at the head gasket. Looks like oil sheen at the joint.

IMG_9207.jpeg

I checked the oil level and it was well within the correct level marks. I added a little just for good measure. I assume that a retorque of the head nuts is in order? What say ye?
 
Any light seepage from the head gasket will take forever to lower the oil level, but retorquing the head is not likely to stop it. It's why I use Hondabond (silicone sealer very judiciously back in the day) on all head gaskets in the areas of known seepage, and some around the perimeter of the o-rings with the head gasket. Personally, I've not had good luck over the decades with dry head gaskets (honestly can't recall what you did on yours, just mentioning).
 
Considering it was race practice on a recently built engine, I'd give a retorque a try... looks like a copper gasket? If so, those generally need a little more clamping force to seal properly as they don't have the "spring" effect.
 
I remember that we had this discussion in the build thread and I am pretty sure I did that. I definitely used copper coat on the gasket. Hard to remember details.
Maybe the hard, high revving riding is part of the reason? It’s not dripping all over the cases but there’s definitely some oil accumulating on the fronts of the carb bowls directly behind the head gasket joint.
 
Emlupi said:
I remember that we had this discussion in the build thread and I am pretty sure I did that. I definitely used copper coat on the gasket. Hard to remember details.
Maybe the hard, high revving riding is part of the reason? It’s not dripping all over the cases but there’s definitely some oil accumulating on the fronts of the carb bowls directly behind the head gasket joint.
Click to expand...
If you used a copper gasket then disregard my method/solution obviously, after I typed it I wondered if you had.
 
Not copper gasket, regular gasket sprayed with copper coat.
 
Emlupi said:
Not copper gasket, regular gasket sprayed with copper coat.
Click to expand...
Ah, okay. I tried copper coat a couple times decades ago and it never caught on with me. The DOHC 450s (at least in my experiences) are prone to seepage in these areas, and I always use Hondabond there with 100% success rate (aside from the one time almost 10 years ago when I listened to other voices and tried it with a dry gasket, had to be done over not much more than 100 miles later).

450 head gasket sealer.png
 
Emlupi said:
Man, I do not want to take that engine apart again.
Click to expand...
Believe me, I know that feeling well. Hopefully a retorque will slow it down if nothing else, and you can always cheat with a thin piece of cloth towel packed in between the top cylinder and bottom head fins to soak it up for the day.
 
LongDistanceRider said:
It'll come down to a tech inspection then, until they DQ you run with it.
Click to expand...
That won’t be an issue. It’s not running or dripping all over the engine cases. Just a very faint wetness on the two carb bowls and only after it has been running. Tech inspection comes before you ever hit the track and it’s not enough for the hot tech oil inspection to ever detect. It took an entire day of riding before I even noticed it and even then it was completely accidental while checking something else.
 
If it's only in that area, what are the chances your mating surfaces weren't perfectly flat after gasket cleaning? Not sure if retorque + doing something like adding additional breather or letting the engine get hot before running it at higher rpm would help?
 
My plan is usually to try the simple solution first, as long as it's not likely to do harm. A retorque seems to be the first logical step.
 
For grins and giggles, check the speedometer seal. I had a leak from it, because the head was hot, the oil accumulated around the head gasket, but turned out the speedo seal had a light leak, and the oil traveled down, made it look like the head gasket, tried to confuse me.
 
Ugh! My cam box leak wasn't helped by a retorque. A second retorque made it run poorly. Probably closed all the valve clearances as I may have gone too far. I will never skip surface sanding all mating surfaces again, not just head bottom face but top of head and bottom of cam box too. Even if it means pulling all the valves and springs. It sits in the middle of the garage now, mocking my distain.
 
I always run the bike in the morning before I go out just to warm it up. I will ride it around the paddock a few times and then put it back on the stands. When it’s time to go, generally one good kick gets it lit and off we go.
I also already have an added crankcase breather at the oil fill cap.

View attachment IMG_9055.jpeg
 
I need to add another foible. I love my mistakes can help someone else. I pinched the breather tube from the cam box and the crankcase over pressurized. Usually this blows out the shift rod seal, but if only partially blocked, creates what appears to be leaks that would otherwise be contained. If you worked on the cam box recently, sometimes the gasket is installed reversed, and it blocks the vent. A pinched vent tube doesn't require a teardown either. :cool:
 
You must log in or register to reply here.
Back
Top Bottom