Niagra Falls of Fresh Oil From Front of Head Gasket

[305explr]

The restoration guide says to "...smear a small amount of silicon sealer into the inside edges of the gasket holes to prevent oil migration laterally through the gasket."

I see now that I used non-hardening permatex gasket-sealant--the wrong product, and worse, applied it to the gasket surface, and worse yet, did so liberally.

The result upon inspection is a noticeable ridge around each oil passage. The pic below says it all.

I can live with this mistake and time spent discovering it. Now I know more about engine assembly than I did before.

However, the twin breather tube fittings adjacent to the carb manifolds are both blocked, and I'm not sure how to unclog them because I'm not seeing where they draw from. (The bike is a '64.) Those get "Y"'d to the air filter, I believe.

Advice appreciated, and thanks again for all the input so far.

[Wilf]

As I understand it, Honda discontinued those breathers in later editions. A small passage goes from each nipple into the intake valve guide. Some owners have removed the nipples and replaced them with 6 mm bolts, and others simply join the two nipples with tubing. There appears to be no need to run them back to the air filter.

Wilf

[Goodysnap]

Just from appearance its looks as though the head was not fully seated to the cylinder. Just what I observed from the photo. Take a close look at those knock pins that they are fully seated and the correct length. They appear a tad high, but that may just be me.

[teazer]

I would be surprised if the gasket goo was the cause. More likely that the dowels are too long. I'd pull them out and check them. You could try drilling the bore slightly deeper in the head, but you want to make sure that you don't also bore it over size.

or take them out and grind a couple of mm off them, clean them up and refit them. Try dry assembly with no gasket or O rings and see how far down the head sits. More than 1mm, it will leak. It should more or less fit flat on the barrels with minimal if any gap.

[305explr]

Goodysnap and Teazer, you guys might be right. The gasket face was cleaned but the engine was already back together (20+ lbs) when you posted. I hand cranked it for a few mins and got no oil leaks, so I slipped it back in the bike yesterday after work.

The leaks are better, in that the engine runs longer before leaking, and the leaks are not as big as before, but the situation is still not at all resolved.

Now I will double check the length of the dowels. I now remember that I DID get a replacement dowel from a list member a while back, but I know I checked its length. I will now doublecheck the dowel lengths and seatings.

This may help someone diagnose the specific problem:

-The gasket is from a SUDCO kit, not a Honda as I'd thought. Different thickness?
-I AM using the Honda green o-rings. How much taller should the o-ring be than the gasket?
-The one leak remains at the front of the head, adjacent to the dowel. The OTHER seems to have migrated to the SIDE of the head, above the spark plug. (And yes, I revisited the 10mm 5 lb nut).

Dowels, non-honda gasket, or o-rings. Some aspect of this combo is not right...

I imagine I will have learned a thing or two by the time I sort this out.

[davebern]

Check that the top of the barrels is flat (as well as the head). Most people pay attention to head flatness, but forget about the barrels. Mine were not flat and I had to get them faced to finally stop cylinder head oil leaks.