Advice on oil leak at head bolt

[Lipdog]

Two of my head bolts seem to be seeping oil after a ride (50 mi today). The first photo below is the rear head, the next one is the front head, and the last a close up of the same one that's seeping on the front head (the one that is used for the upper engine mount). I torqued the bolts when I replaced the gas tanks a few months ago, and the (copper) head gaskets seem to be solid around the perimeter and I don't see any signs of head gasket leaks at the gaskets. At first I thought it was oil that dripped from the Kiwi quick drain and residue from a gas leak I fixed, but it appears it's coming from a couple of the head bolts. I'm a little stumped because, as I understand it, no oil flows through a flattie head. I've been fine tuning the carb and the bike runs great, btw.

So my questions are:
- What is this problem and how do I fix it?
- Can I leave this and ride the bike until the winter, or is this something I need to address right away?

[PanheadFred1]

I'm interested in the answer too.

[T. Cotten]

Are your sparkplugs oily, Lipdog?

....Cotten
PS: Your headgaskets can be checked with soapy water, especially over the intake ports, and all you have to do is kick it. (But headgaskets don't make oil unless they suck air enough to burn your rings.)

[Lipdog]

Are your sparkplugs oily, Lipdog?

....Cotten
PS: Your headgaskets can be checked with soapy water, especially over the intake ports, and all you have to do is kick it. (But headgaskets don't make oil unless they suck air enough to burn your rings.)

Plugs look good. Tan/grey and bone dry but with a bit of carbon on the outside ring near the threads. I just sprayed some soapy water on the gaskets and kicked it. They look solid, no bubbles.

[pisten-bully]

So my questions are:
- What is this problem and how do I fix it?
- Can I leave this and ride the bike until the winter, or is this something I need to address right away?

I’ve had this and waited until the season’s over to address it without a problem. It’s not a lot of oil and the source is the big question. Air flow around the fins and the top of the motor can make a drip of oil be deposited far from the leak. Check your oil level in the tank always (before you go out and when you gas up) and make a note of oil consumption.

I never did find where it was coming from, but it’s gone now!

[T. Cotten]

...I never did find where it was coming from, but it’s gone now!..

So you just took it all the way apart and put it back together, Harry,..

And the gremlin jumped out?

Happens all the time.

....Cotten
PS: Sometimes I wonder if it isn't some raw gas too.
No matter what, the head gasket had to be compromised.

[Lipdog]

Sometimes I wonder if it isn't some raw gas too.
No matter what, the head gasket had to be compromised.

Please help me understand this. The edges of the head gaskets are clean, copper colored. And the mess is *above* the gaskets, on the cylinder heads.

One thing I did was to put a vinyl cap on the quick-connect oil drain, to make sure it doesn't drip when it's hot. There also could be some residual gas toward the intake side of the front cylinder, from when I had a leaky gas tank (now replaced). So I cleaned that the best I could. There don't appear to be any new gas leaks. All of the connections and the tank seem completely dry.

[PRG]

Howdy sir,

That’s unburnt combustion/oil byproducts, a black tar like mix, leaking past your gaskets. With old style fiber gaskets it’s common for these leaks to occur over the exhaust port (area of max heat causing gaskets to deteriorate and shrink and farthest point from the combustion chamber where these byproducts would stand a better chance of being burnt) between the head and cylinder deck. Copper is vastly superior at sealing but all surfaces must be very flat, if not they tend to leak at the gasket head bolt cutouts.

As far as a tan plug is concerned correlating it to oil burning, running short J6’s is the equivalent to using those old fashioned plug extenders once sold in the JC Whitney catalogue to alleviate oil fouling in worn out motors. These plugs are away from the action, where this stuff is splashing around, want an idea how dirty a rich mixtured low compression Chief runs, install a set of extended tip NGK BPE 7’s. Without practice and/or electronic ignition you may not get an otherwise heathy motor to run on both pots. And, as mentioned in a previous post, folks not adjusting their ignition advance to engine load and rpm while underway only add to the unburnt byproducts.

With copper gaskets you can continue to ride with this annoyance, with fiber, once combustion has “breached” that surface seal they tend to get messier faster. On my delightfully worn out 346 I just took to wearing knee length jack boots as my right side pants leg, sock and shoes got ruined with increasing frequency. At your leisure I’d pull your heads, carefully deck them and the cylinder deck topsides, re-anneal those gaskets with a torch, retorque and you’ll be good to go.

[T. Cotten]

Please help me understand this. ...

I wouldn't pretend to understand, either, Lipdog!

But wouldn't a perfect head gasket seal around the headbolts?

Copper gaskets stung me, so I am prejudiced.

And for some reason, that *other brand* spec'd them for castiron heads, and composites for aluminum (or just paint!) Did the Wigwam ever make hem for aluminum heads?

....Cotten

[Lipdog]

Thank you Cotton and PRG. This is making sense to me now, and I understand how head gasket failures around the bolt holes, and especially on the bolts that aren't easily torqued, could lead to this type of seepage. Following PRG's advice, I'll ride for the rest of the season and deal with the slight mess until it starts to rain here, and then I'll pull the heads.

A few questions on that:
- Can I do a head gasket on this bike without pulling the engine? I'm hoping I can do it by just pulling the tanks. I've already welded up a wrench to get to the bolts under the frame and can torque by measuring angle versus the ones I can reach with a torque wrench.
- It seems straightforward to check and deck the cylinder heads if necessary. Am I correct to assume that to deck the cylinder top surfaces, I would need to pull the engine apart?

Any helpful hints on fixing chief head gaskets would be greatly appreciated.

[tfburke3]

when you eventually get the heads off you can make a couple of light passes with a large flat file.The high spots,usually around the bolt holes ,will show up.Then you can see if you can clean them up in place or removal is required.May sound crude but you really can do a nice job with a good file and some skill.
Tom

[T. Cotten]

...A few questions on that:
- Can I do a head gasket on this bike without pulling the engine? I'm hoping I can do it by just pulling the tanks. I've already welded up a wrench to get to the bolts under the frame and can torque by measuring angle versus the ones I can reach with a torque wrench.
- It seems straightforward to check and deck the cylinder heads if necessary. Am I correct to assume that to deck the cylinder top surfaces, I would need to pull the engine apart?...

Twenty years ago or so, Lipdog,..

I did the complete top end of a 350 without even pulling the tanks.

But it took an arsenal of wrenches.

when you eventually get the heads off you can make a couple of light passes with a large flat file.The high spots,usually around the bolt holes ,will show up.Then you can see if you can clean them up in place or removal is required.May sound crude but you really can do a nice job with a good file and some skill.
Tom

I used a "Polish mill', Tom!

But not everybody has 30" or 42" stones.

(You run around it while the stone sits still. Bastard files are "Swedish mills! And disc sanders are "Mexican mills". Am I "canceled" yet?)

Beware the tops of the cylinders can warp as well, particularly over the intake ports.

.....Cotten
PS: Lipdog! Want to try a couple of thin PEEK washer bandaids?

[PRG]

Howdy sir,

First off, with the ready crush of rate of old fiber gaskets along with non uniform deterioration in use (the aforementioned decline at the exhaust valve pockets) the unreal 50-55 ft lbs of torque specified leads to thread upward pull at the bolt holes In the cylinders and light collapse of the alloy downward on the heads at the same location over a period of decades in regular use. The latter exacerbated in the early 90’s with the ascent of the vintage bike movement and a new group of enthusiasts resurrecting these machines often for sustained higher speed use than they were originally designed for. That’s when I started seeing Fours, especially, ruining their heads. Replacing fiber with fiber on damaged surfaces can mask the problem, copper requires a flat surface. A flat fine file works great on the cylinder deck and 400-600 grit on flat glass for the heads. This done with engine in frame, no problem.

Torque, now, this is where purists and (older than me..not many) old timers will scratch their heads at the heresy. That 50 ft lbs taking into account bolt shank diameter and distance from washer flat underside to thread engagement in the deck means this spec focuses entirely on crushing those inferior gaskets into submission to avoid failure at focused hot spots (exhaust) with no consideration for thermal expansion of the metal components. No 70-80 year old heads asked to operated under this duress can do this forever. Fours notoriously begin to crush at the washer lands and though functionally repairable at great expense, visually are ruined as the cooling fins become warped. Vincent’s (without head gaskets, no less) and air air cooled Porsche’s (making 150bhp/Litre on turbos) run no more that 30 ft lbs. 25 ago, after wrenching on a 441 midway across a US tour with its heads ruined,I came home did the above on my 440 and torqued to 30 ft lbs, many miles later, no carbon tracking. On my stock 346 it’s 40 ft lbs and the hot rod 348 at a little over 40. Your results may vary.

[Lipdog]

Thanks very much Tom(s) and Peter. This is really helpful information and I greatly appreciate it!

I will ride it a couple hundred more miles and deal with the mess, and take it apart when the winter rains arrive, hopefully sooner rather than later.

A couple of last questions: How do you measure flatness on the cylinder deck accurately? Can I use the edge of a good machinists straight edge (Starrett, not Harbor Freight )? And for the heads, I may send them to Kiwi or a local machine shop. But if I do them here, I'll probably try Peter's suggestion of 400-600 grit on flat glass. Is a piece of reasonably thick glass (say 3/8") from a glass shop generally flat enough, or do I need something special?

[PRG]

Howdy sir,

Use of a Starrett of any type will be more precise than any tool on the fading production line of the late 40’s as Indian limped to the last, that’s why that power plant is rife with the use shims/various size rollers to account for inaccuracy in casting and machine work. A large fine machinists file for the deck and glass on a flat work bench will be plenty adequate for a stock (compression) engine. You’ll likely be surprised at how uneven both surfaces are for this machine to have run faithfully to this point.

You want to see how long these old trusty trail horses will run, then click the link below on my 346.
https://petergz.smugmug.com/Motorcyc...-Chief/My-346/