Author Topic: Leaking head gasket  (Read 2382 times)

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Leaking head gasket
« on: February 08, 2023, 03:22:43 PM »
I am preparing to remove the left side head on a 1991 V65 with 21,000 miles.  It leaks oil and it's spreading all the way to the swing arm.
Compression is still 150psi on both sides when cold.
From the posts I have read, it seems a straight forward job.  I am armed with workshop manual and Guzziology.
I am expecting the head will not come off easily.  My question is about the cylinder base gasket.  It does not leak and I worry that prying the head off will compromise that joint.
What is the best way to remove the head without consequences?  Or is it a crapshoot?

The right side head is clean, so I don't plan on opening it.  However, I plan on taking the left head to a machine shop and have it taken apart, cleaned and checked out.
Does it make sense to remove the other head as well?  I guess I can do it at a later time, if I see differences in performance of the two sides.
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Offline cappisj1

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Re: Leaking head gasket
« Reply #1 on: February 08, 2023, 03:47:51 PM »
Why you are at it… I would treat both sides to refurbished heads, head gaskets and base gaskets. You will be much happier in the end. The bike will be easier to tune and run much better in the end if you do both sides at once.

But if you only want to do one side you can probably not worry about the base gasket. But you’re only 15 minutes from pulling the jug, replacing the gasket and sliding the jug back on. Just need to collapse the rings when sliding it back on. If you don’t do it now it’s an afternoon worth of work to get back to the base gasket.
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Offline Dirk_S

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Re: Leaking head gasket
« Reply #2 on: February 08, 2023, 04:17:49 PM »
Mind you, I’m only speaking from limited experience with a much newer V7 II, but I would have an extra base gasket on hand as a backup, and have a second set of hands hold down the cylinder while you take a combination of dowel, mallet, and prying device to work at the head.
« Last Edit: February 08, 2023, 04:18:51 PM by Dirk_S »
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Online FarmallA

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Re: Leaking head gasket
« Reply #3 on: February 08, 2023, 04:19:19 PM »
When I first got my V65 Mongrel LaMonza  (Monza frame, Lemans tank, V65motor), the PO pointed out a leak from the right side jug, he thought it was the head gasket.  Turns out it was only the rocker cover gasket folded over.

But I assume you've checked that.

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Re: Leaking head gasket
« Reply #3 on: February 08, 2023, 04:19:19 PM »

Offline Huzo

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Re: Leaking head gasket
« Reply #4 on: February 08, 2023, 05:12:45 PM »
When I first got my V65 Mongrel LaMonza  (Monza frame, Lemans tank, V65motor), the PO pointed out a leak from the right side jug, he thought it was the head gasket.  Turns out it was only the rocker cover gasket folded over.

But I assume you've checked that.

FarmallA
Steve
Good comment….

Offline Scout63

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Re: Leaking head gasket
« Reply #5 on: February 08, 2023, 09:19:23 PM »
Compared to that gearbox this is cake Maurilio. I wouldn’t freshen one head and not the other. Don’t forget that breather hoses come out of the back of the heads on the small blocks and into the air cleaner   Check to make sure that a hose isn’t cracked and blowing out oil by just removing the rocker cover. Also, gently tap the head with a hide or rubber mallet to loosen it. Don’t pry.
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Offline normzone

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Re: Leaking head gasket
« Reply #6 on: February 10, 2023, 08:59:57 AM »
Also, gently tap the head with a hide or rubber mallet to loosen it. Don’t pry.

Only commenting to say that also, breaking fins is unfortunately easy ...  :angry:
That's the combustion chamber of the turbo shaft. It is supposed to be on fire. You just don't usually see it but the case and fairing fell off.

Offline nsmith

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Re: Leaking head gasket
« Reply #7 on: February 10, 2023, 09:25:19 AM »
Never tried it but what would happen if after removing the push rods and of course the nuts and bolts you put the sparkplug in and crank the motor over? 150 psi should blow the head clean off as Dirty Harry would say.
Neil formally from South Dakota now living it up in Arkansas

Offline acguzzi

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Re: Leaking head gasket
« Reply #8 on: February 10, 2023, 11:01:00 AM »
probably separate the assembly at the base gasket unfortunately since it's the smaller of the two, neat idea though!

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Re: Leaking head gasket
« Reply #9 on: February 10, 2023, 12:27:41 PM »
Never tried it but what would happen if after removing the push rods and of course the nuts and bolts you put the sparkplug in and crank the motor over? 150 psi should blow the head clean off as Dirty Harry would say.

Hold my beer... :grin:

Offline n3303j

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Re: Leaking head gasket
« Reply #10 on: February 10, 2023, 01:30:16 PM »
Hold my beer!
Was when you just loosen all the head nuts about 1 millimeter and crank it over live. Each cylinder fires once and the heads are free!
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Offline Scout63

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Re: Leaking head gasket
« Reply #11 on: February 10, 2023, 04:46:16 PM »
Ear muffs Pescatore.
Ben Zehnder - Orleans, MA USA

Offline Murray

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Re: Leaking head gasket
« Reply #12 on: February 10, 2023, 04:52:55 PM »
Hold my beer!
Was when you just loosen all the head nuts about 1 millimeter and crank it over live. Each cylinder fires once and the heads are free!

Well you could go a threaded compression tester and some compressed air, I'd leave the head bolts in a few threads. Not sure about the V65 but on the old square fin big blocks there is a blanking plug that allows access to a head bolt (I think) sealed with an o-rung. When that leaks it looks remarkably like a head gasket.

Offline Frenchfrog

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Re: Leaking head gasket
« Reply #13 on: February 11, 2023, 07:06:48 AM »
Nothing like that on the smallblocs

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Re: Leaking head gasket
« Reply #14 on: February 11, 2023, 01:42:49 PM »
This is getting very entertaining. I'm holding the beer, nsmith.  Did it work?
Compressed air from the spark plug is interesting too.

Thanks for the tips, folks. I was thinking about prying the head, so I won't push on the fins.  Holding the cylinder makes sense.  Compressed air should keep the cylinder down as well.
I have a whole gasket kit from Scout63 and the valve cover gasket is dry.

I'm overthinking it because I'm in the camp of not fixing what's not broken. And I've been tearing and rebuilding this bike for the past 4 winters.  Exactly one year ago, Scout63 helped me fix the gear box.
And there's more to do.  Front shocks seals and a leaky carburetor plug. No idea what to do on the latter.

Anyway, I have tools, manuals, parts, space, support, money and no flipping time to do it.
So it might take a while, but I'll git'er done.
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Re: Leaking head gasket
« Reply #15 on: February 11, 2023, 04:24:55 PM »
Finger nail polish should stop the plug leak.
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Re: Leaking head gasket
« Reply #16 on: February 11, 2023, 04:48:09 PM »
I recall Richardson talked about smallblock head gasket leaks.  Here is my summary, from another website; 

Head Gasket Leaks - The distance between the studs is long and the gasket web is thin, so leaks happen, especially on the outward side near the oil passage. I've solved leaks with Permatex Super 300, as recommended in Guzziology by Dave Richardson.

Take off the head, apply Super 300 to both sides of the head gasket with a little extra in the problematic bottom part, near the oil passage. Wait a short time for it get tacky, and bolt everything back up. I've had luck re-using the old gasket if it looks decent. Torque again.

Base Gasket Leak - Richardson reports that a during manufacturing a drilled stud hole can break into an oil passage, causing base gasket leaks. The fix is to clean the hole, seal stud with Loctite, and reassemble. I refer you to Guzziology for photos and details.
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Re: Leaking head gasket
« Reply #17 on: February 11, 2023, 09:21:29 PM »

I was thinking I don't need ignition, just the piston compression. Your idea sounds more fun, Huzo.
That's one way of decorating the bike with oil and  shooting the head across the garage.

Thanks for the Guzziology reference.
I remember reading about the Permatex for valve covers as well.
Does Permatex harden and make it difficult to remove the gasket later?
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Re: Leaking head gasket
« Reply #18 on: February 12, 2023, 04:31:26 AM »
Reportedly Permatex does not harden, but nothing is eternal, right?  I used it years ago, and I would say it slooowly hardens, over years.
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Re: Leaking head gasket
« Reply #19 on: February 12, 2023, 09:06:17 AM »
We used to use it on iron exhaust manifolds when they had a divot on the sealing flange or were warped and wouldn’t seal with a new gasket. In that application it got hard and generally worked well.
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Re: Leaking head gasket
« Reply #20 on: July 09, 2023, 05:39:19 PM »
I finally had time to work on this project.  The head came right off with a slight tug.  The cylinder stayed in place (but maybe not).
Here is what I found:

Looks like this side is running lean.  The spark plug has the same light tan color.
But why don't both valves have the same color?  A problem for later.

To clean the soot I tried a number of chemicals.  The only thing that worked was engine degreaser.
Acetone worked well on some of the gasket remnants, but in the end I had to pick at it with a piece of wood... and still not done.


I can see why the head was leaking.  There is all kinds of pitting/corrosion that formed under the gasket.
A lot of pitting at the spark plug too.

The cylinder is not much better.


What can I do about the pitting?  I am hoping some of you have seen this before and can provide guidance.
Would Permatex fill the gaps?  Should I get a copper gasket made, or is it time to have it resurfaced?
It is not easy to see from the photos, but I found a gouge toward the top of the head, across those oval holes.
My finger nail sticks into it.  It is away from the compression chamber, so maybe it's fine.

After a few hours of smelling nasty chemicals, I packed things up and noticed oil on the floor.  :shocked:
While cleaning the piston, some of the cleaner got into the stud hole in the lower right.  It must have dissolved the oil
and maybe loosened the base gasket  :cry:

I think I might as well pull the cylinder.
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Offline SIR REAL ED

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Re: Leaking head gasket
« Reply #21 on: July 09, 2023, 08:01:07 PM »


It's possible your Cam chain is too tight and it's causing a leak.........
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Offline SIR REAL ED

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Re: Leaking head gasket
« Reply #22 on: July 10, 2023, 07:26:54 AM »
Never tried it but what would happen if after removing the push rods and of course the nuts and bolts you put the sparkplug in and crank the motor over? 150 psi should blow the head clean off as Dirty Harry would say.

Amen.  Time tested method.

"Works a treat!" as some would say!
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Offline n3303j

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Re: Leaking head gasket
« Reply #23 on: July 10, 2023, 07:46:06 AM »
Amen.  Time tested method.

"Works a treat!" as some would say!
Here, hold my beer for a second
Loosen all head bolts about two turns and start her up.
BANG BANG and the heads are free, but captive.
That's the time tested method. :grin:
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Offline SIR REAL ED

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Re: Leaking head gasket
« Reply #24 on: July 10, 2023, 07:55:21 AM »
Here, hold my beer for a second
Loosen all head bolts about two turns and start her up.
BANG BANG and the heads are free, but captive.
That's the time tested method. :grin:

I'd say the method chosen is highly dependent upon how much beer is consumed previously.

Complete removal of capturing bolts makes a better Youtube video......

But, if you are buying the beer, I'm opened minded enough to thoroughly discuss!!!   :wink:
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Offline Antietam Classic Cycle

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Re: Leaking head gasket
« Reply #25 on: July 10, 2023, 08:48:19 AM »

It's possible your Cam chain is too tight and it's causing a leak.........

??  Pushrod engine, so how would a too tight cam chain cause a leak?
Charlie

Offline SIR REAL ED

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Re: Leaking head gasket
« Reply #26 on: July 10, 2023, 08:52:34 AM »
??  Pushrod engine, so how would a too tight cam chain cause a leak?

But Huzo said.......    :wink:
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Re: Leaking head gasket
« Reply #27 on: July 10, 2023, 12:07:21 PM »
Luckily I didn't have to do anything special.  The head came right off, probably because the joint was already compromised.
The air compressor method also sounds good

When I saw the pitting I immediately freaked out.  After lubricating with beer and sleep, I went to YouTube University and found some useful information.
The cause is still not clear to me, but I have read about improper grounding of the engine.  I can see how this is important for the head since it
holds the spark plug.  But the plug electrode is much closer and the spark should jump there.  Unless the spark propagates through the
compressed mixture as well and prefers a path to ground in between the valves. This doesn't explain the pitting under the gasket.
I guess I will add a wire to the rear most nut, but... damn... really?

Anyway, I need to figure out the repair path, assuming I have to fix it.  Again YTU shows some methods.
One interesting idea is to use JB Weld and sanding down the whole thing flat.
I guess it's time to get a spring compressor, but I am probably going to chicken out and go to a machine shop.
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Offline Ryan

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Re: Leaking head gasket
« Reply #28 on: July 10, 2023, 08:26:47 PM »
The improperly grounded engine is a popular "cause" for leaky head gaskets on Subarus. The theory is that it grounds through the coolant and this causes electrolysis and the degeneration of the gaskets. Kind of rules out that particular theory with an air-cooled engine, and I am not sure how much I buy into this theory, but I regularly check the condition of my grounds on the 'roo just in case!

Offline n3303j

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Re: Leaking head gasket
« Reply #29 on: July 10, 2023, 09:12:21 PM »
Seems to ne the tie rods into the main case are reasonable connectors to the head's earth connection.
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