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Another Head Gasket Failure

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ohio-rider

Posts: 227

Joined: Tue Jun 12, 2007 7:26 am

Location: Ohio

Post Wed Apr 30, 2014 6:40 am

Another Head Gasket Failure

I’ve needed to replace the front head gasket three times in the past eight years on my 45. Now after a fresh rebuild of the engine and only 1500 miles on it I need to replace it again. This time the leak appears to be coming from the head bolt nearest the front of the engine. During the rebuild I decided to try using the paper gaskets instead of the cooper ones hoping that they may last longer, they didn’t. I’ve checked and double checked the heads for flatness each time this has happened and have never found an issue.

My question is why does this keep happening? Could it be my riding style? I rarely beat on it but do ride it with enthusiasm because it’s more fun that way. It’s driving me nuts to keep finding a mess all over the front fender. Any thoughts?
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enigmas

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Posts: 769

Joined: Fri Oct 01, 1999 12:01 am

Location: Victoria, Australia

Post Wed Apr 30, 2014 8:24 am

Re: Another Head Gasket Failure

I prefer using the copper gaskets for a number of reasons including: better transfer of heat through to the cyl head, better sealing conformity and improved squish for the cyl head. I take it that all surfaces are flat and true, that the cyl head fins aren't painted or polished...and that you also use a tension wrench on the head bolts or studs. My bike runs open pipes (2 down the side to the back axle) so heat is not bottled in the heads by a restrictive muffler. I also rev the hell out of it at times without issue.
One last thought, do you use large and thick washers (1/8") under the nuts or bolt heads to distribute the tension through the seats of the cyl head. The seat surfaces also need to be flat and true. My engine is fitted with studs not bolts.
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Pa

Site Admin

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Joined: Sun Mar 12, 2000 1:01 am

Location: Ohio USA

Post Wed Apr 30, 2014 9:56 am

Re: Another Head Gasket Failure

Adding to what Vince has stated, did you inspect the bolt holes in the head and cylinder as well ? Sometimes 1 or more holes will become dished out from burning away gases that escaped over time of minor exhaust leakage. The valley of the dished out area or areas may not be easily spotted with just a straight edge. I would suspect, if the dishing out syndrome I mentioned is the reason you keep blowing head gaskets, the area dished out the most is near the outer rim of the gasket surface area and the inner most area of a valve seat or cylinder bore area. I also think there should be a witness mark caused by escaping exhaust gases which should help you locate the defective spot or spots.
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ohio-rider

Posts: 227

Joined: Tue Jun 12, 2007 7:26 am

Location: Ohio

Post Wed Apr 30, 2014 3:46 pm

Re: Another Head Gasket Failure

The head bolts and washers are original. The washers are the ones with the big chamfer on them and nicely fit the spot faces machined into the heads. The rear cylinder head gasket hasn’t given me any trouble since the second time I replaced it. That one time was likely my own fault but that’s another story.

Here’s an old photo of how I found it when I tore it down for the rebuild. This was head gasket replacement number three and it only lasted about two years with the copper gaskets, which is a lot longer than the paper ones I installed during the rebuild lasted. You can see where this one blew out.

Image
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enigmas

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Posts: 769

Joined: Fri Oct 01, 1999 12:01 am

Location: Victoria, Australia

Post Wed Apr 30, 2014 7:59 pm

Re: Another Head Gasket Failure

Interesting that it's on the exhaust valve side. I'd be checking to see that there's not a ledge or area of the cyl head that overlaps the lip of the cylinder causing a pocket of exhaust gas to erode the gasket at this area. Try annealing a copper gasket before use.
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Pa

Site Admin

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Joined: Sun Mar 12, 2000 1:01 am

Location: Ohio USA

Post Wed Apr 30, 2014 8:38 pm

Re: Another Head Gasket Failure

If she keeps blowing out in that very same area Steve, Either one of the two surfaces are not flat or the head bolt is bottoming out before the gasket gets a good squish equal to all the other head bolts.
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enigmas

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Posts: 769

Joined: Fri Oct 01, 1999 12:01 am

Location: Victoria, Australia

Post Thu May 01, 2014 2:42 am

Re: Another Head Gasket Failure

Excellent point Paul. Sometimes it's the simplest things that go unchecked! :wink:
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knucklebolt

Posts: 199

Joined: Tue Feb 12, 2013 8:27 pm

Location: Six miles East of Cheney, Wa.

Post Fri May 02, 2014 9:37 pm

Re: Another Head Gasket Failure

I'm putting my money on a too long head bolt.

ken.
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ohio-rider

Posts: 227

Joined: Tue Jun 12, 2007 7:26 am

Location: Ohio

Post Sat May 03, 2014 7:16 am

Re: Another Head Gasket Failure

When I take it apart in a couple weeks I’ll check the length of the bolts. That is one thing I never really checked before even though I did run a tap down each hole to the bottom. I have noticed that the worst leak always shows up coming out from the front bolt holes like this old photo shows. In this photo I was using the copper head gaskets.

Image
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Pa

Site Admin

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Joined: Sun Mar 12, 2000 1:01 am

Location: Ohio USA

Post Sat May 03, 2014 12:19 pm

Re: Another Head Gasket Failure

Steve.........if you do find the head bolts are bottoming out before adequate gasket squish takes place, just grind 1/32" to 3/64" off of the bolt lengths. A thicker washer will work also.
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ozwalla

Posts: 13

Joined: Sat Mar 08, 2008 7:47 am

Location: Victoria, Australia

Post Sat May 03, 2014 8:35 pm

Re: Another Head Gasket Failure

I have been dabbling with 45 motors for years and recently have been racing one in C class here in Australia

I have had an engine built with quite high compression which was hard to keep head gaskets on. Changes between races which I got pretty good at.
The solution was obtained from listening to solutions and combining 2 of them.
Along with checking stud lengths washers I now have no problems with annealed copper gaskets ( james). I just head them up in the kitchen on the gas stove to cherry red and quench in the sink.. When home alone!!
I then use a copper cement spray on the gasket and install tensioning to 50 Lb with a tension wrench.
I have not blown a head gasket on this bike for 3 years

Hope this helps
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knucklebolt

Posts: 199

Joined: Tue Feb 12, 2013 8:27 pm

Location: Six miles East of Cheney, Wa.

Post Wed May 07, 2014 8:48 pm

Re: Another Head Gasket Failure

Studs rather than bolts might not be a bad idea.

ken.
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Chris Haynes

Posts: 2616

Joined: Wed Jul 05, 2000 12:01 am

Location: Los Angeles, CA

Post Wed May 07, 2014 11:56 pm

Re: Another Head Gasket Failure

ozwalla wrote:I now have no problems with annealed copper gaskets ( james). I just head them up in the kitchen on the gas stove to cherry red and quench in the sink.. When home alone!!


As I remember 8th grade metal shop it was heat and cool in water to temper and heat and let cool very slowly to anneal.
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45Brit

Posts: 1399

Joined: Tue Nov 27, 2007 2:29 am

Post Thu May 08, 2014 2:18 am

Re: Another Head Gasket Failure

I've always been told to plunge copper, and allow non-ferrous metals to cool slowly, ideally under a layer of warm ash.
Shoot, a man could have a good weekend in Dallas with all that stuff...
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Frankenstein

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Joined: Thu Jun 27, 2002 12:01 am

Location: Interlaken, NY USA

Post Thu May 08, 2014 4:31 am

Re: Another Head Gasket Failure

Chris, that particular sequence applies to steels, where you heat it to the Austenitic temperature, then cool it quickly to trap the carbon in the material in a super saturated crystal lattice, which is the Martensite state, which gives a hardened steel. Copper's a whole 'nuther smoke, as no carbon to deal with. Basically, there you just heat it up to relieve the stresses that have been induced into it, and then cool it, making it soft again.
Heat treatment of steel is a fascinating topic, lots going on inside the steel, again one of those things that early man figured out around the campfire, and scientists later analyzed and gave fancy names to :D
DD
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enigmas

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Joined: Fri Oct 01, 1999 12:01 am

Location: Victoria, Australia

Post Thu May 08, 2014 6:30 am

Re: Another Head Gasket Failure

I'm with 45 Brit on the annealing of copper...'plunge it' man! :wink:
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Dusty-Dave

Posts: 868

Joined: Tue Oct 12, 1999 12:01 am

Location: Ojo Caliente,NM,USA

Post Thu May 08, 2014 5:44 pm

Re: Another Head Gasket Failure

I have very little Hardly experience but if this was an Indian I would be asking if you heat soaked and re-torqued the head at least twice and even more times if it gave any on the last time. I would also ask if you used a ground beam torque wrench and held the torque for a while each time, click type wrenches are fine for production work on new stuff but not here. And of course the things already mentioned.
Dusty
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knucklebolt

Posts: 199

Joined: Tue Feb 12, 2013 8:27 pm

Location: Six miles East of Cheney, Wa.

Post Thu May 08, 2014 7:53 pm

Re: Another Head Gasket Failure

So it sounds like copper anneals whether you quench it, or don't.

k.
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Dusty-Dave

Posts: 868

Joined: Tue Oct 12, 1999 12:01 am

Location: Ojo Caliente,NM,USA

Post Thu May 08, 2014 8:20 pm

Re: Another Head Gasket Failure

knucklebolt wrote:So it sounds like copper anneals whether you quench it, or don't.

k.

Seems to get much softer if you anneal but does get fairly soft if cooled slowly.
Dusty
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enigmas

User avatar

Posts: 769

Joined: Fri Oct 01, 1999 12:01 am

Location: Victoria, Australia

Post Thu May 08, 2014 8:25 pm

Re: Another Head Gasket Failure

Torque wrenches are great and I have several myself and always choose to use them, but if I recall correctly when these motorbikes were being serviced in the field (and perhaps even in specific shops) cyl heads and perhaps everything else including flywheels were all done with 'feel' using the mechanics innate experience. Correct me if I'm wrong on this matter.
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