Cylinder head issue GL1200


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Damgaard
Posts: 35
Joined: Tue May 21, 2013 11:15 am
Location: Denmark, Tonder 4 km from the Danish/German border
Motorcycle: GL 1200 Aspencade 1985

Cylinder head issue GL1200

Postby Damgaard » Sun Aug 03, 2014 2:15 am



Well how to start...
After rennovating my Aspy, new waterpump, timing belts, tensioners etc. 7 days driving and right cylinder head leaked coolant into both exaust ports. Started to hear the hydraulic tappets ticking on both sides…
Both heads off, new valve seals, valve mating and new head gaskets (aftermarket gasket no OEM) Couldn’t see any signs of gasket failure or measure wharping of the heads. Heads looked okay...
All put together again… 4 days later… hydraulic tappets clicked and hammered again. I noticed a little steam, smelling sweet, cumming up from right rear cylinder head exaust port…
Well… now my Aspy is back in my workshop…
I will pull off the right head tomorrow…
I’m planning a trip to the local machine shop for eventually a pressure test/milling.
Any other suggestions for curing my head problem ?
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HawkeyeGL1200
Posts: 918
Joined: Sat Jul 05, 2014 11:53 am
Location: Courtland, Va.
Motorcycle: 1984 GL1200 Interstate
1981 GL1100 Interstate

Re: Cylinder head issue GL1200

Postby HawkeyeGL1200 » Sun Aug 03, 2014 7:32 am

Noisy lifters is an indicator of an oil problem, not a coolant problem, so I think you have two separate issues here.

If you have the heads off, or plan to have them off again, you may want to have a thorough look at the camshaft, rockers and the overall area on the "top deck) for build up that will prevent proper flow of lubricant to the hydraulic valve adjusters.

I copied the following from the service manual regarding servicing the valve train (Section 7 in my service manual)

When the camshaft holders are removed, be sure to fill the de-foaming chambers with clean engine oil during assembly,
which otherwise would allow air to enter the hydraulic tappet adjusters.
Air in the hydraulic tappet adjuster causes excessive tappet noises. Remove the adjuster and bleed air if there is air in any
adjuster.
Excessive noise (Hydraulic Tappet Adjuster)
Air in hydraulic tappet adjuster or improper installation
Worn or sticking adjuster
Clogged cylinder head oil holes or orifices
Broken or weak assist spring
Sticking or damaged assist shaft
Use of improper shim

So, air can get in the "lifters" and that is bad.

The second issue of the coolant leaking into the cylinder(s) is also bad. One thing to seriously consider before you take the head(s) to a machine shop is, which "half" of the head/cylinder is the cause of the trouble? I have seen where a head has been restored to flatness well within the recommended specification, and installed, only to have the gasket fail again. After some serious troubleshooting, the owner found the cylinder frame was degraded and that it was the cause of the gasket failure. Careful SANDING, using a piece of plate glass (because the glass is FLAT) as a sand-paper holder, allowed him to restore the flatness to his cylinders and following the clean up, head gaskets are holding properly.

I am NOT recommending you start taking lots of metal off any part of your engine. What I am working through (in my head and capturing with my keyboard) are possible causes for the symptoms you describe.

The key determination for the coolant (Head gasket) issue is knowing both surfaces (the head and the frame) are flat as it is possible for them to be. The recommended method of using a straight-edge and feeler gauge is fine, as long as your "straight edge" is straight. Ensuring both mating surfaces are flat only means that a good seal is possible. The glass can also be used as a surface plate to determine flatness of the head and cylinder block...

Anyway, it is early and I probably got it all wrong, so read the words I wrote with a healthy dose of skepticism before taking any action on them.. When I read these messages, I often wish I were close enough to jump on the motorcycle and motor on over to have a look at the trouble in person. Many times, all it takes to resolve something is an objective set of eyes...

Here's to hoping you have success the second time through.
I am wrong as often as I am right concerning what is wrong with someone else' motorcycle without having seen the machine in person. Guessing with limited information, as to the source of the trouble, is sketchy at best.

rzaugg
Posts: 88
Joined: Tue Oct 01, 2013 10:04 pm
Location: Cedar Rapids, Ia
Motorcycle: 1984 GL1200 Aspencade
1989 GL1500 Aspencade

Re: Cylinder head issue GL1200

Postby rzaugg » Sun Aug 03, 2014 1:39 pm

Sounds to me like you are doing the right thing, a machine shop would be able to pressure test the head to check for cracks. If there was no gasket failure and you had somewhat of a straight edge to check flatness, that would be my next step. Make sure you give them as much info as you remember, especially if the steam didn't start through the early part of warm-up. Sometimes cracks won't leak till the head gets hot enough, especially with aluminum.

The tappets (valve noise) I agree is probably an oil flow or pressure problem. If you can, hook up a manual gauge and run it till hot, if the valve noise isn't there when cold, it may be a pressure problem. There is just no way of knowing when all you have is a light on the dash


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