View Poll Results: Screwed by a hanging chad? Or not?
The depression is a red herring; that's enough gasket to seal 5+ bar of oil pressure
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Coincidence: mechanical block damage during the first owner's tenure
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Multiple Choice Poll. Voters: 13. You may not vote on this poll
Cam Tower Leak Brain Teaser? Or, there! I am insane now!
05-21-2012, 06:04 PM
#1
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Cam Tower Leak Brain Teaser? Or, there! I am insane now!
In Engine coming out for Head Gaskets and WYAIT's Brian provides some details and pictures of his motor-pull and refurbish. I posted the pictures below in that thread, but wanted to get some new folks to look at them, hence this thread.
Long story short: we have an oil leak at the bottom-rear of the passenger-side cam tower gasket. We used Greg Brown's gaskets, dry, assembled on an engine stand. Driver's side is leak free. We've eliminated bolt and/or bolt torque issues on the passenger's side.
We cranked the engine over without the fuel pump relay, built-up oil pressure, and marked the exterior of the cam tower at exactly the point from which pressurized oil oozes from the gasket. When we removed the cam tower and examined it very closely we found this
at exactly the point of the oil leak. See the oddly-circular depression? It's about 0.001" deep. You can just feel it with your fingers but it isn't as deep as a piece of paper is thick. There's a matching impression on the head surfaces at the corresponding point. The depression leaves a (roughly) 0.001" gap on either side of the gasket thus allowing - at that point on the sealing surface - only about 20% of the gasket to get properly compressed.
This...
... is an OE cam tower gasket. Notice the "chad?" (Note, that Greg Brown's gaskets arrive "chadless.")
Funny that the chad from the OE gasket is pretty-much exactly the size as the depressions on the cam tower and head mating surfaces.
Oh, one more thing: the OE gasket is 0.002" thick.
The evidence we have is:
- the total "depth" of the depression is roughly 0.002"
- the thickness of the gasket is 0.002"
- the area of the depression is exactly the same size as the bolt hole chad from the OE gasket.
- the oil channel wall is a tiny bit bulged-in at the depression
- we did not damage the sealing surfaces
It seems obvious to me that at some point, before we disassembled the motor, that a chad from the OE gasket found it's way under (or over) the OE gasket. Aluminum is not diamond-hard and can deform. During this previous-to-us assembly, the extra 0.002" from the chad began a 27+ year process of putting a chad-sized impression into the mating surfaces.
When we removed the cam tower and cleaned the surface of gasket material we, unknowingly, removed this extra 0.002" of gasket material. Now, there is a void above and below the gasket leaving only 20% of the gasket surface to seal.
Vote early. Vote often. Multiple choice too.
Long story short: we have an oil leak at the bottom-rear of the passenger-side cam tower gasket. We used Greg Brown's gaskets, dry, assembled on an engine stand. Driver's side is leak free. We've eliminated bolt and/or bolt torque issues on the passenger's side.
We cranked the engine over without the fuel pump relay, built-up oil pressure, and marked the exterior of the cam tower at exactly the point from which pressurized oil oozes from the gasket. When we removed the cam tower and examined it very closely we found this
at exactly the point of the oil leak. See the oddly-circular depression? It's about 0.001" deep. You can just feel it with your fingers but it isn't as deep as a piece of paper is thick. There's a matching impression on the head surfaces at the corresponding point. The depression leaves a (roughly) 0.001" gap on either side of the gasket thus allowing - at that point on the sealing surface - only about 20% of the gasket to get properly compressed.
This...
... is an OE cam tower gasket. Notice the "chad?" (Note, that Greg Brown's gaskets arrive "chadless.")
Funny that the chad from the OE gasket is pretty-much exactly the size as the depressions on the cam tower and head mating surfaces.
Oh, one more thing: the OE gasket is 0.002" thick.
The evidence we have is:
- the total "depth" of the depression is roughly 0.002"
- the thickness of the gasket is 0.002"
- the area of the depression is exactly the same size as the bolt hole chad from the OE gasket.
- the oil channel wall is a tiny bit bulged-in at the depression
- we did not damage the sealing surfaces
It seems obvious to me that at some point, before we disassembled the motor, that a chad from the OE gasket found it's way under (or over) the OE gasket. Aluminum is not diamond-hard and can deform. During this previous-to-us assembly, the extra 0.002" from the chad began a 27+ year process of putting a chad-sized impression into the mating surfaces.
When we removed the cam tower and cleaned the surface of gasket material we, unknowingly, removed this extra 0.002" of gasket material. Now, there is a void above and below the gasket leaving only 20% of the gasket surface to seal.
Vote early. Vote often. Multiple choice too.
05-22-2012, 02:20 AM
#6
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That sucks.
They obviously have to be flat to seal. I doubt any sealant will "contain" the oil pressure from that oil galley. I'd get a used cam carrier from someone and put it back together....unless you can find a machine shop that can figure out how to hold that one and "kiss" that surface a tiny bit, cheaper.
They obviously have to be flat to seal. I doubt any sealant will "contain" the oil pressure from that oil galley. I'd get a used cam carrier from someone and put it back together....unless you can find a machine shop that can figure out how to hold that one and "kiss" that surface a tiny bit, cheaper.
07-05-2013, 02:17 AM
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Finishing out this thread:
A very careful application of DevCon liquid aluminum to fill in the divot on head and cam tower gasket surfaces worked perfectly. Bone dry after a year.
A very careful application of DevCon liquid aluminum to fill in the divot on head and cam tower gasket surfaces worked perfectly. Bone dry after a year.
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11-17-2014, 09:53 PM
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11-18-2014, 01:02 AM
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