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| Joined: | 09-17-2007 |
| Location: | San Francisco, California USA |
| Posts: | 221 |
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My theory is that these cam covers and housings have a lot of distortion in them. First there is the originally low tolerance of the manufacturing, second there is the now 40-50 years of time spent aging, and thirdly there is the various heat/stress cycles everything has gone through many times. This third issue also included people not torquing the covers down correctly over and over again while #1 and #2 were also adding more variation to the mix.
The result is covers and housings that aren't uniform. Even if we clean it perfectly and torque it right, things just leak out of the variations.
My remedy to this (and I do have BONE DRY covers) is to do the whole clean and then torque, but then return to the bolts afterwards and individually hand tighten them after the cover has had a heat cycle. What I have found is that on warped covers, the leak begins immediately, and when you go to torque the cover down again it is clearly loose and not holding the original torque value, and is sometimes even loose.
The hand tightening (with care and patience) cinches the gasket down further, allows the gasket to form into the uneven surfaces, and plugs the gaps and stops the leaks.
This is a long process of heat cycling then applying the torque again, until the gasket is ultimately seated and doing its job. You can go the route of simply retouring, but I have found that just light pressure by hand works wonders because most of the time you are simply re-applying a little lost torque when the gasket moved because it was sitting inside of a particularly big gap or inconstancy in the local area of the bolt. You are never going beyond the 14 inch pounds necessary, you are just adding in the 2 or 4 or whatever inch pounds BACK into the bolt to help it massage the gasket into deforming to the gaps it is attempting to seal.
It takes a few times, and often some bolts need only 1 or two cycles to get sealed and others need like 5-6 cycles. The result is a fully dry setup that should be torqued to the correct amount, minus a few inch pounds here and there.
Took me 15 years to figure this out.