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| Joined: | 05-01-2005 |
| Location: | Minneapolis, Minnesota USA |
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Oil passages in the head route pressurized oil from the block to the front cam journals. The front journal has a groove all the way around the center of the journal, and a hole drilled into the cam in the middle of the groove. Then the cam is gun-drilled front to back (ie, the cam is hollow). Oil is pumped to the #1 cam journal, is collected in the grove, fed through the cross-drilling into the hollow center of the camshaft. Then all aft cam journals are fed oil from the cam via cross-drillings at each journal.
If all aft cam bearings had oil, then I have a hard time believing the front journal was oil starved. If #1 was oil starved, then none of the other bearings down stream from it would have gotten oil either. I think you need to take another look, and revise your failure analysis.
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The cam's fore-n-aft position and end float are controlled by a thick spacer/ washer screwed to the back end of the cam shaft. See item 31 in the attached JPEG.
With the shim/ washer properly installed, the cam's end float (freedom to move back and forth) is only 0.001 - 0.008 inch. Not much.
Was that spacer/ washer present, or omitted? If it was not present, the cam could have moved forward far enough for the end face of the front journal to rub directly on the front seal... possibly melting some rubber.
The bolt that retains the shim/ washer to the back end of the cam also plugs the far end of the gun-drilled oil passage through the cam. If the shim/ washer was missing, was the bolt also not present? If so, the cam's center oil passage would have been 'open', venting the cam's oil pressure. All journals' lubrication would have been compromised.
Does any of that sound like what you can see in the autopsy?
Regards,
Tim Engel
Attachment: JH - Cylinder Head.jpg (Downloaded 87 times)
Last edited on 09-07-2018 03:11 am by Esprit2