Quote:
Originally Posted by Smallblock454
That is pretty easy to answer. The oil filter has a valve / bypass. The valve is actuated by a spring. If the oil pressure is too high – especially when the oil is cold – the bypass opens and unfiltered oil runs through the engine. Sometimes these springs also get old. And in the 9x6 oil system the spring loaded bypass is not part of the oil filter itself, but of the oil filter housing - so potentially never gets replaced.
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Yeah, that's a possibility, but the bypass valve should only open when the filter gets completely clogged up. This was not the case in this engine. I think the wear on the bearings would look different also. I opened up the filter and it looks like this:
Hundreds of these tiny metal chips. I also found one or two on the back side but I'm not sure if they made it through the filter material or I just contaminated it when I cut the filter apart. Anyways, I think if these pieces went through the main bearing clearances they would have left a lot of scratch marks on the bearing surfaces and even on the journals. Instead, the wear on the bearings looks smooth to me. So it's more like a wear caused by oil starvation. I'll look into the spin-on filter conversion though, that adds some extra protection against the old bypass valve failure also. Thanks for the tip
Quote:
Originally Posted by Smallblock454
The rod bearing wear doesn't look evenly to me. That should be investigated further.
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I didn't post pictures of the rod bearings. If you meant the main bearings, there is indeed some unevennness. One side must have undergone a lot of impact when the pistons were hammering on the valves, that force went down all the way to the main bearings. This could cause some asymmetry in the wear pattern...
Boxster
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