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Old 10-22-2014, 01:17 AM   #10 (permalink)
oil pan 4
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If the oil filter has a by-pass valve its because the engine needs a bypass and does not have a permanent one installed.
All engines have a couple of oil bypasses built in some where. GMs have the bypass in the block and oil pump its self most of the time. Others use the oil filter to contain the filter bypass.

My 6.5L diesel has an in the block bypass for the filter and a bypass built into the oil pump. I installed a couple of washers to shim and increase in the filter bypass pressure, because I would rather have more filtered oil than unfiltered oil going to the engine.
The oil pump its self has a bypass set for up to 70 psi which it will never come anywhere near that pressure when warm. The oil filters I use (larger than OE spec) do not have a bypass valve.

For example my bug had an incorrect filter installed. When I got the correct one I noticed one key difference, the oil filter had a relief valve. Yeah that's not good for during winter cold starts.

No matter what you do include a filter by-pass relief some where, even if you set it to a higher pressure. Mainly for cold starts.

Messing with the engine oil pump is not an easy task.

The filter bypasses I have seen will open any where between 5psid and 50psid across the filter media. The idea being dirty oil is better than way too little or no oil.
Piston engines usually run pretty low psid , turbine engines run higher psid.
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1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.
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