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Old 10-22-2014, 06:40 PM   #15 (permalink)
performance with economy
Join Date: Sep 2014
Location: melbourne Australia
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Originally Posted by oil pan 4 View Post
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.
Yes, we definitely need a bypass or 2 for the oiling system, cold oil doesn't flow well at all, especially in the winter!

Messing with the engine oil pump is not an easy task.
Most are difficult to access, but some vehicles enable you to pull the sump and take off/modify the oil pump without removing the engine, and others have the bypass valve head on the block capped with a bolt/copper washer.

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.
I would prefer to have the oil filter bypass if the oil flow through it is restricted too much, as the typical filter media tends to swell as moisture is absorbed by the fibres, blocking oil flow somewhat.
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