59 a bypass Oil Filter

[Phil Gillespie]

Just putting all bits back together after an engine rebuild 59a engine.
Noted there is a restrictor on inlet side which is correct. But the outlet line back to sump also has a restrictor in it. This is not correct so best to remove or open up for full 1/4 return line. Aware there has been plenty on oil filters preiously.
This present set up would not work well?
Phil NZ

[51 MERC-CT]

The return holes (2) in an 8BA filter are equivalent to about twice the volume of the inlet restriction hole or .090" diameter.

So if the exit hole is anywhere close to .090, but not smaller it should be OK as is.

[JSeery]

I'm not sure why it would be needed. The two return holes in the filter return pipe should do the job.

If my math is correct and if the exit holes in the return pipe are .063 dia, then the area for one of the holes is .0031 square inches. The two holes would total .0062 square inches. That would require the return line to be at least .090 inches in diameter (.0064 square inches) to maintain the same flow.

Phil, have you measured the return line restrictor to see what size it is? Numbered, lettered and fractional drill bits work good to measure.

[Phil Gillespie]

Originally Posted by JSeery

I'm not sure why it would be needed. The two return holes in the filter return pipe should do the job.

If my math is correct and if the exit holes in the return pipe are .063 dia, then the area for one of the holes is .0031 square inches. The two holes would total .0062 square inches. That would require the return line to be at least .090 inches in diameter (.0064 square inches) to maintain the same flow.

Phil, have you measured the return line restrictor to see what size it is? Numbered, lettered and fractional drill bits work good to measure.

No I havent but the confirmation of size of return hole diameter at 0.090 gives me a figure to check now.
Many thanks for assistance.
Phil NZ

[JSeery]

To me that would be a minimum, and not sure why any restrictor is required.

[Phil Gillespie]

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Originally Posted by JSeery

To me that would be a minimum, and not sure why any restrictor is required.

So checked this return restrictor and it looks like it was on the wrong side as it was 0.060 approx. I already fitted a 060 to inlet. So opened the return restrictor to 2.5mm just over 0.090. All should now be good.
Engine is just been rebuilt, only await fuel pump push rod to fit and she's ready for the first start.
Phil NZ