I am upgrade my gen 6 merc 525sc with a new melling 10778 oil pump and i think i need to take a look on the oil bypass valve. There is have one in the engine block and also one in the Merc remote oil filter/thermostatic block. Dont know for what reason Merc they use two bypass valve??

I think i can blocckoff the one in the engine block where the remote addaptor is bolt on and change for a 30psi valve in the Merc filter/thermostatic block.

I need some advice with that subject.

I blocked off mine

In the engine only or at both place engine and oil filter t-stat mount Merc block??

both

Mine has a diff oil filter boss adaptor, I have a plug in the block

When they are both blocked, what oil filter do you use?

any good quality filter,i use the wix racing filters.

I think there are some out there who only plug the block fitting - the reasoning being that if the block bypass is activated, you bypass both the filter and the cooler, sending hot unfiltered oil through the engine. If the bypass at the filter is activated due to a restriction at the oil filter or a clogged filter, you are bypassing the filter only, and the engine still gets oil flow that has at least been cooled. Some non-synthetic filter elements will swell up and become restrictive if a lot of water gets into the oil, hence Mike's recommendation for the Wix filter. Of course, if the filter ever gets clogged due to water or foreign material, you have much bigger problems anyway!

you can block them off or install the 25013759 part number and they have the stronger spring so it wont bypass as easy..

25013759 BBC Oil Cooler Bypass Valve. High-performance and Bow Tie big-block V8s with four-bolt main bearing caps have provisions for oil cooler lines. This oil filter bypass valve must be installed in the rear hole behind the oil filter adaptor bolt to route oil through the cooler.

They are 30lbs or 11lbs?