Rb25det Oil Port Holes

[Stronzo]

Hello,

Question in brief: R33 rb25det block has three holes in the oil port:

1.First (nearist to the front of the engine and oil pump) -- is the oil feed from the pump.

2. Second (at the center of the oil port) -- is return of clean oil after the filter to the block.

3. Third -- is a hole for relief valve (which bypasses the filter in case of high pressure difference before and after the oil filter) at rb25de. And it should be blocked with a blind plug at rb25det as it has two relief valves in stock oil cooler.

why i`m asking: reviewing mates conversion from rb25de to rb25det (after total engine destruction due to incorrect crankshaft oil clearance) i noticed that all three holes in his block are free (no relief valve and no blind plug in the third hole), so i think this is the reason that caused abrasive wear of everyhing including camshaft bearings.

[Stronzo]

anyone? the question is about hole marked with green -- should it be closed with a plug on stock rb25det or not?

thx.

[Stronzo]

hi,

I have to up this old thread as i have an interesting info on this issue. Look at the picture -- my previous question was about the hole marked with green (oil filter bypass channel). I searched through NISSAN FAST and here is the info on the utilization of this channel in different engines:

all NA RB2x engines have relief valve plugged in this hole.

all R32 RB26 have this hole plugged with a blind plug

R33 rb26 have this hole plugged till 0995 and after that this hole is free (r33 rb25det have this hole plugged till 0297, after that -- free)

all R34 rb26 and rb25det have this hole free.

Actually this hole is an oil filter bypass channel wich should be used in cases of dirty filter or very high viscosity of oil during cold weather starts. And the results of this research mean that after 0995 all rb26s have filter working in parallel and there is always some oil that bypasses the oil filter. This sounds weird.

So the question is -- why the hell -- after less than a year of manufacturing R33 rb26dett -- Nissan opened an oil filter bypass channel and left it till the end of production of this engine (R34)?

this is not just my curiocity, but the second reason i`m asking is that i`m finishing my own engine now and i closed this channel with a plug to drive all oil flow through the filter -- but after this little FAST research -- i`m not sure i was right.

I will appreciate if Sydneykid will try to answer my questions as he`s got huge experience on rb`s oiling system.

Thank you in advance.

[frozenwaffles]

Hi, did you ever get a proper answer on this? I am removing my oil cooler and bought a relief valve to go in there but i don't know how to remove the factory plug?

[GTRPSI]

I remove the relief valve and plug it on all my builds.

Last thing i want is a drop in oil pressure which should NOT happen if the filter is regularly changed with the oil.

Its there for people who cheap out with restrictive filters or dont service their cars.

More trouble than its worth when pushing power....

[frozenwaffles]

yeah that sounds like good advice right there...

another question, is this actually a check valve to stop oil from flowing back away from the filter? or is it definitely the pressure relief valve?

[89CAL]

It is an oil filter bypass valve. In a way it is a check valve, but it doesnt perform the function your every day check valve

Look at the way it is designed in the photo above. Oil comes from the pump in the outer ring through a hole, it then passes through the filter through the inner hole to the lubrication system. The plug is installed in the outer ring so that if the filter is blocked, oil comes in from the oil pump and straight back out through a spring loaded check valve (oil filter bypass valve) So its primary purpose is to allow a passage of oil at 'x' pressure

normal check valve is to stop a oil from flowing the wrong way

bypass valve is to allow oil to flow at a certain pressure.

And thats my boring and slightly pointless talk about some basic hydraulics

[mayor quimby]

I have a rb26dett and removed oem oil block. I installed a greddy sandwich plate, and now my oil pressure before my oil filter is as much as 140 psi. Way too much pressure for my liking. I would like to remove the blind plug blocking the bypass gallery and install a bypass valve. I wanted to know how people have gone about removing the plug.  I was thinking about drilling into the plug and trying to twist/pull the plug out, but I have no idea how thick the plug is / if I'll have enough force to remove it since it's wedged in the block. My engine is in the car, so drilling maybe half way into the plug is my only option. Anyone who has any experience removing these blind plugs, your help would be much appreciated.

Thanks