Take 2 on the OPRV!

[HondaDustR]

Some have already seen my old thread and have heard of the successful oil cooler job with no oil pressure problems.

Can anyone loan me a OPRV alignment tool?

I take it back. Turns out the OPRV was not functioning correctly after all. Once fully warmed up, the pressure would read a normal 4-4.5 bar, until about 2500-3000 rpms. It would then begin to creep higher and practically peg at 5500-redline. On further inspection, the valve assembly did encounter resistance when screwing in the last 10mm or so into the cooler housing... obviously an alignment problem. Since the valve is self-contained inside a solid cylinder, it would seem that it wouldn't matter how exactly it sits in the block, but I figured out why it matters.

The endcap with the threads that is separate from the main cylinder with the sliding piston has about 2-3mm of compressible space between the two sections. The resistance from misalignment causes this to be compressed durring instalation, which I found out will limit the piston travel slightly (about 1-2mm, which ends up leaving the piston about 1-1.5mm over the 4 holes). Aparently, it is enough to inhibit the flow through the valve at higher oil flow rates and cause the oil pressure to creep up at higher speeds.

I did find a solution that seemed to work without totally disassembling the cooler housing (NOT what I want to have to do ). I screwed the valve in and left about 1/2 turn before it contacted the housing and repeatedly tapped the head to try to coax the internal piston spring pressure to expand the cylinder section further into the block. After torquing it down and driving, It was much more like normal, pushing no more than ~4.75 bar at full temp.

I still get the impression that it's not perfect, but it's certainly good enough for me. Besides, I've never observed the pressure that carefully under high revs before the job, so I'm not dead sure what's really "normal". I was pretty sure pegging at 4000rpms and full temp was not normal, though. Hopefully it stays working more or less correctly. If not, I guess I'll probably be borrowing the tool after all. I REALLY don't want to have to drain the cooling system again, and..., and... in order to realign the housing!

My take on this whole experience is:
If possible, use the alignment tool (or equivalent measure), even with the later style valve. The later style valve will not function correctly either if misaligned.

I did install the valve before tightening down the cooler housing bolts, hoping that it would align the galley, but this apparently doesn't help. So, for anyone planning to do this job: yes, you can get lucky and not need the tool, but for future sanity's sake, use it anyway!

[HondaDustR]

Ok, somehow this ended up in the 911 forum. Please someone move it to the 944 boards. Thanks!