refresh951

Will the 3pc OPRV work in the later oil filter housing (that uses the 1pc OPRV)? I need a early 3pc OPRV, anyone have a good deal on it? TIA

V2Rocket

Shawn the filter housings all have the same PN so they should be interchangeable, my understanding is the block is what changed at some point to use the different OPRV style.

Maybe someone can confirm...

I *might* have a spare early 3-piece, I'll take a look thru my boxes this weekend.

Tom M'Guinn

Right, you want to match the OPRV to the block, not the oil thermostat housing. There is an early and late casting of that housing (under same official part number), but the key difference is the later castings have a threaded hole to secure one of the oil cooler hose brackets -- to keep it from turning when you torque it down. The early housing and lines don't have that hole or the bracket.

The early blocks came with a 3-piece OPRV, but it was problematic so Porsche came out with an retrofit 1-piece valve to fit those blocks (944 107 035 11). So if you are sure your block takes an early OPRV, then the retrofit 1-piece is the one to look for (IMHO). If you have a later block (generally 87+ on 951s), then you'd need the late style 1-piece OPRV (944 107 035 02). If in doubt, measure the diameter and report back. I suspect Lart passes these things out at Halloween, but I know I have a handful I'll never use so will check this weekend and report back...

Chris White

toss the 3 pcs - you can get erratic oil pressure with used 3pc OPRVs
If you are using the 86 block you will need the retrofit 1 pcs which is not easy to find used and costs quite a bit.

lart951

10% off for listers (paid) http://www.ebay.com/itm/Porsche-944-...item3aeab810df

V2Rocket

what is the issue with the 3 piece?
dead-nuts simple, spring, plunger, cap...no o rings to worry about?

obviously they saw a need to update to the later retrofit style...but what was bad about the original type?

refresh951

Thanks for the input!

Tom M'Guinn

Unless the housing is perfectly aligned with the block, the plunger can hang up on the lip where the housing and block come together. The OPRV alignment tool was supposed to fix that -- and in theory does -- but not all mechanics are as careful as others and parts can shift, so Porsche made the one-piece units to avoid the issue. Never really sure why Porsche still calls for the alignment tool, since the one-piece units essentially align things themselves, but I still use it anyway so as not to jinx it.

Tom M'Guinn

All my spares are the later style by the way, sorry... If you still want a 3 piece version, I'll look harder though. I know I had one of those...somewhere...

V2Rocket

ahh...gotcha.
i was especially curious because the Subaru EJ engine like in my Outback uses the same type of OPRV as the early 944 style...and that engine wasn't designed until 1989.

KevinGross

http://www.connact.com/~kgross/FAQ/944faqoc.html

MAGK944

Kevin, I'm sure I read in a bulletin that the 3-piece from 85.5 was different to the earlier ones 82-85.5

I'll try and dig it out.

Ltr.... here you go, seems like in 85.5 the 3-piece had different valve material, a longer spring and a different plug to match the spring.

Chris White

If you leave it alone it works fine, once removed you will not get the piston in the same position. After 30 years the piston and bore can get a wear pattern that does not like to get disturbed.

The only plus of the 3 pcs OPRV is that you can play with the spring to change the pressure relief point.