O-ring sizing needed

[djnolan]

Hello All,

I have been trying to find the proper O-ring size for the pressure reducing valve in the 944S head. According to Rennlist post the Parker o'ring numbers: 2-013 and 2-014 but these are SAE numbers and don't fit precisely. The PET does not list a size, only this diagram:

http://forums.pelicanparts.com/uploads26/pressure_reducing_valve_16v_engine1491696914.PNG

What would be the metric O-ring size equivalent that would fit properly?

The clsoest match to this in metric is 1.80x010 and 1.80x012.5 but on the otherhand it would be better to have a precise measurement of the valve to determine the o-ring size.

Need some help to get this figured out for a bunch of S/S2 owners. I have checked with Pelican and 944online and they don't know the proper size.

[944 S2]

I bought Viton 2-013 and 2-014. Worked well no problems on my 91 S2.

[9FF]

See if this helps: www.pff.de/porsche

Here's the Google translate:

O-rings for the pressure reducing valve (94410713900) Since there is apparently no part number for the O-rings of the pressure reducing valve and in the forum so far also no information is to be found in this case, I have written here my experiences and knowledge for posterity. Dimensions of the O-ring seats on the valve: upper seat: - inner diameter on the valve = 13.5mm / outer diameter of the valve at this point = 16mm lower seat: - inner diameter on the valve = 12.5mm / outer diameter of the valve at this point = 15mm - groove width in each case 2mm - Thickness of the old O-rings = approx. 1.5-1,7mm Selected O-rings: I then got different O-rings in the range of these dimensions from HNBR and tried. Unfortunately, I did not get all intermediate sizes, so I chose an O-ring with 10.82x1.78 mm for both positions. A 12x2mm gasket does not fit, is too thick. Thus, the pressure reducing valve did not purge. I guess an 11.8x1.78mm ring would be ideal for the big seat.

[djnolan]

The groove width and the inside diameter is needed to determine the optimum size: O-Ring Groove Chart : The O-Ring Store LLC, We make getting O-Rings easy!

[JD159]

Trust me they fit precisely!! Also, the S2 doesn't have that valve, only the regular OPRV. The rennlist post was what I used for reference.

Edit: Am I wrong about the S2???

[v2rocket_aka944]

unsolicited advice...

i'd use the closest one you can find that fits the grooves and fills the bore in the head.
it's not a critical part so it doesn't have to be "perfect" but a close-enough o-ring will crush enough to seal fine.

note that the 928 DOHC heads (which are almost identical to the 944 DOHC heads) did not use this valve whatsoever...and yet, they almost never experience the dreaded "cam chain pad failure" that the 944S does...whodathunkit..

[944 S2]

Originally Posted by JD159

Trust me they fit precisely!! Also, the S2 doesn't have that valve, only the regular OPRV. The rennlist post was what I used for reference.

Edit: Am I wrong about the S2???

Here's what was on my S2. I'm not the first to use the sizes I mentioned. Lots of discussion I researched months ago on the "other" forum. As was mentioned I don't believe it's that critical and mine has been ok so far. Went back in nice and snug.

[JD159]

Wanted to throw this out there. I had this chat with Greg Brown who is the 928 expert.

Think it is possible to remove the plunger in this valve so that more oil flows to the head at higher rpms? My understanding is that this valve limits flow to the head when the pressure is higher.

[944 Ecology]

It is possible, although one would guess that Porsche would not have gone to as much trouble as they did to include such an expensive and finely engineered part unless there was a compelling reason to do so.

I would tend to leave it in unless you are having oiling problems that cannot be solved by other means.

[michaelmount123]

O-rings sizes for the valve are 011 and 012.

[v2rocket_aka944]

TAKE A LOOK HERE...
http://www.allsealsinc.com/ParcoO-RingSizeChart.pdf

[gheedunk]

I went to change my O-rings out while I had the cam cover off, assuming it has never been touched in 29 years, and I've been chasing a warm idle lifter noise. I've got the set screw out, but the valve is in there pretty good. Is this an indication that the O-rings are in good shape and I should leave it alone, or do I need to manhandle this thing out? Pliers, screwdriver? Any help appreciated

[JD159]

Originally Posted by gheedunk

I went to change my O-rings out while I had the cam cover off, assuming it has never been touched in 29 years, and I've been chasing a warm idle lifter noise. I've got the set screw out, but the valve is in there pretty good. Is this an indication that the O-rings are in good shape and I should leave it alone, or do I need to manhandle this thing out? Pliers, screwdriver? Any help appreciated

Mine were rock hard and it was still in there pretty damn good. I used a screwdriver to pry under the lip.

[gheedunk]

Originally Posted by JD159

Mine were rock hard and it was still in there pretty damn good. I used a screwdriver to pry under the lip.

JD: It finally gave in with a different leverage point. Mine has the typical crud in the v-groove for the set screw, but otherwise looked pretty clean. The O-rings were proud of the valve body, and were fairly pliable (did not break when I removed them) so I suspect the O-rings, or valve was replaced at some point (buried in the handwritten service receipts, likely).

I replaced the O-rings anyway and am ready to install, but how do I know if the valve itself is free? I read somewhere you could apply shop air, but to which orifice? Is there a method to determine function? The "Plunger" or "Screen" portion do not move when pressed. Any help appreciated