Measuring for the big ring on the back of the pump. 64mm inside diameter. ---> Dash 037
69 mm outside diameter.
Thats why a Dash 040 won't fit.
Here's my trouble o-ring. The leaking mess maker. A Dash 014 O-ring (13mm inside diameter). Also a good shot of the rotor and 11 veins inside the pump.
It held the ATF fluid in around this fitting and the spring. That spring is what allows this PS-pump to vary its displacement. This pump is a Variable Displacement Rotary Vane
FIVE DAYS LATER. The Dash 037 arrives. This also shows why I needed to order it and couldn't just reuse the old O-ring. When I took it off, it cracked right in my fingers. I had the pleasure of making that call to the Little Woman five days prior, "Honey, we're down to one car... again." A dash 015 ring goes at the top just above the 037. You can see it sitting in it's groove.
With the rotor and vanes removed you and get at the valving body at the front of the pump. This is the back side (i.e. this side to the rear of the car). Be careful removing the rotor and vanes. The vanes aren't attached to the rotor and will just fall out. The gold/brass side of the vanes go out, by the way.
This is the front side of the valving body at the front of the pump(i.e. this side to the front of the car). Notice two o-rings in this photo.
Having learned my lesson about messing with old O-rings, I just measure this one with it in place. 56 mm O.D.
50 mm I.D. Dash 033. You might want to think about getting a Dash 136
one for this position instead. It's 0.8382 millimeters thicker than a Dash 033 but with the same inner diameter. I mention it because this o-ring looked and measured thicker than all the other o-rings in this pump. In some ways it looked like a square cut ring in which case it would be a Dash 136 Square Cross Section
. Good luck. PM me if you find out what it is, and I'll post it in this thread on the master o-ring list.