Master Cylinder pump question ...

'90 SC - does anyone know the correct position of the o-ring in relation to the master pump filter? (I couldn't tell it's original position because the o-ring became loose at a 45 degree angle in the pump housing when I pulled the filter out using needle nose.)

There's a groove in the filter, but the o-ring is about 1/8 inch larger in circumference than the groove. It seems that the o-ring fits correctly if placed into the pump housing first, and then sliding in the filter.

I've been wondering if the placement of that o-ring makes any difference in the pump working correctly.

Eddie
'90 5-speed SC modified
'90 automatic SC stock

Ha! I remember doing the same thing when I rebuilt the motor on my unit. Would you believe I don't remember how I fixed it?

From what I can remember, I think the o-ring does go in the groove. It may just be a bit stretched from age. If you can't get it to fit as is, you could replace it. But remember that to hold up to brake fluid, it must be EPDM rubber and not nitrile (NBR, SBR) or Viton.

I think the only purpose of the o-ring is to prevent fluid (and grit) from bypassing the filter screen.

In the groove ...

From what I can remember, I think the o-ring does go in the groove. It may just be a bit stretched from age. If you can't get it to fit as is, you could replace it. But remember that to hold up to brake fluid, it must be EPDM rubber and not nitrile (NBR, SBR) or Viton.

I think the only purpose of the o-ring is to prevent fluid (and grit) from bypassing the filter screen.[/QUOTE]

Thank you. You're correct. That o-ring does go into the groove on the filter/screen. I have two of them from a couple pumps. Both O-rings are bigger than the filter/screen groove. If I use tham again, I'll find replacements that will hold up to brake fluid.

Eddie
'90 5-speed SC modified
'90 automatic SC stock

Hey when you put the unit back in did you have any problems pumping up the ball? I recently had mine apart and drained of fluid and when I put it back in the pump runs but doesn't provide any pressure for the rears nor does the level drop. I don't know if there is a special bleed procedure but I have let the motor run for 15 minutes several times and nothing.

John