Anyone familiar with this valve leaking from the top, underneath the line fitting? The valve itself leaking not the brake line fitting.

My 95 940 is doing the same thing. Leaks pretty bad. I have to constantly have a large bottle of brake fluid with me. After cleaning up all part of that valve I have another person step on the brake as I watch. It's seeping out pretty fast from under the large nut which threaded on the top port of the valve. In the middle of the nut, it has a maybe quarter inch threaded hole that the break line connect to. Tried to tighten it but it's already very tight. If I take it apart and work on the bench I'm sure I'll see why it's leaking. However I don't have that kind of time to refill and bleed the entire system. Want to learn more about it and maybe fix it later this year. Thx. Erwin

Was able to loosen the big nut by clamping a large grip wise on the body of the valve. Tighten and loosening for a few times in hope that it will make a better searing surface between the parts and stop the leak. However it did not work. Still leaking. Guess just have to do it the hard way. Taking it apart.

Hi Eyyu,

I haven't tried to dismantle it yet coz I know I'll be needing lots of brake fluid (even just to diagnose what's wrong). Myself not prepared to any messy wet work yet.

My last wet work was months ago when replacing the master cylinder. An easy job it seemed until I tried to align and tighten the old brake pipes nuts into the new MC. Lots of leaked brake fluid around my gloved hands until I can't get any grip - it was so slippery!

The way I look at this valve issue it seems to need new white sealing washer for the big nut and brake fluid friendly O rings. I have limited experience regarding meddling with these proportioning valves.

Looks like re-tightening the big nut doesn't work. I think the nut may be at the end of its travel/thread. Also there seems to be very limited choices on the net/eBay regarding rebuilding these. Replacing them seems to be the only thing.

Regards,
Amarin.

Dear eyyu,

Hope you're well. Before removing the brake proportioning valve from the car - a lot of work - you might do the following: (a) loosen the hex-fitting cap; (b) use brake cleaner to remove oily residues, where the brake line meets the proportioning valve housing; (c) without separating the brake line from the valve housing, put a narrow bead of plumber's pipe joint compound around the "seam", i.e., where the brake line meets the valve housing (d) tighten the hex-fitting cap. If possible, let the car sit for a day.

In the US, plumber's pipe joint compound comes in two forms: (a) white [teflon-loaded] and is best for water pipes; and (b) gray [non-teflon], which must be used on natural gas pipes, but can be used on water/steam pipes.

Plumbers use pipe joint compound to seal threaded pipe connections. Pipe joint compound stands up to pressure - up to several hundred pounds/square inch) - found in pumped water and pressurized steam heating systems. While these pressures likely are lower than those found in auto brake systems, pipe joint compound could seal the leak.

Pipe joint compound is chemically inert and does not cause corrosion. It does not harden unless exposed to air.

If pipe joint compound doesn't seal the leak, it can be removed simply by using a cloth wet with brake cleaner or similar solvent. That is, use of pipe joint compound - without separating the brake line from the valve body - does not risk contaminating the brake fluid.

Hope this helps.

Yours faithfully,

Spook

Spook, Thx for the tip. I'll definite try it. I does scares me to think about taking it off the care, don't have that kind of time now. If that doesn't work, the next thing I'll do is to just take off that large hex cap (not to remove the valve from the car), clean it and put it back with the joint compound you mentioned. I'm sure that will seal it. That way all I need to do is to prime one set of wheel and be done. Erwin

Yes.

My 940 1994 model seems to be leaking from there too. Can't see any real brake fluid only that place is full of yellowish crud. Cleaned them and they formed again slowly months later. This been going on for many years but no effect on braking force. Reservoir fluid level seems intact. So I just left it alone.

Plan to replace it when I could get to a Volvo parts shop. Too expensive for mail order with ongoing customs tax.

If you plan to replace it be mindful there are two versions - for sedan or wagon. This is a brake pressure limiting valve to prevent the rear wheels lock in case of strong braking. So different pressure limits for sedan or wagon.

Regards,
Amarin.

Subscribe