Proportioning Valve and Bleeding

[Raoul Ross]

Another issue on this 85 C10 Suburban cropped up while replacing the fuel pump (the original problem). While replacing the fuel pump the proportioning valve started weeping, all by itself. You know how it goes, bring a neglected vehicle in to work on one problem and another pops-up.

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Found a replacement valve (not easy anymore) but I have one question about bleeding the system after replacement... is there a tool to keep the internal valve from moving while bleeding or should I just use a pressure bleeder on the M/C and open the wheel bleeders? It's been a while since I've done one.

 

[jh86]

I used the tool that threads into switch location

 

[Raoul Ross]

I've kinda looked around for that tool but not finding it... what's it called? Gotta P/N or manufacturer?

 

[Ken B]

Proportioning valve bleeder tool. Amazon 7 bucks

 

[jh86]

This is the one I bought

https://a.co/d/8EupJ1X

 

[ali_c20]

You could gravity bleed the brakes. No pumping and tool required.

 

[Raoul Ross]

Ordered the 'Tool' at Amazon, Thanx guys!

I will try pressure bleeding first and then do the pedal pumping thing if I'm not satisfied.

 

[Toad455]

I just bought the same tool and a new PV_4 valve. I've never used this tool before so I'm interested how it works out for you, I still have to install new lines, master, etc on a new build so it'll be a while before I get to it.

 

[Raoul Ross]

Replaced that proportioning valve and bought a fancy vacuum bleeder, which worked quite well except for one thing. As it pulls the fluid from the wheel cyl/caliper, it also pulls air from around the bleeder threads so you never know if you've got all the air out. I just went by the color of the fluid as the original fluid looked exactly that, the original 1985 brake fluid!

I did buy a locking tool for the P-Valve. It was a pretty red anodized unit... I'm a sucker for anything anodized red, lol.

I still wasn't sure though if all the air was out so I resorted to doing the pedal-pumping method. Every bleeder had a small initial burp of air. It must get sucked in from the vacuum as I closed it off. Otherwise the vacuum bleeder werkt quite well! Not much room to swing a wrench though, took me an hour to get the old one out!

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[Goldie Driver]

Save your old valve. My PV2 lasted around 2 years and started leaking. I noticed no difference between the new and the old and the old one is back on the truck. With no leaks !

 

[hack_man]

Replaced that proportioning valve and bought a fancy vacuum bleeder, which worked quite well except for one thing. As it pulls the fluid from the wheel cyl/caliper, it also pulls air from around the bleeder threads so you never know if you've got all the air out.

One trick I've heard works to prevent sucking in air bubbles is to pack silicone grease around the bleeder.

I bought a spare PV from a dealer years ago "just to be sure" I had one for when mine gives up the ghost and they start making them out of unobtanium.

 

[Chris64]

Replaced that proportioning valve and bought a fancy vacuum bleeder, which worked quite well except for one thing. As it pulls the fluid from the wheel cyl/caliper, it also pulls air from around the bleeder threads so you never know if you've got all the air out...

I had this problem too, which sucked because my family seems to sense when I need a brake pumper and they disappear.

I ended up wrapping the thread with anti-seize which seemed to do the trick. Also because one of the bleeders was completely seized in the caliper. I still prefer the old pumping brakes though. It just always works.

 

[YakkoWarner]

I have never been able to successfully vacuum-bleed anything on any vehicle. Gravity bleeding has worked sometimes if you can get it started and orient the bleed valve straight up, but I almost always end up with the whole find-some-to-push-the-pedal routine which is never easy when you live alone. I have resorted to cutting a length of board to hold the pedal down while I went and closed the bleeder, remove board, open bleeder, press pedal, repeat on multiple occasions.

 

[Ricko1966]

I have never been able to successfully vacuum-bleed anything on any vehicle. Gravity bleeding has worked sometimes if you can get it started and orient the bleed valve straight up, but I almost always end up with the whole find-some-to-push-the-pedal routine which is never easy when you live alone. I have resorted to cutting a length of board to hold the pedal down while I went and closed the bleeder, remove board, open bleeder, press pedal, repeat on multiple occasions.

A little trick for you. Get a piece of vacuum hose that fits the bleeders and a small bolt that will fit the vacuum hose. Drill a hole in a peanut butter jar lid pour 1.5 inches of brake fluid in the jar. Put the bolt in the end of the vacuum hose and put a small slit in the hose just above the bolt. Put the bolt in the brake fluid route the hose through the hole in the lid. Wrap the outer 1/2 of the bleeders in Teflon tape, put them back in the wheel cylinders put the vacuum hose on right rear and open the bleeder. Step on the brake pedal,the pressure blows open the slit when you release the pedal the slit closes preventing air from coming back. The Teflon tape keeps fluid from leaking or air intruding at the bleeder,the 1.5 inches of brake fluid is a back up and helps seal the slit.