Brakes: Hydrovac In-Line, Vacuum Check Valve

[JoeHall]

I understand hydrovacs originally had an inline, vacuum check valve, to prevent damage to it if the motor were to backfire. I also understand those valves are now made of unobtanium. Soo I am guessing most folks are substituting the OEM valve with something else. Can anyone recommend another check valve that will fit easily?

I do not intend to re-install the unit I just sent off for rebuild, with a check valve in place.
Thanks

[studebaker-R2-4-me]

The check valve dilemma is the reason I went with the new Hydrovac from SI, it has the check valve built in. I could not see spending money on a rebuilt only to blow another one without the valve. Good luck finding one, I was told by Dave T-Bow and other vendors they have not heard/seen one in years. If you do find a source let us know because the hydrovac I have can then be rebuilt for future use.

Allen

[JoeHall]

I just ordered one off ebay for $10.95, with free shipping. It is OEM for General Motors (GM #20861501), and still in the original package so I know it is GM quality. It is a plastic, in-line type that can be put anywhere in the line between the hydrovac and the manifold nipple. It ain't "correct" for Stude, but if its good enough for GM its good enough for me !

Will let y'all know how it works, but I cannot imagine it would not, since the principle of operation ain't rocket science

[SN-60]

I just ordered one off ebay for $10.95, with free shipping. It is OEM for General Motors (GM #20861501), and still in the original package so I know it is GM quality. It is a plastic, in-line type that can be put anywhere in the line between the hydrovac and the manifold nipple. It ain't "correct" for Stude, but if its good enough for GM its good enough for me !

Will let y'all know how it works, but I cannot imagine it would not, since the principle of operation ain't rocket science

Yes, the GM valve works just fine....it performs the same function.

[PackardV8]

That's the one I used on my '55 E12 Stude pickup. I did install it down under where it isn't visible.

jack vines

[JoeHall]

That's the one I used on my '55 E12 Stude pickup. I did install it down under where it isn't visible.

jack vines

I plan to locate the valve as close to the hydrovac as possible, and use PCV hose. This is to keep the residual vacuum from collapsing the hose, between the valve and hydrovac, over time.

[studebaker-R2-4-me]

Good to know. thanks for listing to part number


Alllen

[Poppicat]

So do you just leave the OEM bad check valve in the Hydrovac and then splice in the GM plastic one into the hose? My Hydrovac wasn't working(no vacuum), pedal hard , so I took off the check valve and tried to take it apart, no luck, fittings frozen. I squirted some WD-40 on it and then just screwed it back in to the unit. Bad move. Now the brakes don't release unless I release the pressure from the bleeder screw at the hydraulic end of the Hydrovac. Also, when I took off the check valve a little bit of fluid poured out. The unit is shot I'm sure. I'm just trying to figure out how I can keep the brakes from locking up until I can get the unit rebuilt. Any info greatly appreciated. The car is a '56 Golden Hawk. Nick

[studebaker-R2-4-me]

If you have brake fluid in check valve and the vacuum hose,... the hydrovac is shot. There should be no fluid in that region at all.


Allen

[dpson]

I found three NOS check valves in my inventory, the one on the left is part number 1544413, center is 536985 and right is 433715 (which may be a Bendix or Packard number). In checking the parts book it appears the 536985 can be taken apart (snap ring) and the internal parts cleaned or replaced. Anyway I pass this along if anyone is interested.

[PackardV8]

The one on the left I've seen on several Packard V8s.

The thing I like about the new GM is it uses a larger diameter hose. When the booster is quite a distance from the intake manifold, as on a truck under the floor, a large diameter hose makes it work better.

jack vines