Hydrovac info.. ID, PNs and repair parts

[pfarber]

I am concentrating on the Second Series (that's what Bendix calls them) Hydrovacs. How to ID them, what ORD Pns can be cross referenced, and where you might get repair parts. I have one last complete Second Series repair kit to use as a reference. The First Series are a non-starter.. parts for them is gonna be truly hit or miss. Second Series 'vacs are at the edge... you might stumble across a repair kit, but more likely you will need to cobble one together from several kits used by other MVs (the T17, the HalfTrack, etc). Third Series kits are still available, and even professional rebuild services can get you a shiny rebuilt vac for less than a repair kit for a Second Series.

So off we go!

PART 1
Second Series Hydrovac Identification.

The old trusty SNL-G-508 and TM9-1827B are your friends. There are some specific Bendix pubs like 'Servicing the Bendix Hydrovac' I have posted, all in the technical pubs section (the Bendix book is not complete... I need to finish that off and the addendum that came with it). Generally go with the latest revision you can find. I have two versions of the Bendix pub, the second one is more informative and contains corrected information.

ID'ing a Second Series vac is pretty easy. Look at the ID tag attached to one of the J bolts. If you don't have one, fear not. The Second Series vacs on the CCKWs didn't change much.

The vacs numbers are: Bendix PN BX-373163 GM-2176571 (p384 SNL).

TM9-1827b decodes that even further:

Bendix Number	Ordnance Number	Model Number
373163	D-73288	H-35-25P-96

The model number, interestingly, breaks down as follows:
H denotes Hydrovac
-35 Slave Cylinder displacement in 1/10s of an inch
-25P Master cylinder line pressure required for valve run out at 16in of vacuum. P denotes that fluid for actuating the control valve is supplies through the internally drilled passage, and this passage contains no ball check valve, and that one master cylinder hydraulic line is required.
-96 When multiplies by 10 specifies the total line pressure at 16 in vacuum.

So, your CCKW with a Series II hydrovac is generating less than 1000psi (at 16 in vacuum) to stop your truck.

Next, the repair kit.