Packard Forum Index » V-8 (1955-56)

Hey guys,

Sorry that I haven't posted anything since my first question, but that's what happens when work life gets in the way of Packard life. I took advantage of last weeks warm weather to get the Clipper pushed out and took a look at the reservoir, which was completely dry. I assume then that the fluid has been sucked into the vacuum chamber. I filled it back up and checked for leaks in the lines, but didn't find any. So, it must be the compensator valve. Well atleast I have a starting point for this spring. Will keep everyone posted on anything new, and will try to get some more pics taken and posted.

I never bought into the notion that the TreadleVac hydraulic section can get sucked completely dry by engine vacuum.

Unlike more modern systems, the old master cylinders (and not just the TreadleVac) were not completely sealed to atmosphere. Left unused and unmaintained, DOT3 brake fluid will condense to a thick sludge over a long period of time; eventually, you end up with a crusty wax-like substance. The solvent base of the fluid simply evaporated.

It would take a failure of multiple seals for hydraulic fluid to leak out of the hydraulic chamber and into the vacuum shell, but even then, very little would get sucked into the engine. You'd have some warning of that through pedal feel.

If you've topped the system off, bled the brakes and have a nice firm pedal, you probably don't have a leak.

However, if you've simply refilled the master cylinder (no matter who made it) on an ancient garage/barn-find, seals could fail in short order. For vheciles like that, I recommned a complete overhaul of the brake system with new seals and hoses, flushing any steel lines that do not need to be replaced, and refilling with DOT5. You won't have the problem of evaporation with DOT5.

Well finally got a short break in the weather and got my Clipper to the guy that is going to do the engine and T/V overhaul. l got a good look at each of the brake drums. The shoes are in good shape as are the springs and retaining clips. All the brake lines and hoses are new. However he did find rust on the inside of the wheel cylinders. So it looks like my non-stopping experience may not have been the first one. The T/V unit looks like its never been touched. So hopefully a complete rebuild will get me back on the road and driving safely for many more years.

If you rebuild your own TreadleVac which I don't recommend unless you're very familiar with that unit, you can use any brake fluid you want, but note that two of the premier rebuilders of these units void their warranty if you use DOT 5. Or at least that was their position a year or two ago. I've used DOT 5 in earlier Packards with excellent results, but in the many cars, Packards, Mercurys, Lincolns and some GM cars, that I've serviced with TreadleVacs I've always used DOT 3 or DOT 4 and have never had a problem with any of them. That said, I do purge the old fluid and refill every 2 or 3 years.

I don't recall reading that Strain voids the warranty. Is he one of the rebuilders you are referring to? (terrible grammar, I know).

Has anyone ever thot to ask the rebuilders WHAT their reasonong is for voiding the warranty with DOT 5???