Packard Forum Index » V-8 (1955-56)

It sure is good to have someone finally dive in and explore the failure and share their findings with us.

The relief port shown in the DSC08042 image, above, sure doesn't look like what came out of any of the Treadle Vac units that I've ever had apart. Keith's description sounds more like it.

Yet, the replacement valve that came in the kits, back then, appeared of identical design to the original part. Perhaps that's why I never experienced a failure in any of the four running packards that have been in my family.

I've always been more concerned wirh the compensator port valve spring, but with all the talk lately of failures involvng recently rebuilt units, it's starting to sound like a problem with the rebuilder's replacement parts. Glad I rebuilt my own units when I did.

Also the cover hasket in the kits I've used was composition cork, not black paper.

If anyone has purchased a new BTV rebuild kit elsewhere, lately, it would be helpful to have a pic of the contents.

Quote:

Rowdy, your very welcome, anything I can do to help.

And all this talk of "problems with re-builders replacement parts" well, that may very well be true. I'm wondering if the o-ring seal isn't a good enough material to withstand the heat from the exhaust, causing it to swell unevenly and not seal properly.

Relief port may be a misnomer but I both agree and disagree as to the function.

Agree there may be some "spill off" to lube the back of seal, although from the looks of that gasket and reservoir, minimal to none. However, I think there is much more function to the port than that. If the primary seal were leaking under the pressure of the brake application, that passage would give the fluid a place to travel back to the reservoir or somewhere rather than all being forced into the vacuum side through the vacuum side seal. IIRC, the vacuum side is leather and not much use in stopping fluid pressure of 800-1000psi.

Conversely, if the vacuum side is leaking, while some fluid will be drawn thru if there is a leak, the open vent to atmosphere (unless the remote fill reservoir was in use) will let it draw far more air than fluid unless or until the leak is so bad from the primary the whole seal is submerged. If there is no primary side leak other than the minuscule amount of plunger wipe off, then air would be drawn rather than fluid. If, as been noted, that gasket is essentially closing the port, that might explain why so much fluid is being drawn in on the units Keith has seen.

I'd be curious as to any opening in the cover with that arrangement--or if there is an optical delusion in the photo as to height of the port at some point. With that gasket, doubt it but if you look at the illustration, you see the port is open to the fluid chamber and appears lower. Is there any kind of relief channel? This gasket from a NOS Packard kit 436318 for 52-4 version doesn't even have the hole which means the port would be as the illustration-lower than mounting flange.

There is a different kit for 55-6 so wonder what other changes besides vacuum side valves and response were made in the versions Packard used .

Attach file:

---

  (24.81 KB)

Quote:

And that makes me wonder if there isn't a "generic" kit made today that's supposed to cover all makes and models, but actually shouldn't.

Pics later on:

I laid a streight edge across the top of a 56 Exec. BTV master cylinder reservoir in line with the relief port. the area around the relief port is all in the same plane with the the sealing surface of the top of the reservoir.

The reservoir LID is as smooth as a 20's something girls ass and flat.

So, the gasket as shown in the kit would seal off the relief port.

THis may be where part of the BTV failure is occuring. No fluid can get to the seal to keep it lubed and the seal is wearing or gaulding or distorting.

But the gasket shown in Kevin's photo HAS the hole:




Therefore, the '55-'56 kits currently available are correct as far as the gasket goes.

Yes, the gasket has the HOLE but the gasket material completely surrounds the hole just like it completely surrounds the holes of the attaching screws that hold the lid on.

So you're thinking that the correct gasket wouldn't have a hole in that spot therefore not covering the hole, correct?

Kevin AZ. Check the relief port to see if there is somekind of wick in the relief port. I really doubt that there is nor should be.