Brake system air induction; was: Odd HydroBoost (?) Problem

[ntsqd]

It really helps to have like minded folks to bounce ideas off of! Thank you all!

 

[ntsqd]

UPDATE.

Gravity bleed at 335 miles this evening yielded a 40 count with no bubbles. Then I got some, but I was manipulating the bleed screw so it could have come thru the threads. The pedal hasn't changed since the previous bleeding, which is a change as in previous cycles it would have lost the rears ~50-75 miles ago. Drove it after the bleeding this evening and the pedal is still the same, supports my thinking that those bubbles were due to wiggling the bleed screw.

Going to push it on out to 500 miles and the try bleeding it again. Feels like I've turned a corner on this.

 

[ksagis]

UPDATE.

Gravity bleed at 335 miles this evening yielded a 40 count with no bubbles. Then I got some, but I was manipulating the bleed screw so it could have come thru the threads. The pedal hasn't changed since the previous bleeding, which is a change as in previous cycles it would have lost the rears ~50-75 miles ago. Drove it after the bleeding this evening and the pedal is still the same, supports my thinking that those bubbles were due to wiggling the bleed screw.

Going to push it on out to 500 miles and the try bleeding it again. Feels like I've turned a corner on this.

I be shocked if it’s not fixed and I reco doing a victory dance and enjoying a beverage of choice. Nice work!

 

[ntsqd]

I've thought that I had it before, so I'm going to make it prove itself for longer before the victory dance.

I was asked back-channel "why not just use a m/c that doesn't have that thing on the side of it?" and the reason is that this is the OEM application m/c,, not something odd from some other vehicle that I won't remember in 3-5 years. FWIW one of my co-workers has a '67 F-250 cab on an '89 F-350 chassis. He transplanted all of the operating parts from the '89 onto the '67 cab. The whole m/c-booster assembly is the '89 application. I noticed when he was showing off the partially completed MicroSquirt based EFI conversion on the 300-6 (TFI dist. run bby the MS) that the '89's m/c was cast iron, but had this same RPV assembly screwed into the side of it. I can not recall having ever noticed this before.

The Valiant was a "Bitsa". Parts were a bit of this and a bit of that. It gets old when you need a part that you've already had to figure out what works, only now you can't recall what it's OE application was. I ended up starting a binder on the car to document what each part was.

 

[Yeller]

All of mine have one of those binders….. the j truck actually has the least but have had to figure out what they used since many parts listings do not list it, but a ford, Chevy or dodge used the same part. Hopefully you have this licked, fighting brake problems sucks.

 

[Wild horse 75]

UPDATE.

Gravity bleed at 335 miles this evening yielded a 40 count with no bubbles. Then I got some, but I was manipulating the bleed screw so it could have come thru the threads. The pedal hasn't changed since the previous bleeding, which is a change as in previous cycles it would have lost the rears ~50-75 miles ago. Drove it after the bleeding this evening and the pedal is still the same, supports my thinking that those bubbles were due to wiggling the bleed screw.

Going to push it on out to 500 miles and the try bleeding it again. Feels like I've turned a corner on this.

I would guess the bubbles were induced by you at the bleeder screw. 40 pumps is a lot of fluid moved. I think you nailed it.

 

[ntsqd]

No, no, not 40 pumps. 40 count, as-in "one thousand one, one thousand two.... " I was gravity bleeding it and wanted some idea of how long I left it cracked open. That the bubbles didn't appear until shortly after moving the bleeder, and that the pedal is good and hasn't changed makes me think it those bubbles came thru the bleed screw threads too.

 

[Wild horse 75]

No, no, not 40 pumps. 40 count, as-in "one thousand one, one thousand two.... " I was gravity bleeding it and wanted some idea of how long I left it cracked open. That the bubbles didn't appear until shortly after moving the bleeder, and that the pedal is good and hasn't changed makes me think it those bubbles came thru the bleed screw threads too.

Ahh gotcha. I still agree though that you probably induced the bubbles at the bleeder.

 

[nvrstuk]

Definitely doesn't matter if the parts are mismatched ... at all. We all do & know it . We all keep a book, some have books with more pages than others but if you haven't written the book and made 2 copies then we are inviting trouble somewhere down the road.

Put the best ingredients in the pizza.

Thanks for the reminder TS, I need to add another couple chapters... I am way behind

 

[ntsqd]

The book for the dune buggy was a 5 topic spiral bound binder. That was the method that we used for the vintage race cars at VRS.

The book for the Valiant was an Excel spreadsheet. Tabs for each system, way easier. New owner wasn't sure what to make of that, but hopefully it will save him some grief at some point.

I should probably start such a file on Snowball.

 

[nvrstuk]

I'm sure with your background you've written a LOT of books! I always marvel about how varied the careers and backgrounds are of so many here.

I think I just re-write the same book over and over and never finish it!! I'm one of THOSE authors! LOL

Keep the chapters coming...

 

[73azbronco]

Feels to me its likely you have a very small leak someplace that is letting air in and are maybe overlooking a tiny fluid leak. Have you tried wiping all fittings really well and then put witness paper around every fitting? Then stomped on the brakes for a while and checked the witness paper?

For witness paper, I just use scott towel wrapped around the fitting with some painters tape. The tiniest amount of fluid is pretty obvious on paper.

One more, any residual pressure valves left in system? Seems unlikely to cause an issue like that tho.

I would pump up the brakes, then wedge a stick of wood to keep pressure on brakes for a day or two see if the there is leak someplace. Usually any small leak shows itself quickly.

 

[ntsqd]

That is a an idea that I will remember for the next time I encounter something like this, thanks!
A small leak was found. post #44. My proposed remedy is in post #58. So far it appears to be working. Currently has about 350 miles on it when previously the pedal had gone away by 275, max. Going to re-check it at 500, but as the pedal is still good I'm expecting it to be clear of bubbles then.

Hydraulics under pressure will leak down internally over enough time, even if it doesn't have an external leak. I wouldn't expect it to hold even overnight. It's because of this that I've long discouraged the use of hydraulic parking brakes. They're useful for holding position to get out to check something (where a rock is with no spotter, etc.), but they can't be trusted to hold for any longer period of time.

 

[ntsqd]

~640 miles, pedal is still as when it was first bled. I won't be able to do a gravity bleed check until the weekend, but I think this one is solved!

 

[ksagis]

~640 miles, pedal is still as when it was first bled. I won't be able to do a gravity bleed check until the weekend, but I think this one is solved!

Now the victory dance?

 

[ntsqd]

Are y'all starting to understand why I call it "Snowball"?
LOL......

On to finishing the OBA system. Then fixing the back window's electrical. That's going to be fun, my hands don't fit in the tailgate.