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View Full Version : 194 Hydroboost m(?) - No brakes


gngirl
10-19-2004, 12:48 PM
Found out around 8:30 PM last night that the brakes of the car are suddenly all the way to the floor. No brakes. The brakes worked fine when the car was driven last. No changes made or work done ion brakes or in this area of the car. The booth under the dash is moist.

:confused: Is this power steering fluid or brake fluid? (Can brake fluid leak past the boost system?)

Dealers (2) said they do not stock parts or rebuild kits and the master cylinder and rebuild kit are no longer available.

:confused: Does anyone know how to fix or get parts for this?
:confused: Does anyone know a cross reference to the rebuild kit?

Keller
10-19-2004, 02:27 PM
Articles about diagnostics and replacing with vacuum brakes are at http://www.gnttype.org/techarea/brakes/brakespage.html

You may also find info from the old mailing list archives at http://www.ajlc.waterloo.on.ca/gnsearch.html

Make sure you look at Hydroboost, and NOT Powermaster!

gngirl
10-19-2004, 02:39 PM
Keller,

Thanks for the reply. Just remember, if you ever get to Houston, we owe you a few drinks and dinner!

I did locate the information but there was no real specifics for me to understand. Anyway, we located some kits in Ohio and may pick up an extra one. If anyone needs a kit, let me kow and I will be happy to get you "hooked up". The kit is the hydro boost and master cylinder rebuild kit.

Anyone have a exploded view diagram?

gngirl
10-24-2004, 11:18 AM
Update.
Here are the findings for the 1984 Hydro-boost brake system and the associated corrective actions;

General findings
Brake fluid was brown and had “gunk” in it and was brown like used motor oil. YUK!
Brake fluid was replaced and all likes and brake cylinders cleaned. Used a small hand vacuum ($20) at the store to “suck it out” at the master cylinder and out of the lines after disconnecting the lines. The driver side rear cylinder did not “suck” (15 in vacuum) and used compressed CO2 from a cartridge to “blow it clean” (placed the CO2 unit at the bleeder valve). After that, the fluid did move with suction at the master cylinder connection line.

Master cylinder
The rebuild kit is almost impossible to find but after 2 days we located one.
The rubber cup for the front brakes had a piece missing out of it.
Dealers (3), nor auto parts chain stores (3) could locate a master cylinder.
The cylinder was slightly pitted and was honed. It seems like there was water in the system as pitting was at the bottom of the cylinder (4 spots)

Hydro boost unit
PITA to get out, but got it out. (Stretch before you get in there and watch your back!)
The back of the unit (entering the firewall) was wet with some of the power steering fluid and the unit had to be assessed. No one knows of any rebuild kit made for this unit. (Read on and you will understand why)
The unit was 2 seals: Input piston (connected to the pedal) bore seal and a special “formed O-ring” where the housing splits.
This unit is NOT serviceable by the user (Wish I had better news) The connecting rod from the unit to the brake pedal is swaged onto the input piston (1/2 inch diameter) that goes inside the unit. You can not get the input piston out of the housing (either side), so the seal that prevents leakage into your car can NOT be replaced! You would need to stretch this seal at least one inch to get it over the swaged end and onto the groove in the shaft). You may be able to get the swaged end off but you will need a machinist.

The 2 other pistons inside the unit are VERY close tolerance to the housing bore. We just cleaned the seal on the input shaft and hoped for the best. (You can buy a replacement unit for $500 at the dealer)

All the fluid in the power steering unit was “sucked out” and replaced.

Putting it all back together.
After re-installation of the hydro boost and master cylinder, a hand held vacuum pump was used to “suck fluid to the brake cylinders and fill the lines back up”. Remember to start with the farthest ones first (front and back). The fluid was “sucked until “clean fluid” came out of the bleeder valves. There was some old fluid residue in the brake cylinders (As expected). If you decide to go this route, be sure to check the master fluid cylinder level frequently!

The brakes were then “bled” as you would normally. (You can do this without taking any of the wheels off, but need to turn the steering wheel either left or right to get to the bleeders in the front.

Started the car back up and brake light went off after 30 seconds. (not sure where the brake pressure switch is located)

The car has brakes! Good thing to have if you plan or doing any driving!