John wrote:
> ......I observed that when, and only when, you apply the brakes then
> release them, for the next 5 to 10
>seconds you see drips of PS oil comming from the joint between the master
>cylinder and the booster. Obvious first guess is that the seal (assuming
>there must be one of some kind) in the booster is leaking, when you apply
>the brakes the fluid comes out and fills the space between, then when you
>release, the master plunger wants to come back but you've got oil in there
>so it is forced to drip out the gasketless joint.........
The problem is most likely the seal on the rod and piston unit inside
the booster. You must split the unit apart to replace this seal.
>.....So I got out my civy GM unit repair book for my suburban which has
>the same
>booster (by eye anyway)........
A word of caution here......There are two types of brake booster units
used on the CUCV series of trucks. The 3/4 ton M-1009 (Blazer) uses a
different booster than the rest of the CUCV series. The units look the
same but the M-1009 booster has a reaction piston bore diameter of 0.600
with no chamfer or a 40-50 degree chamfer at the opening while the rest of
the series have a 0.688 bore with a 20-30 degree chamfer. Boosters for the
3/4 ton M-1009 have a label on the power booster bracket marked "FY" while
the ones used on the 1 1/2 ton CUCV have the letters "CM" on the bracket.
The M-1009 also uses a different pedal rod than the rest of the series.
> ....I would wonder if I could just by a civy rebuild kit and split the
> housing and only deal
>with the plunger seal leaving everything else in place such as the spool
>valve and accumulator and such, thus only replacing the seal and the main
>housing gasket.......
A check in the -34 parts book for the CUCV should give the GM part
number for the seal or the rebuild kit. It is possible just to replace the
seal and gasket without the need to disassemble the spool valve and
accumulator.
TM-9-2320-289-34 gives the rebuilding procedure for the booster.
Jim
NOTE NEW ADDRESS----NOTE NEW ADDRESS---NOTE NEW ADDRESS------AS OF
JANUARY 4, 2001---------
Jim Gilmore
13 Broadway 3rd floor
Jim Thorpe, PA. 18229
570-325-5216 phone
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