Changed my master cylinder, and now...

[Piecutter]

Started having issues not long ago, while holding a stop I would notice slow brake pedal fade. I looked all over for apparent leakage and couldn't find any. So I figured it was bleeding past the master cylinder into the brake booster. I had a NIB one (master cyl.) lying around and slapped it on. Didn't bench bleed it or anything just swapped em out and filled 'er up and started pumping. Well I never got a pedal back at all. Can't really bleed it for the complete lack of pedal. Also there is now a constant hissing when I hold the pedal all the way to the floor... Has my brake booster taken a sh!t on me too? Or (I hope this is the case) did I approach a two-banana job with a one banana mentality and do something wrong?

Vehicle in question is a '75 FJ40

 

[HawkDriver]

Well the first thing you did wrong was not bench bleed it. Why didn't you, where did you think all that air was going to go? Now it's in the 20 ft of line that you get to bleed out.

I'd suggest that you either remove the lines and 'bench bleed' it on the truck with the hose bleeder fittings, or remove the unit and submerge it and fully bench bleed it. If it checks out then move on to the booster.

My .02.

Good luck man, post up your results, and welcome to the board!

 

[Pin_Head]

Try bleeding it with 2 persons so you aren't sucking back air when you let up on the pedal. We never bench bled any of the several hundred we replaced and the Toyota manual doesn't mention it. If the booster hisses with the pedal up, then that is not good.

 

[65swb45]

Russell makes a one man speed bleeder that has a small checkball built into the bleeder. All you have to do is run a hose into a bucket or bottle, crack the speedbleeder open, and pump away!

http://www.russellperformance.com/auto/brake/sb-toyota.shtml

Best

Mark

 

[Cruiserdrew]

The hissing sound is bad, since it implies a vacuum leak. It should not do that. The factory function tests of the booster are in the manual. I agree you should bleed it properly and get a firm pedal, and then investigate the booster.

 

[Mace]

When you pump the brakes does the motor stumble?

 

[yosemitesamtlc73]

had the same problem delt with it for years 2 new masters all new wheel cylenders and all that good stuff. what finaly solved it was a used booster I got one out of I belive it was a 92 pickup 4x4 well atleast it was a smashed truck that was bought for parts for a 92 anyhow the boster and master off of it was a direct bolt in to my 73 fj40 and now it stops on a dime.

 

[Piecutter]

Took a gallon of brake fluid and a big bleeding session. Got it thanks all.

 

[HawkDriver]

Glad to hear.

 

[projektdotnet]

congrats!

 

[74fj40]

It looks like we may need a new booster - get the whooshing sound when depressed. Have pedal when the car is bled and un-started, then when we start the car, lose most of the pedal and pumping doesn't help.

Is it true that a booster/mc from a later toy truck will bolt right on?
Thanks, Max

had the same problem delt with it for years 2 new masters all new wheel cylenders and all that good stuff. what finaly solved it was a used booster I got one out of I belive it was a 92 pickup 4x4 well atleast it was a smashed truck that was bought for parts for a 92 anyhow the boster and master off of it was a direct bolt in to my 73 fj40 and now it stops on a dime.

 

[yosemitesamtlc73]

yes for me it was a direct bolt in I took the master and booster out of my brothers rold 89-90 toy truck. It bolted right in to my 9/73 landcruiser lines, pedal, and vac all where in the right place even matched the 4 bolt holes in the firewall.