'96 LX450 Brake Issue (1 Viewer)

[goingcamping]

My kid and I went the gym this morning, as we do M-F. Had some light snow last night and the weather was approx. 20F. As we were heading down a hill, the lights at the bottom turned red. My son went to stop and the brake pedal almost went to the floor and it did not stop. I drove it home after the gym and it's almost like it's lost it's boost? The brakes, when fully applied are kinda working; however, if i pushed to the max, it seems the ABS was coming one?

Hx: We replaced all 4 rotors/pads/calipers/fluid about 2,500 miles ago. Followed the FSM for bleeding and was actually surprised the brakes seemed to work well.

Where should I start trouble shooing, Booster? Vacuum lines? Accumulator? ABS?

Thanks in Advance!!
Brett

 

[BILT4ME]

My kid and I went the gym this morning, as we do M-F. Had some light snow last night and the weather was approx. 20F. As we were heading down a hill, the lights at the bottom turned red. My son went to stop and the brake pedal almost went to the floor and it did not stop. I drove it home after the gym and it's almost like it's lost it's boost? The brakes, when fully applied are kinda working; however, if i pushed to the max, it seems the ABS was coming one?

Hx: We replaced all 4 rotors/pads/calipers/fluid about 2,500 miles ago. Followed the FSM for bleeding and was actually surprised the brakes seemed to work well.

Where should I start trouble shooing, Booster? Vacuum lines? Accumulator? ABS?

Thanks in Advance!!
Brett

Was there actually snow on the roadway when you experienced this? Snow will activate ABS when it's completely unnecessary, and it will feel like you have NO brakes.

That said, how are the brakes working WITHOUT the snow influence?

If the pedal is suddenly soft, then it's typically a master cylinder. If the pedal is suddenly hard, it's booster. Yes, either can go out in an instant.

Read the troubleshooting on this in the FSM. It goes through a very detailed process to determine. I've been doing this stuff for a LONG time, and I still went back and followed their step-by-step instructions, just to confirm.

 

[goingcamping]

Was there actually snow on the roadway when you experienced this? Snow will activate ABS when it's completely unnecessary, and it will feel like you have NO brakes.

That said, how are the brakes working WITHOUT the snow influence?

If the pedal is suddenly soft, then it's typically a master cylinder. If the pedal is suddenly hard, it's booster. Yes, either can go out in an instant.

Read the troubleshooting on this in the FSM. It goes through a very detailed process to determine. I've been doing this stuff for a LONG time, and I still went back and followed their step-by-step instructions, just to confirm.

Thanks for responding. I have not gone to the FSM yet, as it's just happened this morning and now I'm at work. As far as snow goes, the roadway was dry, relatively speaking.

 

[BILT4ME]

Thanks for responding. I have not gone to the FSM yet, as it's just happened this morning and now I'm at work. As far as snow goes, the roadway was dry, relatively speaking.

If the roadway was relatively dry (no even covering of snow) then I would lean towards a failing master cylinder.

Not uncommon that a MC will fail "shortly" after a major brake overhaul, particularly if the calipers are pushed back WITHOUT opening the bleeder screw and flushing the old fluid out, rather than pushing it back to the MC. The contaminated fluid pushes into the MC and the grit in it eats the well worn seals quickly and a failure ensues.

 

[goingcamping]

If the roadway was relatively dry (no even covering of snow) then I would lean towards a failing master cylinder.

Not uncommon that a MC will fail "shortly" after a major brake overhaul, particularly if the calipers are pushed back WITHOUT opening the bleeder screw and flushing the old fluid out, rather than pushing it back to the MC. The contaminated fluid pushes into the MC and the grit in it eats the well worn seals quickly and a failure ensues.

I tend to not squeeze on pads with ABS when replacing brakes. In this case I replaced calipers and pads, so there was no reverse pressure needed, just bleeding. I'll take a look and order and master cylinder.

 

[manofthewoods]

My kid and I went the gym this morning, as we do M-F. Had some light snow last night and the weather was approx. 20F. As we were heading down a hill, the lights at the bottom turned red. My son went to stop and the brake pedal almost went to the floor and it did not stop. I drove it home after the gym and it's almost like it's lost it's boost? The brakes, when fully applied are kinda working; however, if i pushed to the max, it seems the ABS was coming one?

Hx: We replaced all 4 rotors/pads/calipers/fluid about 2,500 miles ago. Followed the FSM for bleeding and was actually surprised the brakes seemed to work well.

Where should I start trouble shooing, Booster? Vacuum lines? Accumulator? ABS?

Thanks in Advance!!
Brett

Like post(s) above, the booster will give a rock hard pedal that makes stopping "challenging." MC is my guess, easy to attribute to a 26 year old beast.
As a sidebar, my ABS has saved my butt on ice/hardback more times than I care to remember!
Let us know what you find out

 

[goingcamping]

Like post(s) above, the booster will give a rock hard pedal that makes stopping "challenging." MC is my guess, easy to attribute to a 26 year old beast.
As a sidebar, my ABS has saved my butt on ice/hardback more times than I care to remember!
Let us know what you find out

Will do! Ordered MC and will get it installed tonight/tomorrow.

 

[goingcamping]

Occam's razor...

Bought a new MC, when I went to replace the old one, I noticed the reservoir was well below the 'MIN' line...went looking and could not find any obvious spot where there was a leak.

Proceeded to bench bleed the new MC and then replace the factory Aisin MC, went underneath with brake bleeding 'kit' and made connection and had son pump the brakes...took about 10 pumps and I started hearing fluid, looked around and a line next to the fuel tank was corroded through. Stopped, park his LX back in the street and said "we'll tackle a new brake line tomorrow". Side Note: it's like 28F out and wet from snow halfway in the garage as his lift/tires/rack only allows his LX to make it about 6' into the garage...in my wife's Tahoe's parking spot. Which she ran errands all day and the garage is saturated with slush/water/mag-chloride. The other side is full of my RZR, kid's MX and various MTB...

Often times the simple solution is correct solution.

Thanks for all the input and help guys! It's great to have a source for such good info, and most days you're correct provided the OP's (myself) include all the parameters and in this case two more pieces of info would've probably gotten this solved simpler, either way I am thankful!

Cheers and Happy and Prosperous 2023!

 

[DSRTRDR]

squishy brakes: fluid leak

hard-as-rock brakes: booster

recent personal experience of the latter posted here: '93 80 vs. '97 LX - https://forum.ih8mud.com/threads/93-80-vs-97-lx.756967/page-11#post-14623876

 

[inkpot]

Is it doing the same thing everything you stop?

 

[goingcamping]

Is it doing the same thing everything you stop?

It was...found the leak. about 2' ahead of the LSPV. Ended up cutting the line back to a clean place, used a new 30" 3/16 10mmx1.0 J line, a inline double flaring tool, a new 10x1.0 double-flare fitting and a FxF double-flare coupling and now have excellent brakes...better then my 2022 F250. Of course bleeding took a moment as the LSPV was full of foamy bubbles. I should say, I couldn't bleed all the bubbles (air) out of the LSPV without bending the rod to a more level position (we have a 50mm lift and believe that's what made bleeding the brakes a PIA).

When it's warm and the underside is free of snow/slush I will more than likely do a 100% brake line replacement. I won't use factory (even if available) I will buy bulk line and bulk fittings and go to work...possibly deleting the LSPV.

 

[BILT4ME]

It was...found the leak. about 2' ahead of the LSPV. Ended up cutting the line back to a clean place, used a new 30" 3/16 10mmx1.0 J line, a inline double flaring tool, a new 10x1.0 double-flare fitting and a FxF double-flare coupling and now have excellent brakes...better then my 2022 F250. Of course bleeding took a moment as the LSPV was full of foamy bubbles. I should say, I couldn't bleed all the bubbles (air) out of the LSPV without bending the rod to a more level position (we have a 50mm lift and believe that's what made bleeding the brakes a PIA).

When it's warm and the underside is free of snow/slush I will more than likely do a 100% brake line replacement. I won't use factory (even if available) I will buy bulk line and bulk fittings and go to work...possibly deleting the LSPV.

Yes, you should disconnect the LSPV rod and raise it as high as it will go during bleeding to get maximum flush.

Sorry to hear about the rusted lines.

 

[goingcamping]

Yes, you should disconnect the LSPV rod and raise it as high as it will go during bleeding to get maximum flush.

Sorry to hear about the rusted lines.

27 yo car from MN…it’s not unexpected!

Thank you!!