I have searched but not found anything exactly like this problem. I replaced the master cylinder on my '04 Disco and did the test book bleed. The peddle was nice, high and firm. Today after going some stop and go traffic I started moving over a long bridge and the truck was sluggish and I could smell something burning. I pulled over on the other side and all 4 pads were smoking. The front pads burst into flames. The peddle was jammed to the top of the travel. I splashed some water on them and let them cool down for an hour. I pulled the ABS fuse. I was able to limp home with just a little bit of brake at the bottom of the stroke.

I found this thread https://landroverforums.com/forum/di...ke-hell-79916/

But I'm not so sure. Looking in the RAVE I don't see anything to indicate a back flow of fluid due to temperature. Does anyone have a suggestion on how to troubleshoot this?

Obviously I will need to flush out the cooked fluid. Will I be able to get away with not rebuilding the calipers?

 

When you installed the new MC did you check the adjust of the booster to the back of the MC? Sometimes you will need to check that when installing a new MC as it can cause the MC to basically lockup. Which makes you basically drive with the brakes applied = Hot Lava for pads n rotors.

 

I did not. I looked in the RAVE and I am guessing you are talking about the push rod? For replacing the master cylinder and servo they don't mention making any adjustment. I could see how you might need it. After I installed the MC and did the standard bleed I had the usual soft, sluggish brakes. After the textbook bleed I had a firm high peddle but still with about an inch of travel before the brakes engaged.

What you are saying makes sense but I'm not sure what the specs are to adjust it to.

 

My guess is the caliper piston seals are gone, I would suspect the front abs sensors and brake hoses are suspect as well given the flames.

 

https://landroverforums.com/forum/di...03/#post434427 This post speaks to what can happen if the push rod is making contact and moving the piston inside the MC when the MC is mounted.

The spec to set it to would be just barely touching the piston without moving the piston. If you have too much of an air gap between the two, then you'll end up with even more pedal travel before the brakes begin to work.

I've adapted the use of a domestic MC push rod measuring tool to check for this, in combination with a measuring caliper. I don't know if someone makes a version of this tool that works for LRs. I swapped in a TRW MC recently, and the measurements revealed no need to adjust the push rod. I've not had my hands on any of the cast body MCs, which are cheaper, to know if their tolerances are spot on like the TRW was.

Edit: I forgot to include this troubleshooting trick. If you slot a couple of washers and use them as shims between the MC and the booster, then you can see if the problem goes away. If it does, shorten the push rod.

 

After that kind of brake heat I would certainly inspect all the calipers. If the rotors have a bluish/purple burnt look to them = replace them as they're probably warped due to the excessive heat. That amount of heat puts a lot of stress on all kinds of stuff. From brake calipers, rotors, pads, slide pins, to heck even the wheel bearings if the heat is great enough. I was gonna say check the slide pins, but I doubt all 4 corners would be dragging at the same time.

Several D2's I've worked on had the nut on the end of the push rod loose as a goose and I put it back with some blue loctite to where the threads were no longer shiny. I haven't run into the issue personally but I've heard a lot of people having issues with that push rod and the brake pedal basically dragging the brakes on.

Remove the wheels, remove the brake pads, and check the slide pins for smooth operation. Then see if you can get the caliper pistons to push back easily. If so you might be okay. Lucky for us LR does NOT use Plastic pistons with their calipers like some automakers! Once those puppies heat up they'll warp and after that they're toast no question about it.

I would flush the fluid as well and use DOT4.