Yep, you guessed it! Brake work!
This truck has had a dead pedal since it rolled off of the rollback wrecker. When I say dead, I mean it would go straight to the floor with no resistance. Zip, zilch, nada. I suspected the master cylinder because one of the bails was bent and the reservoir cover was loose. Everything else had water and dirt all over/in it, so I figured the master cylinder did too.
I pulled the old master cylinder off, installed my Dorman bench bleed kit on the new master, installed the new master, filled it with fresh DOT 5, slowly pumped the brake pedal until no more bubbles were visible in the hoses or reservoir, took off the bleed lines, and reinstalled the brake lines. I tried the pedal a few times and was pleasantly surprised at how firm it was!
Next, I installed the Motive Power Bleeder. I like it a lot, but the big rectangular cover is a pain to get sealed sometimes especially if the top of the reservoir casting is a little irregular. Once I got it to hold pressure, I worked my way around the truck flushing out the lines and calipers. Shockingly, the fluid was clean and there wasn’t much air in it at all.
After I cleaned up all of the tools and mess, I reinstalled the intake and fired it up to go for its maiden voyage! It ran, shifted, and stopped well. The only issue with the brakes is the right rear parking brake is stuck on. I hit the pivot with some Kroil and will try to loosen it up tomorrow.
Here’s a little YouTube short of its first trip down the driveway:
First trip down the driveway in my 2007 M1152A1 HMMWV! I spent the afternoon rehabbing the brake system by replacing the failed master cylinder and flushing ...
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