In my perpetual chase of a vacuum leak, I ran into a bit of an odd situation. My brakes seemed to go out the other night, as I was driving down out of my driveway.

It didn't happen again, but it almost felt like when you are in neutral and the E brake isn't working properly, but I was in reverse and had to put extra pressure on the brakes to slow the car down.

Once i got out the driveway I pumped the brakes to see if something was wrong, but it acted normal.

Fast forward to today, and I've tinkered a bit with the car. I took the brake vacuum hose off, and it has good suction (the car dies if I don't plug the hose). I put the hose back on and the brakes seem to be normal. I ran a few tests to see if the brake booster or check valve were the issue, and it doesn't appear they are (the brake pedal is solid, and doesn't sink to the floor or rise up..i.e., I don't think it's losing vacuum).

However, I notice that the car runs rougher whenever I pump the brake, like maybe that is the location of the vacuum leak. I meant to do a water test earlier (but as usual, life got in the way).


my question is, before i do the water test, is a rough idle that is made worse by pumping the brake pedal, maybe sound like a vacuum leak in the vacuum line for the brake?
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1985 245. 246K Gone..but not forgotten. Sold in 2013, found 2018! Still running on the road. Of course.