Hello All,

I would greatly appreciate any help on this as I have recently encountered both the most perplexing and most dangerous problem on any 240 I have worked on. A few weeks ago a friend reported that while driving my 1978 Volvo 245 DL (manual, non-turbo) he pressed the brake only to find that the pedal went straight to the floor with no braking power causing him to (lightly) rear end the car in front of him at a stop sign. After a few pumps the brakes returned to full capacity and he was able to park the car safely. I was obviously concerned and proceeded to check for leaks, there were none, Tested the pedal (master cylinder) for pressure while idling, it was solid and did not sink in the slightest. I removed the wheels and pulling the pads away from the rotor observed that none were seized and each responded when the brake was depressed (not that a seized caliper would explain such a total and short-lived failure). The fluid was looking old and dark, (I bought the car used and hand't yet changed the brake fluid). I decided to bleed everything and since I was bleeding everything and wanted to be especially certain that the brakes didn't fail again in a less fortunate situation I decided to replace the master cylinder as well. The job went smoothly though the fluid was slow to bleed. This was the only abnormality and after wards I tested the brakes with some short stops and felt everything was remedied and could be trusted. I attributed the earlier failure to old brake fluid which might have boiled on the hot day causing a temporary failure.

Then this past saturday I was driving on the expressway when the traffic in front of me slowed. I went for the brake, but there was nothing. Straight to the floor and straight into the back of the car in front of me. No one was hurt but both cars were badly damaged and I felt sick about having caused the accident (potentially much worse) by my lack of care of mechanical capability. The brakes came back instantly after the collision and I was able to drive off the highway and home slowly. In any case I am completely mystified as to what the problem could be, and talking to more experienced mechanics and shade tree 240 mechanics has not shed any light. It seems to me the brakes are a simple system: there is no air in the lines, brand new fluid, and new master cylinder. A problem at the calipers would not explain a total failure such as this. There is no leak, the reservoir has never gone below the max line, before or after. If the vacuum booster failed I assume the brake pedal would be hard to depress (as it is when the car is off) not fall easily, perhaps I am wrong about this as I must admit I don't fully understand its mechanism. I am in a severe volvo doldrum. Just paid the guy I hit more than I paid for the car in the first place. The front end is severely smashed but worst of all the car is a death trap and effectively totaled if I can't find an answer to this mystery.

Please help.

Bob