I have a colleague who has a problem with his Isuzu pick-up van’s braking system. The problem is that air keeps being drawn into the brake fluid system with the resultant braking problems. He bleeds the system, gets the air out, but within days he has the same problem, of having to keep pumping the pedal to get the brake to function properly. He has replaced seals, slave cylinders and master cylinder (first a budget price part, followed by the OEM part on the assumption that there may have been a problem with the first one, but with no luck. The rear axle load sensor has also been replaced, again with no joy. He also replaced the brake shoes (rear wheels). When he did this he noticed that the left wheel shoes had pulled completely away from the drum, possibly to the end of their free travel. It also happens that it is the left rear brake that has the air problem. He has taken the car to a number of car maintenance garages, but no solution has emerged. He has paid over R5000 ($600) so far. Do you have any advice? My email address at work isXXX@XXXXXX.XXX home address isXXX@XXXXXX.XXX This colleague is about ready to replace the booster, which is about the only item he has not renewed. There is no brake fluid leak anywhere in the system. Do you think the system, if under vacuum, could suck in air through the slave cylinder seals, and if so, what could be responsible? Thank you. XXXXX XXXX-XXXXXXXXXX.