My old boss has a mid to late 90s grand Cherokee. At some point someone put something other then brake fluid in it and it has destroyed the brake system. He was told by his mechanic that this would happen if not flushed and some parts replaced immedietly. Now he has called me and asked if I can replace essentially the whole brake system for him. I know the obvious would need replaced rubber lines, calipers and master cylinder. My ? is what other parts would i have to replace. Was the power brake booster affected by this? Also what if any parts have i forgotten about. I want to make sure if i fix it for him that i change everything that has been contaminated and also want to make sure it is something i want to take on. I am fairly mechanically inclined and do alot of my own repairs however where the brake system is concerned i have never had to tackle a job this big so any advice would b appreciated
The brake booster is safe no contamination possible no contact with fluid,the only thing that you did not mention was the brake compensator valve that has seals in it,for flushing the system use denatured alcohol,it will dissolve any thing that is an oil base.
The system will have to power-bled with a Snap-On type power bleeder. This will have to be done several times to remove any sediment that may have accumulated in the lines and other components. But this may not be enough as the 'other' fluid that made its way throughout the lines may have acted corrosively on EVERY component it came in contact with. This sounds like a pass-the-buck nightmare job to me. Further, you'll be liable if the system fails after your repair and someone gets hurt. If this isn't your regular line of work, chances are you dont get carry liability insurance for just being mechanically inclined. Pass on the job, as its complex enough for a shop let alone a hobbyist mechanic.
Sounds like a good plan to me. The power brake booster assists the master cylinder but does not come into contact with the fluid itself, so you do not need to replace that. Like you said, any parts that have seals or rubber parts in contact with the fluid itself would need to be replaced (master and slave/caliper cylinders rubber brake hoses) especially if it has been in there for any significant amount of time as the rubber parts will possibly absorb and swell from the bad fluid in there and simply flushing will not resolve that problem. You would also have to thoroughly flush the disconnected lines well with a solvent cleaner to rid the system of the bad fluid that will cling to the walls of the tubing and then flush with brake fluid well before attaching the new components. Also of concern is if he has an anti-lock brake system installed. If he does, then it would be a good idea to have that replaced as well, but that will cost a lot for that alone, but I wouldn't want to take a chance of the contamination in that causing it to fail when he really needs it. Best to do it right than for it to fail later and face a possible lawsuit, even if he is your boss, or just say that you'd rather not undertake such a serious repair. Best of luck. Yes, if he were to have it power flushed immediately at the time, that would have been sufficient, but now that a lot of time has passed, all of the seals have probably been destroyed and everything I mentioned above would have to be replaced and the lines cleaned thouroughly to avoid any potential future problems. Best if you gracefully decline doing this job as it will be a big undertaking and the risk of a problem coming back to haunt you isn't worth the risk.
