Technical questions and answers concerning all models of VW diesel vehicles.
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so i have an (older)mk2, '86, about now it has going on 500k, still runs good, except for this problem. so a couple of years ago i found my brake booster had rusted out. unfortunately when i tried to disconnect the vac hard line it broke. so here i put an adaptor(made out of plumbing parts and a clamp), seems to work ok and it just sits there. so power brakes work real good. well when my old(oem)booster went in the trash, i had got a supposedly good one from [removed by moderator](the $100 one), had a problem since and the brakes have been checked twice by mechanics, to no conclusion. since ive bought 2 other boosters one from napa(supposed to be good), and one from a used, so this used one is oem, just rusty, so i wire brushed off most of the rust, and its still ok. the one thats not 'new' thats from the junk yard has a smaller diameter push rod, the 'new' ones the rod is thicker. but that doesnt seem to be causing the problem. the rear of the master cylinder has now developed a permanent leak when i depress brakes. the brake fluid was/is going from inbetween the booster and the master cyl, where the oring is. after a few months im ending up swaping out a new master cyl. as leak (under pressure) gets worse. i eat up some amount of brake fluid, havent lost brakes yet,,,(keeping my fingers crossed ). just 3 weeks ago i had change to a new mc, when i did i could see this time fluid build-up in the bottom of booster; so i swapped out to another booster i have, cleaned out fluid with soft soap and water, and set that booster in the sun to dry. this time the 'new' mc i have is just losing fluid from this area(the rear seal of mc), i end up having to fill up resevior 1-2 times every 2 days. i have to check the booster i put in this time for fluid build-up. the only other thing i havent done is to pull the pedal cluster and re-bushing it. i cannt find a reasonable reason why this is a continuing problem, i mean the booster sits flat on firewall and as far as i can tell hooks up normally.