One of the reasons the reservoir would leak is that when you put the plastic reservoir onto the master cylinder you must wet the rubber seals and the nipples on the reservoir with brake fluid. This helps the reservoir nipples fully insert into the rubber seals. If you have trouble inserting the lock pin that is a sign that the reservoir is not fully inserted into the seals. The other possibility that was previously mentioned that would cause you to leak and have trouble inserting the lock pin is if you put the reservoir on backwards. In this case it hits the booster and can't be fully inserted into the seals. All of this assumes the seals were properly installed into the master cylinder in the first place. The "big" end is supposed to be inside the master cylinder. Again, it helps to wet the seals before installing to make it easier and to help them seal. Lastly, a final possibility is that the reservoir is overfilled and as you drive it leaks out the top. In all cases the brake fluid should be clear. If it is amber to dark it is probably way past time to change it! When it is very dirty I remove the reservoir to clean it and wipe it out with alcohol before putting fresh stuff in and flushing the system. This way I don't push more dirt into the system. I don't know about DMCH but typically new or rebuilt master cylinders don't come with reservoirs. You are expected to reuse the old one so if it leaks it probably has something to do with the way you installed it. Very unlikely it is a defective part. Way too often a part is blamed as "defective" because it is handled or installed improperly. BTW it is very hard to bleed a new/rebuilt brake master cylinder once it is mounted onto the booster. It should be bled on the "bench" with the reservoir installed first. David Teitelbaum vin 10757 --- In dmcnews@xxxxxxxxxxxxxxx, "therealdmcvegas" <dmcvegas@...> wrote: > > That is true, you wouldn't expect a new part to fail. But it can sometimes happen with OEM, just as it does with NOS. > > ------------------------------------ To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnewsYahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/dmcnews/join (Yahoo! ID required) <*> To change settings via email: mailto:dmcnews-digest@xxxxxxxxxxxxxxx mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/