81 300d brake fluid reservoir question
 

I just realized that the rear reservoir on my car's brake system is going down, even though the front seems to be holding it's own. What is the order of troubleshooting for this. Just realized it last night, but it's the second time in the last few months, so it's leaking somewhere. If anyone has had this happen, let me know where you found the problem while I start looking the system over. (Just my luck that it won't get above 30* today) Thanks for any ideas on this! {Yeah, I know it can only be so many things, but it usually ends up being the last one I check} :confused:

I would start with the front calipers and hoses. Fluid loss at or into the vacuum booster is also a possibility.

Thanks qwerty. So does this mean the rear reservoir supplies the front brakes? (I haven't even opened my Haynes manual, yet) I've got two transmission linkage bushings and clips that I've got to install, so I thought this weekend would be a good time to get under there and put those in, plus put in the two new plow plugs that I didn't have when I changed the other 3 out a month or so ago. Weather is calling for a low of 11* tonight:(. So, after having weeks of unseasonably nice weather, it's time to get under the car now that the "real" February has returned. As a buddy of mines' shirt says, "I put the PRO in procrastination!" I'm not bragging, but I do have this problem with putting off the things to do list sometimes. I'd say ashamed would be a better word. :o

Yes, the rear section works the front brakes.

Determine where the fluid is going. If you can't find any puddle, more than likely the fluid is leaking into the booster and it would be time for a new master cylinder.