I am getting ready to do my gauge install. I had some leftovers from my last car (Boost, Oil pressure, and EGT). The main problem was that the boost gauge was reading 1 inHg vacuum when not hooked up.

After talking with 42draftdesigns (about an oil temp kit and their installation accesories for the VDO's), I asked if they ever had this problem with the boost gauges. Now keep in mind the guy knew if I couldn't fix this, I was probably ordering one from him, but he helped me anyways. His advice was to "overextend" the needle and it sometimes recenters itself.

So I took off the bulb. If you look inside you can see a brass ring that loops above a center plastic assembly (which I assume is where the needle pivots and the boost line connects). By pushing in and out, pulling up and down, you can make the needle move. I assume the operation is that when pressure is applied in the boost line, it moves a diaphram which somehow moves this ring. All of which is connected to the needle.

So I moved the needle to its full "forward" position and pushed a little bit harder and sure enough, it reset slightly better. Repeat about three times and now it is dead on zero.

Now is a good time to point out that this will void any warranty you have on this gauge, but since mine is over three years old now, it was well out of warranty.

This procedure might work on other mechanical boost gauges, but since I have no experience with those brands I can't comment.

Mod at your own risk.

AC