Agreed. I just completed testing both the electric oil pressure sender and the gauge on my '87. The sender (relatively new - installed a year or so ago) measured resistance values close to what the FSM said it should for various pressures, using my Fluke 8800 DVM.

The oil pressure gauge (meter movement), however, (originally out of an '88 gasser -- I wanted the vacuum gauge) reads about 1 bar high across most of its range, based on a comparison with my new VDO mechanical gauge. This is confirmed with the VW oil pressure switch, which switches at 1.4 bar when the electric gauge reads about 2.5 bar.

All of this assumes that my Fluke and VDO are accurate, of course, but you've got to start somewhere. Even the possibility that the gauge reads high makes me want to have something else watching the oil pressure.

The alarm design is pretty much done. I want to have a working version in my car before publishing it to the forum. It uses three parts from Radio Shack and the VW switch. Total cost about $15.

I'm also working on a coolant high-temperature alarm that will use only two components at a cost of about $3. Sixto, among others, feels that it's even more important than a low oil pressure alarm, at least for the 603 engine.

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970