PeachParts Mercedes-Benz Forum - View Single Post

Jeremy5848 · #**191** 06-27-2010, 07:22 PM

Quote:

Originally Posted by Diesel911

I can only speak in general that the Gauges that come on regular cars from the Factory are not as accurate as add on Gauges or when you connect up a test Gauge. . .

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