Has anyone ever added a mechanical oil pressure gauge in parallel with the electric gauge sender on their W126, W124, etc. diesel to see how accurate the electric gauge is? I'm doing some additional work on the plumbing for my low oil pressure alarm and am thinking of adding an additional gauge to my 1987 300D Turbo (W124, OM603). Just wondering how the existing electric gauge will compare to the mechanical one.

"A man with a gauge knows what his oil pressure is. A man with two gauges is never sure."

Jeremy

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"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

well, since it's pegged at basically 45psi, a mechanical gauge with a 90 psi range would be better for sure.
I have several sets of mechanical gauges and plan to set them once i figure out a good pod location. I've seen plenty of gauge sets on 126's and 123's. so I'm sure it's been done.

In the below pic is what I got with and idle speed of about 750rpm and the Engine Cold; 80psi.

When I reved the Engine hot or cold the highest pressure I could get is about 97psi.

In one of the Manuals it has the Oil Pump Pressure Reilef Valve reileving pressure at 101.5psi (7bar).

So if you want to read close to your full pressure range you would need a 100psi Gauge.
But, if you look on eBay at some of the Gauges you will see that it is hard to find one that has a scale on it that you could read easily if you use a 2 or 2-1/2 inch diameter Gauge.

I think a full 100psi Gauge would be nice to have because it might tell you if something is impending. With the stock gague you only know you have 3 bar.

Attached Thumbnails

 

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84 300D, 82 Volvo 244Gl Diesel

Thanks for the numbers. I have a 100 psi VDO "Vision" series mechanical gauge on order. It will be installed in parallel with the factory electric pressure sender and a VW 1.4 bar switch acting as a low pressure alarm, in my '87 300D. I'll post a description and pictures when I get it installed and working.

__________________

"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

I have an 84 300D I do not know what the pressure is supposed to be on your 87 300D.

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84 300D, 82 Volvo 244Gl Diesel