T&T: Tachometers

Richard Allen rballen63 at gmail.com
Sat May 16 16:22:35 EDT 2020

I have learned once again the dangers of making assumptions. Tom's questions required me to be more thorough in my evaluation of my tachometer issue. It turns out that my dual Stewart Warner tachometers on my single Cummins V470M 185hp V8 diesel are not driven from my alternator. Rather there is a Stewart Warner mechanical tach drive with an electrical sensor mounted behind my high pressure fuel pump. So my problem is not alternator related. Now I am looking for a replacement for the sensor. I don't see the sensor that I have in the current Stewart Warner catalog and I can't read the worn-off, painted-over label on the sensor. I have a request in with Stewart Warner tech support. In the meantime, if anyone knows where to obtain such an item, I would appreciate the info.

Thanks, Tom, for making me look a little harder.
Richard Allen

Tom wrote:

A few more facts are needed relative to your tachometer question.

Are you single or twin engine?

What are the engines.  Are you certain the tachs are driven from the 
alternator?  There are numerous other ways.

What brand are the tachometers?


Tom Collins

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