will this tach work and how? - PeachParts Mercedes-Benz Forum

clarknova · #1 10-01-2003, 05:08 PM

I've got an Equus 4, 6, or 8 cylinder tach that I use for my VeeWee.
I don't suppose this will work for OM617 non-turbo 5 banger, will it?

clarknova · #2 10-01-2003, 07:49 PM

I'm sure this is a stupid question, but could someone humor me?
If this will work, where do I hook it up?
If this won't work, any recommendations for a tach?

engatwork · #3 10-01-2003, 07:55 PM

It won't work because you do not have a #1 spark plug wire

. I use a stobe light from work to check out the rpm of my diesels. We use it at work to "stop" big rotating equipment to look at stuff that you normally can't see when it is running. You vary the speed of the light which is indicated on "rpm" of the digital read out on the light. It makes something look like it is standing still - just don't stick your hand in there.

clarknova · #4 10-01-2003, 08:07 PM

I didn't think so...
So with the timing light, do you shine that on the crank pulley and dial the strobe until the pulley "stops" and then whatever reads on the strobe is the RPM?

sixto · #5 10-02-2003, 12:50 AM

With an 85-up (84-up?) MB Diesel you can put a duty cycle meter or pulse counter on the crank sensor and calculate rpm. Or you can try something like a bicycle cadence meter with the sensor magnets mounted on one of the pulleys along the belt paths. You'll have to do some math and assume the belt isn't slipping but it'll be good enough I'm sure. There are aftermarket tachs for Ford and GM Diesels that attach to the alternator. I don't know how they work but I'll bet it can be adapted to an MB Diesel.

I've seen an IP timing device that reads the pulse through an injection line. That can be used as a tach signal.

Sixto
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87 300SDL
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