6.9 Tach Install

[IDIPlowBoy]

Hello, I have a 1984 Ford F250 plow truck with a 6.9 diesel. I have been looking into install a tach on it but am not quite sure how to exactly. I have been told I also need a diesel specific tach. If ya'll can tell me what you did to install yours, that would be awesome. Thanks

 

[wildman7798]

I spent a fair amount of time researching this myself, to use an aftermarket or factory. The aftermarket stuff is expensive because you need a sender down at the balancer (Approx. $75) then the tachs themselves are somewhat pricey ($150-250). The beauty of the IDI trucks is they are wired for a factory tach. Just to the right of your front cover and oil filler you will see either a large threaded plug or a sender with 2 wires - the factory tach gets it signal from here. If you look near your alternator your should find the other end of the factory plug and harness that go to the dash. I found a used sender on Ebay for $30 and then bought a factory diesel (1980-1986) gauge cluster with a tach in it on Ebay for $80. My cluster was much nicer so I simply put the tach into my cluster. The rub for me was the Mylar or gauge backing from the unit I bought was burned on at the ammeter gauge. So I used my mylar (non tach) and I hard wired and spliced into the 4 wires into the factory harness between the tach and large cluster plug. (very easy to do). There are some really good tech articles about it if you do a little more research but it was one of the first things I did to my truck when I got it and it's very nice. A clean install having a factory tach.

 

[FordGuy100]

I wish I had gone with a factory tach. The aftermarket ISSPRO tach I put on the truck was actually the first thing I ever did to it. Like said, it took two magnents mounted 180* off on the harmonic balancer, and a sensor mounted down to where the engine ground is.

 

[smolkin]

If your engine is original, it probably doesn't have the sensor port. My old '84 didn't. You would have to change the timing gear cover over, not sure what year began the sensor-ported cover. It is doable, there's a tech article or thread about timing that shows how to align the gear I think.

e: Recent thread about this very thing

 

[Garbage_Mechan]

My 86 had the treaded port. I procured a factory tach cluster, factory tach sensor, plug and play! I did dismantle the new used cluster and clean it inside, put all new bulbs. Also cut and fit some styrene to fill in the now unused volt, temp and oil gauge holes since I have all "real" gauges on thop of the dash.