Tach replacement options for Volvo MD11D

[FulmarCT]

My Westerly has a 1983 Volvo MD11D. Last summer a backflow (?) short circuit in the engine wiring fried out most of my instruments, including the original VDO inductive tach.
Replacement options seem to include 1) replacing it with the original or upgraded tach (23715874 I believe, appx $500) or installing one from tinytach.com. My alternator has an unused W lead, and alternator driven tachs seem to be a whole lot cheaper than a replacement inductive tach. Is it as simple as wiring up a new tach from my alternator? None of the other boards seem to discuss that option.

 

[smokey73]

By an induction tach do you mean one that senses the passing of the "teeth" on the flywheel? If so, I installed a VDO tach that that uses a multiple of different sensing modes and can be calibrated to the number of teeth on the flywheel. As an advantage to this one is that you can use a digital optical tach on the engine to "calibrate" the flywheel sensor in a way to get a very accurate tach reading. It was not very expensive and fit the opening in my existing panel with only a little modification. Works like a champ and is easy to read.

 

[smokey73]

Here are the installation instructions. If I recall correctly someone else does the manufacturing and it is not called VDO now, maybe just Viewline but the instructions are the same, You can google for Viewline Tach and see if it fits your needs. They have different sizes.