Tach problem

[Boosted_Nelson_Inc.]

I've got a truck 600 miles from home with an annoying problem.

My new M35A2 w/w, which is currently still at Redstone Arsenal in Alabama, has a tachometer problem. While picking up 3 other trucks with approved EUCs, I found the 4th truck that had not been approved yet, checked the fluids and fired it up. It started right up, but the tach only reads about 0-100 R.P.M. and just bounces around in that area. It stays in this range whether it is idleing or being revved up (I found out that the M35 has a C-turbo while checking this). Is this probably going to be a problem with the tach itself, a loose connection with the tach cable, a bad tach cable (I bought a spare from Saturn Surplus), or something else? I didn't get a chance to poke around more because we wanted to cover the 600 miles to home that day.

200-250 miles of the trip headed north on I-65 to northern Indiana has some good sized hills, and I'd really like to be able to downshift using the tach, rather than hoping the speedo is correct and downshifting by speed. We're going back for this truck Tuesday night, and if it's probably a bad tach, I can pull a good tach out of one of our other deuces and swap them.

I did search the forum and it seemed like everyone else who had tach problems had no movement at all from the tach (or at least they didn't say it was moving).

If anyone is looking at trucks in Alabama on GL, be warned that quite a few seemed pretty rusty (like the truck with the tach problem and the M109A3 and CUCVs we brought back).

 

[datsunaholic]

If the tach is one of the newer, plastic-housing tachs I've found them to be less than reliable. The housing warps if there's any side strain on the cable (and there always is a little as the cable isn't a perfect straight shot from the firewall). I ended up buying a used, metal-housing 70s vintage tach to replace the bouncy, sticky (it'd sometimes spin all the way around and get stuck on the peg the other way) plastic-housing tach that came with my Deuce.

 

[Boosted_Nelson_Inc.]

I knew I should've taken pics of the truck when we were down there. I can't remember what style the tach is. I guess it looks like I probably need to find all my TMs and swipe a good tach from my brothers M109.

 

[jwaller]

all my tach issues have always been cable related. I also had the drive cable break inside the back of the tach. that was fun to get out. I have a few new tachs if you need one.

 

[dabtl]

Do not forget the possibility that there is a problem with the tach drive. Check it by removing the cable and see if it is rotating properly. Pesky things.