tach problem

[datsunson]

77 a/t 280z

the tach is acting very strange. it will rise w/ engine revolutions, but will then stop at the highest rpm it was just revved to. it stays and won't go back down!? it can be revved higher, but it sticks at the higher rpm on the tach and so on until it hits the rev limiter. the needle will then go back down after the car is turned off and sits for awhile. is it time for a new tach?

[sblake01]

Rev limiter? I wasn't aware that a 280Z had one. But, seriously, it sounds like it's time to replace the tach.

[MEZZZ]

I agree, my '77 did the same thing. It would work fine for a little while and then stick where I last revved, usually about 3000 or so. After I turned the car off, it would stay there, if I tapped it, it would peg down to 0. It seemed the hotter it was out, the quicker it stuck. I read a post on here about something swelling a little with the heat. Regardless, I bought a new (to me) gauge set from a '77 on Ebay for $10.00. Everything but the clock worked I was told. I finally put in the tach a couple weeks ago and it was working flawlessly. Keep an eye for a tach on Ebay, I've seen them listed for next to nothing. Its in my opinion, the easiest guage to replace too, unless you have a dash cap

[JimmyZ]

Perhaps the faceplate is rubbing the needle or button. Try taking it apart and moving the needle by hand. If the hand doesn't stick it's something electrical in the tach. Look at the circuit board. I seem to remember a resistor going bad in a tach I had years ago. (240Z tach) The resistor was visibly baked. I could have replaced it since the colors were discernable but swapped the tach instead.

Sblake's route is much easier.

Edited August 18, 2008 by JimmyZ

[JerseyJoe]

I fixed a 240z tach that had the same problem by loosening the bushing directly below the pointer needle. If you pull the needle straight out, there is a brass bushing with slots on either side you can grip to tighten/loosen. That is if the design is similar to the 240z tach