Is It Easy to Replace a Tach?

[Cacia]

One of these has stopped after intermittently sticking. (no way to unstick it?)

Can I order it on-line and just connect it just like the present broken one?

 

[DennisS]

That's pretty much all there is to replacing the tach. Are you sure its the tach and not the sending unit. Try hooking it up to the wiring of the tach that is working, if it works, it's the sending unit. It always looks like a simple job when you start. First thing is to always check the ground, the black wire. Is it tight, corroded etc at the other end.

 

[Cacia]

is the "sending unit" the computer output in the engine? It must be giving an RPM input?

Okay, hook it up to the other one first. Gotcha. It was sticking and would actually start working when I would tap it...

 

[Wildcard]

I'll be home in a week. I'll fix it for you then.

 

[Wildcard]

PS, after looking at your pics, it looks like the shrink tube connectors have not been shrunk? Remined me to look at that too....

 

[cobaltblue]

Are the LCD displays for hours or digital tach? If they are for hours, hook it up to a battery to get the correct number of hours before you install it. Otherwise, they may be able to program it for you when you order it.

 

[Cacia]

uh..shrink tube?

When you remove any wires, tape the ends so they cannot touch other wires. When you are working on electronics make sure the battery is off. I've been doing marine electronics for 20 years, experience (screwups) has made me wary. I always disconnect the positive lead when working on any electrical equipment. Be careful, two of the wrong wires touching each other can get expensive. tape, tape,tape.

good, tanks a lot.

hook it up to a battery to get the correct number of hours before you install it.

Thats one for WC. (swooooosh)

oh Brian the Honda 50's you flush running the 90's you don't, I think.

 

[Chuck Tribolet]

The engine generates a signal to the tach. On older engines, it was a pulse coming of
the "alternator" (really more of a magneto). On more modern engines, it comes from
the computer, or from some widget that drive the computer.

The advice to swap the wires between the two tachs was good. That will quickly pin
down whether it's the tach, or the sender/wiring. Since you said it was sticking, I
suspect the bug will be in the tach.

I agree that it looks like the connectors haven't been heat shrunk. Ths may be
because they aren't that type (bad) or because they never got the heat gun. The
hot melt glue lined heat shrink connectors are great because A) they glue to the
insulation and help keep water out. B) they are fantastic strain relief.

As long as the battery and shore power are disconnected, you don't need to tape
things up.

And thanks for the pictures. They were worth 10K words each

 

[Darnold9999]

Too funny - have to fix one of my tach's - not electric - a long steel wrapped cable with another small cable inside. Suspect the inner cable is fraying causing it to jump and therefore the tach is jumping all over the place.

I think it might be time to go electronic. Now to find a tach that will work with a 1965 reverse rotation engine - and a new tach that will fit in the hole in the dash.

Would rather have your problem! But vintage equipment is always fun .

Good advice on all fronts, particularly the part wher you look at the shrink tubes. Everything will last a lot longer if you take care of this!

 

[pipedope]

Gage needles often stick because of static electricity on the face.

Mix a little fabric softener in water and wet the face of the tach with it.

This probably won't fix it but it is so easy to try that it is worth the few minutes.