Tach sporadically makes a screeching noise

[Guest]

Title says it all. I have not been able to pin down a pattern but the tach, out of the blue, will start making a horrid screeching sound. When it starts screeching, the tach needle will start bouncing over about a 300 rpm range. Sometimes, revving the engine a bit will stop it. Other times, whacking it with my hand makes it stop. Any thoughts on how to repair this?

[eil]

The squealing is probably coming from the bearing in the back of the tach where the cable screws in. You can (and arguably should) squirt some kind of oil into the bearing in a regular basis. I think I used lithium grease in an aerosol can. Not sure what's the best thing, though. Note that you have to get it into the bearing, not just squirt it into the center hole. Otherwise it just goes into the hollow interior of the tach where it doesn't do any good.

In my experience, a squealing tach or speedo is already gone but if yours only does it occasionally, maybe there's some life left in it still. You might want to find a spare to have on the shelf just in case.

[trtsmb]

The squealing is probably coming from the bearing in the back of the tach where the cable screws in. You can (and arguably should) squirt some kind of oil into the bearing in a regular basis. I think I used lithium grease in an aerosol can. Not sure what's the best thing, though. Note that you have to get it into the bearing, not just squirt it into the center hole. Otherwise it just goes into the hollow interior of the tach where it doesn't do any good.

In my experience, a squealing tach or speedo is already gone but if yours only does it occasionally, maybe there's some life left in it still. You might want to find a spare to have on the shelf just in case.

I'm already shopping for a spare. I'll try to get some lithium grease into it.

[tkent02]

The grease goes in between the part that spins with the cable and the big threaded tube that it spins in. It may help to take the tach off and turn it upside down to get the grease to go down in there where it's needed. I have had a few of them run fine for years after a good greasing.

[Brendan W]

The cable would be worth a look as well. Mine started whining and jumping a few hundred rpm. Cleaning and lubricating the cable stopped it winding up.

[trtsmb]

The grease goes in between the part that spins with the cable and the big threaded tube that it spins in. It may help to take the tach off and turn it upside down to get the grease to go down in there where it's needed. I have had a few of them run fine for years after a good greasing.

Thanks for confirming that. I was thinking it would be easier with the gauges upside down.

[steve murdoch]

Whatever you use as a lubricant don't over do it.
Years ago i used about 6 drops of Mouse Milk, a penetrating oil.
The excess could end up fogging up the tach face.

[trtsmb]

Whatever you use as a lubricant don't over do it.
Years ago i used about 6 drops of Mouse Milk, a penetrating oil.
The excess could end up fogging up the tach face.

Thanks for the tip. I'll use a light hand with the lube.

[JEEPRUSTY]

I used 90 weight gear oil on mine
dripped it into an inverted tach
flipped it before the oil could get all the way into the tach
has not made a soubnd since