B7800 Tachometer Problem

[camaro350man]

Hello everyone, hoping someone can guide me in the right direction.

I recently had my tachometer stop working on my 2004 B7800. It would go up to about 300 rpm on the dash when running and thats it, no matter the engine speed.

Now that I have my firewood completed, I pulled it in the garage and started testing it. I disconnected the cable from the dash and found that it is spinning when it's running and seems to spin faster with higher rpms. My next thought is that it must be the guage itself but I cant find any sort of replacement items other than a whole new dash which is not something I want to do as it's well over a $1000.00.

Any thoughts on what avenue I should take next? Thanks for any suggestions.

 

[GreensvilleJay]

remove dash, remove tach from dash, open and repair. sounds like simple old skool mechanical unit.

 

[camaro350man]

remove dash, remove tach from dash, open and repair. sounds like simple old skool mechanical unit.

I wasn't sure what makes up those units themselves or what can go bad. I was going to try to just replace it.

 

[GreensvilleJay]

They are simple mechanical devices and one possible cause is that the indicator pointer(hand) is no linger firmly attached to it's shaft. Remove the hand, small drop of nail polish, press back on, let dry, use drill to test spin.

 

[BAP]

There are places that repair and restore tachometers and speedometers for older vehicles. If you google them you will find them if you decide not to try and repair it yourself.

 

[Runs With Scissors]

On my 2501, the tach cable broke near where it attaches to the engine.

Easy fix.

I suspect that something similar has happened to yours.

If I were you, I would disconnect it from the engine side, see if you can pull the “inside” cable out and inspect it.

If the cable is good, you 'most likely' have a stripped gear on one side of that cable.

 

[camaro350man]

On my 2501, the tach cable broke near where it attaches to the engine.

Easy fix.

I suspect that something similar has happened to yours.

If I were you, I would disconnect it from the engine side, see if you can pull the “inside” cable out and inspect it.

If the cable is good, you 'most likely' have a stripped gear on one side of that cable.

I dont think it's the cable as it spins appropriately with the engine running. I tried stopping it with my fingers when it was spinning and it wouldn't stop which has me thinking the issue is on the guage side.

 

[camaro350man]

They are simple mechanical devices and one possible cause is that the indicator pointer(hand) is no linger firmly attached to it's shaft. Remove the hand, small drop of nail polish, press back on, let dry, use drill to test spin.

I'll try to dig into it today and see what I can find. That'd be an easy fix.