Hour meter not reading but tachometer works

[timj]

Recently we removed and reinstalled our service alternator a Kenyon OP 120A Serial No. 122057.

Once reinstalled the tachometer works fine but the hour meter does not.

The tachometer is a VDO 4000 rpm with a older mechanical hour meter.

We would appreciate any advice re connections etc.

I cannot find any reference to Kenyon on the internet. Is it an over -branded model from another manufacturer?

[osirissail]

I have to assume that your "hour meter" is part of your tachometer instrument and not an external hour meter. Given that assumption - hour meters are simply "turned on" by applying power to them. They have internal "clocks" that then move the digits.

They are not dependent upon any function of a tachometer or an alternator other than possibly as a source of power or a switch to turn them "on."

All of which leads me to the simple conclusion that the instrument has a partial failure - the tachometer portion works, but, the hour meter portion is not being "turned on."

You can always install a separate hour meter somewhere. Normally they get their power from an engine oil switch sensor such as your "no oil pressure" warning light and a relay. However any engine mounted sensor switch will suffice.

[timj]

Thanks for info. Yes it is part of the tachometer integral and analogue. I have just heard that the "tumblers" can wear out. We guess the instrument is about 20 years old. It is probably coincidental that our reinstallation of the alternator coincided with the hour meters demise