tach

[KEVMAR]

I have a 1983 120 hp ford lelham diesel engine.. the tach starts to bounch back and forth when I go over 1500 rpms any thoughts as to why and what should I check? thank you
Kevin g
new Bern NC

 

[RT Firefly]

Greetings,
Mr. K. STAY OFF BUMPY ROADS! First, easiest and cheapest, check all your electrical connections including grounds (I'm assuming electric tach'). IF a cable tach', replace cable.

 

[Larry M]

I have a 1983 120 hp ford lelham diesel engine.. the tach starts to bounch back and forth when I go over 1500 rpms any thoughts as to why and what should I check? thank you
Kevin g
new Bern NC

Check the drive belt for the alternator. It could be slipping. I'd also check the alternator itself. A lot of the Lehman tachs are alternator driven. The diagram is from VDO.