Factory tach available w/6.2?

[Steve_87K5]

I have never seen one, and I can't find any ref to it in my '85 wiring diagram. Are the 6.5 factory tachs driven off the signal from vacuum pump mounted ESS?

 

[arveetek]

There was no factory tach available for the 81-87 body style 10-30 series 6.2L diesels. The larger trucks however, like the C60, used a diesel tach that read 0-4000 rpm. Those were usually with the 3208 Cats or the 8.2L Detroits. You might be able to make one of those work. But they also had air pressure guages on the same cluster, with a tiny fuel guage on the bottom of the tach. Kind of funny looking, if you ask me.

The later model body style 6.5L with factory tach uses a signal from the alternator.

There are some who have used the sensor off the California vacuum pump to drive a factory 0-5000 rpm gasser tach. But that takes more electronic know-how that is above my head.

Casey

 

[Pookster]

My 92 6.2 k2500 has a tach- I have no clue where or how it owrks, but it works- so I can only assume that that particular tach did work with the mechanical injection 6.2 motors.

 

[arveetek]

It should run off the alternator as well.

I should re-phrase what I said above. All '89 and later new body style diesel tachs operate off the alternator, including both 6.2L and 6.5L engines, mechanical or electronic. There were no 6.2L diesel tachs offered in the 81-87 body style.

Replacing the alternator in the later model trucks can cause tach readings to be off, because of different sized pulleys used by rebuilders and aftermarket suppliers. It's best to use the original or GM replacement pulley when changing out the alternator.

Casey

 

[Steve_87K5]

Casey, by any chance do you know the part number of the ESS used on the vac pump, california models? I'd like to get my hands on one. thanks.

 

[arveetek]

No, I don't. But you might try calling The Diesel Depot. I hear that they might have some.

Casey