Factory diesel tach

[hunters628]

Hey guys, I’ve finally bought a factory diesel tach, thanks Dave, and now I’m trying to figure out how to wire it for my 6.2 diesel. I’ve read mixed things. Some say stator tap, some say you need a factory ESS, I’ve read somewhere you can use a Dakota Digital DSL-2 kit. What’s the right way to do this? You can still buy a new ESS but they are around $300. If a stator tap will work that would be the cheapest route since I need a alternator anyway. My second choice would be the Dakota Digital kit. Seems pretty nice to use. Uses a flywheel pickup and has a brain box that outputs several types of tach signal including 12v and HV. Let me know what you guys think. Thanks in advance!
Hunter

 

[AuroraGirl]

If by stator tap you mean using your alternator I dont see why that couldnt work. Dont they have a post that has an AC voltage that varies directly with speed alternator is spun? if you would like i could look in a 1980 manual for how the oldsmobile diesel engine read a tach signal? i think 82 was whjen 6.2 started?

 

[AuroraGirl]

Nevermind.. the only reference to a tach was on the HEI distributor page. The 350 diesel mentions in a wiring diagram a generator monitor circuit, but it looks like 1980 was vastly different from even 1979 on diesel electrical... and you have a 6.2.

 

[Blue Ox]

The only Olds Diesel I ever came across with a tach was an alternator tap.

The O.P. needs to know what kind of signal his tach calls for before he can figure out how to install it.

 

[hunters628]

The only Olds Diesel I ever came across with a tach was an alternator tap.

The O.P. needs to know what kind of signal his tach calls for before he can figure out how to install it.

That’s what I’m trying to figure out. The cluster it’s in is out of a diesel c50/c60 so it would’ve either been a 8.2 Detroit or Cat 3208 if I’m not mistaken. Is there a way to tell from the tach what signal it requires?

 

[Blue Ox]

I'm just going to guess, but those engines have tach drives, so there was probably a signal generator driven by them. There's no provision on a 6.2/6.5 except some had a signal generator on the vacuum pump/oil pump drive. How may wires does your tach have on it?

BTW, your 6.2 turns to 4K RPM, the DD and 3208 maybe top out at 2800. How high do the numbers go on yours?

 

[hunters628]

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Looks like it’s a 3 wire. 4K rpm. Truck has 3.08 gears so shouldn’t be hitting 4K often. There is a engine speed sensor for these that is still available new. Costs about $300 so I was looking if there are other ways to skin this cat. https://www.jegs.com/i/ACDelco/065/215-97/10002/-1 these were used in the 91-93 trucks that still had 6.2s and had a 4l60 trans. I don’t need the vac pump since I don’t have ac so this is an option. Just looking for a cheaper one lol. Thanks

 

[Blue Ox]

That's the signal generator I was talking about. The later trucks used belt driven vacuum pumps so they only had the adapter to drive the oil pump. There are other hall-effect sensors available, but even if the signal is compatible what are you going to use to drive them?

 

[hunters628]

That’s a good point. That’s why I was wondering if a stator tap would work. I read somewhere, can’t find it of course, that the 3208 didn’t have a speed sensor so they used a stator tap for the tach. But now that I think about it, I’d have to have the exact same size drive pulleys to have the tach be accurate at all and that wouldn’t happen. I believe that sensor I linked is a VR sensor so it would put out an AC signal. Probably no adaptors out there that do it. I know it was a factory option on 6.2 truck to get a tach and I can’t see GM producing a different tach for each diesel. So that sensor must be the one. Guess I’ll have to bite the bullet and give it a shot!

 

[Blue Ox]

Most of those medium duty diesels had tach drives. But I have no idea how the vehicle manufacturer attached a tach. If it's an alternator tap it's a different type of tach than a pulse driven tach.

You might try shopping the bone yards for that drive. $300 seems a bit much. www.car-parts.com

 

[hunters628]

Okay I think I just solved this saga and if so I will do a full write up in the future. I did a deep dive on the Diesel Place forum. I found a thread that dead ended, but had some answers. A guy said he had a custom signal amplifier made by Widget Man to convert the signal from a stator tapped alternator so the necessary input for the tach. The user has been inactive for years now so I couldn’t contact him. I did some digging and couldn’t find anyone or a site affiliated with Widget Man until I stumbled across a eBay listing for a MSD tach adaptor that just happened to say widget man on it. I messaged the seller and he remembered the exact appliance person I was referencing and now he sells the amplifier on his eBay store. I’m going to buy one and see if it works. It looks to be a fully programmable unit and he says you can make it work for any alternator/pulley combo. The unit is only $60 so definitely worth a shot! https://www.ebay.com/itm/143554785386

 

[AuroraGirl]

Okay I think I just solved this saga and if so I will do a full write up in the future. I did a deep dive on the Diesel Place forum. I found a thread that dead ended, but had some answers. A guy said he had a custom signal amplifier made by Widget Man to convert the signal from a stator tapped alternator so the necessary input for the tach. The user has been inactive for years now so I couldn’t contact him. I did some digging and couldn’t find anyone or a site affiliated with Widget Man until I stumbled across a eBay listing for a MSD tach adaptor that just happened to say widget man on it. I messaged the seller and he remembered the exact appliance person I was referencing and now he sells the amplifier on his eBay store. I’m going to buy one and see if it works. It looks to be a fully programmable unit and he says you can make it work for any alternator/pulley combo. The unit is only $60 so definitely worth a shot! https://www.ebay.com/itm/143554785386

thats good to hear, cant wait to hear how yours goes

 

[militaryjeep]

That guy has some interesting products!

 

[Mike Gresham]

Okay I think I just solved this saga and if so I will do a full write up in the future. I did a deep dive on the Diesel Place forum. I found a thread that dead ended, but had some answers. A guy said he had a custom signal amplifier made by Widget Man to convert the signal from a stator tapped alternator so the necessary input for the tach. The user has been inactive for years now so I couldn’t contact him. I did some digging and couldn’t find anyone or a site affiliated with Widget Man until I stumbled across a eBay listing for a MSD tach adaptor that just happened to say widget man on it. I messaged the seller and he remembered the exact appliance person I was referencing and now he sells the amplifier on his eBay store. I’m going to buy one and see if it works. It looks to be a fully programmable unit and he says you can make it work for any alternator/pulley combo. The unit is only $60 so definitely worth a shot! https://www.ebay.com/itm/143554785386

That fellow's name is Gene Kook (no kidding). His email is [email protected] . He can provide a small electronic box to convert any signal to drive that 4000 rpm tach. Tell him what you have and where you want the signal to come from and he will calibrate the box for it. Those tachs were used on the big trucks with Cat engines and the tachs were driven from the large flywheel.

Hope this helps.

 

[TPISly-C10]

That fellow's name is Gene Kook (no kidding). His email is [email protected] . He can provide a small electronic box to convert any signal to drive that 4000 rpm tach. Tell him what you have and where you want the signal to come from and he will calibrate the box for it. Those tachs were used on the big trucks with Cat engines and the tachs were driven from the large flywheel.

Hope this helps.

thx for the info just got a C60 diesel tach that i want to retro fit in my OEM C10 cluster!