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Tachometer Advice

Discussion in 'GM 6.2 Diesels' started by joeq, Apr 9, 2016.

  1. joeq

    joeq Member

    40
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    Mar 19, 2016
    CT
    Going to a local swap meet tomorrow, and would like to find something to install a tach to my truck. I hear this is almost an impossible feat for our diesels, but would like to have it look factory. Converting a gas tach to a 62 is "barely" possible, but not easily accomplished. The aftermarket ones, don't have the factory look, I'ld like. At this point, I'll take "almost" anything. (Except digital display.) Does anyone here have a tach in their square bodied truck? I can't find any info in the search column.
     
  2. NVW

    NVW Well-Known Member

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    Castor, AB.
    I'm sure by brothers 87 6.2 had a tach, IIRC they were driven off the oil pump drive at the back of the engine.
     
  3. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

    8,779
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    May 9, 2008
    ZEPHYRHILLS FL
    Early tachs could have been driven off the oil pump pickup, or the alternator. If you can get a gasser tach, you can buy a DAKOTA DIGITAL adapter, and run it off your alternator output.
     
  4. joeq

    joeq Member

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    Mar 19, 2016
    CT
    The 6.2 in my truck, has a vacuum pump, that is nothing more than an oil pump drive. My truck doesn't use any vacuum. I wish there were a mechanism that could be adapted, to convert it to an electrical signal. Or something from a 6.5 that might work in that hole instead? I've heard of using the alternator as a signal, but not sure where you take it from. Some aftermarket ones, even put a clamp around the alternator housing, and pick it up that way. Not sure what brand.
     
  5. Will L.

    Will L. Well-Known Member

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    Boulder City Nv
    Yes, you need an ESS: Engine Speed Sensor. It takes the place of your oil pump drive/ vacuum pump unit and has a 2 wire output that can wire straight to a tach.

    I'll post a pic when I get back to my house after a bit.
     
  6. joeq

    joeq Member

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    Mar 19, 2016
    CT
    Seriously Will?! All I need is a speed sensor to run the tach!? That would be too easy. What type of tach would it run? A factory diesel tach? A stock gas motor tach? An aftermarket one? All of the above? Is that sensor from a 6.5? Do you have one in your HumVee? Thanks for checking.
     
  7. Will L.

    Will L. Well-Known Member

    6,739
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    Jan 25, 2013
    Boulder City Nv
    My Hummer uses an Autometer as the factory tach. It's a 2 wire tach, that ties to a juction for signal from ESS and feeds my TCM for the 4l80e. Most aftermarket tachs need to be calibrated after install.

    Post pickup trucks use a feed from the cs 130/ cs144 alternator- I can't remember which wire- any help someone? Adding just the wiring might be easier yet.

    You can also get an external pickup that goes on the outside of an alternator. Those suck- easy to bump and mess up.

    ESS:
    image.jpg
     
    FellowTraveler likes this.
  8. joeq

    joeq Member

    40
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    Mar 19, 2016
    CT
    Thanks for the photo Will. I see those drives are pretty expensive to purchase. Anywhere from $250-500 bucks. If I could find a used one for $50 or less, I would do it, and use the 2" Autometer tach, to fit in my lower left pod. If I can't find one reasonable, guess I'll have to go to the alternator.
     
  9. Will L.

    Will L. Well-Known Member

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    Jan 25, 2013
    Boulder City Nv
    What alternator are you running?

    ESS look junkyard, Craigslist,etc. I have never heard of one wearing out. No way would I pay $250 for one.
     
  10. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

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    May 9, 2008
    ZEPHYRHILLS FL
    He should have a 10 or 12 SI alternator on it. Teh CS-130 didn't come out until the late 80's. You have to crack that alternator open as it only uses a 2 wire regulator, so you have to add in the stator output wire for a tach signal. Another option you might not have considered is to go and buy a tachometer for a diesel boat. The older style is connected directly to the alternator, and most are calibrated with dip switches in the back of the tach. You would have to either swap over to a newer style alternator like the CS-130 or AD series with a 4 wire regulator plug to get the raw output signal to hook to the tach, swap to a marine style alternator with the seperate tachometer wire, swap to a 3 pin regualtor plug style for your current alternator style(same setup as the previous setup, just different plugs), or crack your current alternator open to add in the tachometer wire to signal the tach. There are options out there to add a tach. I also believe at one time Leroy had a small digital universal tach that he was selling, so that would be another option.
     
  11. joeq

    joeq Member

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    Mar 19, 2016
    CT
    Guess I'll have to see what I can find at the swap meet today. Appreciate all the info men. I'll keep you posted, and won't let this thread dry up, W/O some results.
    (PS, I believe my alternator is a 10 or 12 Si. Not sure which one....yet.)
     
  12. cornemuse

    cornemuse Active Member

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    50
    Jan 11, 2013
    San Diego north county
    I went to 'Ecology' auto wreckers & 'picked' a tach (actually the whole insturment panel) and the tach sensor and tach amplifier+base from a ('83 - '84) mercedes (123) diesel sedan, coupe, SD. Made a bracket to hold the sensor within 1/16" from harmonic balancer on my 6.2 Blazer, mounted tach amp on wheel well, switched power from glow system & always power from batt (<- for clock on tach). Works just fine. The slit in the harmonic balancer disrupts the magnetic field in the balancer which the tach sensor picks up. Take the tach out of the inst panel & make a case for it.

    (I used one of the water pump mounting bolts to mount the bracket to the engine)

    -c-
     
    WarWagon likes this.
  13. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

    8,779
    1,944
    May 9, 2008
    ZEPHYRHILLS FL
    You have options out there for not alot of money.

    Heres an alternator driven tachometer. It comes from Taiwan, but it's cheap enough to chance it.
    http://www.ebay.com/itm/85mm-Electr...ash=item35ebd68d6e:g:~IoAAOSw~OdVVFwt&vxp=mtr

    Or BurningOil(a site vendor here) can get you one of his that is even easier to install. It clamps around one of the injector lines, and has a digital display that goes inside the cab. It would be the easiest one of them all to put in.
     
  14. joeq

    joeq Member

    40
    9
    Mar 19, 2016
    CT
    I would like to see a photo of your set-up.
    Frank, I like the looks of this tach, seeing my factory gauges have red tell-tales, black faces with white numbers. But I was maybe hoping to mount it in my lower left pod, which will only accept a 2" face. This tach is 3 1/2", but would mount on my column between the speedo and fuel gauge. (If I choose to go that route.)
    Came back from the swap meet today, with nothing more than a LHS rocker replacement, and a worn dash pad, that's 50 times better than mine. Couldn't find a factory tach anywhere, (gas motor), or even a clock to put in my dash.
    The hunt continues.
     
  15. WarWagon

    WarWagon Well it hits on 7 of 8...

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    Nov 15, 2009
    AZ
    The top plastic housing cracks and lets water in. Not worn out but INOP regardless. RTV Silicone sealing the crack gives you longer life before it has to be replaced.
     
  16. joeq

    joeq Member

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    Mar 19, 2016
    CT
    I'm in Ct. I wonder how many 6.5s are in the bone-yard, and how many of them will part them out ? Don't think it'll be an easy find.
     
  17. EWC

    EWC Active Member

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    Jun 14, 2008
    Might want to look into the larger trucks , C60 or C70's , as they had tachs . Also the Hummers had a tach drive with a cable end , maybe Will has seen this .
     
  18. joeq

    joeq Member

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    Mar 19, 2016
    CT
    Not sure where to find trucks that big from the 80s era. I know the tachs aren't posted on Ebay, or Craigslist, or they just don't exist. I guess I could try and find "truck junkyards" in the area, but not sure they exist either. Worth a try I guess. And the Hummers, not sure how many military vehicles are being scrapped either. I guess I could post a want-ad somewhere. Thanks for the tips.
     
  19. Will L.

    Will L. Well-Known Member

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    Boulder City Nv
    95, my year hummer, was the last year with a pedestal mount tach.(pic). They all drove off the ESS afaik. 96 was all ds4 turbo with tach off the alternator.

    gclid=CjwKEAjwxce4BRDE2dG4ueLArHMSJADStCqMjvx2rtcvKa85vLRRVes0_FKidSy1C-wzin0i5DlP1hoCx-vw_wcB
    http://www.jegs.com/i/Auto+Meter/10...tnumQ262P_lBRkEGNrXDrL9I1xwNnV2MJtRoCqf_w_wcB

    I'm not sure what hummer or hmmwv maybe(?) used the cable drive. I know these are around, but never used one, the marine thing Ferm mentioned.
    http://discountmarinesource.com/p-44326-faria-diesel-tach-sender-90901.aspx?

    There are a lot of options out there if your willing to drop a couple hundred bucks. For a new tach and pickup sensor.

    On the ESS: Maybe post wanted to buy ad incase somebody hasn't seen the thread. Also call the 6.5 resale outfits like Boyce equipment and Teds?
     
    FellowTraveler likes this.
  20. FellowTraveler

    FellowTraveler Well-Known Member

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    Sep 29, 2014
    Nature Coast
    The white terminal (A) on the 4 prong connector is tach signal, when running dual gen/alt use the passenger side unit..(GM UP-FITTER C/K MANUAL)
     
    Will L. likes this.

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