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Author Topic: Tach issues  (Read 1367 times)
NonHippieBus
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« on: August 16, 2013, 10:33:50 PM »

Hi-

8v71 in my pd4106 with a Dixson HD tachometer.   On the latest roadtrip, take has begun to wander and jump (mostly downward) and sometimes seems steady but reading low.  Occasionally works as it should.  Any suggestions?

Can this be a sign of other issues?
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TomC
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« Reply #1 on: August 17, 2013, 08:25:06 AM »

Loose wire or fitting.
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
akroyaleagle
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« Reply #2 on: August 17, 2013, 02:14:10 PM »

If it is wired to the altenator, try it with the lights or some other load on it.
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Joe Laird
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chessie4905
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« Reply #3 on: August 18, 2013, 04:27:05 AM »

   If it reads from a flywheel sensor, check sensor for grease/ dirt build up and clearance setting. And any poor connections at engine.
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GMC h8h 649#028
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NonHippieBus
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« Reply #4 on: August 18, 2013, 02:10:50 PM »

I don't know whether it reads at the alternator or the flywheel.  My factory manuals don't cover tachometer information.  Where would the flywheel sensor be located? 

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eagle19952
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« Reply #5 on: August 18, 2013, 02:39:36 PM »

Look for a device that looks similar to this somewhere in your bell housing <usually....

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Utahclaimjumper
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« Reply #6 on: August 18, 2013, 05:38:36 PM »

 You can bet being an 06, it will be on the alternator, its also an "add on" unit so it won't be listed in your manuals. Mine had a cable driven(from the blower drive) generator that produced a three phase current that was measured by the head, very accurate and made in Germany.>>>Dan
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Utahclaimjumper 
 EX 4106 (presently SOB)
Cedar City, Ut.
 72 VW Baja towed
Sam 4106
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« Reply #7 on: August 18, 2013, 06:19:27 PM »

Dan, you would lose that bet on the 4106 that we had. Tach drive was as pictured above.

Good luck Sam
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1976 MCI-8TA with 8V92 DDEC II and Allison HT740
Lin
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« Reply #8 on: August 18, 2013, 09:25:00 PM »

If it is alternator driven, I think that there will be a connection for it on the R terminal-- the one the measures at about half voltage (12v on a 24v system).
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You don't have to believe everything you think.
Oonrahnjay
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« Reply #9 on: August 19, 2013, 11:08:04 AM »

Mine had a cable driven(from the blower drive) generator that produced a three phase current that was measured by the head, very accurate and made in Germany.>>>Dan   

    Yes, very accurate, but it smells like many $$$$ to me!    BH  NC   USA
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Bruce H; Wallace (near Wilmington) NC
1976 Daimler (British) Double-Decker Bus; 34' long
6-cyl, 4-stroke, Leyland O-680 engine

(New Email -- brucebearnc@ (theGoogle gmail place) .com)
Utahclaimjumper
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« Reply #10 on: August 19, 2013, 12:14:15 PM »

 The tach and speedo where both made in Germany as a matched set and trouble free for the 16 years I owned the coach, the present owner has had no problems either, so why cheeepout when it comes to your ride man??>>>Dan
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Utahclaimjumper 
 EX 4106 (presently SOB)
Cedar City, Ut.
 72 VW Baja towed
Oonrahnjay
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« Reply #11 on: August 19, 2013, 12:48:22 PM »

   The tach and speedo where both made in Germany as a matched set and trouble free for the 16 years I owned the coach, the present owner has had no problems either, so why cheeepout when it comes to your ride man??>>>Dan 

      Yeah, $$$ spent on quality is usually the best money spent.   
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Bruce H; Wallace (near Wilmington) NC
1976 Daimler (British) Double-Decker Bus; 34' long
6-cyl, 4-stroke, Leyland O-680 engine

(New Email -- brucebearnc@ (theGoogle gmail place) .com)
NonHippieBus
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« Reply #12 on: August 20, 2013, 05:07:14 PM »

Look for a device that looks similar to this somewhere in your bell housing  







Winner!

I found the pickup on the bell housing near the right valve cover,  near where the generator oil supply line is.  Basically this is the top of the bell housing on a v-drive like mine.

Found a loose wire.  Hopefully this is the source.  Right now we are camping in beautiful St. Maries Idaho, next trip is home to Oregon and some relax/work at the Oregon Coast.  Will report back after the road test.  

Thanks everyone.
« Last Edit: August 21, 2013, 05:06:49 AM by NonHippieBus » Logged
technomadia
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« Reply #13 on: August 20, 2013, 05:56:06 PM »

You can bet being an 06, it will be on the alternator...

Our 4106 has a tach driven by a magnetic sensor on the flywheel housing, like the one pictured above.

I just upgraded our dash gauges, and now using the same sensor I am using the Diesel Tach from SpeedHut.com - and so far it seems to be working perfectly.

  - Chris
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Cherie and Chris / www.technomadia.com
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eagle19952
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« Reply #14 on: August 21, 2013, 06:44:24 AM »

Winner!
I found the pickup on the bell housing near the right valve cover,  near where the generator oil supply line is.  Basically this is the top of the bell housing on a v-drive like mine.

Glad I was able to point you in the right direction.. Smiley
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