8070 tach
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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=130104
Printed Date: 02 Jun 2025 at 6:10am
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Topic: 8070 tach
Posted By: charlesbendal
Subject: 8070 tach
Date Posted: 16 Oct 2016 at 10:00pm
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I have a non working tach on my 8070 I have a good power and ground on the back of the tach. I checked the resistance of the sensor and got 280 ohms. I checked the continuity of the wires one gave me .4 ohms the other .6 ohms. This all means the tach should be bad correct or am I missing something? I've put 3 tachs from agco in none move off of zero.
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Replies:
Posted By: Ron(AB)
Date Posted: 16 Oct 2016 at 11:06pm
Did the 3 tachs work at all??
What about the hour meter?
When you say good power… is that the full alternator voltage?
What about the connections at the firewall?
Recheck the grounds at the bottom of the hood frame, just ahead of the firewall. I like to use copper antisieze on that bolt or high zinc paint to prevent rust.
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Posted By: Acfarm
Date Posted: 17 Oct 2016 at 9:58pm
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Might make sure the sensor is close enough to the flywheel; if it is too far away won't get any reading....
~Warren
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Posted By: tornado8070
Date Posted: 18 Oct 2016 at 5:28am
I had a bad tach from Agco last winter. Rpm wouldn't read and proof meter ran backwards. Exchanged it and it worked. Make sure you have the PIN settings correct on the back. Good luck
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09’ DT205B, 08’ DT220A, 83' 8070 MFWD, 83’ 8070 85’ 8050 MFWD, 83' 8030, 82' 8010, 85’ 6080 MFWD, 84’ 6080, 79' 7020, 85' M3 RWD, 85' 920 diesel,AC C-50 forklift.
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Posted By: charlesbendal
Date Posted: 23 Oct 2016 at 5:09pm
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None of the 3 tachs moved at all. I removed the tach from the dash and hooked it up to the sensor with short wires and of course powered the power post and grounded the ground. I did this with a new tach and again with my old tach. I threaded the sensor the whole way in then threaded it back out 1 turn. I also tried the sensor out of my 8050. When this first started the tach was reading about 500 high now the old tach won't read at all. I never ran any of the new tachs long enough to see if the hour meters work. I feel like I checked the switches on the back about 100 times. As you can imagine this whole deal is very frustrating.
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Posted By: Daehler
Date Posted: 23 Oct 2016 at 7:21pm
Im in the same boat, just haven't bought new tach. Hope you get it solved.
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8070FWA,7080 BlackBelly, 7045,2 200s,D19,D17,G, WD,45,UC,7 AC mowers and lots more!
"IT TAKES 3 JD's TO OUT DO AN ALLIS, 2 TO MATCH IT IN THE FIELD AND 1 FOR PARTS!"
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Posted By: charlesbendal
Date Posted: 23 Oct 2016 at 7:23pm
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I had a neighbor mention that maybe the flywheel is rusted and the magnetic sensor may not be getting a good reading for that reason
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