Farm Equipment - 7080 Tach

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7080 Tach

Printed From: Unofficial Allis
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=49243
Printed Date: 24 Apr 2024 at 1:58pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: 7080 Tach

Posted By: dnel45
Subject: 7080 Tach
Date Posted: 19 Apr 2012 at 10:58am

Our 81' 7080 tach has been acting up recently, it would be working fine and then all of a sudden it would bounce up and down back to zero when the throttle would pick up. Then it would work fine again. Then today it seemed like it was registering very low RPMs, and sometimes would stick at 500 RPM and wouldn't move from there.

Never have had a problem before, are these tachs run off of the alternator as part of the wiring harness? Where should I start investigating? Any suggestions appreciated. Thanks

Replies:

Posted By: Lynn Marshall
Date Posted: 19 Apr 2012 at 11:31am

Yes, the tach is run off of an electrical signal from the alternator.Usually the alternator is to blame if the tach is not right.I would check the alternator to be sure it is producing the correct voltage.Also,check the connections at the alternator to be sure they are clean and tight.You might even check at the rear of the engine where the engine harness connects to the cab harness.

Posted By: dnel45
Date Posted: 19 Apr 2012 at 11:39am

Okay, yeah that sounds like a good starting point with some electrical contact cleaner. Thanks.

Posted By: Adam Stratton
Date Posted: 19 Apr 2012 at 12:50pm

I second that, I have had a bad connection on my 7045 that would cause it to shoot all over the board. Make sure your belts are tight and the pulley is still tight on the alternator while you are there.