4w-220 tach repair
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=25989
Printed Date: 31 Oct 2025 at 10:00am
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Topic: 4w-220 tach repair
Posted By: frankmi
Subject: 4w-220 tach repair
Date Posted: 19 Feb 2011 at 9:40pm
| Who are you guys using to repair tachs. I have a 4w-220 that has a working tach that does'nt read correctly. Ran low rpms before overhaul and now runs way to high after overhaul. Has a new pick-up so it isn't that! Name or number would be appreciated. Thanks Frank/mi. |
Replies:
Posted By: victoryallis
Date Posted: 20 Feb 2011 at 7:12am
| We just replace the whole tach. How do you ike the 4W-220 have wanted one for years? |
Posted By: Allis Fields
Date Posted: 20 Feb 2011 at 10:26am
 IS it a electric one? I have one, nos, I can't use. ------------- Allis orange blooded by family. Allis Diehard by choice |
Posted By: MUM FARMER
Date Posted: 20 Feb 2011 at 10:48am
| Hi Frank wish I had a answer for you did they put a different flywheel in when you rebuiit the engine? If you get tired of your 4w and want to sell it I might be interested I have quite a few 4W220s If you find a source to fix you tach I would like to find out I have several that arent working |
Posted By: monitordoc
Date Posted: 20 Feb 2011 at 10:50am
|
WHER DOES IT PICKUP SIGNAL? ALTERNATOR OR FLYWHEEL. DID YOU CHANGE BELTS , PULLEYS ETC. THE FLY WHEEL SENSOR NEEDS TO BE SET --I THINK--10 TO 13 THOUSANDTHS.
THERE IS INTERNAL ADJUSTMENT ON ALL AC ELECTRONIC TACHS. IF IT'S CLOSE NOT RECOMENDED. ------------- WD,D17-S4,180,D21 |
Posted By: injpumpEd
Date Posted: 20 Feb 2011 at 11:24am
|
8000 series tractors have a pickup over the flywheel ring gear teeth. Have you set the gap? Screw it in, then back it out 1/2 turn or so. I am guessing a 4W220 is similar to an 8070.
------------- 210 "too hot to farm" puller, part of the "insane pumpkin posse". Owner of Guenther Heritage Diesel, specializing in fuel injection systems on heritage era tractors. stock rebuilds to all out pullers! |
Posted By: DougG
Date Posted: 20 Feb 2011 at 11:30am
|
Wouldnt that one be mechanical drive? |
Posted By: injpumpEd
Date Posted: 20 Feb 2011 at 11:35am
|
magnetic sensor picks up pulses off the ring rear teeth on the flywheel. Programed number of pulses per revolution. I use ISSPRO's electronic programmable tach's on older tractors that were mechanical, or not high enough rpm scale. (210 AC 2500 tach, run 2800-3000 for pulling)
------------- 210 "too hot to farm" puller, part of the "insane pumpkin posse". Owner of Guenther Heritage Diesel, specializing in fuel injection systems on heritage era tractors. stock rebuilds to all out pullers! |
Posted By: frankmi
Date Posted: 20 Feb 2011 at 8:02pm
| It is an electric tach. and the flywheel is the orig. one! The overhaul was done at an allis/agco dealer and installed there so I believe it was done correctly, they have done a lot of overhauls on the larger allis tractors. I believe it is the tach. cause before it would'nt hold steady on the rpms. Must be no one does repair on these? Thanks any way! Frank/mi. |
Posted By: Hurst
Date Posted: 20 Feb 2011 at 8:25pm
|
Have you tried looking through some auto magazines for like 60's and 70's cars? I know there are a few shops that specialize in rebuilding that era's electronic gauges. I can't imagine a tractor tachometer being a whole lot different in design from other electronic tachometers. Hurst ------------- 1979 Allis Chalmers 7000 5800 Hours |
Posted By: frankmi
Date Posted: 20 Feb 2011 at 8:33pm
| AllisFields----How much are you asking for your tach.? (Does it work? Will it work on 220/8000 series?) Frank/mi. Thanks |
Posted By: injpumpEd
Date Posted: 20 Feb 2011 at 8:43pm
|
I think its for a combine, it is rpm and ground speed. dont think it'll work on 8000 series. try adjusting the air gap by turning the sensor in until it touches ring gear, then backout 1/2 turn and lock the jam nut. erratic readings could be the sensor itself, or its adjustment, or wiring to it.
------------- 210 "too hot to farm" puller, part of the "insane pumpkin posse". Owner of Guenther Heritage Diesel, specializing in fuel injection systems on heritage era tractors. stock rebuilds to all out pullers! |
Posted By: monitordoc
Date Posted: 20 Feb 2011 at 10:15pm
|
YOU SAY BEFORE IT DIDN'T HOLD STEADY RPM-- DOES IT NOW? WHAT RPM DOES IT DISPLAY? FIRST ADJUST THE GAP OF THE SENSOR AND MAYBE TEMPORARLY REPLACE IT WITH A NEW ONE TO BE SURE OF THE PROBLEM.
I REPAIR MANY OF THE ELECTRONIC A-C TACHS EVERY YEAR AND HAVE FOUND IT TAKES ALOT TO WRECK ONE. ------------- WD,D17-S4,180,D21 |
Posted By: frankmi
Date Posted: 21 Feb 2011 at 9:33pm
| Has a new sensor. It has a steady needle but at about 3/4 throtle it maxes the needle out at 3000 rpms! Thanks Frank/mi. |