1974 MF150 Diesel Won't Start Without Jump Starter

[spankyscamp]

It sounds like the chassis grounds are not good. We have a MF135 that will do the same thing. clean the grounds and it starts on its own with no booster pack. When you put on a booster pack you are just giving it a better ground.

 

[Bentrim]

Proper troubleshooting begins at the battery.
Take a volt reading before attempting to start. Should be 12.75 for a fully charged battery. 12.25 or less is a dead battery. Take reading directly from the posts not the cables. Now take a reading from the cables. Less voltage? clean the terminals. Take a reading from the battery post on the starter to ground. Low voltage? Clean the battery terminal and connections. With the voltmeter hooked to the battery and showing over 12.5 volts attempt to start it. Does the voltmeter drop below 10 volt? Bad battery. Using jumper cables can sometimes make a good connection to the battery if the cables are corroded or can cover for a bad battery.

Once tractor is started check voltage at the battery should be above 13.5 volts. Anything less the charging system needs repaired. If original you should have a Delco alternator with a regulator mounted in front of the dash on the right side. You can replace the alternator/regulator setup with a later 10SI (one with an internal regulator)that was used on 70's GM cars but will need to change the wireing slightly.

 

[aircommuter]

When cranking you should have a minimum of 9.6v at the starter terminal, it should be the same on both sides of the solenoid. I see you rebuilt the starter, does that include the solenoid? 13.6v is the minimum charging voltage at the terminals. If you don’t have either of these minimums keep going back up the cables until you find those minimums. Then you can see where the change occurs. Best test method for the battery itself is a Midtronics MDX600 or similar. You could get a free test on machine like that at a parts store. I keep one in my shop because I am 35 miles from a store.

 

[Lavender Valley]

Fellers. I bought a '74 MF150 about this time last year. 1249 hours. Had the fuel injector pump rebuilt mid-summer, and I rebuilt the starter and installed new key switch early fall. Started using it mid-Winter but the only way I can get it to start is by jumping the battery. Turn the key and nothing. Not even a click. I've tried removing cables after running for a while, thinking something might be grounded and pulling power. No change. The battery is a NAPA Legend July 2022. Reckon the battery's gone bad that quick? Any help will be appreciated.

Hi, probably your battery, but, Massey Ferguson had some different safety systems, depress the clutch, or, High/low in neutral and I recall one model here in New Zealand had a positive earth. Keep in mind all safety systems are normally a break in the earth—food for thought.

 

[wtstarters]

Most common solution is a bad ground. (1)Battery cable grounded to tranny or frame. (2)Tranny or frame grounded to engine, (3)starter grounds to engine. Any of these points can create a bad connection (thank you pressure washer). Easiest way to check for one of these is to use one leg of a jumper cable. Connect one end to clean neg battery post, other end to a clean starter mounting bolt or starter thru bolt. That by passes any ground problem in between. A lot of the newer equipment has a ground cable directly to a post on the back or side of the starter. Ford/Lucas has used that for decades.