MF 240 Intermittent Electrical Problem

[random]

I know how hard it is to troubleshoot intermittent problems and that I need to take a methodical approach, and have been trying to doing so... but... no luck yet and I thought it was possible wiser folks than me may have some pointers I can use. (It is too dark and cold to mess with it tonight...)

This is a MF 240 Diesel, made in the UK. I have two wiring diagrams and neither quite matches the tractor. I am the second owner and have had it for 25 years. It was very low hours when I got it and I doubt it was much modified.

The problem: Turn the ignition key and nothing happens... OR it makes a loud click and then nothing happens. It will go weeks between doing this. I'll try a bunch of different things and it will work fine for a few weeks, I'll think I fixed it, and then the problem returns.

One notable symptom is that in the loud click version ALL power to the tractor stops working for a period of time. If I disconnect the battery, let it sit for a few minutes, hook it back up, the lights etc. work. Hit the key to start and they all go out and won't come back until I've done the disconnect and wait thing again.

I've replaced the starter (with solenoid) probably unnecessarily. I've replaced all three fuses. At one point I thought I'd isolated the problem to the fuel gauge, but no...

At times the battery will read about 13 volts when not connected, but 7 when connected.

My thinking is that either there is a short somewhere (maybe more than one) or there is a relay I don't know about which needs to be replaced.

Any suggestions will be very much appreciated.

 

[ptfarmer]

How old is the battery, I've come across a problem a couple of times that where simular to what you are experiencing with relatively new batteries, and it was the battery that was the problem (a bad connection inside the battery).

 

[tractorsam]

If your battery voltage doesnt consistently read 12.5 or
more volts when disconnected I would second looking at
the battery. If you have a local auto parts store or repair
shop maybe see if they can test it. If not do you have
another battery you could try?

 

[random]

(quoted from post at 02:13:31 11/30/23) If your battery voltage doesnt consistently read 12.5 or
more volts when disconnected I would second looking at
the battery. If you have a local auto parts store or repair
shop maybe see if they can test it. If not do you have
another battery you could try?

I may not have been clear on that point. The battery always reads good voltage when it is disconnected. It is when it is in the tractor and the terminals are on that *sometimes* it will read low across the terminals. Disconnect and it is fine. Still, today I'll try another battery and see if it makes any difference.

 

[MF#1]

Check the ground cable where it connects to the frame. Ensure that BOTH battery connections are SUPER clean and bright at BOTH ends. A battery cable can look good but have internal shorts/corrosion. A good test light would help diagnose immediately after it clicks and doesn't start, suspect everything and assume nothing, including the battery. Good Luck!

 

[random]

(quoted from post at 14:28:37 11/30/23) Check the ground cable where it connects to the frame. Ensure that BOTH battery connections are SUPER clean and bright at BOTH ends. A battery cable can look good but have internal shorts/corrosion. A good test light would help diagnose immediately after it clicks and doesn't start, suspect everything and assume nothing, including the battery. Good Luck!

Thanks. I today I replaced the battery with a brand new one I had just purchased for another purpose. Symptoms are the same. Tomorrow I'll start going over the cables as you suggest.

Question: Doesn't the fact that all power goes out for a few minutes then comes back imply there is a relay or circuit breaker somewhere? (None appears on either wiring diagram...) I'm not sure it will help me to know, but sometimes knowledge is power.

 

[MF#1]

From the AGCO parts book online I didn't see one either. It appears that you have the Lucas electrical system, also known as the Prince of Darkness that can develop strange and intermittent electrical issues. When the problem occurs have you tried to Jump the solenoid battery cable to the smaller post with a chrome wrench or screwdriver to see if it starts? You would have to have the L-S-H lever in start(S) to do that. IF it starts then suspect a wiring issue to the key, through the neutral safety switch, or a bad battery cable OR connection. That is why you need to methodically go through each and every wire/wiring connector from the battery to the key to the neutral safety switch to the solenoid, even the new one. I've had one bad ground from the battery prevent starting before so it is possible. When you replaced the starter did you wire brush the starter to bellhousing surface to ensure good contact? I've also bypassed BOTH battery cables using a quality set of jumper cables(after removing the cables from the battery) and connecting the negative to the starter frame bolt and positive to the solenoid to eliminate questionable battery cables. It may take some time but you should be able to isolate the problem to one or two issues. EVERY Massey I've ever had or used had a no-start at one time or another due to a bad connection or failed part, and that was with the Delco-Remy system so EVENTUALLY it will happen. Keep at it!

 

[used red MN]

Are the internal surfaces of the battery terminals clean
as in mostly ..shiny lead.. they need to be, not a black
scale. If they are clean and the voltage varies from 13
to 7 across the terminals either your probes are not
contacting the terminals correctly or your meter is
bad. Make a shiny spot with a screwdriver blade on
each of the terminals and the posts. If the reading are
not the same through a variation of probing these 4
spots ..Houston we have a problem..! Secondly, I would
recommend this quick check. Grab the battery cable at
each location it connects to the terminals that are
on each end and pull it like you are pulling the head off
a snake. If they pull out this may reveal an otherwise
hidden problem.

 

[random]

OK. I took the battery cables off and cleaned (file, sand paper, wire brush) every part of the connections at both ends. Hooked it back up and it started. Has started 3 times now... so looking promising. But it has done this before, as I said it is intermittent, so we will see.

It doesn't explain all the power shutting off to everything...

The dash lights and hazard flashers are working, but not the headlights... so I'll try to figure that out next.

I will update here if the problem comes back as it has in the past, but for now I'm hoping it was a case of some crud in the connections and/or a something loose in one of the battery cables which would go on and off depending on vibration etc.

 

[MF#1]

Good for you!! If you can see where the dash lights get their power from the wiring diagrams then make sure those connections are clean and bright. Also, if you get another no-start I would suggest jiggling the wires to the neutral safety switch then clean them up too. Suspect everything and assume nothing! I've always had headlight problems at one time or another, usually caused by vibration or corrosion. The light switch can also be a source of frustration so clean and check. Good Luck!