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Discussion Starter #1
I just purchased a 1972 series iii diesel. It drives well but having some initial issues.

1) The red charge light in the instrument panel is always on. When I tried to place a charger on the battery, the charger even after 10 hours would not indicate it was topped off. The battery does have enough energy to heat the glow plugs and start the truck. Also when I removed a terminal from the battery and checked the alternator wires on the back of the alternator (Lucas acr 20) when the engine was running I did not recieve any voltage reading. ( I later read I should not remove the battery leads when the engine is running.)
Do you think I need a new battery, a new alternator or both?

2)What might cause the speedo to bounce. It seems to settle near the correct speed but then Quickly starts to bounce again. What should I do?

3) The fuel gauge does not move from empty. How do I determine if it is the in tank sender gone bad or the gauge in the panel itself.

Thank you for any suggestions.
 

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1. Test the alternator as per a quick Google search. That will tell you what to do.

2. Google wibbly wobbly speedo for advice ( not joking )

3. Check the fuses. Then measure the resistance across the fuel sensor and shock it changes with fuel level. If it does suspect the gauge. To be honest if it doesn't move at all it might be disconnected.
 

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If the battery was in the truck when you bought it then you are on someone else's borrowed time. Go buy a new battery whether you need it or not. That's new-to-me-car 101. Have the alternator tested at your FNAPS. Then get back to us.
2 Lube the inner cable of the drive.
3 Maybe the 9V voltage stabilizer is kaput. It's a little thingy behind the dash. Otherwise yeh, your sender prolly crapped.
In the not too distant future replace the belts and hoses, along with doing the brakes and clutch. Renew all fluids and grease all your grease points. Again, new car 101 baseline maintenance schtuff.
 
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Series 3's use a voltage stabilizer for both the fuel and temp gauge. Is the temp gauge working? If it is then check the ground on the fuel tank, located at the sender switch on top of tank, under seat. Stabilizer is located on the back of one of the gauges in the dash.

Not seen many speedos that don't jump around. 'cept Briggs's :popcorn:

Sounds like the battery is toast. Started with a jump?
 

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Discussion Starter #5
Thanks for all the suggestions. I will dig in and see how it goes. I will start with a new battery.

The temp gauge is working so I will check the ground for fuel sender ASAP.

Is the charging light measuring th functionality of the alternator or it an indicator of battery voltage. I have a separate voltage indicator which has been consistently dropping which lead me to believe I had a battery/alternator issue.
 

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At least on my gas 2a, the charging light comes on when it's not generating. The ammeter shows the net amount of current being consumed or produced.
 

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The charge light shows the alternator is not working. If you get a replacement change to the later 65 amp ones used on Defenders. They are a lot better.
 

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Quick check: If the alternator is working, you should read 13.5-14 volts across the battery terminals with a volt meter as it charges the battery with the engine running. If it is less then probably the alternator is at fault.
 

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Discussion Starter #9
I have been doing a bit more research and have seen that it may be possible to install an overdrive on the my 1972 Series III Diesel. Has anyone had experience with this and if so which system is the most reliable and which provides the most increase is final speed?
 

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I have been doing a bit more research and have seen that it may be possible to install an overdrive on the my 1972 Series III Diesel. Has anyone had experience with this and if so which system is the most reliable and which provides the most increase is final speed?
Global Roamer Corporation

You probably won't go much faster with the diesel. Maybe a bit. It will be a quieter though.
 

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You bought a series 3 diesel. There is no increase in speed. Enjoy it offroading through the water though. ;)
 

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Global Roamer Corporation

You probably won't go much faster with the diesel. Maybe a bit. It will be a quieter though.
Agreed! Mine topped out at 80KPH with 235/85/16s and Roamerdive OD.

The two happiest days of NA diesel series owner: the day he buys the truck and the day he sells it. I remember those two days of my life very well....
 

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Series NA Diesel

Jruhl,
The guidance offered here on the alternator, speedo and fuel level issue is all very good information. Regarding your question on an Overdrive for your truck. I have a 66 NA Series IIA diesel 88 and after driving it for a couple years, I decided to install an overdrive gearbox. After evaluating options, I chose to go with a High Ratio gearbox. Prior to making this change, the truck would comfortably return about 24-25 miles per gallon of fuel with a comfortable top speed of around 52 MPH. With the high ratio installed, and with ten years of driving, the truck will return 26-28 miles to the gallon and can drive at 65 MPH with some room to spare. When I've provided this information to folks that have recently bought a diesel or are contemplating a diesel install, I always strongly advise going through the entire chassis/driveline of the truck, especially if you anticipate driving at highway speeds for extended periods. The high ratio gearbox will increase your gearing by 33% on the high range side and leave the low range side as standard. The caution is; Basically, if your intent is to run the truck out of its intended original design speed range, you need to really be sure the rest of the truck is up to the task. - Mark
 

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Jruhl, The guidance offered here on the alternator, speedo and fuel level issue is all very good information. Regarding your question on an Overdrive for your truck. I have a 66 NA Series IIA diesel 88 and after driving it for a couple years, I decided to install an overdrive gearbox. After evaluating options, I chose to go with a High Ratio gearbox. Prior to making this change, the truck would comfortably return about 24-25 miles per gallon of fuel with a comfortable top speed of around 52 MPH. With the high ratio installed, and with ten years of driving, the truck will return 26-28 miles to the gallon and can drive at 65 MPH with some room to spare. When I've provided this information to folks that have recently bought a diesel or are contemplating a diesel install, I always strongly advise going through the entire chassis/driveline of the truck, especially if you anticipate driving at highway speeds for extended periods. The high ratio gearbox will increase your gearing by 33% on the high range side and leave the low range side as standard. The caution is; Basically, if your intent is to run the truck out of its intended original design speed range, you need to really be sure the rest of the truck is up to the task. - Mark
solid advice
 
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