86 2.4D Cranks Slow
03-06-2020, 01:27 PM
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86 2.4D Cranks Slow
Hi,
I'm new to the forum. I have a 1986 2.4D long box standard cab pickup. Lately, it sounds like it is cranking a bit slower than usual when it is cold. My first idea was to measure battery voltage during cranking, using the min/max voltage setting on my multimeter, to check for bad batteries (it has two). While it has been sitting in the garage, it dips to 9.95V at the battery terminals while cranking. I'm going to try later and see how low it goes when it has been siting outside. The batteries are coming up on 6 years old, so I'm pretty sure they could stand to be replaced soon, but I'm curious what is a normal minimum voltage to read at the battery terminals while cranking.
I suppose the next logical step would be to check for minimum voltage while cranking at the starter itself, to see if there is any issue with the cables. I do not believe this could be an alternator issue, because the batteries are a solid 12.6V when the truck is off.
Thanks for any ideas/help
-Max
-Max
I'm new to the forum. I have a 1986 2.4D long box standard cab pickup. Lately, it sounds like it is cranking a bit slower than usual when it is cold. My first idea was to measure battery voltage during cranking, using the min/max voltage setting on my multimeter, to check for bad batteries (it has two). While it has been sitting in the garage, it dips to 9.95V at the battery terminals while cranking. I'm going to try later and see how low it goes when it has been siting outside. The batteries are coming up on 6 years old, so I'm pretty sure they could stand to be replaced soon, but I'm curious what is a normal minimum voltage to read at the battery terminals while cranking.
I suppose the next logical step would be to check for minimum voltage while cranking at the starter itself, to see if there is any issue with the cables. I do not believe this could be an alternator issue, because the batteries are a solid 12.6V when the truck is off.
Thanks for any ideas/help
-Max
-Max
03-06-2020, 02:02 PM
#2
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IF it were me, which you're not, but IF it were, I would take the battery into a auto parts store that does the free testing, and have them load test your batteries. That is what will tell the tale.
Before you do, though, pull the terminals off and clean the battery posts and the inside of the terminals. Use one of those battery terminal cleaners that have a hole with wire around it for the posts, and a wire brush to clean the inside of the terminals. ANY corrosion can have a very detrimental effect. If there's a lot of corrosion built up, clean it off with a mixture of water and baking soda on a toothbrush or something similar, and then use the battery terminal cleaner tool. Both the posts and the terminal mating surface should be clean, bare metal before you put them together. Same for where the wires connect to the terminals, however that is. Clean, bare metal, both the terminal, and the wires.
Having said all that, the voltage you should see at the battery positive terminal to ground is 13.9-15.1VDC with the engine running. With the engine off, about 12 - 13 VDC. Best way to be sure about a battery, though, is a carbon pile load tester, which most auto parts stores that do the free part testing have.
Good luck,
Pat☺
Before you do, though, pull the terminals off and clean the battery posts and the inside of the terminals. Use one of those battery terminal cleaners that have a hole with wire around it for the posts, and a wire brush to clean the inside of the terminals. ANY corrosion can have a very detrimental effect. If there's a lot of corrosion built up, clean it off with a mixture of water and baking soda on a toothbrush or something similar, and then use the battery terminal cleaner tool. Both the posts and the terminal mating surface should be clean, bare metal before you put them together. Same for where the wires connect to the terminals, however that is. Clean, bare metal, both the terminal, and the wires.
Having said all that, the voltage you should see at the battery positive terminal to ground is 13.9-15.1VDC with the engine running. With the engine off, about 12 - 13 VDC. Best way to be sure about a battery, though, is a carbon pile load tester, which most auto parts stores that do the free part testing have.
Good luck,
Pat☺
03-06-2020, 02:20 PM
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I just checked it again, after it had been sitting longer. This time battery voltage dipped to 9.65 while starting. Once running, it starts at 12.6, and builds up slowly to about 14, over several minutes. It wasn't struggling to crank though as bad as it does when it is really cold. I will leave it overnight and check it again in the morning, I bet it will go below 9V. I'm going to take your advice about the load test, and terminal cleaning -there are lots of nearby places who will do the load test for me. thank you!
Last edited by max_alberta; 03-06-2020 at 02:21 PM.
03-06-2020, 05:52 PM
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Took batteries to Canadian Tire, got them tested. Both tested good. Bought a battery post cleaner. Cleaned posts and terminals. The terminal on the passenger side battery ground had a big crack on it I didn't notice until after cleaning. I suspect truck was getting power from only one battery for last little while. Will buy new terminal tomorrow and see how it goes.
03-07-2020, 11:48 AM
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6 year old batteries are probably getting close to the end of their useful lifespan. Just something to keep in the back of your mind. Make sure their water is up to the right levels, in all the cells. Only use distilled water to add to a battery.
When starting the truck, the measurement you need in the amperage the battery(s) can supply to the starter, not the voltage, although, due to Ohm's Law, the two are inextricably linked. E=I*R, or voltage equals current times resistance.
Anyway, the battery should be able to provide 90 amps to the starter. It tough to measure amperage that high, though. You have to put the meter in-line with the path of current flow, and ensure the meter can take that kind of current. Most meters are made to measure tenths of amps, at most. Best to let a shop with the right meter do it. Otherwise, you'll be getting a new meter pretty soon.
Finally, did you check to ensure the heavy-gauge wire going down to the starter has nice, clean contacts at both ends? The end where it attaches to the starter can develop a lot of corrosion easily. It's a good place for oil, dirt, water splashing onto the contact, etc, can happen. Make sure the negative lead is off the battery(s) before you pull off the wire to the starter. Look at the terminal on the wire, and where it hooks to the starter. They should both be clean, and free of any form of "interference". Corrosion, dirt, oil, you name it, it's bad. If necessary, clean then with electrical contact cleaner, and if necessary, sand them both a little with fine-grit paper, until they're nice and shiny. Apply a thin layer of dielectric grease to both, and put them back together. I use that stuff everywhere. Both ends of the spark plug wires, any connector I have to take apart and put back together, etc. If it's electric, it gets the grease.
I wish you the best of luck!
Pat☺
When starting the truck, the measurement you need in the amperage the battery(s) can supply to the starter, not the voltage, although, due to Ohm's Law, the two are inextricably linked. E=I*R, or voltage equals current times resistance.
Anyway, the battery should be able to provide 90 amps to the starter. It tough to measure amperage that high, though. You have to put the meter in-line with the path of current flow, and ensure the meter can take that kind of current. Most meters are made to measure tenths of amps, at most. Best to let a shop with the right meter do it. Otherwise, you'll be getting a new meter pretty soon.
Finally, did you check to ensure the heavy-gauge wire going down to the starter has nice, clean contacts at both ends? The end where it attaches to the starter can develop a lot of corrosion easily. It's a good place for oil, dirt, water splashing onto the contact, etc, can happen. Make sure the negative lead is off the battery(s) before you pull off the wire to the starter. Look at the terminal on the wire, and where it hooks to the starter. They should both be clean, and free of any form of "interference". Corrosion, dirt, oil, you name it, it's bad. If necessary, clean then with electrical contact cleaner, and if necessary, sand them both a little with fine-grit paper, until they're nice and shiny. Apply a thin layer of dielectric grease to both, and put them back together. I use that stuff everywhere. Both ends of the spark plug wires, any connector I have to take apart and put back together, etc. If it's electric, it gets the grease.
I wish you the best of luck!
Pat☺
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