Failed Attempt

[Reno81K20]

Today I went to pick up an 85 C-20 Silverado not far from my house. Once I got there with my brother, we tried jumpstarting the beast and it was a no go. I brought the battery out of my 81 K-20 to see if that would help. Again no go.

So we tried a variety of things. Still this truck would not sputter or spit. I did notice that the ground wire from the battery to the engine had been modified so it grounded on the frame rail and then continued on to the alternator bracket. Im thinking this may be the issue. Either that or the cables are just fried and need to be replaced.

Even when we had the jumper cables hooked to my brothers truck the 85's motor would barely crank. Is there something else I could be missing? The tow truck will drop this new to me truck off tomorrow. So I might be able to try working on it on my next day off.

Pictures to be posted soon, The 85 will be a donor for my 81. I can't wait.

[old Rusty C10]

first off check the condition of the cables and their connections then if the battery is bad jumping it will not help

[walkerb]

Is it a stick truck?

[71swb4x4]

If it's turning over than it's probably not the ground.
When was it last run? If it's been a while I would start by pulling the plugs and checking their condition, hopefully none of them are rusty. Then squirt a little oil in there and turn the engine over by hand.

[Reno81K20]

Thanks for all the info. Its an automatic truck. And im not sure when the last time it was ran. I don't think it was too long ago, maybe a month. Once it gets dropped off I will definitely pull the plugs and give them a once over.

Im not really worried about this truck running yet. I will be pulling the bed off and putting it on my 81 K-20 4X4 and maybe swab cabs as well. It would be nice to have power windows instead of window cranks to deal with. And then comes the 6 inch lift and all the fun stuff.

Again thanks for the info and things to look for.




Is there an "Introduction" thread on here anywhere ?

[Reno81K20]

Problem fixed. I got home last night and the seller had dropped off the truck to my house. Seems the problem with it starting was due to the slight incline it was sitting on?? HHmm . But they were able to get the truck started and drove it to my house. Still think I will change out the battery cables and put a fresh battery in there to see if the problem still exist.

Thanks guys for the input.



Chris (Reno,Nv)

[wilkin250r]

You might be surprised at how much juice it takes to cranks a starter, especially these old starters with no gear reduction. Your 12V is actually about 13.5 at full charge, but if that drops down even to 11 volts you're probably not starting. And below 10V you can't even jump start, the battery actually becomes a drain on the donor vehicles electrical system and pulls too much power away and doesn't pass enough to the starter.

The jumper cables are also a bottleneck. They aren't designed to pass full cranking amperage through them, they are designed to provide a small boost to the existing system on the dead vehicle. Just another reason why it may be difficult/impossible to jump start a vehicle with a completely dead battery.

I'm glad your new truck finally got started. I highly doubt it was the incline that made it not start initially.

[franken]

A charged battery is 12.6V. With the engine running the voltage is closer to 13.5.
A battery even a few tenths less than 12.6V needs a charge.

[wilkin250r]

Just to clear the muddy water for anybody curious, both Franken and I are correct, but we're talking different circumstances. Real life is rarely ever black and white.

A fully-charged battery is indeed 12.6~12.8 volts. Most automotive batteries will hold an additional small surface charge, and if you take a meter to it directly after charging, you will usually measure 13+ volts. This surface charge doesn't last long once you put a load on it, even a small load, so it's not really considered part of the "charge". Take a battery at 13.5V and run your headlights (no engine running), you'll watch your voltage drop from 13.5 to 12.6 within a minute, then it will hold at 12.6 for the next couple hours.

Just for the record, this isn't a "I have to be right" moment, that's not why I'm posting this. I just don't want people to get confused, because if you pull your battery off your charger and take a meter to it, you're likely to read way over 12.6V

[Reno81K20]

Sorry I havent been posting updates. Work keeps getting in the way.

I tried starting the 85 C-20 the other day and it still cranks over very slow. And I had to add a bit of gas to the carb, then it fired up. My brother is telling me it may need a new fuel pump. Personally Im betting it may be the cables and possibly the starter. At the end of this month I have a week off. So I plan on pulling the starter and getting it tested. Ordering new battery cables and battery, and will look into a new pump and some fuel lines.

Currently Im still deciding what I want to do with the 81 K-20. Think it may just get a 6in lift 35's and paint. It will be a long term project for sure.

[Corts60]

Ensure that all cable connections are clean, as stated above. You grounds should be attached like this:

Battery to engine
Battery to body
Engine to frame
Engine to body

This will solve most of your problems I bet.

[wilkin250r]

I would start with the battery and cables myself. I supposed it's possible for a starter motor to get "weak", but the vast majority of weak starter motors are problems with the voltage (battery, cables, solenoid), not the motor itself.