Slow crank

[I Bleed Blue]

Bought a 94 factory turbo idi with the turbo off cause it needed to be rebuilt. So I finished that installed it back on the truck. Now here’s my issue. Slow turning over! So I figured it was the starter since it hadn’t ran in awhile. Got it tested... it was bad replaced it. Also put two new batteries on the truck. Still same issue. It’s acting like the batteries are dead. Put a new starter solenoid on it same thing. Wondering if anyone’s had the same issue before I start chasing wires....

 

[Golden Helmet]

How do your battery cables look? In my experience, my truck is sensitive to bad cables. When my truck started cranking slow I replaced the positive cables and it felt like a brand new starter. A few years later it slowed down again, so I did the negative cables, and again it felt like new. After it slowed yet again, I got a new starter, and now it REALLY cranks fast

 

[IDIBRONCO]

You could pull the ground cables off of the block and clean the cable ends and the block where they mount really good.

 

[Tumbleweed210]

I...with the help of some othets...recently found that my 4/0 starter cable had developed EXCESSIVE RESISTANCE to current flow. And upon removal and autopsy, found the GREEN-GOO from Hades had indeed invaded the cable almost end to end.
The tell tale sign is a cable too hot to touch, and faint (or full on) smoke coming from said cable...or maybe just the ends.
The check is to disconnect and OHM that shucker. Every cable known to man has an acceptable OHM rating.

Anyhoo, budget only allowed for a 3/0 replacement, and it t'werks fer me.

Might fer you...

 

[BeastMaster]

Most of times I have seen something like this, it was a grounding issue, as everyone carefully inspects the path the current takes to get to the starter, but does not inspect the path back.

Tumbleweed posted one I haven't seen yet, but sure see how that could happen, knowing wicking.

 

[chillman88]

After you check the cables good...

Where did you get the new starter? Parts store remans are hit or miss these days. If you eliminate all the other options, you might need to exchange it.

 

[Tumbleweed210]

Summit...they've got a NEW (not reman) high torque model for the IDI; or at least they did two years ago when I got mine. Free shipperatin' too.

 

[DrCharles]

The check is to disconnect and OHM that shucker. Every cable known to man has an acceptable OHM rating.

Unless you have a really good ohmmeter (Kelvin connection, 4-terminal) the resistance of a few feet of 4/0 should not be measurable. (0.05 ohm per 1000 feet!) If you see any resistance on your Harbor Fright digital meter (on top of what it reads with the test probes shorted, that is) it's time for a new cable.

I recommend measuring the voltage drop between the ends of the cable, while under cranking load (several hundred amps).

Anyhoo, budget only allowed for a 3/0 replacement, and it t'werks fer me.

3/0 has 0.063 ohm per 1000 feet. It'll work just fine. You will never notice the difference between that and 4/0. Say your starter is pulling 500 amps on a cold day, and your cable is 5 feet long = 0.000315 ohm, * 500 = 0.16 volts drop in that cable.
The bigger 4/0 reduces that to 0.125 volts. Big deal.

Plenty of folks here want to spend the extra money for huge cable, but it's really a waste.

 

[dgr]

....

Plenty of folks here want to spend the extra money for huge cable, but it's really a waste.

But it feels so manly. Yeah, I gots a 420ci clacker clacker under there with 4/0 cables.

What's the VD on 2/0 cables?

 

[DrCharles]

Here ya go... http://www.interfacebus.com/AWG-table-of-different-wire-gauge-resistance.html

The stock cable IS 2/0... 0.079 ohm per 1000 feet. Note that these figures do vary quite a bit with temperature - but on a hot day you don't need as many cranking amps either.

Assuming the same 500 amps for a cold engine, 0.20 volts. Your cranking system can't possibly be in such bad shape that the difference between 0.20 volts drop (2/0) and 0.12 volts drop (4/0) will matter! Don't forget that the internal resistance of even a properly charged battery is several milliohms. The CA and CCA figures are rated at only 7.2 volts (not 12) after 30 seconds at 32F or 0F respectively.

I run a recently-replaced stock size cable on my huge manly 445 ci diesel with two batteries, and it works as designed... should be no problem on that little girly-man 420 ci

 

[dgr]

Good to know. I need to get some cables made for my stud style batteries

 

[pelky350]

Half my starting and charging issues have been issues with the battery cables in some way. Started getting a slow crank and poor charging and this time my grounds were barley loose where the terminal clamps onto cable. A half turn on each and it turns over at almost idle speed again. Makes a huge difference in starting with solid connections everywhere

 

[Tumbleweed210]

But it feels so manly. Yeah, I gots a 420ci clacker clacker under there with 4/0 cables.

What's the VD on 2/0 cables?

I tend to agree with yer assertion there sir...I let 'em hang freely and sing Basso_Tenore whenever the chance presents.......however;

As far as the three ought -vs- four ought...er...contravesy. I spent a sum total of $38, at me local Weld Supply(with ends crimped for me, because I don't own that tool).
I was replacing a 4/0 installated by the PO..that smoked fiercely every time I'd crank it up....and....

The kicker....I must say...was the hunerd dollar-plus price tag of the pre-made stockish replacement. Call me frugal if ya must...or somewhat cheap if ya want...at the end of the day I'm still singing Bass wit a couple o Jacksons and a George or three, in me pocket for fuel!

BTW: I was lookin at an ampacitty chart that started at ten foot...so's I durdent figure Drop would count for much. Right-O, learn sumpin knew every day!!!
Thanks for sharing!

 

[Pat Tavelli]

I had the same issue with my 89 idi. I was going to replace the starter with a gear reduction starter. Still may in time. But first I ordered new cables from Rock auto and installed them. Truck turned over like she was brand new. My old cables needed some love, but I didn't realize how much.