Starter is turning over very slowly

[Edahall]

This is a continuation of the following thread:
Intermittent Loss of Electrical Power
http://www.thedieselpageforums.com/tdpforum/showthread.php?t=32658

I had a problem with intermittent loss of electrical power and ended up cleaning the connections that go to the starter solenoid. That fixed that problem. Now, another problem as crept up. The starter is turning over very slowly. It is turning so slowly that the engine is barely able to start. I noticed that when I removed the wires from the solenoid, that solenoid terminal stud was was not solid. It felt kind of loose. I wonder if this might be my problem. The only thing I can think of is that I might have a bad battery. Is there a reliable way to test the batteries?

[Gearstix]

If I remember right you can load test batteries. Don't know how to do that yet though. I know you can buy a load tester.

[76m880]

you want to have At least 850 Cold Cranking amps per battery, i found for me to get the most reliable starts i had to upgrade to a 31 series Batt. but you have to mod the batt boxes to make them fit.


Also if your batterys are not good they can Cook the starter, I suspect that the starter is bad or the Batt's are low

[DieselCrawler]

most auto parts stores can load test your batteries for ya... can test starter too, but not load test it, you already know it will turn over, all they will tell ya is that is does or doesn't turn over. But I do second that you need 2 good, matched, batteries, and a good, quick starter for best results...

[Edahall]

Another thing I should add is if I turn off the vehicle and immediately go to restart it, the starter turns quickly like it should. However, if I wait for 30 seconds or more, it turns over very slowly.

[76m880]

Another thing I should add is if I turn off the vehicle and immediately go to restart it, the starter turns quickly like it should. However, if I wait for 30 seconds or more, it turns over very slowly.

batteries :)

[spiff]

Given the loose terminal stud (if I understand what you're saying, I suspect the selenoid is toast. Is the selenoid constructed in such a manner you can tighten the stud?
Otherwise I see a new selenoid in your future. They're pretty cheap.

Lloyd

[Robyn]

The battery cables on these rigs (Side terminal) are a real source of issues when they get time on them.

If the cables are more than a couple years old, replace the lot of them.

The issues that can arise are bad connections where the cables are crimped to the ends.
The core of the cable corrodes and then all thats left to do the work is the outer few strands that are soldered.

The crossover cable that ties both batteries together often will not transfer power to the battery that connects to the starter.

Early trucks (92-94) had the main power feed to the chassis from the RH battery and the alternator tied to the LH battery.
If the connection on the LH battery becomes bad + or - then the system will suffer as the RH battery will receive little charge.

The later trucks 95 and up had the power feed off the LH battery to the Chassis as well as the alternator feed.

If one battery is sour then this would explain the quick response right after a shut down as both batteries are still up.

The best choice for batteries in these trucks is a pair of the spiral wound sealed cell units. Napa offers some as well as other brands (optima)

Two 800 CCA units would be a good idea.

Check the batteries (load test)
Replace the cables + and - on both sides as well as the crossover.

Replace the solenoid on the starter or if the starter has a lot of time, rebuild it.

The electrical system as it relates to the starting of these diesels is worked hard and requires things to be a top shape to function correctly.

Poor voltage and amperage flow in any rig with electronic controls is the root cause of many issues and driveability complaints

Be sure your cables are all top shape from the batteries to the starter, power relay box, to the grounds and so on.

This area is so often overlooked as the side terminal jackets hide so much.

A custom set of cables made using fine strand welding cable and soldering the ends on (Copper eyes) and using the top terminals on the Optima is a very good way to make the setup really sound.

If you do it this way, use the top posts and get some of the Marine type battery terminals that clamp to the post and have the little stud and wing nut.
Use Dielectric grease on the connection at the battery.

Best

Robyn

[DieselCrawler]

Robyn, you're post are always worth reading... lots of great info, detailed, easy but most inportaintly, fun to read...

As an electrician by trade, I'll second every thing Robyn said about good connections being top priority, along with good, matched batteries... meny of my starting woes have come from the issues mentioned there... 'cept for the time the cab filled with smoke when my ammeter gauge burned up! (some electician I am... long story)

best of luck on solving this issue...

[Edahall]

Thanks for all the helpful replies. That was a good tip to use top post batteries and use the little stud and wing nuts to clamp things down. That happens to be my current setup and it seems to work very well.

I had my batteries tested yesterday and one battery failed the load test. The battery that failed happens to be the older of the two batteries. I'm going to buy a replacement tomorrow. What are your thoughts on mixing batteries (marine with a non marine /smaller battery with a larger battery)? The good battery is a non marine 750 CC. I want to replace the bad battery with a larger possibly marine 1000 CC battery.

[DmaxMaverick]

Non-isolated battery pairs should ALWAYS be of the same type and capacity, and equally important, age. If the batteries are not within a few months of each other, their characteristics will be different, and the collective lifespan and performance will suffer. To answer your question, no. Bad idea.

Also, what do you mean by "marine"? Deep cycle? Or marine cranking? What works in a boat is not always good for on-highway vehicles. A marine battery is not necessarily better than a "standard". Your off-the-shelf "standard" battery is designed for use in highway vehicles. Some better than others, however.

[76m880]

you want over 800 CCA

[Robyn]

Toss in a set of Optimas and let er rip

RC

[DmaxMaverick]

Toss in a set of Optimas and let er rip

RC

Yep. That'll do it.

[Edahall]

Update:
The problem with slow cranking is fixed. It was the battery. I replaced the old battery with a new Interstate battery and now the starter cranks over faster than I have ever remembered it cranking.

Thanks for all the help and tips.

[offrdk5]

Hope you got 2 new GOOD batteries. If you didn't you will be replacing the other one soon. Been there, done that, won't do it again!!!

[Robyn]

Ideally batteries that have to run as a pair should be matched and replaced as a pair too.
Unfortunately at times the cubic pocketbook :eek: says otherwise.
When the system suffers, a good carbon pile draw test of the batteries, each done seperately is in order, and the bad battery replaced.

I usually replace batteries in my diesels as a set, BUTTTTTTT there have been times that other things required $$$$ too and so a fresh replacement went into one slot only.

Best

Robyn