Help with no crank issue

[Shanto]

I bought a 2006 ram 1500 with a 5.7 engine from my friends company.
They sold it because they were told by the dealership that it needed a new engine. So i wanted to test it first to see what exactly was wrong and if it was worth fixing before a complete replacement. The battery was dead and had massive corrosion build up on the terminals when i picked it up so i replaced it with a fresh battery off the shelf. the one i had handy was only 600 CCA.
When i tried to start it it turned over a few times very slowly and then the starter just clicked. try to start it again and all you get is a click. if you hold the key for a couple seconds both battery cables start smoking. positive smokes more.
with a volt meter hooked up its dropping from 12.6 to 6 volts when trying to engage the starter. being that the battery was fresh i suspected that the battery cables may be questionable. So i removed and sanded down every corroded terminal and bolts connection on both the positive and ground cables as well as the fusebox. However i am still getting the exact same issue. Im wondering if the battery terminals themselves might be bad because they look to have been replaced before and im afraid the corrosion might have traveled down the cable.


Today i got a phone call from my friend who works for the company i bought it from and i asked him some more details.
Basically he told me the boss (whos not mechanically inclined) was pulling a trailer on the freeway and the engine died. said he pulled it over to the shoulder and tried to start it and all the dash gauges were flickering and lighting up (like a dead/bad battery connection). They towed it to the dealership and he says the dealer was vague but said it needed a new motor.
His company usually fixes everything without questioning the dealer, but since the truck was a bit older of the fleet they decided not to fix it. So i wonder if the dealer even diagnosed the issue or just tried to sell them a motor they may or may not need.
you would think that if the battery was corroded and dead they would have at least cleaned the connections or tried a different battery to diagnose the "bad engine" condition. nothing was stored in the memory when i hooked up my scanner to it.

Basically, i think i need to replace the battery cables and put the correct battery in it to see if i can get it to crank over so that i can do a compression test. I considered removing the positive cable from the starter and bypassing the battery directly to that connection to see if i could get a good crank out of it. sort of isolating the cable to see if thats the issue.

was curious if any of you guys that are more experienced with these trucks may know of any common issues that could cause something like this..

it has 200k on the clock, but its practically all highway miles. it also has a rebuilt transmission and differential with a completely overhauled a/c system. so if it needs a motor, im ok with it. but even with a new motor i would still need to address this electrical issue. so first things first

thanks guys,
Shanto

 

[TERRY G ABNEY]

I would see if there are any engine codes ,,but if it shut down on him it could be a number of issues an very fixable,try as you described to see if you can get it cranking better , you could pull starter an have it checked,,see if the engine turns over with a socket if you can get one on the front pulley somewhere ,,if engine spins easy manually that way then something is slowing the cranking , could be cables , battery ect .. maybe something else ,,rare but I have seen a starter lock up on a manual transmission setup that the vehicle would not roll

 

[Shanto]

There are no codes stored at the moment. so no luck in that regard.

i plan on tinkering with it this weekend. confirming the engine turns over by hand was next on my to do list.

i do also want to test the starter. in auto shop we used to put them in a vice and jam a 2x4 into them and engage the solenoid. maybe not the best way to test but it sure was effective.

i would also like to mention that i am getting full function of all the electronics/lights in the truck. just not enough juice to crank it.

are OEM battery cables the way to go?

does it sound logical that if the battery/cables were in poor shape it would have caused the issue im experiencing?
you would think that once started the alternator would keep it going, but if the cables from the alternator to the fuse box were bad too maybe it wouldnt be able to provide enough amperage to function?

 

[BWL]

If the starter is engaged, but can't spin the engine then it will start smoking from overload. Best bet is to try and manually rotate the engine from the front main pulley thats linked to the crankshaft. If you can't get it to turn then it's seized. It may be it was low on oil and seized up. He tried to start it and held the key on too long trying to get it to crank and overheated the starter. No code for a seized engine.

 

[JohnnyMac]

Agree with BWL. I'm guessing that either motor is super tight and the starter is drawing way too much current or the starter itself is burnt up. For the vdc to drop to 6 while cranking is an indicator of either a bad battery (which you say is good) or something causing way too much load on the battery. Unless the cables are burnt and cracked, they're probably fine. Maybe pull the plugs and look for any metal stuck to them that would indicate that the engine burnt up and try cranking with no compression.