Slow Cranking V6, new battery and starter...stuck engine?

[doubledeala]

Working on my uncle's LS. Not sure of the history on this car but it's been sitting dead for about 5 months. He just got back in town and wanted to take use his car again.
It cranks very slowly, probably 2 slow 'whirs' and quits.
At first, I thought it was the battery so I tried to jump start it. Didn't work. Had battery tested and replaced as a result of, figured it needed a new battery anyways.

Pulled starter out had it tested, all good. Put it back in, slow crank.

Checked voltage drops and honestly, I was in a hurry and it's freezing out here so I might have missed something or did something wrong.
The battery is wayyy too far to connect my multimeter from the battery terminal to the starter so I connected a jumper cable to the negative terminal and connected my multimeter leads from the cable to the starter body and then the cable to battery positive. Repeated for positive terminal on battery to starter positive post.
While cranking - From neg terminal to starter body, very low, like 2 mv. Neg terminal to battery positive...7.XX V - which is telling me some power is going through the multimeter and not the starter.
Cable resistance issue? Maybe. So I took jumper cables and connected neg battery terminal to starter body, battery positive to starter positive post.
There should be a straight line to the starter so any resistance in the previous cable would be negated by the jumper cables right? They're pretty hefty jumper cables so I'm sure it can carry the current.


So, I check the oil, bone dry. I'm thinking the engine is locked so I pour in new oil and now I'm at a standstill.
Starter can't rotate with locked engine so it's causing high resistance and current decides to flow through the multimeter -- my theory.

It's an auto so I can't just push the car to rotate the crankshaft. It's a very tight fit in the engine bay to get to the crank pulley.
My cousin is in the process of removing the radiator and intake manifold to pour some diesel down the spark plug holes and turn the crankshaft pulley by hand. Cross fingers...

Any suggestions thoughts or commens?

 

[oddball]

Er. Your voltmeter analysis is a bit off. If any current related to starting was going through your multimeter, it would melt. Starters pull 200 to 300 amps while cranking.
The 2mv ground potential difference is almost certainly within the noise of your meter's sensor, and one would expect a difference due to the massive current and the negative plane runs through the body.
Your jumper cables would have to be 2ga or larger to handle the load without getting warm, which I highly doubt. It's hard to find 4ga jumpers. Common ones are 8ga or 6ga.

The test where you got 7V is useful. The voltage while cranking shows how healthy the battery is. 7V is a little low but not terrible.

So does the engine turn at all now? If it's totally locked, then there aren't many options besides pulling it.

For future reference, when jump starting, you may need to leave the good car running and connected for several minutes (10, 15) to get a base charge in the dead battery, and keep it running while cranking the dead car. It also helps to keep the good car running at ~2000 rpm.

 

[LS4me]

How cold is it? When I was in Oklahoma City for ATC school in January it was so cold the engine wouldn't start. It would do just what you described, but wouldn't fire-up!

 

[doubledeala]

Er. Your voltmeter analysis is a bit off. If any current related to starting was going through your multimeter, it would melt. Starters pull 200 to 300 amps while cranking.
The 2mv ground potential difference is almost certainly within the noise of your meter's sensor, and one would expect a difference due to the massive current and the negative plane runs through the body.
Your jumper cables would have to be 2ga or larger to handle the load without getting warm, which I highly doubt. It's hard to find 4ga jumpers. Common ones are 8ga or 6ga.

The test where you got 7V is useful. The voltage while cranking shows how healthy the battery is. 7V is a little low but not terrible.

So does the engine turn at all now? If it's totally locked, then there aren't many options besides pulling it.

For future reference, when jump starting, you may need to leave the good car running and connected for several minutes (10, 15) to get a base charge in the dead battery, and keep it running while cranking the dead car. It also helps to keep the good car running at ~2000 rpm.

The current only flows through whatever device as it is drawn - multimeters don't draw much current at all.
Even if the jumper cables were too thin to carry the load, the power would run in parallel with the current cables and assuming equal resistance in both cables, total resistance would be fractional.

Correction - I got about 9v at the battery terminals while cranking, and 7v at the starter body/positive post -- that is what i used as a voltage drop but it could have just been that the multimeter leads weren't on clean contact points.

Without having watched the crank pulley while cranking, I don't know if it turns at all but the starter does sound like it makes a couple 'whirs', signifying the starter turning engine.

Jumpstarting did nothing for the car, same slow crank with old and new battery. I also trickle charged both batteries during and after all the testing.

 

[doubledeala]

It was probably 15 degrees outside the first day I started working on it. Never over 30 though.
I've got plenty of cars that start fine in below 0 weather so I don't think weather would really stop this car from starting.

 

[fudge12]

Do you still get the "two cranks and dead" issue? I'm leaning towards a bad starter. It's possible that the starter could be failing under load and working properly when taken out. Try replacing the whole starter.

 

[joegr]

... and turn the crankshaft pulley by hand. Cross fingers...

Any suggestions thoughts or commens?

How did that go? Seeing how much resistance there is to turning it by hand would at least narrow it down to engine or electrical. I'd certainly do that before taking a chance on replacing the starter. Do be careful not to turn it backwards. It you do, the timing chains may jump.

 

[doubledeala]

Do you still get the "two cranks and dead" issue? I'm leaning towards a bad starter. It's possible that the starter could be failing under load and working properly when taken out. Try replacing the whole starter.

I thought I mentioned it before but I did replace the starter after it burned out after all the testing. I've been careful not to do much more testing on the new starter, even though it's got a warranty. I just don't feel like replacing it a bunch of times.

Joegr -
It's been below freezing out and just don't feel like working on the car after work.
I PLAN on taking off the radiator or at least the fan to get to the crankshaft pulley. My sights are set on it though. Right now I've got diesel dripping into all spark plug holes.