PROBLEM SOLVED! It was a seized AC compressor! 2004 S60 2.5T, VERY slow crank, no start

[ericbeatty43]

It turns out that the problem was the AC compressor. It had seized up and would not spin for anything. I removed the serpentine belt and it spun like a top and started within the first second of cranking. Now I just need to get the mobile AC service to come over and remove the refrigerant so that I can replace the compressor.


Hello friends,

Here's the particulars. Both the starter and battery are brand new. I have thoroughly cleaned both terminals and cable clamps on the battery, the negative connection point in the trunk, the ground cable clamp from the engine timimg cover to the passenger side firewall, the mating surface of the starter and transmission housing, the heavy ground cable from the transmission housing to the driver side frame, the positive cable connections to/from the engine bay fuse box and the positive cable connection at the starter B terminal for the both the alternator cable and the cable from the fuse box.

In short, every connection point along the starter circuit is now bright and shiny and conductive. And yet, I've got a situation where the engine cranks very slowly and does not fire/start up.

Using my Fluke 77 multimeter, I've measured a total voltage drop of 500 millivolts (.5 volts) from the positive battery terminal to the B terminal on the starter.I then measured the following segments of the positve path:
Positive battery post to fuse block positive mounting stud = ~250 millivolts (.25 volts)
Positive cable eye on battery cable to cable eye on starter power cable = 10 millivolts (.01 volts)
Starter power cable eye to starter B terminal = ~250 millivolts (.25 volts)

On the negative/ground side, the total voltage drop is between 800 and 1100 millivolts (.8 to 1.1 volts) as measured from the battery negative post to the transmission housing/starter housing mating point.

Please note that all the voltage drops measured and described here were taken while the engine's starter was being cranked.

So - what have I overlooked? What am I missing? I've been wrestling with this for a few weeks now.

Thanks in advance for any advice or insights you can share!

[abscate]

Measure the voltage drop while cranking.

100 amps of cranking current will change the resistance if the cables are grungy…a highly technical EE term

[ericbeatty43]

Thanks for taking the time to read my post and reply.

I should have included in the OG post that all of the voltage drops that I measured and listed were taken while cranking the engine. I'm going to edit my OG post to include that information.

[br0dy519]

It's a new battery.. but what's the standing voltage on it, and is there any sort of current drawing the battery down when everything is locked and off? Try to knock out the simple things first.. the alarm siren has a history of drawing phantom power when it's failing.

[volvolugnut]

Can you measure actual voltage across the starter when cranking? Maybe also voltage across the battery terminals when cranking? Voltage drop info is good, but the cranking voltage is what will turn the starter.
What is voltage across the terminals of battery at rest? Not right after cranking. Measure right on the lead terminals if possible.
volvolugnut

[jonesg]

i would put a jumper cable directly to the starter terminal to eliminate the car elec system.

[Vova585]

Voltage drop while cranking? Sorry, but i dont think it is a right test here.
Lets bring it back to basics. Iflt sounds like we are dealing with hard start/low starting rpm which lead Eric on his chance of voltage drop.
1. Battery is new... but what happened to the old battery? Were you having the same starting issues with old one? What type of battery is this? Is this baterry fresh/charged and of appropriate CCA for the car?
2. Remove the battery and bring it to the place that can load test it. Electronic devices are ok, but they are only 50% right. You need proper load test with substitute load of about 35-40% of battery capacity and see if it is holding.
3. If the batery is testing with flying colors then I would reconnect it and put the booster pack with it and see if anything changes. Alternatively and faster, substitute the battery from other car if available.
4. If battery is 100% great- measure how much amps your starter is drawing. You can put a jump cable between chassy and engine ground closer to starter to verify ground pathway(quick). If it is totally better- amazing, you know where to dig. Nothing changed- hey it was quick.
5. Baterry and cables are good...
I would remove the starter(you already cleaned all the connectors at starter, terminals(have you checked for voltage drop between post-cable clamp, post cable after the clamp, post- ground bolt, post chassy? See if there is something basic that might be of an issue. ). And look at the insides. It is 2004 and if it is original, it is likely full has so much wear and full of dirt that simple cleaning and making sure brushes are adequate and easy moving, can help you. What about the bushings inside?

[vtl]

Unbolt the red cables from fuse box and clean all oxidation really well.