Troubleshooting - motor wont turn over

[Murray_Calavera]

Hoping to get a few ideas to help troubleshoot this issue, I'll try to keep it short. 

A mate popped the motor in his 2018 LDV T60 with the 2.8 turbo diesel motor. He swapped it and I was his phone a friend when he got stuck. 

The new motor is in, however it won't fire. The battery is literally brand new, when you crank it the volts very quickly (say 2 seconds of cranking) drop to 8 volts and the engine stops turning over. Watching the belts, I'd say they move about 5cm before coming to a stop. We put a booster pack on, no change. 

The only potential issue I'm aware of is, when we pulled the motor the grounding strap was still attached. The strap copped a thrashing before we realised what was going on. It looks okay-ish but it's going to be replaced to rule it out. 

The main challenge is, I wasn't there for 90% of the work. This is his first time doing any major work on a car and he was learning as he was going. He thinks everything has been put back together properly, however I'm not entirely confident that this is the case. 

It would be good to get some ideas about what else to check. The car isn't spitting any codes so that doesn't help. 

I've attached a photo, because why not lol. 

 

[joshuaho96]

15 minutes ago, Murray_Calavera said:

Hoping to get a few ideas to help troubleshoot this issue, I'll try to keep it short. 

A mate popped the motor in his 2018 LDV T60 with the 2.8 turbo diesel motor. He swapped it and I was his phone a friend when he got stuck. 

The new motor is in, however it won't fire. The battery is literally brand new, when you crank it the volts very quickly (say 2 seconds of cranking) drop to 8 volts and the engine stops turning over. Watching the belts, I'd say they move about 5cm before coming to a stop. We put a booster pack on, no change. 

The only potential issue I'm aware of is, when we pulled the motor the grounding strap was still attached. The strap copped a thrashing before we realised what was going on. It looks okay-ish but it's going to be replaced to rule it out. 

The main challenge is, I wasn't there for 90% of the work. This is his first time doing any major work on a car and he was learning as he was going. He thinks everything has been put back together properly, however I'm not entirely confident that this is the case. 

It would be good to get some ideas about what else to check. The car isn't spitting any codes so that doesn't help. 

I've attached a photo, because why not lol. 

 

I have seen a case where the starter motor shorting against the casing caused a massive voltage drop + so much EMI that it caused all the sensors to spew garbage data at the ECU. Test the battery to make sure it has acceptable CCA/capacity first, I have gotten "brand new" batteries before that couldn't even power a 10W light bulb without dying probably because it sat in a warehouse too long without being charged. Only easy way to diagnose this 100% is put an oscilloscope on the battery and also look at key sensors to see if there's any clues.

[MBS206]

52 minutes ago, joshuaho96 said:

I have seen a case where the starter motor shorting against the casing caused a massive voltage drop + so much EMI that it caused all the sensors to spew garbage data at the ECU. Test the battery to make sure it has acceptable CCA/capacity first, I have gotten "brand new" batteries before that couldn't even power a 10W light bulb without dying probably because it sat in a warehouse too long without being charged. Only easy way to diagnose this 100% is put an oscilloscope on the battery and also look at key sensors to see if there's any clues.

The easiest way would to be ignore the oscilloscope, grab a multimeter, and make sure all the main connections are right. An oscilloscope will give 99.9% of even technicians so much grief, as they have no idea what things should even look like on an oscilloscope. Which is also even more likely for someone who's first ever major work on a car is this

If the battery volts are dropping down so low, the LDV will reboot the ECU, when it does so, it will drop out the start circuit. If this is occuring, the battery voltage should also come back up.

Give it a few tests, even simple ones like when you're attempting to crank it, measure voltage from the engine block, to the negative terminal. You might find you've got really bad connections somewhere.

My guess is the "new" motor has something like a shit starter motor, at which point, you can swap the starter motor from the old motor, to the new motor.

Before I did any of the above though, I'd 100% confirm the battery in the vehicle. Most jumper packs are absolutely useless, especially if a battery has a bad cell for example. Also the new modern "jump packs" if you don't know what you're doing with them, you won't even get them into high current stage.

So go back to basics, check the battery, especially with a known good one as a replacement test.
Check ALL the wiring, this includes where they're bolted onto the battery, and bolted onto the starter motor.
Check all the earth straps are on.
Measure your resistances across your earth straps. A good check here is to measure voltage across the earth straps while you're trying to crank it. If you're seeing voltage, you've got high resistance joints!

Oh, and once you've done the above, check the battery over again.

[Murray_Calavera]

1 hour ago, MBS206 said:

If the battery volts are dropping down so low, the LDV will reboot the ECU, when it does so, it will drop out the start circuit. If this is occuring, the battery voltage should also come back up.

When you key off, the volts come back up to normal on the battery. Crank it and back to 8volts. We tried it maybe 5 to 10 times, same thing every time. 

1 hour ago, MBS206 said:

measure voltage from the engine block, to the negative terminal

I've never done this before, how do I do this?

1 hour ago, MBS206 said:

My guess is the "new" motor has something like a shit starter motor, at which point, you can swap the starter motor from the old motor, to the new motor.

Funny story. When my mate installed the starter, he only had the connectors done up finger tight. When we tried to start the car the first time, the starter motor got cooked. The new motor didn't come with any accessories, the starter motor in the car now is from a wrecker. I assume its good but can't 100% confirm. 

1 hour ago, MBS206 said:

Before I did any of the above though, I'd 100% confirm the battery in the vehicle.

The battery is like a day old, we bought it then started trying to get the car firing that day. I mean it is possible that a brand new battery is faulty, however after the above starter motor story, I'm inclined to believe my mates handy work is to blame and not the new battery lol.