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. 

 

[GTSBoy]

2 hours ago, Murray_Calavera said:

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. 

Depending on exactly where that voltage is being measured, that is most likely the battery is f**ked. If the multimeter probes are on the battery's own terminals, then it is f**ked. If they are on the car's terminals, then there is a bad connection. Either are fatal to the attempt to start it.

2 hours ago, Murray_Calavera said:

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

Literally just put it on the 20VDC range, put one probe on the battery's -ve terminal (ideally not the car's terminal) and the other on the block somewhere exposed/metal, like an engine mount bolt head. You can also test the earth lead is steps, so from battery to body earth, body earth to engine connection point, engine connection point to some other spot on the engine, to see if you can isolate where a shit connection actually is.

[Murray_Calavera]

56 minutes ago, GTSBoy said:

If the multimeter probes are on the battery's own terminals, then it is f**ked

Yeah I had the probes on the battery terminals. 

58 minutes ago, GTSBoy said:

Literally just put it on the 20VDC range, put one probe on the battery's -ve terminal (ideally not the car's terminal) and the other on the block somewhere exposed/metal, like an engine mount bolt head. You can also test the earth lead is steps, so from battery to body earth, body earth to engine connection point, engine connection point to some other spot on the engine, to see if you can isolate where a shit connection actually is.

Sounds good. What reading should I expect to see in a car that runs well? 

[Duncan]

While I agree I'd start with a bad earth connection issue....I also reckon a new to the car/second hand starter is also cause for suspicion. Can you test it out of the car with a pair of jumper leads?

Also, if could be neither....does the engine turn over OK via the crank bolt? It could be an assembly issue and the starter is trying too hard as a result

[MBS206]

I'd enquire on the wrecker starter too. Likely it could be bad.

 

The check Duncan has mentioned too, is also a great point to look at.

If it was a wrecker engine too, it could be bad, OR it could have an issue such as being hydro locked. 

Pull all of the glow plugs out, and see if it will turn over. (I'm assuming that LDV motor has glow plugs).

[GTSBoy]

8 hours ago, Murray_Calavera said:

Sounds good. What reading should I expect to see in a car that runs well?

Well, all the power should be getting dissipated across the starter motor. Therefore, ideally, the voltage drop across the earth lead should be convincingly close to zero. Certainly you'd want it to be only a volt or so at max, because otherwise that volt doesn't turn up at the starter to do what is required. A car can probably survive a bad enough earth to crank and start with only 9V or so at the starter motor, maybe even a bit less.

But you're seeing only 8V at the battery terminals when cranking, so there can't even be that much available over at the starter, which simply won't do.

I would have thought that you couldn't pull enough current (with a healthy starter) to make the battery drop to 8V locally. But I was ignoring the possibility that the starter is in fact crook. If it has shorted windings (or maybe the solenoid is borked and shorting to earth) then I guess it could pull a stack of current and not even look like wanting to turn over.

So follow the other boys' reccos too. Because they are just as likely at this point.