Cold start issues leading to non starter

[Sprech]

Found a video. This is *exactly* what's happening. I would add the cranking speed on mine appears to be even slower than in the video below. I will ask the garage for a starter motor replacement.

VW Passat B6 2005 2.0 TDi 140PS No Start Condition - YouTube

Q: So if the starter motor is not going as fast as it should, could this explain why they found a fault with the engine speed sensor, with their diagnostics tool?
Q: How much should it cost to replace the starter motor - parts and labour?

[RichardSEL]

For goodness sake. Stop guessing. Start diagnosing! A VCDS Autoscan will show a drained battery condition by reason of its "Terminal B"
voltage readings taken at the time faults occur

Those are ridiculous times to check for a "drain test". Main agent (or VAG indie with VAS) will be doing a VAS diagnosis first (like a VCDS Autoscan) which they charge an hour for (it takes max ½ hour) And then will connect up the equivalent of an ammeter in series with the battery + lead to see what current's being taken when car enters sleep mode (shut down and locked up, no lights on, no one inside)

[Sprech]

I hear you. Would you attach the VCDS immediately after the first failed attempt of cranking?

[RichardSEL]

No, I attach VCDS on arrival. Perform an Autoscan and with that report see what each module is reporting. Then clear all faults in each module. So then you have a record of what's been reported in the past.
Next stage is to try start car. If there's very low crank speed or difficulty in starting then take another Autoscan and see what's happened at that time. If there's reports of "Terminal B" voltage or volts being reported as low (bear in mind unlike cars of old these electronic-controlled cars are very sensitive to battery volts) take it from there.

I wouldn't speculate until you have this info -- it'd point you onto the right track with the most recent info reported

[Sprech]

As the weather is now good, the problem has gone away. Starts first time. Called the garage to discuss, as I was meant to bring it in today, but if it starts first time I'm not sure they can diagnose much.

They suggested fly wheel clatter, and hinting it needs to be changed, although it was changed at 70K - it's done 108K. Here a video from this morning:

https://www.youtube.com/watch?v=6pHHr403A6c

Clatter? I'm not sure what it sounds like.

[Sprech]

They say they won't do an amp test with clamp. It's not something they normally do and they don't know how much a good starter motor should draw (they're VW/Audi specialists). I don't understand why.

They want to replace the starter motor because it's a reconditioned one - but from what I understand this is common. Some £200 + 1.5 hours labour. Considering they already cost me £500 for not fixing anything, I'm actually feeling a bit miffed to be honest.

I just don't understand why they don't do the amp test? Looks easy to me, apols but I'm no mechanic, but it should be possible to remove a fuse to the fuel pump, and then crank?

[RichardSEL]

As the weather is now good, the problem has gone away. Starts first time. Called the garage to discuss, as I was meant to bring it in today, but if it starts first time I'm not sure they can diagnose much.

<snip>

Lead-Acid batteries will deliver marginally more power (thus increase crank speed) in warmer weather rather than colder. That means your battery's nearly finished rather than fininshed. My old factory-fitted Moll was fine in summer and those last warm autumns we had. But come the colder winter, would give a lower crank speed. Perhaps could've taken it through to the next spring, as that winter was mild but didn't want to risk it if there was a freeze. It was my daily commuter

You can only get an indication of whether the starter motor's drawing too much current on startup. Battery volts should drop to minimum 11V-ish as motor cranks (this is on a petrol 2.0L tFSI, don't know whether TDi's figures are different). The series Ampere test they won't do is probably because they havn't got a series Ampere meter that reads up to 40A. I was suggesting the series Ampere test for the drain to see whether there's any current being taken when the car's "gone to sleep".

Halfords will perform a battery condition test. The meter they use is a high load taking like 30A and a voltmeter. This needs to be done after the car is parked up in their car park switched off for at least an hour to allow any internal current leaks (which is what old battery's also do) to discharge

Battery problems can be easily diagnosed with the dealer tool VAS or with VCDS. At this distance, don't know how else to help you

They suggested fly wheel clatter, and hinting it needs to be changed, although it was changed at 70K - it's done 108K. Here a video from this morning: VW Passat TDI - listening for flywheel noise... - YouTube
Clatter? I'm not sure what it sounds like.

Was it changed for a Dual Mass Flywheel or a cheaper solid one? Only had a manual Passat B5.5 for a year so no DMF problems' experience

[Sprech]

The car has had a brand new battery for a few months, so it's not that.

Why wouldn't they have an ampere meter? It's a clamp, not inline. I bet one can pick one up on amazon for 20 quid (whether it's accurate is another question)

I spoke to another vw specialist yesterday who suggested a simple RPM test on the starter motor... Sounds logical to me.

[niall campbell]

I think you need to check battery amps, should be 12.5volt when switched off and go up to 14.5 volt at 1,500 rpm with heater on full blast and lights on.

Batterys will show dud cells in cold weather and there is nothing to suggest that a new battery can be faulty neither.

It could be the alternator is not fully charging the battery

[RichardSEL]

What is the make of battery that this garage fitted? How much?

I've suggested a VCDS diagnostics Autoscan, but you havn't done that.
I've suggested a series Ampere meter check when vehicle has gone to sleep (multimeter would do this) but you havn't done that
I've suggested a Halfords battery capacity load test, but you havn't done that
I and others have suggested volts check when charging, and on startup, but you havn't done that

What's the point in us replying making suggestions on how to diagnose if you're not going to do any of them?