Crank shaft damage/replacement spacer

[MMarkM]

Right so I'm terribly mechanically inclined so not really sure what the MD is talking about. To be fair the lady telling me wasn't either and I asked for a written report.

Car is 2019 Rapide AMR. The problem was that in 3rd, 4th and 5th gear at 5200rpm the engine would momentarily stop, I think "hesitation" isn't the right word as it felt like a complete loss of power so quite a jolt before power coming back on maybe a second later, maybe less than a second later. Under warranty and fair play to Harwoods sent a wagon to collect the car. They've called to day and explained this - " they've added/replaced a spacer on the crankshaft as it was found to be damaged"

That actually sounds quite worrying to me? Anyone else any idea what this is all about? I actually had exactly the same issue on my Vanquish S but was told it was a software issue, so could be 2 totally different things but the fault felt exactly the same

[oilit]

I would ask for an engineers report - to me it ‘feels’ like a cause versus effect scenario - is the damaged spacer the root cause or the side effect of a different root cause?

[F1NDW]

Mark you have done the right thing and asked for an engineers report. All they have told you is that it was the waffle sprocket and let the poor girl who won't have an idea what a crankshaft is tell you. I would be very pissed off with the MD.

[Nigel_O]

I'm modestly mechanically minded, although no expert on Astons. However, I'm struggling to see how a worn crank spacer could cause a momentary (but total) cut in power

I wonder if they mean a thrust washer, but it still couldn't cause a full power cut, UNLESS the ECU is smart enough to know when crank end float is excessive and it cuts the power

[CAPP0]

Nigel_O said:

I'm modestly mechanically minded, although no expert on Astons. However, I'm struggling to see how a worn crank spacer could cause a momentary (but total) cut in power

I wonder if they mean a thrust washer, but it still couldn't cause a full power cut, UNLESS the ECU is smart enough to know when crank end float is excessive and it cuts the power

I'm also modestly mechanically minded (I'm actually a qualified mechanical (not motor) engineer, but that was a long time ago), and alongside agreeing with everything Nigel says above, I would add that you can't just "add", or replace, a thrust washer on a crankshaft; not only are there fairly precise tolerances etc to consider, but the thrust washers are internal to the engine so you'd need to access the crankshaft in order to do so, which at a very minimum means sump off, (whether that's possible with your car with the engine in situ I don't know, and I somehow doubt they'd dismiss this in such an offhand manner if they'd had to have the engine out).

The only other thing I can think of as a possibility is that one of the sensors on the crank needs a (external) spacer in order for it to sit at the right clearance from the crank and that's what they mean? But why would something like that wear? Even if my assumption on the configuration is correct, they'd be unlikely to have any form of unlubricated interference fit, so what wears and why?

I'm quite sure someone with a far more intimate knowledge of these engines will be along to explain better than I can.

[MMarkM]

Mechanic just called me, cappo was right! It needed a spacer on the crankshaft sensor! So nothing to worry about!

[Dewi 2]

MMarkM said:

They've called to day and explained this - " they've added/replaced a spacer on the crankshaft as it was found to be damaged"

My engine rebuilding experience is limited to race engines for Mini Coopers, but that was decades ago.
I can remember the Mini engines having a pair of spacers on the crankshaft centre journal. You can only see or access them, when the crankshaft is removed. Obviously an engine out job on that car, because the gearbox is below the engine.

I wonder where the crankshaft spacer on the V12 engine is, and how much dismantling is involved to access it?



Edit - I have just read your post Mark. So the original explanation was nonsense.

Edited by Dewi 2 on Wednesday 15th September 19:11

[8Tech]

CAPP0 said:

Nigel_O said:

I'm modestly mechanically minded, although no expert on Astons. However, I'm struggling to see how a worn crank spacer could cause a momentary (but total) cut in power

I wonder if they mean a thrust washer, but it still couldn't cause a full power cut, UNLESS the ECU is smart enough to know when crank end float is excessive and it cuts the power

I'm also modestly mechanically minded (I'm actually a qualified mechanical (not motor) engineer, but that was a long time ago), and alongside agreeing with everything Nigel says above, I would add that you can't just "add", or replace, a thrust washer on a crankshaft; not only are there fairly precise tolerances etc to consider, but the thrust washers are internal to the engine so you'd need to access the crankshaft in order to do so, which at a very minimum means sump off, (whether that's possible with your car with the engine in situ I don't know, and I somehow doubt they'd dismiss this in such an offhand manner if they'd had to have the engine out).

The only other thing I can think of as a possibility is that one of the sensors on the crank needs a (external) spacer in order for it to sit at the right clearance from the crank and that's what they mean? But why would something like that wear? Even if my assumption on the configuration is correct, they'd be unlikely to have any form of unlubricated interference fit, so what wears and why?

I'm quite sure someone with a far more intimate knowledge of these engines will be along to explain better than I can.

This is what I believe to be the case. The air gap between the crankshaft trigger point and the crankshaft sensor was probably too wide and so the pick-up (sensor) has been moved closer to the crank. I am assuming here that the gap is fixed by means of shims (spacers) to get the gap correct although in most cases I have seen, the pick-up can me manipulated to a degree in a pinched housing......set the gap then tighten it up. I dont suspect it as wear as such, just not quite within tolerances from the factory, but close enough to work most of the time.
Where the MD has stated damaged, there is always the possibility that a small bit of road debris just happened the interfere with the sensor gap and moved or chipped it just enough to increase the air gap.

Edited by 8Tech on Wednesday 15th September 21:21

Edited by 8Tech on Wednesday 15th September 21:22