2.7 TDV6 RH camshaft pulley spoke failure

[twr7cx]

There's been a number of failures of the 1311317 RH Camshaft Pulley on the 2.7 TDV6 engines. On all pictures that I've seen it's the spokes of the camshaft pulley that look to have failed. Anyone determined a cause on why these metal spokes are letting go? Has anyone started to replace this pulley as part of the timing belt procedure now to avoid metal fatigue? How common is this issue? Are more happening now as the engines age?
It seems that a few have been very lucky where the failure has resulted in just broken rockers (rather than valves and pistons) and not written the engine off, but many don't seem to have had the same fate requiring a replacement engine.

The LH side has a different pulley design and I've not heard of that side failing.

Have any 3.0 TDV6/SDV6's suffered from the same failure issue (or do there cranks die first)?

[Eric SDV6SE]

Can't say I've seen that before. Indicates side loading on the pulley, which could occur by incorrect belt fitting procedure, as in trying to walk the belt on in order to avoid removing the tensioner.

These spokes and cam wheels are normally radially loaded, meaning the spokes would be in compression and are usually ok for a casting. However, they do look skinny, and a decent aftermarket billet unit would resolve that issue quite easily.

[Graeme]

The same pulleys were originally fitted to the 3.0 although in more recent times the part numbers for both the left and right have been superseded.

[twr7cx]

The same pulleys were originally fitted to the 3.0 although in more recent times the part numbers for both the left and right have been superseded.

Interesting.
Microcat lists:
1311317 for the RH
1324372 LH
for all the 2.7 TDV6 and 3.0 TDV6/SDV6 in Disco 3 and 4.

[Graeme]

The latest part numbers appear to be LR120556 (RH) and LR120557 (LH).

[DazzaTD5]

Yes common enough to be yet another point of failure.
Ive had them come in for a normal timing belt change and it was broken.
Other engines have stalled or running on the left bank which unfortunately is engine replacement.

I dont think its in the items to replace when doing a timing belt change though.

While its easy sometimes for repairers or others to list it as an item to change out, its not always in the budget for owners.

[oka374]

I'm no engineer but the design of the pulley is pretty suss, the spokes are relatively thin especially when you take into account the width of the belt and pulley and also how the spokes are right at the front edge which would lead to the aforementioned side loading causing the failure.
It should ideally have been a machined part rather than cast as cast doesn't handle flexing very well.
Designed and machined out of an appropriate metal would be the ideal way to make it.
How are the superceded ones made?

[twr7cx]

The latest part numbers appear to be LR120556 (RH) and LR120557 (LH).

Interesting.
Land Rover's own page seems confused about what they suit. At LR120556 - Land Rover Pulley | Jaguar Land Rover Classic Parts it lists Discovery 2010 onwards in the top right blurb, but doesn't include them below in the Part Applicability section.

[twr7cx]

The Land Rover instructions for installing the timing belt only indicate that the window alignment with the groove is the start point to be set at - there's nothing stating that's where it needs to stay.

The instructions state:
Step 4: align the tensioner window with the groove and torque to spec.
Step 5: torque the camshaft pulley bolts.
Step 6: remove the special tools from the camshaft pulleys and flywheel/flexplate.
Step 7: rotate the engine two complete turns clockwise.
Step 8: refit all the special tools to confirm alignment.
Step 9: remove special tools and reassemble.
There's nothing about rechecking the tensioner position, or that it shouldn't move from where it was set at it initially. It's open that the initial setting was just that - the initial setting and has no relevance to where it should remain.

Now I'm certainly not arguing that this is correct, just attempting to explain the thought process that can result in the tensioner not being readjusted post two clockwise rotations..

An alternative installation direction that I found online is:

The advice for checking after two rotations is as you say to see if everything lines up as before, but also that the tensioner window remains the same. The tensioner is designed to self adjust as the belt stretches over time, so some movement has to happen or the belt would run slack and jump the teeth. However, during installation it should not have any appreciable movement after crank rotation, and needs to be reset if it does. Something has gone wrong during setting. (initial belt teeth not seated or pulleys not adjusted correctly)