V12 crank damper for 6.0L

I create this as I didn’t want to resurrect one of the old thread, as those were really old (10+ years)

My early 6.0 V12 has a tendency to get low voltage on startup , while making belt noise, during the first seconds

after reading several threads about the crank damper being a potential suspect

I did the suggested test, ie mark the alternator pulley and the others, start / stop the engine , then check for relative movement

I didn’t hear noise on the 3 attempts I did, but when getting back bellow the car showed that the pulley is now on a different position :frowning_face:

the engine still runs fine, but I won’t take chances

according to Jaguar parts catalog
the PN for part #12 is either ebc9389 or NHF1411AA , none of those being available anywhere

so the questions :

  1. I marked 2 of the timing “star” (part #14) arms and the facing areas of the pulleys : is that correct ?
    (just in case …)

2 if anyone has a spare damper pulley for my 6.0 V12 , let me know
(4 pulleys, but with wide micro ribbed alternator belt, hence no chance to use the more commonly avalable previous design with V belt for the alternator)

3 I’ve read about damper rebuild, but those are in USA, any one got a place in Europe ?
as I doubt I can get a spare for this part, I’ll have to send this one and wait until it comes back)


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No need to mark timing star, it can’t move in relation to the crank position since it is bolted to the hub itself.
I have a 5.3 damper on my 6 litre. It was a little suspect so l rebuilt it using a simple alignment jig and polyurethane. That was some 8 years ago and had no issues.
If you can’t get the damper you need, or wish to rebuild another option could be changing alternator pulley to suit 5.3 damper drive.

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thanks for the feedback
I used the star a reference for the alt pulley, as it was easier to reach, and fixed to the inner part of the damper
before :

and after :

I’ll have another test using some different color paint

changing the alternator pulley might be a temporary solution to wait for the part being rebuilt


I may have found a source in Europe, and I’m expecting a definite answer .
It seems to have a new part, and the cost would be similar to a rebuild : I’ll believe it when / if I see it, and will report back

edit : 48h later, and no answer from the said source : not much hope this will go further soon :frowning_face:

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still no answer from the possible damper pulley supplier, so will try and call them next week

I did another test to take better pictures , no screeching noise either, but about 30° of rotation of the alternator pulley for a single start of the engine
(all blue dots were lined up facing one of the star branch before the test)

If you can’t find a replacement, I recommend Damper Doctor

He rebuilt my harmonic balancer on my 1972 XKE V12. Car is still in pieces so I don’t have any driving experience to report

thanks Craig
my concern is finding a transition part, as sending the damper to US and back will add significant delays

Baxtor’s suggestion could be a plan, as sourcing the 5.3 damper variant is easier, and would “only” need to swap the alternator pulley from 5 v grooves to single V

My 5.3 marelli damper has the polyvee alternator pulley. l believe the change to the ribbed belt happened at engine number 8S57572 which was pre marelli, so any marelli damper should do the job.
Chances are that any 5.3 damper you get will have the crank taper lock, l believe the 6 litre is parallel bore, but they are still a straight swap.

good to know that : I’ve seen several posts (including yours) confirming that fitting the 5.3 version to the 6.0 cranck can be done by forgetting the spacers
but I thought that the single V / ribbed pulley changed occured with the change to from 5.3 to 6.0L, hence de different part number for the crank damper
all dampers I’ve seen are single V, the ribbed version with specific part number being unavailable

according to jaguar parts, the 120 amp alternator was fitted to 6.0 and 4.0, from VIN 185820 - to VIN 188104, using a 55mm multi grooves pulley (JLM11149]) , while 5.3 used a Lucas alternator and single V

some variations in the final builds may have caused such changes

My 95 6 liter North American spec uses v pulleys.
And strangely, the A/C compressor has a double v pulley but only uses one belt.

I think as you say, the final build of v12s was using up stock on hand versus absolute blueprint. My vin is 1998xx

As far as l am aware, the xjs used the same bolt on v belt pulley for accessories all the way through to end. The single v belt for compressor is normal.
The change between v belt and polyvee only applies to the single (alternator only) drive on the damper itself.

I didn’t manage to reach the European source, but ebay seems to have a source for the 5.3

the “broken timing disk” thread gave confirmation of baxtor information about the alternator pulley

the easiest solution for me is probably to get the5.3 damper and a set of shims

edit : probably not the cheapest, though , as shipping and import fees add about 400$, so nearly tripple the cost :unamused:

some light in the dark, as I got contact with the European source through a German speaking friend : this seemed to help more than my English attempts
costs being cheaper than the shipping alone from US, order is taken, just need to transfer the money to them (no Paypal currently “for technical problem”) so there’ll be a bit of delay until they confirm they received it and process the order.
Estimated delay is about7 to 10 days : I’ll keep you informed of the results
crossing fingers :crossed_fingers:

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They did mine.
Fast turnaround and good price.


slight update : the company confirmed they received the money transfer, and my order is in process
still :crossed_fingers: until I receive it

final answer : the company can’t provide the part, their supplier does not make the part anymore :frowning:
(it needed 2 emails and several phone calls by a German speaking friend to finally have the answer )

I should get the reimbursment soon, but back to square one : I reckon I’ll need to order à 5.3L part from the ebay source, but need to double check the compatibility with 6.0 fitting

Why not source a used 6.0 damper in USA, have them ship it to Damper Doctor, and then back to you? Then sell your existing damper as used.

Car-part.com is a USA Based junkyard database search. They turn up a damper for a 94 XJ12 (which may or may not cross to the XJS). The seller is https://www.jag-land.com/ and no price is given.

thanks for the link
The idea was to get a part before taking my car apart, so that could be a way to do it.

I’ll search in Europe too
As baxtor suggested a 5.3 damper would fit the 6.0, I’ll have a seach on a wider part list

Moss seems to have the part too

I’ll ask them if they really have it available or just on their website

5.3 marelli damper will fit the 6.0 litre marelli and visa versa. Only difference really is one has taper lock and the other does not. Bore size same and location key positions and timing are all maintained.

XJ12 is different belt drive l believe. Needs to be XJS. XJ12 is Serpentine.