Today I got the car up on jack stands and was prepared to change out the PS pump. But I checked all the pulleys again and this time could get at the A/C compressor underneath. As suggested by Pistnbroke above, it did seem that the clutch could have some play in it.

BUT.

I ran the engine for a while, whilst underneath the car and got this nagging feeling that the sound was actually coming from the middle of the car... I shuffled back toward the transmission and it really seems that way. sounds to me like it's coming from the toque converter... Oh dear....

What I don't understand is how that rattle can be affected by the A/C and other drive belt accessories? I'd have thought they don't exert enough drag on the crank to get to back to the transmission!?

 

When the AC is not on you can put the stethoscope on the end of the AC clutch which is not going round and listen to the bearing .
If its the tranny you should hear it with the belt off .
If this grumble was the tranny don't you think it would have been reported on here as a common problem?

More videos, please.

 

Thanks... yeah I'm holding on to a little hope that it's still the compressor pulley so I've been looking for a replacement. But there doesn't seem to be any clutch/pulley kits available for the XK8 - the closest think I can find is this bearing: https://www.ebay.com/itm/12187285181...UAAOSwMoZcZDQL

I shot some more video yesterday I'll upload in an hour or so!

 

Here's the next installment - You might want to skip through some of the talking to get to the sounds underneath...!

In conclusion I did think the A/C pulley needs to be looked at... I have managed to find a few replacements here for example:
https://www.ebay.com/itm/NEW-Newpart...5el000b4500004

But for these kinds of prices I'm wondering If I should just get the whole unit and remove the bits I need from it now and keep the rest as a spare or incase I can't just get the pulley off in-situ!

 

Hi,
You may have two separate issues here.

There is still a low-level rattle apparent with the belt off, and I agree that it sounds to be coming from the transmission. Note the torque convertor has been replaced (ZF didn't ever put 'Barney Purple' coloured parts in their trans, AFAIK).

You might feel a tiny bit of end float on the compressor pulley, but any wobble would indicate a failing bearing. Perhaps replace the pulley bearing as a first move if everything else looks OK?

Take a look here:
https://www.rockauto.com/en/moreinfo...&pt=6628&jsn=8

...before considering the bearing that you linked to.

I sense you're getting a taste of the (probably irrational) affection that most of us have become addicted to, and they are something special to drive IMO.

Weight is around 2 tons.

 

Haha yes that purple torque convertor is a puzzle... I guess it means it's been looked at before, so I'm not sure if any conclusions can be drawn from that?!

I'll try and get a quote and timeframe tomorrow for someone in Houston to do the trans fluid change and maybe investigate a bit... And that will help me decide whether to attempt it myself - it looks a bit tricky but not impossible from what I've seen...

And yes a bearing...Maybe I should just get the whole compressor unit and use the pulley from it, saving the rest as back-up...

I certainly am spending an irrational amount to time thinking about this cat...! And I'm usually a dog person...

 

WTF are you doing with that jack ...that not a structural member. Sounds like the flywheel is scraping on the casing...have you checked the fore aft movement in the crankshaft ? The thrust bearings could be worn ..you can usually change after you take the sump off . The load on the belt could be pulling the crankshaft forward or backward moving the flywheel just enough to touch the casing.
Anyone know if the thrust bearings are either side of the centre crank bearing or at the rear ?

 

Listening to yours and mine I am more and more convinced that the flywheel is catching on the bell housing case.
This is caused by a slight misalignment in the aux belt run which has worn the rear crankshaft thrust bearing . ie the crank pulley is aligned slighty behind the others so the tension pushes it forwards wearing the thrust. When you turn on the AC this puts load on the belt which pulls the crank forwards.
One crazy way to check is this ..if you have an old aux belt cut off one of the belt grooves with a utility knife so the belt is narrower then fit it to the rear grooves of all the pulleys except the crankshaft where you fit it to the front . This will push the crankshaft back towards the gear box. If the noise goes change the thrust bearings.
Changing the thrusts is easy . Drain oil . remove sump pan . take off centre main bearing cap which gives access to the thrust . Replace at about $10 each ( fit many US fords /bronco etc ) Replace and torque up the bearing cap etc.

 

Hmmm that does seem to make sense thanks!
move ordered a used compressor unit so hopefully the clutch bearing will be good in it and I can switch that out… at the same time, if it is that straight forward and inexpensive maybe I should replace the thrust bearing too… I wanted to do an oil change anyway.

And I was under the impression that was a jacking point?! There’s an arrow on the plastic valance covering the cross member that points to it… I think it’s even in the handbook?! 🤔

 

You're OK with the jack (see attached) as it's a dry-state car I'd put a wood block between though to help save the plastic cover

 

Did not look like the aluminium cross beam to me .
Having looked at a just purchased manual the thrust bearings are in the centre of the crankshaft ..remove the cap and push them round and out . there are only two half bearings .
Mine makes the same noise but as the air con would not be used much in the UK ..already too cold...mine is not so worn.
Might try a small pri bar to see if you can move the purple part back and forth though you should use a dial gauge to check the movement.

 

Excellent... I have some ramps coming today so that should make things easier... And I've received a used compressor to hopefully get the pulley off.

Are you really in Coventry btw? I grew up just outside of there!

 

Yes living in rugby at present but spent working life specializing in vehicle fault diagnosis and have consulted at all the local car factories. So perhaps my 6 groove belt idea is not so daft.

 

Having researched the thrust bearing issue it seems its not possible to replace the thrust bearings in situ.
I am going to order a new aux belt and trim the old one to 6 grooves fitting it to load the crank inwards. My scrap noise is very minor . Any signs of scratching on that purple paint? The hole you are looking through should have a mesh over it to keep stones out . Maybe a camera probe to look behind the flywheel.
Unfortunately unless you have a heated garage working on the jag is out of the question unless its serious as its now too cold in the UK

 

Yes it does have some scratches on it, they seem quite random though, not like something that has worn or rubbed over time.. maybe a stone got in there or something? It does seem quite exposed like that...

My mum lives in Rugby! I spent much of my late teens staggering around the town center from pub to pub haha

 

I got under the car just now and can confirm that there is a little torque converter movement back and forth when levered with a screwdriver… I guess that shouldn’t happen?! 🤦‍♂️

 

So check if this if also at the front of the crankshaft ....

 

Did you give up ? Return it or sell it ? Go to england etc ...no reports for a while . I must admit those seats would put me off .....
I have my new aux belt so I am going to cut the old one to 6 ribs and wind it to push the crank shaft back as I have a very small chirrup from the bell housing end . Will let you know soon as its only 2 degrees at present

 

No I haven't given up! My work is kinda 'Feast or Famine' and it's been a busy time so I've been driving around a lot with clenched buttocks... so far so good, the noise is still there.

Today I got around to switching out the A/C pulley with the used eBay unit I got... The rattle is certainly better but the replacement was also not a great example... I painted myself into a corner with it unfortunately because I need the car during the week so I know I have to find a new bearing and do the whole thing again... It's not a nice job but at least I know the bearing no. I need now and what I need to do it. The A/C doesn't seem to be working as well so I think the parts from the used unit were worse in some respects...it's cooler here now so at least I don't need the A/C so much and I can put the new bearings into the good pulley and pressure plate soon.

I still hear the low vibrating rumble coming from the front of the transmission so I'm looking forward to seeing how you get on with your de-ribbed belt. I went along to the local Jag indy here in Houston and he basically said that it sounds like the transmission has been rebuilt and something might not have been done right. But if it's running fine then just keep driving until it's not and at that point it will need a proper rebuild... I kinda take his point, I thought I could just get him to do a filter and fluid change and have a look at everything and see how it looks but it's $500 for just that. And it will need to be done again if the tranny is pulled down the road.

I'm flirting with the idea of finding an old transmission that I can buy and rebuild in the meantime to have ready to go....

 

I did the 6 rib belt ..you need a bandsaw ( or electric fret saw ) to take one off ..its too tough for a utility knife.
Fitted and started up and the grind diminished to zero after about 30 seconds. Tried again today and it was gone.
Now to your last post.
I dont think your problem is in the gearbox part but in the torque converter which is nearest to the engine.Seems to be touching the housing. So changing the fluid will not help.
I still think the problem lies in worn crankshaft thrust bearings allowing the torque converter housing to move forwards.
Critical to your diagnosis is to check for play in the crankshaft fore and aft movement. Lever the crank pulley back and forth to check for play. This will be the play in the thrust bearings ( which you cannot change in situ).
After a more extensive test I may try to move the crankshaft back slightly with a washer behind the front pulley which will cause the belt to produce rearwards pressure. My problem is slight yours needs more investigation to see where it is touching the housing
2or 3mm turned up on the lathe. from what I can see it just has a keyway