I recently picked up a '95, 40k on the clock, which has good records and seemingly attentive previous owners. Taking it out for a shakedown run, the accessory belts consistently squeal at higher RPMs. I know the most likely situation is worn belts, but what else should I keep an eye out for, accessory-wise? Common to fail bearings on air pump? Balancer would just be on start-up, right?

Intermittent airbag light was disclosed on sale. They tried a new module, so I'm thinking intermittent has to be clock spring, which looks like is not "currently" available from Jaguar. In the Jag parts world, does "Not currently available" mean temporarily or permanent? I'm experienced in the Porsche parts world, and a lot of the '80s model parts (for everything but 911s) are quickly becoming permanently unavailable (I have 3 new-in-box idle air regulators in the garage). Anything that needs to be stocked up on for another 30 years of running the XJ? Fuel injection/ignition bits, most likely?

Ends up the Euro mechanic in my town is a Jag V12 specialist, so I'll be in good hands (and broke). They're doing a post-purchase inspection, but want to go into it with correct expectations so that I'm not just dazzled by their experience and nod blindly.

Looking forward to discussing with you guys as we go on. Love the car. I mean, it's FANTASTIC.

 

Start=up squeal is the usual scenario, yes. But I don't see why it couldn't happen at other times.

Yes, fuel injection, ignition, engine management stuff. My V12 experience doesn't include the later models like yours so others will have to tell you which parts should be at the very top of your list.

Jaguar began phasing out X300 parts some time ago, bit by bit. I have doubts that anything presently NLA will become available in the future, especially parts specific to the lower production XJR and V12

Cheers
DD

 

There's a good list in this thread, watch the wrecking yards like a hawk, just like you do with Porsches, very similar situation with unobtanium parts.
https://www.jaguarforums.com/forum/x...rities-278596/

Belts: look at the belts from underneath (take the plastic under tray off if you still have one). That will give you a good idea of what's going on with them and the balancer. Check the belt tensions, alternator adjustment is from below, other two are on left and right sides from top'
https://www.jaguarforums.com/forum/x...-belts-203179/
pn's and advice.

Watch your cooling hoses for any issues, important that they are all in good shape.

In haste

 

There is an excellent X300 / X305 document made for the airbag test and there was a common issue with internal to the main control module ( light blue color ) located behind the passenger airbag , circuit board "safer " thermal fuse ( fuse replaceable) ( hard fault ) , but your issue is internment if at all

Your replacement main control module may have already had this fuse blow



See this link for different fuse part #s

Airbag Control module thermal fuse - Jaguar Forums - Jaguar Enthusiasts Forum

If you do have to source an airbag it can't be legally shipped by mail as has an explosive , so personally picking one up at a salvage yard works



There is an airbag self - test on every startup to have the light but not while traveling , see Normal Operation page 1 of the below attached Doc

The components of the airbag system will have a separate yellow wire harness to distinguish them with one ( safer module) above the engine ECU on the chassis wall

" Airbags for Dummies " by Brendan McPhilips as he works in the airbag industry from my understanding

See file at the very bottom


Most important thing is to not put a meter on the circuit unless the airbag is protected from blowing

See also :

There is a link with most of your tech docs and 6 part as I split large manual on post # 4

Repair Manual - Jaguar Forums - Jaguar Enthusiasts Forum

and

801S TITLE (jagrepair.com) starting on page 193 , you will have 2 engine management versions both mixed in this doc , later Nippon Denso ECU and earlier Lucas / Marelli as the ECU is located just fwd of the right front door hinge under a small cover

This will be a pic of a right hand steering model inline 6 engine ECU of the same location




See also these 2 for parts reference :

Search Genuine Jaguar Xj 1995 - 1997 (from 720125 To 812255) (x300) Classic Parts | Jaguar Land Rover Classic Parts

and this one out of Ohio with good service

Jaguar Parts and Accessories — Welsh Enterprises

Lots of stuff on E - Bay

The engine coolant temp gauge on the cluster is a dummy gauge and not accurate ( it can be modified ) and there is no overheat red light

On the V - 12 you should keep on top of the coolant system and it's workings to protect the V - 12

There is a V 12 engine coolant level and transmission ( a General Motors 4L80-E ) servicing level procedure for the V - 12 that those owners would know better about

Look for a orange dot on the transmission body in this TSB

08-2-03 (jagrepair.com)

 

Belt squeal might be fixed, famous last words. Gates has a nifty app for tensioning drive belts by frequency, Gates Carbon Drive, for bicycles and motorcycles that use belts instead of chains. Hold the phone microphone by the belt, pluck it, and it reads out the frequency.

A/C belt was a bit below the service manual re-tensioning spec, so after a minute of adjusting the idler the wrong way I finally got it back up to 90 Hz. Hit the starter between readings to even out the belt tension.

Is belt retensioning common, or is this the warning sign that the belts are about to go?

 

Belts in the past days where a time replace item of 5 years

To be more confident on the road and more yet to protect your V - 12 ..........................................

 

I’m of two minds on this. The belts on the engine are OEM labeled. I would think those are of higher quality than the cheapo stuff that’s made now. At 40k miles, it might only be at half its life on a quality belt, to be replaced with something of unknown quality since OEM is NLA.

 

A dilemma many of us face. And complicated by the fact that, nowadays, even ordering a Jaguar labeled part from Jaguar itself is absolutely not a guarantee that you'll get the same quality as the actual OEM part originally installed.

I recently bought an '05 S-Type with 39k miles. The cooling hoses appear to be original....and still in good condition. But running on 19 year old hoses is contrary to conventional wisdom. Do I change them? Am I really gaining anything if I replace them with lower-grade new parts?

Cheers
DD

 

Rubber parts service life is a function of time and not miles , belts even have a on the shelf in the store life date to be removed from the shelf

I could not replace something on a aircraft without following these rules including chemicals / adhesives

Depends on what risk you want to take and the consciousness of things going bad

 

Ends up the squeaky belt wasn’t the A/C-PS, but rather the water and air pumps. Which, on closer inspection, makes sense as that threaded rod was missing its locking nut on the opposite side.

Two things to note for the archives and future searchers, since I couldn’t find anything about it when researching. The threaded tensioner rod, EBC9087, is an M10-1.0 thread. Very fine, not the normal fine 1.25 pitch. I had a couple spare 1.25 nuts in the garage that started okay, but nearly stripped the thread off the rod as I kept working down. The nut should go down with fingers until snugging to the trunnion.

Also, I’ve gotten the tensioning direction wrong, intuitively, on both belts now. Turning the nuts in the direction of the open end of the threaded rod tightens the belt.

 

Welcome Jeremy! I just saw your intro post. Curious about the wheels on the car, what are they? I like them. Seems like the car was somewhat de-chromed. Not a bad thing, they really went all-out bling for this model in the USA.

FYI if you want to replace the airbag module, it is a generic Ford unit from the era. I recall I used a NOS unit for a Taurus. I have the relevant numbers from it if you want them. I did not try to replace the thermal fuse as pictured in my airbag unit above. Seems soldering a new one in could ruin the fuse? Also keep in mind that faults in the system if not corrected first, will likely blow a new unit (fuse) quickly. You will want to use Brendan's terrific airbag guide. Most people find that there are no faults to be found, but the fuse has failed anyway, due to age, heat, power surges, etc. There are some useful threads in the X300 section as it is the same system as the X305.

 

Thanks for the welcome! I got it on Bring a Trailer earlier this month and was told the wheels are 19ers from an XKR. The second owner was a Jag mechanic who swapped a lot of bits in to kind of make an XJR 100 lookalike. Rides a little harder over broken pavement than I’d prefer, but it feels fantastic at speed on the smooth stuff.

It’s just boggling to me how intermittent the airbag light is. It’ll be fine for several days, then pop for a couple days, then be fine again for more. I’ve got half a mind to just scrap it and find a nice Momo wheel from an XJ40.

 

The light will always be of for 5 or 6 seconds on startup ( a self test on startup )

 

It's not that. When it fails the self-test, the light remains on constantly until it passes the self-test on a future start-up.

 

I knew I'd seen those wheels somewhere!



I believe those are called Atlas wheels. They might be the last of the 5x4.75 bolt pattern with the 1/2" lug nuts and 73.9mm huge Jag hub. I have early 2000s XK8 Lamina wheels on my XJ12 and I like them a lot. 17x8, same size as the original XJR. Direct swap, much easier than finding anything in the after-market to fit a Jag from the era.

 

They look like Penta's , my dream as not cheap and hard to find