New owner 1994 XJ12, things to check first?
#1
06-10-2018, 11:42 PM
New owner 1994 XJ12, things to check first?
I've picked up a 1994 XJ12, manufactured in April 1993, but sold and titled in the USA as a 1994. So it is an "early" 1994, and for example only has the driver airbag.
I don't know a lot about the car yet, but the seller provided a lot of receipts and other service documentation, copies of the Service Manual, and quite a few used and new spare parts.
At the moment the only known issues are a slight, light miss at idle once the engine is warmed up, and I believe my brake accumulator may be dying after 24 long years as I'm getting the infamous "brake and ABS light upon initial hard braking".
So that all being said, is there anything I should put on my short list of things to inspect/check for a just purchased XJ40 with about 90k miles and specifically an XJ12?
Here's the car: https://www.jaguarforums.com/g/album/10004431
.
I don't know a lot about the car yet, but the seller provided a lot of receipts and other service documentation, copies of the Service Manual, and quite a few used and new spare parts.
At the moment the only known issues are a slight, light miss at idle once the engine is warmed up, and I believe my brake accumulator may be dying after 24 long years as I'm getting the infamous "brake and ABS light upon initial hard braking".
So that all being said, is there anything I should put on my short list of things to inspect/check for a just purchased XJ40 with about 90k miles and specifically an XJ12?
Here's the car: https://www.jaguarforums.com/g/album/10004431
.
#2
06-11-2018, 12:20 AM
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It's very important to keep the Marelli ignition system 100% up-to-snuff.
Pull the distributor cap and inspect the cap and rotor for wear or, worse, scorching/burning. If the rotor fails (burns through, typically) one entire bank of cylinders goes dead. This loads the cat converter with raw fuel. Bad ! Fires have resulted. Don't wait.
Make sure the plugs and plug wires are in good shape. Resistance here promotes rotor burn-through. Gap plugs to .025"
Tons of reading about Marelli ignition in the XJS section but this covers the high points.
If you're driving and feel a sudden loss of power, stop immediately. You've almost certainly lost a bank due to Marelli failure.
V12 cooling systems must also be kept to 100%. Clean radiator, correct thermostats, proper bleeding.
Cheers
DD
Pull the distributor cap and inspect the cap and rotor for wear or, worse, scorching/burning. If the rotor fails (burns through, typically) one entire bank of cylinders goes dead. This loads the cat converter with raw fuel. Bad ! Fires have resulted. Don't wait.
Make sure the plugs and plug wires are in good shape. Resistance here promotes rotor burn-through. Gap plugs to .025"
Tons of reading about Marelli ignition in the XJS section but this covers the high points.
If you're driving and feel a sudden loss of power, stop immediately. You've almost certainly lost a bank due to Marelli failure.
V12 cooling systems must also be kept to 100%. Clean radiator, correct thermostats, proper bleeding.
Cheers
DD
The following 2 users liked this post by Doug:
al_roethlisberger (06-11-2018),
Lawrence (06-11-2018)
#3
06-12-2018, 04:29 PM
#4
06-13-2018, 02:05 AM
Veteran Member
Congratulations Al! That is a beautiful car. It is certainly very rare. You have now joined a very exclusive club. Not only the V12 club, but the USA One-Model-Year-Only XJ81 club! How did it feel to make the purchase, a little like skydiving maybe?
OMYO XJ81 Al. Not a bad nickname!
If you need a new compressor/power steering belt, it is the EBC1500, and it is readily available and not expensive. See my post in the X305 section about my belts experience (if you haven't yet).
I see you are going to make a lot of friends in this section too (seriously)! But now you've got the bug for sure and are officially incurable. But with this disease, who needs a cure, right?
OMYO XJ81 Al. Not a bad nickname!
If you need a new compressor/power steering belt, it is the EBC1500, and it is readily available and not expensive. See my post in the X305 section about my belts experience (if you haven't yet).
I see you are going to make a lot of friends in this section too (seriously)! But now you've got the bug for sure and are officially incurable. But with this disease, who needs a cure, right?
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al_roethlisberger (06-15-2018)
#5
06-13-2018, 07:30 AM
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The injectors themselves fit directly into the fuel rail....so 12 fewer hoses to worry about. But the rail itself has a couple rubber joiner hoses and I reckon there are others in the engine bay....but I'm no authority on Xj40 cars, that's for sure
Cheers
DD
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al_roethlisberger (06-15-2018)
#6
06-15-2018, 09:59 AM
Senior Member
Hi Al,
As an owner of a 1996 XJ12, I can tell you that these V12 engines are very durable but there are a few things you need to pay close attention to.
The cooling system, as designed, is just adequate for our big engines. Now that these cars are 20+ years old, they most definitely aren't at their prime. Proper coolant flushes and changes are very important, as is checking all the hoses (there are many!) and also the integrity of the expansion tank (they can leak at the seams). Stand next to the front wheel well on a hot summer day, car running, and you'll feel the massive amount of heat POURING out. Underhood temperatures are incredible! Once you turn you park your car and turn the engine off, expect temperatures to climb another 10+ degrees before leveling out. My '96 has a belt driven fan AND two large electric fans. The electric fans are wired to run at either low or high speed when the key is off, if coolant temperatures are high (maximum 5 minutes to prevent dead battery) to help get underhood temperatures lower and help the heat soak issue. I'm actually looking at a timer solution to extend that 5 minutes to 10, as well as trying to incorporate an electric auxiliary water pump to circulate coolant while the fans are running.
Turning the car off when very hot, then restarting while still hot has caused dropped valve seats on these engines. Beware!
As you will find out, parts for the V12 sedans are VERY hard to come by. Many are NLA at the dealer. Oil coolers and its hoses cannot be sourced. Radiators are $800+ last time I checked. Motor mounts are ~$900 each. The same $40 A/C hose for my XJ6 is ~$300 for the XJ12. You don't want to know how much cataltyic converters are. Just keep this stuff in mind, and plan to use used parts as well as rebuilders to keep these cars on the road.
The Marelli injection system does need an eye kept on it, as stated here already. You do NOT want any raw fuel (from misfire or a whole bank being down) getting inside the cats. Unless you can find a PDU with the appropriate adapters, you won't have any luck diagnosing the Fuel Injection system at that kind of level.
Front ends take a beating on these very nose-heavy cars. Same for the rear motor/transmission mount bushing and spring. The foam bushings decay and break up, and the rear of the motor bounces and thumps about.
Do NOT alter, adjust, or fiddle with the throttle linkage, especially the rods across the top of the engine. Trust me... it is VERY hard to get both banks back into correspondence.
The saving grace for these cars is that 90% of the parts are straight late XJ40 parts so they're pretty easy to come by.
Good luck with the car!
Nick
As an owner of a 1996 XJ12, I can tell you that these V12 engines are very durable but there are a few things you need to pay close attention to.
The cooling system, as designed, is just adequate for our big engines. Now that these cars are 20+ years old, they most definitely aren't at their prime. Proper coolant flushes and changes are very important, as is checking all the hoses (there are many!) and also the integrity of the expansion tank (they can leak at the seams). Stand next to the front wheel well on a hot summer day, car running, and you'll feel the massive amount of heat POURING out. Underhood temperatures are incredible! Once you turn you park your car and turn the engine off, expect temperatures to climb another 10+ degrees before leveling out. My '96 has a belt driven fan AND two large electric fans. The electric fans are wired to run at either low or high speed when the key is off, if coolant temperatures are high (maximum 5 minutes to prevent dead battery) to help get underhood temperatures lower and help the heat soak issue. I'm actually looking at a timer solution to extend that 5 minutes to 10, as well as trying to incorporate an electric auxiliary water pump to circulate coolant while the fans are running.
Turning the car off when very hot, then restarting while still hot has caused dropped valve seats on these engines. Beware!
As you will find out, parts for the V12 sedans are VERY hard to come by. Many are NLA at the dealer. Oil coolers and its hoses cannot be sourced. Radiators are $800+ last time I checked. Motor mounts are ~$900 each. The same $40 A/C hose for my XJ6 is ~$300 for the XJ12. You don't want to know how much cataltyic converters are. Just keep this stuff in mind, and plan to use used parts as well as rebuilders to keep these cars on the road.
The Marelli injection system does need an eye kept on it, as stated here already. You do NOT want any raw fuel (from misfire or a whole bank being down) getting inside the cats. Unless you can find a PDU with the appropriate adapters, you won't have any luck diagnosing the Fuel Injection system at that kind of level.
Front ends take a beating on these very nose-heavy cars. Same for the rear motor/transmission mount bushing and spring. The foam bushings decay and break up, and the rear of the motor bounces and thumps about.
Do NOT alter, adjust, or fiddle with the throttle linkage, especially the rods across the top of the engine. Trust me... it is VERY hard to get both banks back into correspondence.
The saving grace for these cars is that 90% of the parts are straight late XJ40 parts so they're pretty easy to come by.
Good luck with the car!
Nick
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al_roethlisberger (06-15-2018)
#7
06-16-2018, 05:18 PM
Thanks for the detailed feedback 
To be honest, that is a little intimidating from a risk/cost perspective, but good thing I paid next to nothing for this XJ12
First thing I'm going to do is replace the wires, plugs, cap, rotor and cross-fuel lines for peace of mind. While I'm at it I'll probably also pull the injectors and have them cleaned because it really is inexpensive.
I do have a slight miss at warm idle now, and it isn't as quick off the throttle as I would expect. So something isn't quite right, but I'll just take it one bit at a time. ...after all, it's just "fuel, air and spark" right
.
To be honest, that is a little intimidating from a risk/cost perspective, but good thing I paid next to nothing for this XJ12
First thing I'm going to do is replace the wires, plugs, cap, rotor and cross-fuel lines for peace of mind. While I'm at it I'll probably also pull the injectors and have them cleaned because it really is inexpensive.
I do have a slight miss at warm idle now, and it isn't as quick off the throttle as I would expect. So something isn't quite right, but I'll just take it one bit at a time. ...after all, it's just "fuel, air and spark" right
.
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#8
06-16-2018, 09:55 PM
Senior Member
I have lots of reading for you... I would try to view as much of this information as possible!
Of particular interest is the 1994MY V12 Introduction Guide. LOTS of practical, useful info here.
Also, the 6.0L Lucas/Marelli Engine Management System Manual will be VERY important.
Look at the TSB for Spark Plug Wire Routing. This was a REAL issue on my XJ12. There are LOTS of wires, and lots of places for them to short out on the block. Print it out, it'll help you when you replace your spark plugs.
Speaking of spark plugs, there is a new part number for a revised plug for your car.
There's an older, but still valuable, Jaguar Battery & Charge manual which goes into testing for parasitic draw... Very useful for you.
Please check them all out!
Nick
Of particular interest is the 1994MY V12 Introduction Guide. LOTS of practical, useful info here.
Also, the 6.0L Lucas/Marelli Engine Management System Manual will be VERY important.
Look at the TSB for Spark Plug Wire Routing. This was a REAL issue on my XJ12. There are LOTS of wires, and lots of places for them to short out on the block. Print it out, it'll help you when you replace your spark plugs.
Speaking of spark plugs, there is a new part number for a revised plug for your car.
There's an older, but still valuable, Jaguar Battery & Charge manual which goes into testing for parasitic draw... Very useful for you.
Please check them all out!
Nick
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#9
06-16-2018, 11:35 PM
....wow, thanks That's a lot of good information.
And well look at that, my car is subject to the hood pad recall, which has not been done. I'll have to call Jaguar of Cary next week to see how they plan to honor that. When checking the online VIN recall decoders, the VIN comes back as an error:
Not really surprising. I'll have to go find my "born with" VIN versus the USA VIN then try I guess. It was mentioned in my "majestic" thread that this "born with" VIN might be stamped on the firewall, but I can't find it.
But it is clear that the pad hasn't been replaced, and it is indeed hitting the throttle linkage, and my serial portion of the VIN matches.
Surprisingly they took care of a recall for my 1997 XJR a few years ago that required new PROMs for the ECU. So I guess we'll see what happens with this even older recall. Technically it appears they should still be required to perform the work from what I've read on the NHTSA website.
The cable routing and rough idle TSB is also very interesting. I'll definitely look at that first before replacing anything. Wouldn't that be interesting if it is such an easy fix?
.
That's a lot of good information.And well look at that, my car is subject to the hood pad recall, which has not been done. I'll have to call Jaguar of Cary next week to see how they plan to honor that. When checking the online VIN recall decoders, the VIN comes back as an error:
An error occurred with your request. LAND ROVER does not recognize your VIN. Please contact LAND ROVER by phone at 1-800-637-6837 or go to their website http://www.landroverusa.com/ for recall information about your vehicle.
But it is clear that the pad hasn't been replaced, and it is indeed hitting the throttle linkage, and my serial portion of the VIN matches.
Surprisingly they took care of a recall for my 1997 XJR a few years ago that required new PROMs for the ECU. So I guess we'll see what happens with this even older recall. Technically it appears they should still be required to perform the work from what I've read on the NHTSA website.
The cable routing and rough idle TSB is also very interesting. I'll definitely look at that first before replacing anything. Wouldn't that be interesting if it is such an easy fix?
.
Last edited by al_roethlisberger; 06-17-2018 at 12:17 AM.
#10
06-17-2018, 11:08 AM
Veteran Member
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al_roethlisberger (06-17-2018)
#11
06-17-2018, 11:41 AM
Oyster Metallic
Thanks 
I have to say I agree. I've had a number of gold/champagne colored vehicles over the years, and all looked fine, but this gold really looks great in the sun... even with it's deteriorating (checking/ghosting) clear coat. It really pops, and photos don't do it justice.
.
I have to say I agree. I've had a number of gold/champagne colored vehicles over the years, and all looked fine, but this gold really looks great in the sun... even with it's deteriorating (checking/ghosting) clear coat. It really pops, and photos don't do it justice.
.
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