I have been searching for hours to get all of the typical maintenance for my new 1991 V12.

I am going to try to consolidate this post with everything that should be done for these vehicles (specific to v12) to avoid a Marelli fire and to increase its chances of lasting for many decades to come. Normal car maintenance not included here (brake fluid, ps fluid, oil, etc.). Some of this is my guess work.

1.) Cooling

Replace the hoses every 15k and flush the system. Rubber hoses are better for many reasons, including easier clamping and to avoid sudden failure. When buying hoses go with something quality, possibly made from EPDM, or going OEM. Jaguar XKS in san Luis Obispo has the best deals on a hose set for $80. I do not know how good the quality is maybe someone can chime in.

Clean out the banjo bolts above the radiator while replacing the hoses.

Replace the thermostats every 30k years with 180 degree ones. Ensuring they have the pin at the top (12 o clock).

2.) Ignition

Replace distibutor cap, rotor, and wires every two years. More often than other cars due to proximity and heat.

Look into replacing the dual coil with a single coil. Know if you have Marelli or Lucas...

3.) Fuel

Replace the fuel lines, if not done recently with more robust material (teflon, etc.). Rubber lines should be checked every 20k and replaced with any signs of cracking.

Check the fuel harness. Any cracked or brittle connectors should be replaced. Advised to make a new harness, or buy, when any signs of aging are seen on a connector.

https://www.jaguarforums.com/forum/xjs-x27-32/ignition-coil-fuel-line-help-please-107828/


Please add anything missing here and links to other posts that are relevant. This should hopefully save a lot of searching for a lot of people.

 

Replacing hoses every 15k miles seems too often, IMHO. A decent quality hose will last much longer.....although one might very rightfully question the quality of hoses these days, as your post suggests.

IMHO thermostats don't require routine replacement. Opinions vary, obviously.

Personally, I would visually inspect Marelli cap and rotor every 12/12 .....and replace * if needed *. Engine heat isn't the crux of the problem here. Excessive resistance, and wear, is. Fresh, properly gapped plugs and plug wires in good condition are equally vital. Use a dab of silicone sealer under the rotor.

Cheers
DD

 

Agree with Doug.

I do stats/radiator/ hoses/ belts every 5 years. My Jags are ALL Daily Driver, so a tad more use than the Garage Queens.

Being 1991, you are Marelli, and the visual check time etc Doug states is a good idea.

ALL fluids, and I mean ALL, (except engine) every 2 years.

Engine oil every 3 months, regardless of kms travelled.

Sparkers every 5 years whilst waiting for the radiator to come back from the shop.

The rest is simple common sense.

 

3 months for engine oil? Seriously?
Isn't that a bit excessive?
The stuff I am using is about £10 a litre so it will cost more than petrol over the year!

 

Your car your choice.

I average 2000kms per month, and oil is cheap where I work. $35 per 5 ltrs, $70 +$12 for filter, done and dusted.

The current S Types, we got 2 of them, get the same.

Oil $60.
Filter $12.50

Last price for a V12 engine was near on the National Debt.

Madames PreHE has well topped 500000kms, and sure, it leaks oil, drinks the fuel (guzzle is more the truth), especially the way she drives it, goes like stink, starts on demand EVERY time, and only stops when she says so, what more can a human want?.

That was my service standards, do what fits your style, no one will critisize, especially the car, coz whatever YOU do is probably WAY better than the poor beast has had for a very long time.

 

$35 (aus$ ?) For 5L of oil is very inexpensive (£16). I would guess that you get a large discount else £3.20 per litre suggests poor quality oil, which I would be surprised at.

As you said it's personal choice.
I use Motul 300V brand 15w 50 full synthetic Ester based oil at £80 for 5L
Or 20L for £300
Aim to change every 9000miles (14,500Km approx)

 

YEP.

The V12 requires NO fancy oils, unlike the S Types.

I run Castrol Magnatec 10W40 in the V12's, and the price is OK.

Good quality Premum Mineral 15W40 is $25 for 5 ltrs all day, which I dont use, just sell it, thats the job.

 

The previous owner was a jag mechanic and he redid all the fuel lines on the injectors. He used hose clamps?? Even though he is (was) a jag mechanic I am skeptical of his choice to use hose clamps. Some of them are cut through.

Should I replace all of these with injector clamps?

 

The short fuel injector hoses should not be clamped since they are barbed. Using a hose clamp on a barbed nipple leads to the hose tearing at the sharp barb ends.

The line leading to the fuel rail usually has Jag specific collars at the ends that mate to metal lines with specific bends. Here is an example:
Steal This Fuel Tank Return Hose 1982 1991 Jaguar XJS V12 Coupe New | eBay

They are not crimped, the collar serves to prevent the hose from expanding and thereby getting loose. The advise usually dispensed on the boards is to take your lines to a hydraulic shop and have them make the hoses with the collars using your current metal lines.

It looks like your wrench had decided to go the path of least resistance and cost. It's functional I guess.

 

My 89 Marelli was my daily driver (to and from work) up until I moved to the country a couple of months ago. I've owned the car the for about 6 years.

It still has its original Marelli distributor cap, the rotor has been replaced at some stage. There are NO signs of burning on the rotor or cap.

IMO the Marelli fires are due to a lack of maintenance, primarily not replacing the front spark plugs. If the spark plug fails the HV (High Voltage) has to go to ground and it will find the path of least resistance, usually the lead, then the lead breaks down and fails so the only way then via the inside of the distributor.

From personal experience - The PO had not replaced the front 4 spark plugs for who knows how long, this caused failure of a HT lead when I removed the exhaust the Cat on that bank was burnt. If I had left the plugs and lead I too would had suffered the Marelli fire.

Just to make this clear for some, you can not replace the Marelli dual coils with a single coil. It is possible to replace the dual coil Lucas system with a modern single coil----------CARE MUST BE TAKEN to ensure the primary and secondary winding resistance is correct or you could toast the system.

 

So your saying there should not be any clamps at all. are there any reported issues resulting from using clamps?

As long as it is functional it is ok with me. However, I am still concerned about using hose clamps instead of fuel injector hose clamps.

 

Right, no clamps at all. The nipples are barbed. The hoses just press on. That's it.

Barbed nipples + clamps = bad !

Cheers
DD

 

My findings after doing hundreds of EFI hoses on V12 engines.

Damage CAN occur to the "sharp" section of the barb that "bites" into the inner lining of the hose. Usually from a blade etc when cutting the old hose/s off.

This damage will ALWAYS leak fuel, no matter how many clamps are used, not good.

Choices, dependant on what item is damaged:
Replace the injector/s
Replace the fuel rail
Replace the other damaged component/s.

NOT VIABLE in the real world.

I CAREFULLY take the "nipple" and using a very fine "Wet/Dry" paper wrapped around that nipple, and remove the damage. This will ALSO remove the "sharpness" of the barbs, obviously. Some have been so damaged, I have had to use a very fine file (Contact Points File for those old enough to know what they are), and even MORE carefully file that nipple to remove that damage.

Once done, and the new 7.5mm EFI hoses fitted, NEW EFI stryle clamps are mandatory.

I have never had an issue with this rectification process.

GREAT CARE is required, as HIGH pressure fuel is being messed with, so if confidence is lacking, get the professionals involved, as safety is paramount in my book.

Just a side note: The PreHE has NO such arrangement. It has STANDARD swaged ends on the rail, and EFI clamps, and runs the same, if not higher fuel pressures.

A lot of these "upgrades" as they are called, were for production time restraints, and the next "upgrade" was o/ring seals between the rail and injector, as they simply "plug in".

 

By the way, that plastic cover over the cruise control servo....it goes under the servo, not over it ! It's a heat shield.

Common mistake


Cheers
DD

 

At the very least l would change all the worm drive clamps to EFI style clamps. Ideally there should only be the ferrules and push on hose but it's up to you. If you disassemble one of the fuel rail joints check out the barbs, they are very sharp and very capable of cutting into the hose.

 

major paint to have to redo someone elses work. this guy was a jaguar mechanic at a reputable shop in silicon valley... I looked up 30R7 and it is a low pressure fuel hose... shouldn't it be high pressure hose...

I found this write up which I will follow when I get around to this, first is the cooling system.

 

Should be R9 l think. I wouldn't be taking my jag back to him but l would be suffering the pain and redo all those hoses properly. R7 can stay on the outlet side (L/H) of the fuel rail to return hardline.

 

Ok, so I will replace the hoses with 3m of Gates Gladiator 7.9mm high pressure fuel hose with no clamps on the rail unless I notice the nipples were cut then I sand with about a 500 grit and use an EFI clamp on the nipple. I use ferules on every other nipple which can be had here for $1.40 each. Get intake hose remanufactured at a hydraulic shop (hose and fittings in the bay area) and an R7 with clam is fine for outtake return hose. Use EFI clamps whenever clamps are needed.

Get a new harness if needed or make your own.


Back to my original post and on to the cooling system:

It was mentioned hoses, stats and radiator every 5 years? Does that mean replace the radiator? - Im assuming it means a flush? I would think every two years for a flush. Based on experience Iam going to stick with every 10 years for thermostat replacement. It seems common for them to go after 10 years.

I guess what I am getting at here is an updated maintenance schedule based on knowledge gained through the years.

 

Aagree with your work plan in principle.

If you find ANY nipples that need sanding off, I would use 1000 W&D (Wet and Dry), so the small scratches will be minimised. The 500 sounds a tad rougn to me, but I am a strange guy.

THEN, if you have to sand ONE, do them ALL, then they ar all the same, and teh thought process in the brain can be used for other things. Thats what happened with mine. 6 at random were very sad, so I sanded the lot, then clamped them ALL.

I would use that EFI spec hose on ALL the hoses, again, it keeps the guess work to a minimum.

I dont run that RH FPR, so my supply hose simply goes from under the brake booster (RHD) direct to the fuel filter (now located inside the engine bay), then direct to the fuel rail inlet.

The radiator part is to remove and flush (professionally, not the garden hose), and I simply doo all the hoses/belts/stats while there is so much more room. The time frame just sits well with me, and since ALL my Jags are Daily Drivers, teh kms mount up real quick (usually 40K KMS /year). First signs of radiator issues is teh temp gauge sitting a tad higher than it did last summer, and teh thermo fans coming ON a few times more than last summer, and as I said, the 5 years just fits in there nicely. Our summers are 44c++, so it has to work hard, and I drive it like I stole it, just as it was designed.

 

You remove the radiator to have it flushed!? Is this entirely necessary or can you flush it in the vehicle?