Hello fellow XJ owners and interested readers! I have been motoring along in my XJ12 quite happily for some time now. But one day last month, my trip was cut short due to a sudden and disturbing massive oil loss.

After passing by a group of slower vehicles on the freeway, I first noticed the smell. I didn't see any smoke anywhere in front of me. But when I looked in the mirror, I was shocked to see my car trailing a heavy blue cloud! Moving over as quickly as I could, I came to a stop in a huge cloud of dust and smoke. The engine was running and I noticed the oil light and zero oil pressure, just before I quickly shut down and got out.

A good samaritan whom I had just passed was kind and concerned enough to stop behind me to be sure I was alright. We could see the oil draining off the entire underside of the car. There was a lot of smoke. I was very concerned and a little embarrassed! Slowly, the smoke subsided.

I began the investigation soon after returning home on the flatbed. The oil filter was intact. I couldn't see any source of a leak anywhere, even after removing the left front wheel. I added more oil and started her up to make sure no damage was done due to lack of oil. The engine idled just fine, but the oil was gushing out! What a mess. Next day, I disassembled the left air intake and air pump hoses to look deeper. I eventually discovered a small hole in the top of the oil cooler hose right near the exhaust manifold.

So then the car went to the shop for rebuilding of the hoses. The shop replaced both cooler hoses with new hose, but didn't actually "rebuild" them using similar fittings or collars. They only removed the old dry hoses and clamped new hose sections onto the existing metal sections of pipe, using standard hose clamps. I have doubts about the durability of this repair. Anyone have any input regarding this method of hose repair?

The oil line that failed has the metal to rubber transition right near the exhaust manifold. It probably would have been better (and a better design) to extend the metal pipe section further away from the manifold. Nonetheless, that hose endured 22 years and 92,000 miles of extreme internal and external heat!

Be aware of this, fellow XJ12 owners (and V12 XJS owners too). That hose will fail sooner rather than later at this age. I'm not the first to experience this either! I think the repair job wouldn't be too difficult with the car on a lift. Not having one, I left this job to the specialist.

1 of 19, have yours been done??

 

I have not replaced any of mine to date. I have not checked the condition of either and will be doing so directly. This is what makes this forum rock. Information shared.

 

I usually park on gravel so hadn't noticed until now, after I placed a drip pan, that oil is leaking out of the repaired connections at no less than three locations. The largest leak is from the connections of the pipes above the oil filter. My guess is that the O-rings were not replaced.

The original hoses were metal-reinforced and looked bigger than the replacement hoses, which are not labeled as oil-resistant and seem quite soft. I suppose they will last a while, given proper connections, although it seems like the hot oil will degrade them after a few years.

The pipe/hose closest to the manifold (where my leak was) has a black coiled heat shield around it, about 6 inches long. I believe it is supposed to be located right up near the manifold. I found that mine had slipped down the hose and so had no effect, probably for a long time. Even if it is in position, at this age those hoses are probably crispy and in need of replacement in most cars. Just be sure of the method and materials your shop plans to use to "rebuild" those hoses. This was not what I expected.

 

After more investigation, I discovered the shop's method of repair of the oil cooler lines, and the reasoning behind it. I did this on my own without again consulting the specialist that did the work, since they lost my trust after committing so many blunders (with other work they did too), and not owning up to them.

The two metal crimp connections and two push-on fittings for the oil cooler were all cut off. New barbed pieces of aluminum pipe were welded onto the ends of the old pipes, and new hose was installed with simple hose clamps. I later doubled-up the hose clamps because of the leaks. The large leak in the area near the oil filter was not from the cooler pipes connection above it, but from the new oil filter, which was loose! Silly and careless.

I looked up the type of hose they used for the repair. Continental etc. etc. Turns out it is a reinforced 300psi highly oil resistant hose. Great! But... it is only rated for 88C/190F. The engine oil gets hotter. In the near future I can replace the hoses with the high-temp version easily, thanks to the new barbed connectors.

I was surprised that the shop did not at least reuse the push-on connectors for the oil cooler. Seems that would have been easier for them rather than welding new connectors on. But they did a number of things with my car that I didn't understand or agree with, especially considering their so-called expertise with the marque. I corrected several other things myself too. So far, so good, knock on polished burl walnut!

 

It appears that the genuine "inlet" hose MNA7460BA is still available, although pricey at around $200USD.

The "return" hose MNA7461BB seems to be NLA though ....but maybe you could find is NOS somewhere.

https://www.jaguarclassicparts.com/u...ipes-6-0-litre


An alternative would be to use the original hose, or find some other old used ones, and take them to a hydraulic hose shop. I'm sure they could take the original fittings and properly attach new flexible hose in-between. I guess that may not be an option if your shop mangled the original connectors on the oil cooler itself though.

So, quick question, how exactly does one undo and remove the push connectors on the oil cooler end of the hose? I have a V12 cooler, but the hoses were cut off and the push on connectors are firmly on the cooler and I don't want to destroy them.

I'm planning on using the cooler on my XJR as an oil cooler or maybe a piggy-back intercooler radiator.

.

 

Hi Al!

My assumption was that the shop was going to do exactly that. Their repair method was more complicated than simply replacing the rubber sections of the original pipes using proper crimp connections.

The push-on fittings are released by a sleeve of the proper size inserted around and into the fitting to release the internal locking ring. Here are some interesting articles from Richard at GeorgiaJag including a write-up on the oil cooler hoses and connectors:

Articles

Happy Holidays.

 

Perfect, the articles show the oil line quick-connects disconnect just like most modern fuel line connections! Thanks for the link to the articles.

Sorry to hear that the shop didn't do such a good job.

.

 

Last month I replaced my rebuilt oil cooler hoses, only a year and a half after they were rebuilt. The connection nearest the exhaust manifold was leaking, and failure seemed imminent.

My job was relatively easy to some degree, because I did not have to remove the oil cooler or the two metal pipes from the engine. I only had to undo and remove the rubber sections, which were hose-clamped over the new barbed sections installed by the shop. I could reach the four connections from underneath the car on ramps, although like most jobs on this engine, access was still difficult.

The hose used by the shop on the rebuilt lines was not of the proper spec. It was not a high temperature hose. Leaks were a problem right from the start, until I added more hose clamps as I explained above. That gave me only one year leak-free.

The first new hose the shop put on was Continental ContiTech Insta-Grip 300 (oh, how I hate made-up silly combination words used as trade names). It is designed to use with the proprietary barbed fittings as a push-on hose, without needing any clamps (or collars). It was rated at 300 PSI and 200 degrees F. The first time the oil temp reached 200F, I'm sure that the hose was softening and oil was getting past the triple barbed fittings. Continental has a high-temperature version of this hose, but the shop chose not to acquire and use a correct spec hose.

I searched for the Continental high-temperature replacement hose, but could not find it available in small quantities. But I did find a suitable hose by Parker. This hose is rated at 350 PSI and 300 degrees F. It is also a push-on type, which is apparently standard practice in industry these days for lower pressure hydraulic systems. I found it on The Bay, sold by the foot. Only 5 feet total is needed.

An important factor that I am uncertain about is the size (inner diameter) of the factory original hose. In my case, I never saw the bare connectors of the oil cooler. They were cut off, and 5/8" (16mm) barbed aluminum fittings were welded onto the ends of the oil cooler and engine pipes. I am estimating that the factory originals are a 3/4" (19mm) pipe and hose, but I need confirmation. It is obvious on my car that the new barbed fittings are smaller than the originals. Another unexplained oversight (or shortcut) by the repair shop.

In summary, welding replacement barbed fittings onto the original oil cooler and pipe ends does work, but why go to this trouble if the factory original fittings are already 3/4"? The correct hose used over the original fittings, with the original removable connectors used at the oil cooler, makes much more sense.

Two options for the correct hose to use would be:

Parker Push-Lok 836 Hi-Temp (blue or black hose)
Continental ContiTech Insta-Grip HT300 (black hose)

Both are available in 5/8" (10), 3/4" (12), and smaller sizes (4,6,8). Both are highly oil resistant, and designed to be used without hose clamps. For peace of mind, you can put a hose clamp above the barbed area if it makes you feel better! I did.

Not a single drip, weep or seep of oil from any of my new connections with the new Parker 836 hose in place. If you find yourself doing this job, just be sure to lube it up, this hose is extremely tight fitting over the barbs! It helped to warm the hose to fit it.

 

That's terrible that they half-assed the repair and modified your oil cooler fittings in order to able to do it. Only to require you to correct the job that they were paid to do in ther first place. They should have asked you if you prefer an OEM repair or what they did. I can confirm from experience with an ATF cooler that the hose-on-pipe with clamp will leak, only a matter of time. Hopefully your new hoses will bring better results.

 

Thanks again sleek jag for all the info. I decided to add this to my preventative maintenance list to my new 96 XJ12. Mine hasn’t been touched since the factory and I can confirm the right size hose is a push on 3/4 or 12 size. I noticed the pressure rating for the hoses you suggested are 300 PSI in the larger size. So after a bit of research I found the Aeroquip FC598-12 is a perfect replacement and is 350 psi in the 12 size. Also looks identical to orginial. Cost about 10 dollars a foot. So almost 70 shipped for 5 feet. I dremeled off the metal sleeves that were around the ends of the hoses, careful not to cut the barbs underneath. Ended up having to cut the last bit with a pair of metal clippers than razor blade the hose off. Put new hose with plenty of assembly goo. Your right was real hard to push on. Finished it with quality Oetiker 17800172 hose clamps, two per fitting for a total of 8. They fit perfectly and I used two because....well because I’m paranoid I suppose haha. These are real nice hose clamps, I’m going to be using them more often.


Old hoses

3/4 inch barb

Another photo through tire well



Moved over the metal label rings and the wheel well protector to keep an original look.

 

G’day Gents,

My oil cooler hose burst on the way home one day and I did exactly what you have done, pulled over and had to be flatbedded home.

The cost of genuine Jag replacement parts was exorbitant so I took the U/S hoses to a local hydraulics workshop and sourced some replacement hi temp/pressure hose and then stopped at an irrigation supply shop and bought some double width bolt up hose clamps.

That was well over ten years ago and I’ve had no trouble since. Occasionally when I’m under the car I snug up the clamps but they’ve never loosened enough to need much tightening.

Cheers,
Jeff.

 

Thank you John that is good work. I wish I had done my own, either as you did John or as you did Jeff. My new correct rated hoses are holding up wonderfully so far, no worries at all. Knock knock. But it is something that I look at almost every time I am under the hood. Not so much for the durability of the hoses, but the welds on the pipes. John that new hose looks to be the steel-reinforced kind, as is the original. Still, the oil got through mine in a big way after all those years!

Why on earth would my Jaguar indy shop cut off the original fittings, then weld on 5/8" step-down barbs when 3/4" hose would fit right over the original pipes!?! It is bewildering that they could commit so many blunders. There were like a dozen in this one visit, no kidding.

I was looking for some quality hose clamps before, but never found any. Thanks John I'll get some of those. Cheap clamps don't clamp evenly in a circle.