I was driving along and the low-water light came on, so I pulled over and opened the hood. To my utter surprise, the upper radiator hose had slipped off at the radiator end. The hose clamp was still intact and and not loosened. About 148k miles - I've put on about 15k.

I know the cooling system is under pressure, but how could that hose suddenly pop off like that? Anyone else experience this?

 

I can only think the hose clamp wasnt tight. Or u have a massive compression blowby from cylinder to cooling system. But that would have other obvious signs.

If the clamp is non adjustable u can use a screw tight clamp or put a drop of silicone on the rad pipe before putting on the hose so that it helps it stick.

 

I suggest change your thermostat as a precaution. Increased heat means increased pressure.

Also change your coolant tank cap, which should have a calibrated pressure release.

 

The clamp is a typical worm gear drive type. I had to loosen the clamp quite a bit to get the hose to slip back on (I keep various tools in trunk).

Good idea on changing out the thermostat and coolant tank cap.

 

I had this on one of the V12's, and I eventually traced it to a bad NEW pressure cap. Designed for 15lb, and when tested 35psi still not blowing off, another, tested, cap at 15lb, all sweet.

The thermostat is also a good idea, they do wear out.

Lastly, the radiator may be getting partially clogged "internally", this will also give that same result eventually, although overheating is usually first in that case. These alloy/plastic radiators have very small passages as compared to the older copper/brass units, so do clog easier.

 

called a 'Jubilee clip' in my end of the Commonwealth.. but maybe different in the Americas after you had that Tea Party..

I don't know whose Jubilee, either.

 

Fair dinkum Al, what you drinking?. I might have to visit and participate HAHAHA.

However, you are right. Worm drive is more common over here than Jubilee.

 

Yep - I'm going to order the upper hose, reservoir cap, and thermostat and pick those up tomorrow. Probably a good idea to do all that anyway.

Then a flush is also in order. Anything special to do or watch for when flushing?
(I had 2 '95 Z28's who's engine uses "reverse flow cooling" and was a finicky affair).

Also, I suspect the x300 requires the cooling system to be bled of air?

 

OK, I always flush "bottom to top" as in reverse the normal flow, and I use the garden hose, with a blow gun (attached to the compressor) and about 40psi MAX, a rag to plug some of the gap, and go for it. There are fancy "flush guns out there, but the garden hose, with blow gun and rag all stuffed in the lower hose hole works for me.

Since the X300 radiator is easy to remove, I do it out of the car, less gunk sprayed all over the engine, and this also allows you to clean the exterior of the core.

Refilling is simple, just do so slowly so the small bleed hoses can bubble the air out without getting overloaded.

Do not fill that header tank too full, the Min and Max marks are a fair way down inside that tank, so it looks empty, but that is the design.

When you do the thermostat, be VERY CAREFUL. Some suppliers list an o/ring seal for the stat cover. I have NEVER seen an o/ring seal on an AJ16, and fitting one will snap that housing soooooo easily. The $$ will exit the wallet just as fast, It is a standard "paper type" gasket, so make sure you order one. The part number is NBB2217AC.

 

Okay, went to my local Jag parts supplier and picked up:
* upper hose
* thermostat and gasket
* expansion tank cap.

Wire brushed thermo housing and bolt threads, installed new thermostat and hose. Fired up the engine and allowed it to get to operating temp ... all seems to be fine.

However, this is only temporary, just fitted the hose to move the car around the driveway/garage. I've discovered another issue while installing the hose on the radiator side ... i thought that the upper hose had blown off, but i think the upper radiator snout had broken off partially ... isn't t there supposed to be a raised ridge around the outer circumference, so the hose won't slide off?

The broken off piece was not in the hose end when I opened the hood and discovered the blown-off hose - I simply slid the hose back on and tightened the clamp. Either that or the snout was already like that (from previous owner?) and i've been lucky all these miles? Either way, it does appear the end of the snout has broken off at some point.

Do i need a new radiator, or can a new sleeve be pressed/glued in? (I've enhanced the snout's color so it stands out, it's not really that "rusty"):

 

That is plain scary.

Someone has bodged that pre your ownership.

If it were mine a new radiator would be sourced, no matter the $ involved. An overheated engine will cost significantly more than any radiator.

If a suitable snout piece could be found then glued into place would be needed. I use a "Made in USA" product called "Rapid Fix", which is a 2 bottle repair pack, with liquid in one bottle, and powder in th3 other, and it works a treat.

Check out the suppliers supporting this site, or try XK Unlimited in San Louis Obispo, who have got me out of the brown stuff over the years. Then of course the scrapping yards in your market may be worth a try, coz there are virtually NO X300 cars in those yards down here.

 

Here's an example of the OE Jaguar cooling system hose clip fastener (arrowed in red):



There's two reasons Jaguar use this type of hose clip instead of Worm Drive clips on plastic cooling system connections:

1. quicker to fit in production
2. cannot be overtightened

The damage to the radiator stub outlet is typical of that from overtightening a Worm Drive clip. When using Worm Drives as a replacement on plastic, great care must be taken.

Graham

 

Thanks Grant and Graham for your valued feedback - much appreciated !

The spring-loaded hose clamp makes much sense.

 

I was driving in high elevations for the first time in my 1999 Jaguar XJ8 and I started experiencing a problem where the overflow reservoir would dump a bunch of coolant every time I stopped. After a bit of searching online I found that my reservoir tank connections were swapped, which seems to be a somewhat common problem. I also found that my radiator cap did not hold any pressure (I could blow right through it.) So I swapped the hoses and put on a new cap (which I could not blow through.) Several days later, after a long highway drive I parked the car. When I started it up again I noticed the low coolant indicator had come on. When I opened the hood I saw that the upper radiator hose has come off on the engine side. I reconnected it and topped off the coolant. At first I figured that the clamp must not have been tight, so I tightened it further. A few days later, after a 14 hour highway drive I parked in my driveway and when I got out of the car I saw that the hose had popped off again.

I'm trying to identify and address the problem and would appreciate any input.

Also, both the new radiator cap and the one I replaced come apart every time I removed them. The threaded top comes off and the guts of the cap stay in the tank until I pry it out.

Where can I get a cap that will stay in one piece when I remove it?

The temperature gauge always stays exactly in the middle once the engine has warmed up. Should I replace the thermostat too anyway?

 

Really?? The thermostat housing should have a "lip" around the perimeter of the housing's end (where the hose slides over). Is there not a lip on your housing?

And what type of hose clamp is used there?

"Which" cap?

How many miles? If mileage is high or you dont know the history, I'd replace the thermostat, housing gasket, and the overflow tank's cap.

 

There is no lip on my thermostat housing and it looks like the end may be broken off, as the edges as no very even. The hose was held on with a standard worm-gear style hose-clamp. I guess I'll be needing a new one.

The cap I am referring to is the one you remove to add antifreeze up on top about a foot or so from the windshield.

I've got about 148k miles. Is that considered high mileage for a Jaguar?

I'm new to owning a Jaguar; is there a good online source for inexpensive quality parts?

Thanks!

 

Whoops, meant to say "are not very even" rather than "as no very even"

 

If you click on this link (thermostat housing), you'll see there is a slight lip - you should replace it, and I'd say replace the thermostat, its gasket, and the expansion tank cap (those are all clickable links).

The expansion tank cap should *not* fall apart on you as you describe. I replaced mine, since it should be done whenever you replace the thermostat. Even my previous ET cap is good and doesn't "fall apart". You must have an aftermarket replacement.

You have the same mileage that mine has and mine runs as if it has 1/2 the mileage.

As far as inexpensive parts, the source depends on the part. I've bought parts at my local Oreilly Auto Parts, ordered parts from RockAuto, and sometimes I have to visit Motorcars (the one with the links in my first paragraph) because I need a genuine Jag part - fortunately, Motorcars is a 10 minute drive for me.

 

Happened to me on my 95 xj6. In my case it came off the radiator connection. There is no lip on the radiator . It's not rusted off. My radiator is clean but had no anti freeze when I purchased it.I drained it and replaced the anti freeze through the upper hose removing it from the thermostat housing. Six months later it popped off the other end. I contributed it to the stress I put on it earlier. I suggest these clamps just give out with age. I replaced all of them with clamps from a local racing supply. My father who was a very skilled mechanic always used non hardening permatex sealer on hoses to stop cold water leaks. I chose not to because of the lack of a lip. Go for some good clamps first before getting carried away replacing perfectly good parts. My question is why would they make them without lips? When mine blew a guy in a XK8 was next to me . How fortunate.
Regards
FMFZ12007
Regards

 

Yes this has happened to my 01 xjr with 215,000 miles the lip worn down to a smooth surface and blew off on the highway. Pulled over put a screw clamp on filled coolant and got 3 miles down the road and blew again, then filled with water in my trunk that I had and it was cold and cracked the coolant tank. So had to get towed. Bought a used rad and tank and am back on the road.