Uncharacteristically warm yesterday, so got the XJ8 out of the barn and took it for a drive, first time in a month. Went up to the post office & back, maybe 4 miles, and upon return discovered the top radiator hose had popped off the motor end. Do these squeeze clamps perish? I put it back on, refilled with appropriate coolant, and it drives fine. Didn't notice a high temp situation on yesterdays drive, definitely not overheating today. No oil detectable in coolant, no coolant in the oil. Any thoughts?

 

A similar thing happened to me on my way home having just bought the car (great start heh ?), although it was the bottom hose that popped off the thermostat housing (which I since had replaced with the new alu one). Its the "bottom" hose (LH as you look form the cabin) that was prone to disconnect and some owners double clamp these with jubilee clamps.
No disrespect intended but is this the hose you're talking about...?

 

1. Amend your signature please, because that had me confused, did not think Jaguar built an XK8 L, but they have built some weird one offs!


2. Check the hose, and the thermostat housing ( which I believe is plastic ) for corrosion/ general ageing.


They are known weak spots, and replace with upgraded aluminium parts.


3. Check your thermostat. But for the price, just replace it. You do NOT want to overheat these V8s!

 

I have read of instances where the lip on the plastic crossover pipe eroded, allowing the hose to slip off. It might be time to replace it.

Is the thermostat tower plastic? If so, consider replacing that with aluminum, new thermostat also.

Take a good look at the upper and lower radiator hoses, and the short connector to the crossover pipe.

 

The plastic 'ridges' on the pipe tend to deteriorate and the hose does slip off.
I have seen it DOZENS of times and it happened to me more than once!!!

The advantage of the spring clamp is that it will tighten as the rubber 'collapses' during a process known as 'cold flow'. Cold Flow meaning | Rubber Dictionary
The disadvantage is that it is a SET clamping force.

Sounds like it is time to service the cooling system with some new parts.

bob

 

Yep, Kyle 04, it is the LH side, didn't notice it was lower than the RH one. And, Thanks, Andrew, I never noticed my signature was wrong. Fixed that, too.
Now to order the aluminum parts..Parts Geek? Christophers?

 

Shop around, prices vary incredibly. I think I bought my new crossover pipe, last water pump, last TST, new aluminum thermostat tower, and hoses from Welsh. Add Rock Auto, Motorcar LTD, maybe Barrett. You save shipping with one provider . . . but aggregating the parts list will show the best deal. eBay may provide the fastest research and sourcing. Try to stay out of the clutches of the dealer.

I discovered two winters ago that when it gets to freezing and below the radiator hoses will slip off (it was 6*F when I lost my lower hose). I now use screw clamps and tighten all four a couple of times each winter and keep a bottle of 50/50 coolant in the car.

 

...... while you.re in there you may think about replacing the water pump with a metal impellor one, quite cheap and easy. Be careful of the plastic bleed pipes while you're working (coolant resovoir to radiator running across the LH engine cover), they are prone to snapping at the quick fit union if accidently leaned on (how do I know this - doh!).
The "outlet pipe" assembly, from the top hose to the block can also corrode although made from plastic. Mine was regularly depositing plastic debris into the cooing system so was replaced (the new part comes with a new coolant temperature sensor and is quite cheap).

 

When you replace the cross over plastic pipe you will get a new temperature sensor with it. Save the sensor out of the old one just in case. The stupid temp gauge will always read mid scale so that is no help. My new one had enough resistance difference to cause the fans to run all the time. Took two more sensors before I got the fans to turn off.