My wife was driving our 2000 XK8 coupe today. I get a call that something is wrong. I drive out (luckily she wasn't far) to see what's up. I get the hood/bonnet open and see that the hose from the thermostat housing to the lower rad. connection was blown off the fitting at the thermostat housing. This despite there being two hose clamps on it. I waited until the car cooled down and reconnected the hose and refilled the coolant (a parts store was one hundred yards away). The car started up, I carefully drove it home, and there doesn't seem to be any ill affects.
I was waiting to change over to the aluminum housing but not anymore. One is on ordered with the aluminum crossover pipe. The parts store guy says it happens all the time with the plastic thermostat housings. I assume he means cars in general because I don't think this particular store gets a lot of Jaguar owners in it.
I am going to watch the oil and other things to make sure there are no issues. I don't know how long my wife drove the car once the coolant was evacuated and neither does she.
Has anyone else experienced this anomaly ? What else should I watch for ?

Stephen
15 Jaguars from 1959 through 2001, from show to parts

 

Fairly common problem, but usually the upper radiator hose connection to the outlet pipe. You mention the aluminum crossover pipe. Please provide more info, as I am not aware of such a pipe, which I am guessing is a replacement for the outlet pipe AJ85885.

 

stephenniz,

Sorry to hear that your wife had a problem with the coolant hose blowing off your Jag. Whilst I never had this problem with my 1999 XK8, I had alot of hoses blow off with my early 90s BMW. So I'm guessing it is common with plastic parts. My BMW had the classic problem of aged plastic, with cooked worn plastic fitting, either cracked, bits broken off etc. so the clamps couldn't be secured properly. I recently did an overhaul of the front coolant system on my Jag XK100 so am familiar with the area.

+1 to RJ237 who suggested replacing the coolant tower with an aluminium upgrade. Pic below of what I think you've ordered.


However, like RJ237, I'm not aware of an Aluminium crossover pipe (pic below of what I'm referring to). If you have found an aluminium verson of this please let me know (I'll be very interested as it's a known weakness of our X100).


Right, onto what to look out for (in this particular area). Big question and I've done lots of pre-emptive work to prevent the common problems. One common fault is that the top cap of the tower tends to break in the plastic version probably due to age. Another is breakage of the wiring connection to the coolant sensor (in the cross over pipe).

Another thing to consider is why the pipe blew off despite your clamps? My understanding is that the plastic male fitting, on the thermostat fitting on the tower, should be complete and undamaged. It should have ridges on it that help secure the coolant rubber hose and clamp. These plastic nubs may be worn. Plus the hose itself should be have the direct 90deg bend straight onto the tower. If you look at the Aluminium tower pic, it has a better designed fitting with an enlarged ridge at the end, so the clamp is fitted securely "behind" it.

There is a Youtube video of this area, in the "To the Garage" series. It does go into detail on the hose alignment. Link below.

Another thing I would be wary of, is the state of your cooling system. Is the engine running hot too much, as overheating is an engine killer? There may be a reason for it, ie thermostat stuck, so I would keep an eye on it esp. the coolant level in the tank. Also I'm not sure of the service history of your car, but if someone had mixed the orange/green coolant types, it could have gelled up in the system and reduced the efficiency of the overall system. Well worth looking at what comes out of your spillage - should be a bright clean fluid (either clear orange/red). If not, worth a flush with a cleaning chemical and refill. You've already done it once so you should have a super clean system. Be aware that the expansion tank has a sediment trap at the bottom - easy enough job to take it out and wash it clean - you may be surprised at the rubbish in it accumulated after many years.

 

I saw an aluminum crossover pipe for sale , used on Ebay. It is with the aluminum thermostat housing.

 

I am getting a new thermostat with the housing kit. I will take your advise and clean out the expansion tank.

 

The XKR uses an aluminum pipe. I don't think it will fit the XK8 head.

 

I just chcked the part number for the T-stat . hsng. wtr. outlet pipe and it is the same for the XKR and XK8 for 1996 through 2002.

 

I'm not sure what your source is, but SNG Barratt Lists the XKR pipe as AJ81981, and the XK8 as AJ95885. I have worked on both and know for certain that the XKR is aluminum while the XK8 is plastic.

 

This is the one from a 2000 XJR. As RJ said it is different than N/A engine.

It is aluminum and won't work on a N/A engine. It is different because of the cooling of the supercharger. Post the link to the ebay part. If it is trully the N/A crossover pipe in aluminum, that seller will be quickly out of stock because quite a few of us would purchase one .

 

Source was Welsh Ent. part search