Water hose Blow off?!
 

1999 VDP. Just acquired. Dream.
Been smelling anti freeze and see no leaks, seepage, overflow tight etc. She leaks NOTHING. Because of this I ALWAYS watch temp gauge. Yesterday Had to run up to my office, came out after 10 minutes and anti freeze was all over ground! Well here it is I thought, opened hood and was shocked to see the water hose that goes into thermostat housing was OFF! (We called it a gooseneck) Easy fix, added water and all was fine. I assumed PO (Previous Owner) had changed hose and did not tighten. I thought this was the source of the smell. Today, I drove her to the supermarket, after dropping off some papers (one stop) I come out to see, Anti freeze!! After two people complimented, "nice Jag!" on way in, I now have to lift the hood to see the same issue? UGH. Called my daughter to bring a screw driver, water and some rags. I noticed PLASTIC GOOSENECK, and flaking at end.
Research at home shows this part is now made of aluminum. I ordered one.
Looking for confirmation of a correct diagnosis? Easy install? Advise?
Are there any issues to pressure build up? Thanks.

Most replace the thermostat, thermostat tower, short connector hose, water pump and both radiator hoses at sam time since labor is about the same for one or all. TST tower is pia, however. Lots of threads and youTubes on all . .

Common problem. The plastic is rotting away due to time and temperature. It probably wasn't that the clamp had not been tightened but between plastic failure and cooling system failure the hose was blown off by over pressure. Your car is 16 years old and if the hoses and plastic coolant system parts haven't been replaced it is long past time to do it.

The thermostat housing, including the 'gooseneck' should be replaced with the aluminum version you apparently found along with the thermostat, water pump, radiator cross over pipe and the upper and lower hoses as well as the 3" hose about to burst in the following picture.

Yours look anything like this?

https://cimg6.ibsrv.net/gimg/www.jag...c961dbed7b.jpg

Current discussion on the XK8 forum with lots of links to further information: https://www.jaguarforums.com/forum/x...cement-137120/

Thanks
 

Thanks for the confirmation. All hoses a
have been replaced, but not housing. On way. Will have to check water pump as well. Thanks again.

Hose blowing off
 

I had this problem, but for me, the cooling fans were not working. Agree with all the advice above. Just relaying another thing to check out. With the A/C on, the cooing fans should be on.

Had exactly the same thing happen with my 2002 4 litre Sovereign. It turned out to be the lip on the thermostat outlet stub, that stops the hose coming off when the hose securing clip is tightened, the part of this lip that is at the bottom of the stub and unseen, had degraded and broken off so there was nothing to stop the hose blowing off. By the way, the temperature gauge is just a placebo, once the engine is at the required temperature, the gauge stays there. If you slowly lose coolant you won't see a gradual rising of the gauge. You will only see any indication once all the water is lost and you get a low coolant message. Replace the tower with an aluminium version as suggested along with all the hoses and a new thermostat. This forum has a lot of information to enable this work to be carried out. Bill W.

Same problem with my wife's 99 XJ8L the first week she had it. As she drove home it went into "limp home" mode a few blocks from the house. When she pulled into the driveway the hose blew off and all the fluid hit the hot block and steam came pouring out. She thought the engine blew up. Called me and I called Hennessy jag they picked it up with a flat bed. The result was new water pump, thermostat and housing. Had the tensioners checked at the same time and they replaced all the chains and tensioners. This was 12 years ago and she has not had a problem since. She still drives the jag to this day. She will not part with it. Our cars were parked outside for two days while new wood floors were installed, they used the garage for all the wood and saws.

This happened to me on the first day of ownership - driving back from picking the car up. I had the thermo housing replaced shortly afterwards as well as the top tensioners.
Some owners (including me now) replace the theromstat outlet hose clamp with two jubilee clips .....