This afternoon, the lower radiator hose blew off of the thermostat housing. Luckily, I was parking it after a highway run at the time and I shut off the engine very quickly. Dodged another bullet!

What is going on? Should I replace the thermostat?

The lower radiator hose was replaced 8 months ago. Was the worm drive clip too loose?

Thanks again,

Dan

 

Could have been a loose clip. Tightened all clips on radiator hoses.
Also replaced the expansion tank cap. First replacement in 10 yr?

 

Dan:
Thanks for the report back. I resisted offering my opinion since I try and limit myself to one controversy at a time and I used my monthly quota already.
Cooling hoses blow off because they are not on right OR because something is wrong with the pressure relief cap. If the car overheats, the coolant should blow out the pressure relief.

 

Thanks, Ross.

I believe I picked up your opinion on the matter in an earlier post and was guided by the suggestion.

Dan

 

The problem can be many fold, but notice that when the engine cools that lower hose can suck flat which pulls/works off the hose from the t stat housing. This is the largest and longest hose on the cooling system so its the one that generally go flat. Many times when you start the car and its close it comes off the rest of the way, or in your case after driving. Make sure the secondary reservoir behind the left foglight has coolant in it and that the pipe from the reservoir to it is not plugged so that coolant flows back into the reservoir when it cools. Also the hose gets soft with age and the ribs on the t stat housing cover it clamps to gets worn off. This all can contribute to you issue and you may want to replace the cover and lower hose too. I cant see your car from Texas so nothing specific

 

We had this same problem happen 3 times on our Vandy. Twice we drove somewhere with the car operating at "normal" temps, parked then came back out 30 minutes to an hour later to find a large puddle under the car and the hose off of the housing.

The first time it happened, I questioned whether the hose "had just been loose". So I sorta cleaned the ridges on the housing, replaced the hose and made sure to tighten the hose clamp down the way I knew it was meant to be.

The second time, I inspected the hose more thoroughly and replaced the hose clamp.

The third time, my son had just taken the car (undriven and cold) and was only about a mile from home when the hose came off. Fortunately he heeded the message indicator and stopped immediately. After putting it back together to get her home, I was determined that it was the hose. After calling the local Jag ******* here in San Antonio and being quoted a ridiculous price for a hose that had to be ordered...and after calling all the parts houses to find none could help, I went back out and took a closer look at the hose. The hose looked good, but I decided to trim it back anyway. I also spent a fair amount of time FULLY cleaning the housing ridges, then I went one step further and spread some Indian Head gasket material on the grooves, replaced the hose and tightened her down. Thus far, no more problem (knock on wood) for the last 9 months or so.

 

This is a weakness in the Jag.
I had a similar problem recently; had the relevant parts (including thermostat housing etc) replaced by an all-metal casting normally used by sports cars. Darned expensive, though.