I thought I would throw this out to the crowd here, and see what they have to say.
I recently purchased a 95 xj6, and as many of us have experienced with second hand jaguars they can come with a litany of problems. The one that I'm concerned with right now has to do with the cooling system, it had developed a small leak that would only present itself after driving. I narrowed the leak down to a dodgy looking lower radiator hose, at least I hoped that was the case and I felt the hose should be replaced anyway. I ordered mine directly from Jag since I didn't want to risk a second rate part for this, upper hose is easy to swap lower hose is a little more involved.
After I swapped in the new hose I was feeling rather smug, and enjoyed running some errands for the wife in my repaired car. Unfortunately after about 45 minutes of driving the leak returned, I heat cycled it several more times while trying to diagnose the issue until I was sure that it was my brand new lower hose.
When I went back to the dealership they were brilliant about replacing the hose, and offered me some advice on checking out whether or not I may have a blown head gasket.
My questions are these
1) if I indeed am passing combustion gasses into the cooling system wouldn't the pressure relief component of the coolant reservoir cap allow the excess pressure to bleed off without damaging hoses?
2) wouldn't I be having heat issues when I'm running at speed? It has never gotten hot on me, it's actually been very well behaved in that respect.

Thanks for reading, and I look forward to hearing what you all have to say on the matter.
John

 

You can conduct a very simple test to figure out whether combustion gases are getting into the coolant. The test kit can be had at most auto stores, so is the fluid. You warm up the engine, fill the test tube with fluid, connect the kit and run the engine. If the liquid changes color - you have combustion gases making their way into the cooling system. Usually it happens via a blown head gasket.

No need to go to a dealer for this, it's a simple operation that any DIYer can do.

 

If the hose was leaking...the hose was leaking. No need to invent problems you don't have. Did the new one leak in EXACTLY the same place as the old? "Lower hose" has a lot of ends as I recall; and several of which terminate at magnesium/aluminum ports that are prone to corrosion and leakage. Any indication this is your problem? There are threads here and there with pics of the corrosion, nasty stuff, that.

 

I agree that it was most likely a faulty hose, and it was indeed leaking at one of the areas where another hose tees out of the main hose. When I was able to pinpoint its location I marked it with a paint pen before taking it back to the dealer. The ports on my water pump were very corroded, but I had grabbed another pump at the pick and pull and I was able to clean it up just fine. This was actually the primary reason for replacing the old hose, I didn't like the crustaceans that were growing around the ports. I was mostly looking to verify what the tech at the dealership said about head gaskets needing to be replaced at around 100k miles for this very issue.

As an update, I have put the new hose on and filled the system with distilled water (I will go back drain it out again to refill with the proper mix of antifreeze). It still has no signs of exhaust gasses entering the cooling system and drove the 20 miles to work without a hitch today. So for now it does appear that I received a faulty hose

 

Glad to hear it.


I've not heard of 100k MI head gasket problems on these. AJ16's are widely held as bulletproof.


I HAVE heard that crank sensors and fuel pumps give up around 100k, fortunately neither has failed me at 159k.....
How is your heater? If weak, now would be a good time to backflush it and or soak it with some flush solution, before u go back with antifreeze

 

Okay, so the new hose is leaking!!!!
I went out to parking lot to show off my jag, and there she sat proudly showing a puddle under her. This time the small hose going to preheat the intake manifold is the culprit. clear as day it's leaking where the small hose meets the main hose.
I'm getting frustrated to the point of just building a manifold to feed all the other components and using hoses that don't have all of these joints vulcanized into place.

 

Even the dealers are supplying after market hoses, uro I believe. Mine has been okay but several members have complained.

 

I ordered these from Rock Auto:
1995 JAGUAR XJ6 4.0L L6
ÜRO PARTSMNA4510BFRadiator Lower Hose$ 36.89$ 0.001$ 36.89
ÜRO PARTSCBC1582Radiator Upper Hose$ 6.10$ 0.001$ 6.10
about this time last year and in a week I'll have one year of service and 22K miles on them, no problems thus far:


https://www.jaguarforums.com/forum/x...enewal-101914/

 

I thought about ordering one of those but foolishly thought the dealer would have a higher quality part. I intend to order one from Rockauto today. I'm no stranger to Murphey's law, and figure it's better to have a spare and not need it than the other way around.
As an update the third hose seems to be holding up just fine.