XJ8 4L 111k miles, I'm loosing coolant slowly over say a six week period when the light comes on and I have to top up with Pint or so.
I've had a water pump @ 90k and can't see any visible signs of a leak.
The car is used daily, any ideas anyone.

Note. Car runs superbly.

 

There are several places that have a history of slow leaks. If there are not tell-tail signs of dried orange residue anywhere I would suggest that you rent a cooling system pressure tester from one auto parts chains. Pump it up and you can probably find the leak with the engine cold.

 

Had one of those, and in my case if was a hair-line crack on one of the inlets on the water distribution pipe (the plastic piece that connects to the heads and then radiator hose). It was realy hard to see and I only found it by squiezaing the radiator hose, and that's when I noticed the leak form the pipe.
It's only ~$40 online ($100 at the dealer !!!) and takes about 15min to replace.

 

my 2000 VDP had the same type of leak. It was the plastic hose connector that had a small crack in it. It required the entire octopus hose be replaced !

 

I also lose coolant over a long period of time and have to top it up. I'm going to Jaguar next month for a coolant flush so I'll ask them to find the leak.

 

i recently fixed my mysterious coolant leak after about a year of people trying to figure it out. one guy said it was the radiator and another couldnt find anything under a pressure test.

i finally decided to tackle the problem myself. took off the intake manifold and found the two heater hoses leaking. also, the plastic heater hose connector along the back firewall on the driver's side was leaking. since i had everything apart, i replaced the entire octopus hoses along the firewall. now, no more leaking coolant.

 

I am also suffering the same problem. I had 2 mechanics look at the car and neither could trace it.

 

The plastic connectors Jaguar uses at many points in the coolant system can't stand the force of over torqued screw type hose clamps, so if you've had any hoses replaced where screw type hose clamps have been used, there is a possiblity that they have been torqued too much to the point of cracking the plastic. A dealer will use the spring type clamps when replacing a hose. Just had the thermostat housing and inlet replaced on my 99XJ8 for this reason.

 

Hi all,

I just found out that there is a coolant leak somewhere. The "low coolant level" message appeared about 10 days ago, I topped up the coolant (about one liter). Today the message appeared again, another liter to top it up.

My question is if there is somewhere an overview of the cooling system, listing all the components (hoses, seals, o-rings, valves etc) so that I can go one by one looking for the leak?

thanks.

 

Try this:
www.captainjaguarscathouse.com/Parts_Illustrations/XJ8%2098%20ON/1%20of%204/

Look at files 1_J_05.tif, 1_J_06.tif, 1_J_07.tif and 1_J_08.tif

 

The Jaguar Technical Information System (JTIS) was the official Jaguar dealer documentation until they went on line in '03. A copy is available free for download on this forum:

https://www.jaguarforums.com/forum/s...ead.php?t=9933

Read the 'HELP' file first as it is not intuitively obviously how to navigate around the information.

 

thanks Kansas, exactly what I was looking for.

 

Hi all,

I think I found the leak, but ?!?!?

I had the feeling that I loose the coolant mainly when I drive like crazy (sport mode on and foot on the floor)

So I drove like that for few kilometers and than lifted the car looking for a leek. It wasn't difficult to find, it was dropping on my face. What confuses me a bit is the place where it leaks.

It leeks from the "Header tank" (see the pic., number 5) which is in the front part of the engine space on the lower left side. It seems like the actual leak is from the hole on the side of the tank (in the red circle on the pic.) I tried with a plastic strip and there is just a hole there.

So my questions are:
1) Is it correct that there is just a hole in the Header tank? no tube going to it, no pressure valve, just open hole?
2) If there is supposed to be a hole, what could be wrong in the system, that the coolant overflows there? + How does this "header tank" work than?

Thanks a lot for any help.

 

hi all,

I think I found the problem, just to be sure can someone quickly confirm it please.

I think the problem is switched hoses, see the picture (I think they should be the other way around). (I bought the car recently and I'm finding funny things like this)

 

it looks like your assumption was right, you need to swap those two hoses, i attached a picture of how they look on my 2002 XJR.

 

very slow leaks tend to occur in the small lines that run from the overflow to the radiator on drivers side. The o-rings wear out in the 3 connections and allow a small amount of coolant to leak that usually burns off as u drive.

 

Same problem on my 98 VP. There were no obvious leaks. Finally found with much checking with mirrors etc, what appeared to be a leaking water pump. Replaced the pump which was probably the easiest one I've ever changed. Actually the pump was fine. The gasket was bad. The new pump was different and had what appears to be a much better gasket. The leak was so small that it would never drip.

 

Hey guys,

I have got the same problem as mentioned on my 2002 XJ Sport. A slow drip was found near the hole under the front passenger side bumper when Sport Mode is on. Not sure what Sport mode will do to change the water pump behaviour but it seems to be the case. What I did was just refilling the coolant then drive normally for 3 days with sport mode on - then I got an empty coolant tank. Can anyone share the diagram of the coolant system so I can run through it? Don't have a jack lift but it's a good idea to inspect with a mirror!

Thank you!