I don't even know how to respond to this "advice". Sasie007, please leave your electrical connections in place. They did as they were built and identified an issue.

So for the short term, you have a small leak or possibly overheated and lost some coolant and you can top it off. If it runs low again, you'll want to bring it to a shop to fix the leak.

 

sorry for the bad advice

 

Look for the leak now ! You know it makes sense.

These things never go away on their own, and all the time you run around in your car, the coolant is leaking away, so you'll get the message again sometime, probably fairly soon.

 

I have a 2004 xjr and noticed a coolant leak, got a coolant low warning. I think the Ford coolant was the same spec and is orange. Decided as there is a leak somewhere and it looked like it was the back( about 3/4 hose) with plastic connector.To take it off with a slide wire sort of mechanism to hold the hose connection to a slot in the nipple of the tank. Mine seems to be leaking there and from what I can see at that connection, leaks when pushed. It looks like this Engine Coolant Recovery Tank Hose Genuine Fits 2004 2007 Jaguar XJR Super V8 | eBay.

Wondering is there is supposed to be an "O" ring as this connection does not seem to have a squeeze connection like all the other hose attachments. My car only has 72k miles on it, and while it is 11 years old, and because I got the part out will probably replace the tank even though it doesn't seem bad. I am suspecting the connection. Anyone have any experience with this?

 

The idea behind the rtv is not so much as to make a seal as it is to be something sticky to keep the o-ring from moving. So, a little bit in 2 or 3 places evenly spaced around will do the trick.

 

I ended up replacing my expansion coolant tank( about $160 for the xjr) and found it was not the problem with a leaky nipple, as seems to be a common area of problem at the bottom back of the tank. The slide on piece ( why they didn't use a clamp like is on the other connections baffles me) actually has an O ring on the inside I found. It is part of a 3 armed piece of tubing assembly that goes to the intercooler pump. I found that with a hook tool was able to fish out the o ring and replace it. I found at my local Ace hardware a 1-1/16 x/13/16 x 1/8 ( part 357338) O ring that seems to fit and and took care of that leaky connection. So far so good.

I took Frasers suggestion and went out at night with a flashlight( torch to the English) and looked for any signs of leak. I have not seen anything, but at times smell coolant in the area. Don't seem to be losing any on the level. During the changeout lost a bunch of fluid and replaced it with the Orange coolant and distilled water ( 50/50). On the XJR you have to take off a bunch of hoses and lose ( get a small cork or one that I cut down to stem the flow from the cooler jacket atop the engine) a bunch of coolant as it drains.

 

Hey Fraser, is the "header tank" you talk about the same as the coolant over flow tank? I replace the coolant tank and themostat housing along with the plastic Y fitting for the heater and hose at the back of the engine about 2 years ago. The other day I got the low coolant light and it was low but I can't see where it is leaking from.

 

I love it that I got a warning when my coolant was only 3/4" low. This defies common sense..

 

I'm not Fraser but the header tank is the same as the reservoir tank, which is also referred to as an expansion tank. The pic in post #3 points right to it.

 

So the easiest way to start your search for the elusive leak (and they can be tiny pinhole leaks) is to go out on amazon or your local auto parts store and pick up some UV dye. Buy a $10 UV flashlight. It will show itself at some point. Some of the hoses are hidden under engine vanity covers, at the firewall behind the plastic etc, so be thorough and yes, you should remove the under scuttle cover and look from underneath as well.

For those that have the SC and can't see the infamous hose beneath, a leak down along the transmission is a tell tale sign that's your source.

Another option is to get a system leak down tester, which in my neck of the woods can be rented for free from an auto parts store. Just connect it to the reservoir where the cap goes and apply no more pressure that your cap is rated for.

 

can any one tell me the resistance of the coolant switch when showing full
ie at the correct water level,is it 0 ohms or a set resistance,as a short to earth may put up a fault code?

 

It doesn't work on resistance it is a switch, either open circuit=infinity (Mohms) or closed =0

 

If the leak is not the coolant tank nipple, go to the thermostat housing. The housing on the XJ8 is plastic and can have various failures. It fails internally by fracturing around the bypass valve seat which can cause overheating, and it also leaks at the large diameter o-ring. This leak will show by running down around the water pump pulley. Replacing it is pretty fussy, but can be done by a good DIY guy. Keep in mind that this car does not have a separate thermostat, it is built into the housing so you have to replace the whole thing.

 

NOT SOUND ADVICE MR MECP TECH. NEVER,NEVER,NEVER bypass ANY SENSOR OR SAFTEY DEVICE, THEY ARE THERE FOR A REASON. YOUR ASKING FOR TROUBLE.
Im a MECP Master Tech specializing in auto electrical
This is what I did. On the bottom of the reservoir there is a electrical connector with two wires. disconnect it. Get a paper clip or piece of wire and complete the loop. ie put the wires together. Boom no more bullshit message. Now just pay attention to that temp gauge when driving. Every now and then pop the hood and check level of coolant. The message will never come back for the life of the car! i promise!! enjoy!

Ive also bypass many other stupid sensors for many cars.[/QUOTE]

 

Yesterday I got the same dreaded "Coolant low" message. I had the expansion tank replaced last year and the car has been mostly sitting and not driven much since. So I am puzzled by the new leak. Can I just keep topping it off without spending more $$$ on repair or causing harm to the coolant system?

Thanks.

 

For me it would depend upon how much coolant I was losing and how quickly.

The problem is if the leak is small now could it get much bigger suddenly when miles away from base?

So I personally would look for the leak. Maybe do what Philwarner has done and put a chemical in the coolant that glows under a black lite.

 

+1 look for the leak. I just dealt with this. Started as a small leak, no coolant loss detected, only dried up coolant. After investigating it was the water pump, which one day started going south rather quickly.

All changed out and now going through the process of topping off...

 

My coolant is red color, is that wrong? I just topped off with distilled water and will check the level again tomorrow.

 

Mine is closer to red than orange, its Dexcool. My opinion.

If you keep topping off with distilled water you will end up with a lower than 50/50 mix and far less effective coolant.

 

I just want to apologize to all who feel like im an idiot and giving horrible advice. I came to understand that all sensors are there for a reason. I had a leak on my 2nd overflow tank. Bought a new one, the floater works so I decided to plug the harness back in. All is well and coolant message is not on.

When I first comment on bypassing the coolant low sensor, I didnt think deep enough of how important it can be. I was under the impression ill pop the hood and check the level every few days. As long as I dont see the message.

To all the veteran members who commented on my foolish bypass, I just want to let you guys know that I respect you guys and I listened and took your advice.

If you look at the endless hours of modifications Ive done to my car you can see I try really hard

Cheers!