I know this has been cussed and discussed a lot recently due to lots of problems with leaks and low level sensing. So I would like to put forth my observations.

When I bought my car two years ago with ( now has45,ooo miles) no warnings, no problems. Then I found out the sensor had been shorted out to get rid of the warning. New sensor. Got warning with full tank. Did research and found that magnet can come out of the float. Magnet found on bottom of tank. Found out from one nice member that it can be put back in. Tried that and unsuccessful without better tool. Before buying better tool did more research and found that magnet fell out again after member had reinstalled it. So it will probably fall out again. Didn't buy better tool. More research discovered that with good magnet false warnings still happen. Solution. Even with nearly full tank fill tank right to brim. This make no sense. Float with magnet only moves less than an inch up from the bottom when it hits a stop. Tank holds a quart of coolant. Any where near three quarters full to full will put the magnet up as high as it will get. The tank would have to be almost completely empty before the float and magnet will drop any at all.

Now, I was going to buy a new tank with new cap and sensor. But why??? My tank is fine and doesn't leak. With a new tank and a good float with a magnet it will still give me a false warning which is like no warning at all. And the magnet will fall out eventually and not stay in even after putting it back in.

Am I missing something here???

I'm sure I will get some really good responses to this one.

EZDriver 2000 XK8

 

Considering that the Jaguar temperature gauge is really only a 'too late' alarm of overheating and engine damage I would want a fully functional low coolant level sensor.

 

You have two warning systems for coolant loss:

1. low coolant warning light
2. temperature gauge

As your investigations into the sensor fault have shown, the low coolant warning triggers when the coolant level in the expansion tank is dangerously low. ACTION: stop immediately, refill expansion tank and check for leaks. DAMAGE RISK: low

The temperature gauge is next to useless and unlikely to move before the engine is already seriously overheating. ACTION: check bank balance for potential engine rebuild. DAMAGE RISK: High

Next to tensioner failure, overheating is the next best way to jeopardise an XK8 engine. Better to have some advance warning.

Graham

 

I bought an UltraGauge just to use as a temperature alarm. It was a bit of a nuisance to navigate and program, but it monitors temp continuously and I have the alarm set at 215 F. I plug it in when I start up and keep it in the door pocket. Some day I may learn to use other functions, but for now it's cheap insurance.

 

Thanks RJ237. Your idea is the first I have heard that makes sense to protect the engine from over heat. It would be nice to have a low level coolant sensing system that works. But I have yet to figure out how to reliably. False warnings are just as bad as no warnings at all. I have seen too many airplanes continue to fly with the engine fire warning on since there was always a failure of the sensors and no fire. A lot of aircraft land gear up because the warning system was always giving false warnings. Right now I have no confidence in the low level coolant sensing system. I want a real live temperature measuring system. And when one is available I will get it. In the meantime I'll get an ultraguage.

Thanks again RJ237.

EZDriver 2000 XK8

 

I know you have two warnings on overheat. And neither on work worth a darn to the point they are useless as I carefully explained in my original post. RJ237 has the best idea.

 

I see no "fill to this line" embossed anywhere on our 2006 XK8's coolant expansion tank. When the engine is cold and I unscrew the coolant expansion tank cap and look inside the tank, where should the coolant level be? Ours typically appears to be a couple of inches below the cap. That may be too low. Advice here would be much appreciated....

 

Detailed in the 2003 onwards Model Year Driver's Handbook Section 7-7:

The coolant level must only be checked when the engine is COLD.

The coolant level should be up to the bottom of the filler neck of the header tank.

Graham

 

The sensor in the Expansion Tank monitors coolant LEVEL.

The temperature gauge indicates coolant TEMPERATURE. We are both in complete agreement as to how useless this is.

Graham

 

Hi Graham. I really appreciate your input on this and other posts I have submitted. And as you say we totally agree the guage is useless. But I think the level sensor is also useless due to it being unreliable. When I put the new sensor before the magnet fell out my wife got the warning when she was thirty miles from home on a 100 deg day in Texas. She stopped and called on out new cell phone. I explained how to check the level after it cooled down. Coolant fine. Drove home. Magnet out. When you have a sensor as unreliable as this it is better not to have it at all. Others have had warnings for no known reason. My solution is simple. I check the level frequently along with evidence of leakage. I do this almost every evening. I don't want my wife to have to go through that again. I will get the Ultra guage and use that with a warning. And later do the mod to make the OE guage read correctly. But that stupid float and magnet falling out and some other unknow reason causing false warnings sucks.

Thanks again Graham for your input. I wish I could rely on the level sensor to work. If I could I would buy a whole new system.

 

I have not removed the level sensor and will not as long as it appears to work, but I wonder if there is not some way to keep the magnet from falling out.

 

I'm the chap who put the magnet back in the float only for it to fall out (and disappear) 24 hours later. For the life of me I cannot see why the magnet is not sitting in a blind hole and not a hole drilled right through the float. Then the only way it could fall out is if the car was upside down - when low coolant level would be the least of your problems.

I ended up getting a new expansion tank/float/sensor. What a surprise.

I really could not drive around withe 'Low Coolant Level' and bright red light on the whole time whilst telling myself, as we say in the antipodes, 'She'll be right'

As alluded to above, eventually she would definitely NOT be right.

 

This sensor has to be available separately. It's madness to have to replace a perfectly good Expansion Tank just because the snap-in level sensor has failed.

Did some digging and have come up with the following UK supplier:

SENSOR-COOLANT LEVEL

Also found a US supplier through PartsGeek but the site won't load through a link on this post.

British Parts UK and Jaguar World Monthly both give the same Jaguar part number (LNA-5740-AB) which suggests the sensor could be ordered as a separate part through the dealer network.

British Parts UK webpage lists the sensor as fitting all XK8 and XJ8 form 1997 to 2002. The Expansion Tank on my 2005 looks remarkably similar to the one on my 2001 so the sensor may fit right up to 2006. This needs some further checking.

Graham

 

For those in the US, RockAuto Auto Parts has the sensor for $55.00

AIRTEX / WELLS Part # 5S11748

Rock Auto is my first choice for basic mechanical parts, filters and suchlike items. Also, a quick look online will bring up free 5% coupons that you can use as well.

Fast service, easy returns.

 

Try Nalley Jaguar, a forum sponsor. They give a 15% discount and free shipping.

 

Getting the sensor as a seperate part was no problem. I have a good one as I have said in an earlier post. Problem is the magnet is not in the float. Not going to buy another tank just to have the magnet fall out again. Rather get the the ultra and have something that is reliable.

Getting a new tank with everything looking good is fine until your wife gets stuck in the outback or a farm road on a hot day in texas when the system is giving a false warning. That has already to my wife once and it is not going to happen again or I will get rid of that piece of junk.