Hi Folks

Today I got the red light and "low coolant level' message. Hot day in Florida... but it went away as soon as I slowed down to below 50 mph. I waited for the car to cool down a bit and added less than a pint of 50/50 coolant/water mix to the reservoir.

Is that amount enough to trigger the warning message? I looked around under the car and hoses and did not spot any leaks. I'll double check the level again tomorrow morning with the engine completely cold.

If the level is still ok, should I worry about something else, say, thermostat or coolant level sensor?

thanks!
G

2003 XJ Sport, 73K mi

 

I don't know what the capacity of the coolant resevoir is. However, dropping below the sensor lever and adding a pint of coolant to remove light is reasonable. Don't know how long you've had the car, or when, if ever you've added coolant. But if it's been forever, I wouldn't be too worried. However, give the top end a good look at while running, especially back around the throttle body, I did have a "norma" connector back there with a very slight leak that resulted in my low coolant level. For a complete piece of mind you could pressure check the system. Although I've read that doing it yourself can be a hassle, chasing down adapters and all. I'm sure someone else will chime in with input.
Afterthought, actually it's been my experience that most small coolant leaks will occur after shutdown during the cooldown, enough system pressure to leak, and yet not be sealed up do to proper operating temps.
Good luck.
Ralph

 

If less than a pint filled it up, then you likely have a sticky coolant level sensor - common. It's a float with a magnet that slides past a magnetic reed switch. If debris builds up on the tube around which the float slides, it will start sticking.

It can be cleaned without too much effort. Someone has a good write up on this - I think perhaps Gus... hope he chimes in.

 

If its a slow leak, most likely it is, you wont' be able to spot the culprit until it gets worse. Mine finally got to the point where I was able to locate it.

My first was on the underside of the expansion tank. Easy to spot the dried coolant.

I'm not sure if your 2003 had the troublesome t=stat housing or not. My second leak eventually led me to the passenger side heater hose assembly connection. Visible from the bonnet bay up top, just behind the block.

 

I have had the low coolant warning come on a couple of times in the last 12-years. It doesn't take much to trigger it. I usually just topped up the resevoir with a small amount of coolant and was done with it. I have only had a couple of problems with the coolant system -- a busted upper hose at about 30K and a cracked thermostat housing at about 90K -- otherwise no problems, but two or three times I have had to top off the coolant over 93K miles.

 

My 02 has only had coolant added once or twice in eight years. The tank holds a fair amount of fluid but the sensor is a quick to go off.

I just had to drain my tank to remove it when I did the O2 sensor -- I recovered almost all the coolant and was surprised to see how little loss it took to set off the sensor. The tank needs to be almost to the top otherwise you will get an occasional alert.

 

I have had this warning light flash a few times before. It would flash somewhat intermittantly. It went away as soon as I added a bit of coolant to the resevoir. I havn't seen it since. I was suprised to find how sensative it was once I added the amount I did.

 

I have had my light come on also, 99VDP.
Pulled over let cool down only to find level was about a teaspoon low!
Seems to be very sensitive.
The reason being, I have heard, is that if your car overheats just ONCE you could melt Nichol
coating in engine.

 

Thanks for the suggestions, everyone!

I checked the level this morning and it was topped off. So far so good... I'll keep looking around for leaks but I just may end up flushing the system and replacing the coolant, since I don't know if this has ever been done.

I bought the car with 65k miles and the manual recommends a coolant flush around 70k, I believe? Does that really make a difference?

Cheers,
G

 

sure it makes a difference, just like other fluids have their purpose in a machine, the coolant degrades over time, and it is critical in transferring heat from the engine into itself, then releasing it again thru the radiator. That transfer occurs more efficiently with new fluid, thereby keeping the engine cooler (or more accurately, cools it quicker)

A good drain and rinse (no need to really flush our cars if maintained well) will also remove any particulates or other sediments that end up in the system.

Of course, it also prevents freezing of the coolant as well, but you already knew that. I'm not sure if older fluid will actuall have a different freezing point or not.

 

When my car was 5 years old I inquired about the coolant change and the dealer checked it and told me it was fine. At that time I was told that they revised the change interval to 10 years. This was on my invoice and I discussed with another party at the dealership.

My 02 had a build date of 9/01 so its just about 9 years old -- when I removed the coolant from the tank I was shocked at how clean it was.

MB lists a change at 15 years -- Porsche does not list a change -- they do say 150k on one. Lexus is saying 10 years 150k.

The stuff last a long time !

 

hey i just had the issue today...the Low Coolant Warning came on about 1 minute after startup...i went back to my parking spot to look for coolant on the pavement and did not see any...i did check my resoviar and sure enough it was low...i stopped and got some anti freeze and topped it up and it looks fine...the manual says to fill it up to the base of the filler neck so i checked later and the day and it looked A-ok...except the fluid does look Brown and Nasty...is that ok? also i just had my serpentine and supercharger belts changed and i am wondering the mechanics didn't top up the radiator after disconnecting the hoses to get the belts in...what do you all think? i'll also let you know if the top off worked for me

 

@pdog, you don't take the hoses off to change either belt. I guess it was time for a top up, when was the last time you checked your coolant level? Does the collector at the bottom of the r.h. wing behind the bumper have any coolant in it?

 

you know i didn't think you needed to take the hoses off, but when i got the car back, i noticed the spring clamp was gone on the big radiator hose coming off the engine to the radiator on the right side and it was replaced with an old school radiator hose screw clamp...it wasn't there before so i guessed the mechanic took off the hose to get to the belt...any big deal replacing the spring hose clamps with screw down clamps?

 

No, I've gone stainless Jubilee screw clamps on mine, can't stand the spring clamps, they rust and are a pain in the...

 

I had similar problems on mine where the low coolant level would come on periodically and a small amount of fluid would correct it. Bugged me because I could never see any leaks but I did catch a whiffs of burned coolant.

It finally showed itself - visible leaking from the upper hose. I went ahead and replaced both upper and lower hoses. The upper (short hose) cost about $8.00 and the lower (long hose) around $70 - both from Motorcars. I also replaced the tension clamps with the screw down hose clamps - much easier to deal with.

I haven't had the light come on in several months and I no longer smell cooked coolant.

Joe
98VDP

 

Be careful to not overtighten the screw type hose clamps. There are plastic parts in the coolant circuit that can be cracked or crushed with a screw type clamp. The thermostat housing inlet for example is one of them.

 

I recently had a similar issue. My 2012 XF ran normal until I put it in dynamic mode. Afterwards, I would smell coolant burning. I took it to the dealership and they did pressure test and was fine but did not test it in dynamic mode, as I asked. That evening, I ran it in dynamic mode and heard a 'pop' and the car started smoking. Low coolant alert cane on. I also heard a noise like a diesel engine.
Currently taking car back to dealer and pissed off cause the rep said they never tested in dynamic mode even though they noted I said that the problem was in dynamic mode. Do I have any recourse in Maryland against the dealer for negligence?

 

You would be cleverer to ask in the XF section. The X308 doesn't make much in common apart from being a Jaguar and being a car...