Engine Coolant Low Warning

[OllieG]

Just a quick one (hopefully!)

My 2004 4.2 V8 S-Type is intermittently showing the "Engine Coolant Low" warning message.
It's becoming more frequent and usually happens 5-10 minutes into a drive and stays on for 1-2 minutes, but does also come on randomly at other times but never for more than a few minutes.

I've checked the coolant level and it always seems fine, in fact I've slightly over topped it up.

Has anyone experienced anything similar?

[steve_m]

Probably a dodgy sensor or a loose connection?

[OllieG]

Yeah, that's what I was thinking/hoping...

Anyone know whether that's a common fault?

Anything else I should consider, check or look out for?

[BrizzleJag]

Probably a dodgy sensor or a loose connection?

I agree, I would certainly check these first.

[J44EAG]

An air lock within the cooling system can sometimes occur. Bleed off at the highest point just like bleeding domestic central heating radiators.

Yes, I`ve had this on my X350R which shares the same lump as the 4.2 S-type units. The R is even more complicated as it effectively has two cooling systems sharing the same header tank. Air in the system can and does cause spurious error messages and the occasional message centre and or high gauge readings.

Its also worth noting that thermostats on these V8 powered cars rarely last more than 80K miles. I`ve had two give up around that mileage. The engine has what Jaguar called a "precision" cooling system and a good thermostat is vitally important in its control. The stats become sluggish at that mileage and cooling system maladies often happen. Changing a stat every four or five years is well worth considering. I know it seems daft to change out what appears to be a perfectly decent component, but believe me, it does make a difference to the way the engine runs. I`ve driven nothing but V8 Jags for the last fourteen years so have got to know these cooling systems pretty well. The CHT sensor near the thermostat is another 80k only reliable lifed item. High gauge readings with a normal temperature give the game away. Confirmation is bad starting. Got the T-shirt!

Mike K

[OllieG]

Hi Mike,

Thanks for your answer..

After a few more days the red warning was showing more or less constantly, so yesterday I had a go at bleeding off any air.
Took it for a run and for about 5 minutes I thought it was cured, was just patting myself on the back, and... Warning came back on.

It definitely doesn't seem to be loosing any coolant.
It's also had a new thermostat a couple of months back.
And there doesn't seem to be any symptoms of overheating.

So, time to replace the sensor?
I've also read that a too-weak coolant mixture can cause the warning to come on as the float doesn't float if the viscosity is too low.. Does that sound plausible?

[Lighthouse60]

Did you get the sensor changed on this issue, and did it resolve things? I'm having exactly the same issue as you - "engine coolant low" warning, but coolant not low.

Thanks for any assistance,

David.

[J44EAG]

Try scraping the crud off the sensor in the header tank with a long screwdriver. That often works! Also check its external connection for corrosion and remove if present. This is a classic case of start with the basic checks before buying new parts.!

Mike K

[wbcountyrs451]

Hi
Bought a 2006 S Type Sport 2.7D (V6) diesel on Tuesday. Service history up to 1000 miles ago. After a couple days "Engine Coolant Level Low" displayed on the dash. OK, stopped at first garage and filled up with a coolant/antifreeze mix. All was well for a few days.
Then after a 50 mile run, in the carpark I notice water under the engine, on bending I could see a steady pouring of water coming down from about 2 feet back. Damn! probably a burst water pipe. Left the car for a few hours to cool then quickly filled it with hot water and made a rush back keeping an eye on the temp gauge and any warning message. Got back OK. Once cooled down I checked the water "FULL" The next day I did another 50 mile run and checked again "FULL"
OK maybe a faulty Radiator Cap.....the one fitted showed 120kpa but all I could find online was 140kpa. One supplier suggested using 110kpa.
I'm reluctant to use 140kpa if 120 is the correct pressure in case the extra pressure causes more problems.
Can anyone suggest what may have caused the outpouring? Remembering that 2 days after I bought it the "Low engine Coolant" warning came up on the dash. Each loss of water did seem to be on days where the temp was around 30 degrees. It currently seems to be OK.
Any suggestions would be appreciated.
Regards
Bill