Low Coolant warning stays on
 

I just had my 2000 XJ8 A/C fixed by an Indie shop. They replaced the low side A/C section hose (with 2 hoses MNC7310BF & MJA7312CB) & replaced driver side engine mount.

A/C blowing cold again but, as I drove away, the RED low coolant light came on! I had to go somewhere & the temperature gauge never went above the exact center (where it always is after engine warms up).

After I got home & car sat overnight, I had to add 24 oz. of 50:50 coolant mix.

Usually, 1x/yr. I need to add ~ 8 oz but, never got the light before.

I called to ask if they were into the coolant system & they got back to me & said the mechanic opened it up & probably it was an air pocket.

I was not happy with this sloppiness but, as long as there was not a leak, all it cost me was coolant & time. My plan was to recheck in 1 week to see if coolant was still full.

2 days later, yesterday, I again got the RED low coolant light!

Now, I figure I must have a leak caused by the tech, when he worked on my AC. I expected I’d need to add another 24 oz.

This AM, after car sat overnight, to my surprise, it only took 8 oz b4 coolant level was up to bottom of filler neck!

I drove off & the low coolant warning light remained on! Despite a few ignition cycles, it remains on! My temperature gauge still never goes above the exact center.

What is going on here?

I think I have a leak despite no dripping on my driveway but, why did the 1st fill turn off that warning & 2 days later, the 2nd fill fail to turn off the warning?

I’m confused.

Ask the shop if they saw any coolant leaking .... I'm not sure why they would look if they did not. Also -- not sure what they would do to cause a leak .. especially one you would not see.

Two things. The float can stick .. and also get water logged. It's not an uncommon problem. Also, the temp gauge is not really a gauge --- it sits in teh normall range for an extended temp .... so when it's goes high ... it's a real problem.

Keep the system filled ... and keep checking .... Call them back

They were closed today. I plan to call Monday AM.

It is very hot here in Phoenix.

Possibly, a small leak may not make it down to the ground & a small amount of coolant burns off or evaporates?
Maybe when they "opened up" the coolant system, as they admitted, they put it back together sloppily & either failed to fully tighten a hose clamp or damaged a lower hose?

Where is the float?

First, check whether the connector is well connected to the coolant level sensor. It is the orange one on the first pic, marked with number 1 on the second pic.

https://cimg3.ibsrv.net/gimg/www.jag...616118f05e.jpg

https://cimg2.ibsrv.net/gimg/www.jag...19293e6cff.gif

You can see the float, white cylindrical piece, if you look inside the tank in the direction towards the left side of the car (you will probably need a torchlight). If the float is sitting low, you can nudge it with a piece of wire or a screw driver and see if it comes up.

Thanks!

I will remove the engine cover @ the coolant cap & check tomorrow.

I did not need to remove any engine cover to see the wiring connector & it seems solidly connected. I jiggled it.
Coolant still 100% full. Have not driven more than 10 minutes since topped off coolant. Just drove it from driveway to street & red, low coolant light is still on.
Tomorrow I’ll try to stick my finger into the reservoir to see if I can feel the float.

I will also call the shop.

Have not driven since Saturday. Coolant still 100% full. Stuck gloved index finger deep into reservoir & felt all the way around several times. I could feel no float. I started car & still Red low coolant light on.

I dropped car at that Indie shop. They will look at it tomorrow. I was again told it may be an air pocket.

IDK what the tech did to replace those 2 A/C hoses & engine mount. Maybe he removed the lower radiator hose & dumped all the coolant & poured it back in after repair complete?

XJ8 Coolant Warning Light
 

Hi all, I had my low coolant warning light come on the other day, stopped and checked it but it was only down a bit there was still coolant in the bowl. I toped it up with only about 150-200ml and set off that was all it seemed to need. My thoughts are that it needs to be always at full level so the warning does not come on. My temp gauge is always in the centre. As I have only had the car for 12mths I am ot sure what coolant is in it so I am thinking of having a system flush and starting fresh before the Australian Summer hits!!

Its an 1998 XJ8 Sport X308 3.2lt

Any of your thoughts would be appreciated.
Cheers... Roger

That is only ~ 6 oz. low. Mine has been down 8 oz in past years with no warning light.

You need Orange colored OAT Coolant/Antifreeze. I dilute 50:50 mixture with distilled water. You can also purchase pre-diluted.

I buy Dex-Cool Prestone 5/150 Orange Extended Life. Organic Acid Technology (OAT)




https://prestone.com/products?detail=AF888

Section 3-8 of my vehicle care handbook states:
"The cooling system should be filled or topped up with a mixture of 50 per cent demineralised water and 50 per cent Jaguar Anti-freeze, Coolant and Corrosion Inhibitor conforming to specification WSS M97B44-D, coloured orange, Extended Life Coolant."

You cannot reach the float with your finger. As I mentioned earlier, you need to shine a torchlight into the tank and use a piece of wire or a thin long screwdriver to nudge the float. The float is notorious for getting stuck on its plastic shaft in the bottom position due to formation of calcium or something which prevents the free sliding of the float up and down the shaft. You should move the float up and down a number of times to free it up.

Indie shop called. No leak! Sensor bad. He says it is overfilled! He wants to order new sensor & will keep car overnight & s/b ready tomorrow.

I insisted I did NOT overfill, just filled 24 oz 1st time & 8 oz 2 days later to bottom of filler neck, just as manual states. He says air pocket probably is gone & worked out through top tank.

They are gong to replace the sensor @ N/C. This is good news but…why?
Why would they pay for part & labor if they do not think they caused the problem?

I think the bad (or simply stuck) sensor is not caused by them but, the low coolant was caused by them.

If coolant level drops again, I will have to take it to Jaguar.

I will be very surprised if I drive it for 1-2 weeks & the coolant level does not drop a lot once again. I sure hope I am wrong.

BTW, when fill to exactly bottom of filler neck, you can see the shape of the fluid changes & looks like an ellipse. Reminds me of old car batteries where you would add distilled water to the cells & when the shape distorts, you are full.

Otherwise, battery or Jaguar coolant level…it is difficult to tell if you are ½, ¼ or ⅛ inch below the filer neck.

Thanks Steve, difficult to get Prestone in Australia however Valvoline has a Dex-Cool with an OAT formulation. As I am not sure whats currently in it I think the complete flush is the go and start fresh. The Valvoline Coolant Zerex Dex-Cool Pre-Mix 5L 938.05, is readily available here in Australia.

Thanks for your reply.

Cheers... Roger

Guess you should ask the shop again ... just to be sure ---- if they did indeed have to remove a hose and drain the coolant when they installed the motor mount.

If they really did not drain anything and it's just a coincidence -- you will have to watch. Opening the cap should not have cause a problem. Explain to them that this is important on this engine as having low coolant can be very serious with all AL engines.

The filling procedure requires running the car with the cap off and then filling the tank -- you fill it up and the car takes care of the level by sending the excess tot he overflow in the fender. You only do this once .

I can't fined the service procedure .. but one of the jaguar mechanics posted it a long while back. Maybe try and search.


2000 X308's got the orange from vin F00108. Prior was yellow and prior to that was blue.

You can get the proper Jaguar coolant at any Ford dealer -- or as I do ... online. Just use the Ford specification and get motorcraft .. you will get the proper orange XLC *extended life coolant".

Car back from shop!
They say they did not just replace the bad sensor. They replaced the entire expansion tank which comes with a new sensor.
WHY?

I asked if I could speak with the tech who did the AC repair to ask exactly how he “opened up the coolant system” I was told he had left already. I wanted to know if the tech had removed the lower radiator hose, dumped all the coolant & then after the AC repair, replaced the coolant.

I’m having trouble believing that an air pocket could explain the need to add 24oz. Coolant & 2 days later another 8 oz. However, as I said, not a drop on my driveway, even when the car sat overnight. The shop also insists there is no leak.

As they said, there was N/C for this repair. I mentioned that I was going to stick a long screwdriver in the tank & try to move the float up & down to see if it was just stuck.
The SA shook his head & said your float was moving correctly & the float is different than the low coolant sensor, which was bad.

So, I looked up these parts in the SNG BARRATT catalogue.
Expansion tank $140 - $152 (MNC4400AC)
Coolant cap $16 – $19 (Pressure Cap, 1.0 Bar MJA4440BA)
Sensor $26 –$33 (Fluid Level Sensor Part # LNA5740AB)

So, why would they spend ~ $180+ on just parts for me? It had to have taken the tech at least a half hour maybe an hour so that's another $60-$120.
Yesterday, I was wondering if they actually found a loose hose clamp, explaining the leak & discovered the bad sensor & since the part was only $30, they tightened the loose hose clamp & decided to eat the cost of the sensor & it would not take much time to drain some coolant & replace the sensor which seems to plug into the bottom of that expansion tank. But now they have replaced the entire tank & not charged me.
I do not see how that AC repair could have been the cause of a bad sensor.
I also do not see the float listed in the parts catalogue. Maybe it is part of the expansion tank & not sold separately? Why is there a separate low fluid sensor & a float? Does the float position send information to the sensor?

Anyway, that is a lot of free parts & labor for a shop to do if they did not cause the problem.

Yes, I’m looking a gift horse in the mouth. LOL.

There is no need to drain any coolant when replacing the sensor as the sensor sits in a (dry) plastic tube that is part of the tank. The float is also an integral part of the tank and it sits around the mentioned plastic tube. The float has a small built-in magnet and, when above the "min" coolant level, the magnet of the float switches "on" a miniature magnet sensitive switch inside the level sensor and this signals that the level is good. If the float (and its magnet) drop below "min", the sensor switch goes off and the warning light comes on. To replace the sensor takes 2-3 min.

What the shop has done is strange indeed, if the fault was only in the sensor. Perhaps they felt guilty about something they have done but they are not telling you. The only reason to replace the whole tank would be if they damaged it which caused a leak but very small which was evaporating before dripping on the floor or if they somehow damaged the float.

I checked the coolant today after car sat all night. I had driven it 25 miles Wednesday after picking it up from the shop. I expected it would be completely full to bottom of filler neck. It was NOT! I had to add 12 oz & still a bit below bottom of neck. WTF?!
Looking @ “new” cap in daylight, it does have writing on it but, very faded. Very hard to see. Yesterday, I had though it was all black, unlike my OEM cap which had very visible writing. Same as caps I saw online.

Did they get a junk yard, used part? Maybe all 3; tank, cap & sensor from a salvage Jaguar?

I will check coolant level in a week… if I do not get the warning light again.

Do not keep filling it up to the neck but weight to see if the warning light comes on. Filling to the neck is certainly an overfill and the excess coolant will be pushed into the overflow tank (in front of the left hand front wheel arch liner), i.e. the level will self-regulate. As long as you do not get the warning light, you are fine.

Regarding the overflow tank, the coolant that is pushed into it due to expansion when the engine warms up is supposed to be sucked back into the header tank during the engine cool down. However, if the tank cap is faulty, it may allow the overflow into the overflow tank but not allow its return into the header tank. If the cap looks old, I would replace it.

I know about that overflow tank, it is difficult to see. Can’t tell if full or empty.

BTW, why do you say filling to BOTTOM of filler neck is an overfill?
My Vehicle Care Handbook, page 3-7, states: “The coolant should be level with the bottom of the filler neck of the header tank.”

I was actually not quite correct when I said that. What I meant to say is that, if filled to the neck, some coolant will certainly be pushed into the overflow tank as there is no space in the header tank for it to expand. If then, due to a faulty cap or if the vertical pipe in the overflow tank (which should go to near the bottom) is broken, the system cannot suck the overflowed coolant back. In that case, the level in the header tank will get lower but, if there is no other problem in the engine (like head gasket leak) or in the cooling system, the lowered coolant level will not go further down since, for the next warm-up cycles, it will have enough space in the header tank to expand and no more coolant will overflow.

Just monitor the warning light and, if it still comes on after some time, you either have slow leak somewhere or a small leak in the head gasket.