Low Coolant Level

[RichardSEL]

Not sure whether I've got this "Coolant Level Sensor" problem or another but...

Drove back this new to me XJ8 '01MY three weeks ago from north Wales (isn't it?) to SE London and throughout startup, test drive before purchase, and return no problem no message on dash and no red light "COOLANT LEVEL LOW"

Drove around over the past fortnight plus a couple of trips (Brighton, Worthing and back and Newhaven and back) and no red light "COOLANT LEVEL LOW"

Last couple of days getting that message when on startup that stays lit. First time removed expansion tank cap with engine warm (not hot) and there was pressure and air expansion caused forced overflow of seemed like red coolant. Replaced only with plain water with the engine running (but not with the heater set to high) with cap off to middle of filler tube. Water accepted so assumed car hadn't been looked at forever and this was just a built up over time air lock.

Following morning warning light came on on Sidcup bypass (but not at startup). Again topped up (about a teacup full) light goes out. Checked by startup only yesterday and no warning light.

Checked underneath car and no coolant leak or drips visible. Firing is fine, no mayonnaise. Coolant temperature gauge stays at correct middle throughout. Thoughts?

[J44EAG]

I would check for a connection issue at the sensor. It might be worth removing the sensor and cleaning. A coating of coolant gunk can often cause malfunction. It is possible the sensor is defective, in which case replacement is a good idea. From my own experience, install only a Jaguar genuine part.

Consider also the possibility of an air lock at the highest point on the system. This is the filler cap with the hex socket and is the point that a cooling system should be filled and burped to avoid air locks. You will have to go easy with this cap and the thermostat tower itself. Yet again Jaguar made these parts from plastic and they are notorious for breaking up given age and heat. An alternative aluminum version is available on the aftermarket and I know Berkshire Jaguar Components stock them. They are a similar price to the plastic parts but are far more resilient to failure especially where the three thermostat housing bolts are concerned. The plastic versions when old have a habit of letting go the threaded inserts which spin in the plastic and make dismantling a nasty experience.

The X308 has several fail points which were engineered out on the X350. You will have come across the tensioner issues. Water pumps with plastic impellers later gained metal updates together with modified thermostats and the thermostat tower as discussed above. Once up-dated, these cars lift to the next level as regards reliability. Sensor failure however affects the entire Jaguar range and is common on other makes also. Sensors can become unreliable with age, heat effect and mileage. They are usually good for 80k to 100k miles after which reliability can become an issue. Most failures centre around cooling system components and various coolant hoses and small vacuum pipes. Nothing lasts for ever.

Mike K

[RichardSEL]

Yet again valuable advice from this forum

I'm just gathering quotes for the work I want done (tensioners, ATF, etc.) that includes cooling system flush out and refill. So if it happens after that little lot still, will investigate further.

Either of the two firms will of course notice any coolant drips that I've not seen. One has already said that they want to keep overnight and drive around the day after works to make sure all's alright before I can collect. That firm I like...

[RichardSEL]

Driving around together with four or five startups today gave the "COOLANT LEVEL LOW" warning and red light on two occasions today. On both was on dual carriageway or M25 so, knowing I only had topped up a teacupful last time it happened, just kept on driving watching the temperature gauge which maintained its half meter reading without any change.

Then about five miles after fault came on, it went out again and stayed off.

This was repeated when on Sidcup by-pass -- went off again. I will press up and burp the system meantime (this time with heater on HI) but did at least switch to HI this time and heavy heat came thru cabin.

Will take down the sensor tomorrow as you suggest Mike K to see whether it's gunked up and check its free movement operation. Nothing can go wrong doing just that...

[Brakebuster]

the sensor is a ' reed switch ' and has no moving parts to check

the moving part is ( as in my description ) the floating magnetic ring within the coolant tank its self, this moves up and down with coolant level acting magnetically on the reed switch pushed up into the ' pot '

i doubt you have an airlock given the constant temp on the gauge , however, its not a bad idea to ' burp ' if your confident nothing on that tower will break ,

BB

[RichardSEL]

Given I've got to add half to a cupful of water to switch off the warning -- last time the level was about 1" below the filling tube -- guess I've got a slow coolant leak somewheres and the float is doing its job in telling the sensor.

Will investigate more later today. But finding said slow leak could be interesting.
Anyone know of any common points to look? Can't get underneath, and nothing to see on roadway after parking overnight.

If I can't find anything today will have to do a burp and take it somewhere at least with a ramp to see what / where's the escape.

Obviously fearing the worst: head gasket leech, but don't have that smell nor any steam when hot, no misfire, no mayonnaise

... to be concluded

[J44EAG]

I had a similar issue with my V8 S-type. Never did find the leak but fixed it by adding a rad sealer named K-seal. Apparently the RAC use it.

Least said, soonest mended!

Mike

[RichardSEL]

Welp, I've pressed up the system with the cap off. There seemed to be a slight emulsion on the surface of the coolant that tainted the coolant colour a sort of brown. It's definitely not the red of the anti-freeze that's in there so I assume previous owner/s knew of this and hadn't had it refilled with the proper anti-freeze mix.

Ran on idle with occasional blip of the throttle for 20 mins with the heater on "Hi" and not much air seen to come out, just the occasional one bubble burp. What I did see though (and I've never seen this before) is a slight effervescence surfacing into the top of the coolant neck. Only the amount you'd see in a glass of champagne. This started about when the temp needle was one graduation before half, and stopped about when half temperature was displayed.

It took a ½L

Ray at Surry Jags is on holiday. But they said they'd have a look on Wednesday morning, but coz of the work they've got on, even if they find a hose or something leeching won't be able to do anything about it there and then

That was at 2pm this afternoon. Replaced expansion tank cap with level at bottom of filler tube, with engine at idle. Now (5pm) with engine off level's one inch below bottom of filler tube.

May have to go the K-Seal route if nothing found on Wednesday...
Thanks again for the thoughts... most welcome

[J44EAG]

Its worth a Mk 1 nostril sniff test when you next remove the cap. Combustion by-product gas is quite distinctive. There are sniffer kits around which would give a more positive indication as to the presence of combustion gas in the coolant system. Is there any sign of water dripping from the exhaust tail pipes?

The scum and effervescence is a tad worrying. Ray at Surrey Jags is very well thought of locally. He will no doubt get a handle on the issue for you.

Mike

[rod3751]

Hi Richard, I had a similar slow loss of coolant which turned out to be a very small leak from the radiator in the oil cooler area. I had to top up every couple of weeks but could not find the leak and nor could my local garage.
Eventually my 2002 xj8 3.2 se overheated on the way into Cheltenham neccessitating a call out by the RAC. I swear the temperature guage never moved off normal but the car just stalled in slow moving traffic! This time when the engine had cooled sufficiently and was topped up,the RAC guy spotted a slow drip from the bottom of the oil cooler/radiator. I was able to drive home with the RAC following. During the downtime i changed the radiator, coolant level sensor upgraded water pump and thermostat. While i had the radiator out and there was some room, i checked the tensioners and thank god they were the aluminium type.
Take heed of Mike's warning re the thermostat tower i managed to crack the top hexagon cap and had to buy a new one the rest of the tower was ok.
Hope you sort it, best of luck.
Rod

[RichardSEL]

Didn't smell anything from the slight effervescence (which stopped during idle) or occasional burps. But I wasn't sniffing for anything there. Did at the tailpipe though, and there were no abnormal smells nor water coming from them
On some cars in my past have seen water coming from exhaust as a sign of good combustion, so don't know if these engines do that? Anyways, nothing noted -- did have it on idle for ½ hour when I bought and there was a drive around the town before purchase. I checked then and nothing seen

The scum is only really thin emulsion -- a surface trace like you'd see if there's a trace of petrol on the surface of a puddle with the colours. It stuck to a clean rag when inserted into filler neck. Yes, oil cooler was my thought too, as had this fault been there thru previous owners would've shown itself as mayonnaise by now if head gasket leeching. On these engines too? But don't even know the architecture of these XJ8 3.2L lumps yet.

Overnight coolant level has not dropped further from yesterday's 5pm 1" from bottom of filler neck.

Wont drive it until Wednesday when I take it into Surrey Jags in Croydon for their diagnosis -- will just daily check level's not moving further down. No sense in getting paranoid about it -- I've got timing chain tensioners and the ATF and filter for that

Thanks for the support. Will come back once Surry Jags have seen

[RichardSEL]

Some kind soul has offered to do a sniff test for me -- except it's up in Norfolk -- still would avoid any "vested interests" colouring the result by a private test being done.

Meantime today's non-started coolant level seems to have gone down by a further ¼". But there's still nothing showing on road...

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[J44EAG]

Did you top up when hot? If so, when the car cools, the water level may we drop.

Mike

[RichardSEL]

Yes, I did press up when on idle. So guess it's now at the correct level for when cold. I haven't added any water since. I'll carry some when I go to the workshop tomorrow but drive it with its existing level to see effect.

BTW, is there any block diagram of the cooling system for the XJ8 around? Might be worthwhile actually understanding what I'm looking at

Rod, I keep on looking down the rad toward the road expecting to see the tell-tale signs of green leech and a few drip marks on the tarmac. But nothing!

This morning, when I removed the reservoir cap there was a brief bubbling sound from the front NS somewheres, and the reservoir's coolant level kinda wobbled. Did my usual squeeze of the two reachable top end hoses and both give a movement of level. But level was the same as yesterday's

Were there an internal leak of coolant to oil / oil to coolant in the oil cooler would expect there to be mayonnaise showing by now which is why I need that block diagram...

>>later>> Just found this this thread, five pages long, it might help someone else, or confuse as there's several posters there that have a slow coolant leak too. One mentioning "aluminium tower" whatever that is (yes, I too have got some flecks of white similar to the thread's pic) another poster with cracked expansion bottle, another hoses...
http://www.jaguarforums.com/forum/xj-xj ... etc-85061/

[J44EAG]

Mayonnaise would only be present if a head gasket had gone adjacent to an oil way or if a cooler had given up between the interface, Richard.

This link should help you.http://www.google.co.uk/url?sa=t&rct=j& ... NwdrKUf4YQ

Mike