So I decided to drive my girl to work today, and noticed toward the end of the drive my temp gauge was higher than it usually is - still around the N but edging up a bit north toward the dreaded H. Typically, it's midway between the C and almost to N, so this was hotter than usual. Also, the auxiliary fan was on when I locked the car, and stayed on (don't know for how long) as I walked away.

I'm thinking/hoping this isn't a "get the flatbed and don't drive her home" situation, but I'm also wondering if this is still in the normal, acceptable range of engine heat? I've only had the car since March, and on the road in April, so I'm still getting used to what's typical for her. Thanks!

 

First you need to determine what your actual engine temp is.....in *degrees* . I say this because there's a wide variance in the notoriously flakey XJS gauges. Use one of those hand held infra red thermometers at the thermostat housing areas. That'll get you in the ballpark. "Middle of the N", for example, might be 185ºF on your car but 205ºF on the next.

Also remember that it isn't *coolant temperature* alone that is at issue. More important is proper coolant *flow* to all areas of the engine. It's lack of flow causing hot spots/steam pockets that causes most of the problems with dropped valve seats.

Cheers
DD

 

At least check the coolant level before starting it again.

 

+1 on the above posts.

Another thing is to check in front of the radiator for any blockages. Look through the grill slats and see if there are piles of leaves or accumulated dirt etc on the radiator fins and carefully vacuum them out. The XJS is notorious for this and many owners, although keeping the exterior nice and shiny, forget to clean out this area.

Also is it hot where you are? It's pretty toasty in NC at the moment and if you drive around in a lot of stop and go traffic with the A/C blasting, it's quite normal for temps to be elevated a little. That's why Doug's point is so important, you need to know what the coolant temps actually are.

Cheers,

Allan

 

I checked all of the fluid levels and looked for leaks before starting her up for the return trip home - didn't notice any accumulated gunk near the radiator, but will look at that tomorrow. It was much less humid in the afternoon, and the car seemed much happier. The gauge stayed at N, the aux fan did not come on, and aside from her typical erratic gauges all was well.

Checking the coolant was something of a challenge in work clothing with my hair down, though - do you have a trick aside from using my phone's flashlight app to peer down the tube to do so? Also, if coolant is needed, WHERE do you put it (my "driver's handbook" tells one how to check it - sort of - but is vague on doing anything about it after that, although it does offer dire warnings about using water or anything other than Jaguar coolant and spends much time on "specific gravity," making me a bit cautious about what to add if it's needed...) My colleague was amused at how snug everything was under the bonnet, too :-).

 

if you are peering down the spout of the header tank on the LH inner guard to see liquid of any sort, you got PROBLEMS. That spout should be full at all times.

Adding coolant is quite tricky to get right, but if it is that low I would be adding water as a MINIMUM. OK, NOT THE RIGHT STUFF, but better than nothing to get home, SERIOUSLY.

This low coolant issue really needs sorting before any more driving on a regular basis is undertaken.

MY OPINION. If the V12 is your first venture into Jaguar world, please sort that cooling system NOW. It is far more important than washing the car, or shining the tyres. These cars have become badly neglected in the real critical areas, no matter what the seller said, and will cost you the national debt if left as is and driven like that.

I wrote a paper a looooong time ago on filling the cooling system on these beasts, and I have attached it if you are interested.

Bleeding the V12 cooling system.doc

 

Dont forget to bleed all the air out of the system. Dont forget the radiator bleed screw located on the drivers side (left hand steering cars). On mine it's a 10mm hex head on the top of the radiator. Best to park car on an incline so the air will collect at that point. Good luck.

 

OK, now I'm beyond concerned. The tube I peered down is the one with the honking big cap that says "Coolant" on it - more in the middle of the engine near the radiator I'd say. Was that the correct one? If so, I shall indeed be bringing the girl to my mechanic pronto! I'd say thanks for the info on how to fill it but it was a bit overwhelming to be honest :-).

 

Spoke with the mechanic - am going to recheck (yeah, I looked in the wrong place) and buy the correct antifreeze (Peak 100% in the blue bottle) and fill if/as needed. Then...we shall see. MANY thanks for all the help and info!

 

Grant, great write up!!

Gina,

Here is a pic of the engine bay of a 90 V12, hopefully yours is the same

I have marked the two caps with arrows. You would use the one marked by the red arrow to fill up the coolant levels. (I believe that is the one you looked down?)

The cap marked in yellow is for the expansion tank that Grant was talking about. Don't open both caps at the same time as coolant will run out of the expansion tank spout. (Assuming there is coolant in the system )



Cheers,

Allan

 

Yup - I looked down the wrong one :-). MANY thanks - that is a cleaner looking version of my engine exactly. Now, one more question...I DO need to open both up to add fluid, correct, so that I can make sure not to add too much? THANK YOU all so much!

 

My head explodes everytime I see that engine. Boy is it tight in there...

Just looking at it makes me want to unravel all of the hoses and cables.

 

definitely get a thermometer to check with.

Sometimes my car runs under the N and lately it has been running above the N. Is it overheating? No. My gauge or sender is messed up. I have checked it and confirmed the same temperature each time.

Seeing as my voltage gauge is wonky, fuel gauges only half works, and I'm not sure if the oil pressure is correct, I would wager that my gauge is just messed up.

I keep a IR thermometer in the trunk nowadays, just for peace of mind.

 

Not necessarily, if you first open the expansion tank cap and it is full then you probably just need to top up as per your handbook. (I actually think this is probably what you will find )

If you don't see coolant (bad) then yes take off both caps and pour coolant in the filler until it comes out of the expansion tank spout. If this is the case then it is likely that you will need to bleed the system to get trapped air out.

You have Grant's instructions on doing this and also Greg offered up this less detailed version

Bleeding the V12 cooling system is a bit tricky, so you might consider having or watching an experienced mechanic do it this time round. Just make sure he/she really understands how the system works, most don't!!! Like many systems in the car, the cooling system does not quite operate in the same fashion as other cars.

When it comes to Jags, I like to paraphrase Mr. Orwell, 'all cars are created equal but some cars are more equal than others'

Cheers,

Allan

 

Filling and bleeding is one of those things that is best done as a DIY as long as someone takes care to obtain the proper instructions and follows them to the letter. Grant has kindly attached instructions. I expect that they would be very complete.

This is because it takes time and patience, as well as multiple tries. This is less likely in a shop setting because customers would have a heart attack when presented with the bill.

Consider your choice of coolant carefully. I believe that the V12 used conventional coolant. A lot of the "universal" coolants are very similar to the dreaded DexCool. The manufacturer just doesn't disclose it. Prestone and Peak are particularly vague about their coolant formulations.

Zerex markets a conventional coolant that is actually labelled as being conventional coolant. It is harder to find than the Zerex G-05 which is a nice coolant, but it is not the old green either, it is a BASF Glysantin variant.

Peak Blue is probably not what you want:

http://www.boyerpetroleum.com/documents/peak-af.pdf

It looks like Peak Force is the conventional and is marketed for fleet use. In the Zerex, you want "Original Formula".

 

MANY many thanks, everyone. Allan was right - by checking the CORRECT cap I just needed to top off (although Grant's very comprehensive document is going right in my folder). It look about 11 oz total - I used an old, clean, dry sports water bottle, 12 oz size, to make it easier to fill and that seemed to work well.

Now, for the recommendations for an infra-red thermometer - any recommendations on type/brand/where to buy? I've seen them at Harbor Freight but figure you're all a better source than Google :-).

Thanks again - as a new Jag owner, and not a mechanic going into it, it can be a little daunting with all the horror stories out there, and I appreciate all the info and guidance!

 

The link below is not a laser thermometer, but they are an incredible bargain for what they do.

- digital temperature display
- programmable temperature compensation
- programmable relay/alarm control

AutoSpeed - $25 Temperature Controller and Display!

Temporarily duct taped to my thermostat housing on the engine side, it tracked the coolant termperature sensor output on a obd-ii scanner quite closely. Some few degrees of offset compensation might be called for. That can be programmed using the buttons.

If it does not fit into your interior styling, you could always mount it under the hood and just extend the alarm output to a piezo buzzer and led for the interior.

If anyone needs a fully programmable fan controller, this unit is probably the easiest to work with.

 

I forgot the most IMPORTANT thing about the XJ-S.

They are ALL female, and a sense of humour is mandatory for happy ownership.

I know Gina has a sense of humour, she has a V12.

NO OFFENCE INTENDED, I AM JUST A "GRUMPY OLD JAG OWNER" , as my daughter constantly reminds me.

 

Grant, +1 on the above except for the last line

I doubt anyone was offended in any way. Personally, I always listen to the sermons of the good St. Francis, informative, dead on accurate and inspiring!!!

Cheers,

Allan

 

Yep, and my wife is "The Minister for Everything", just ask her.