I need some help here before I start digging.
I drove across the state yesterday and the radiator fluid light came on (low fluid). The temp gauge stayed low so I drove to an auto zone. They didn't carry the orange fluid so I added water to the top off. It did not seem low but the light went off and I had no further problems. 300 miles back and forth same day.
Today, I drove about 8 miles and when I turned off the car I noticed the high speed fan kept running. this never does this. The temp gauge was in the middle where it always is. I opened the hood and let it cool down. I added some orange fluid to the top off even though it was pretty full. I then drove about 3 miles to Staple, then the grocer store. The fan ran again at the grocery store for about 5 minutes. I drove home (5 minutes) and the fan kicked on when I parked it and the gauge red light was on and moving to the top. I shut it down and the high speed fan ran for 5 plus minutes. I checked the gauge and turned it back on. Gauge was normal, fan kicked on again when I was turning it off (2 minutes) and ran for about 2 minutes. The fluid does not look great and it def. is not orange.
where should I start?




2002 Jaguar Super 8 -103000 miles Florida car

 

You will find many threads here about the Temperature Gauge - it is absolutely USELESS! It will sit in the middle of the scale until the engine is seriously overheated.

The coolant level indicator is also unreliable. It can stick and give false low coolant warnings.

It sounds as if you do have a genuine overheating issue when the fans are running continuously. The commonest cause of this is a sticking thermostat............ in the XJ8 as well as in the XK8.

Graham

 

Thanks Graham,
I have looked high and low for information on this cooling system here in this forum. I read in one place that there are two reservoir's. I can only find the one near the throttle body that has the cap on top. That is pretty full and green in color even though it clearly states to use the orange stuff. I am going to drain and flush but I can't even find the filler cap for the radiator. Apparently, there is no radiator cap. How do I get to the drain plug? Is it just a screw on the passenger side (right side) of the radiator bottom? Where do I flush with a hose? It can't just be this reservoir all the hoses are tiny. Do you know of any DIY links for flushing this system out? If it is the thermostat where is that? Is it easy to switch out? Thanks for your help

2002 Super 8 103K

 

Classic indication of a Bad Thermostat. Replace it immediately!

 

Ok, how do I do that? LOL............I can't even find the second reservoir.
Where is the T-housing on the Super 8? Can I just put in a new t stat or do I need to change out the housing? I want to flush out the coolant, it's greenish and hasn't been changed in forever.

2002 super 8 102k

 

Before getting into details, let's confirm what you have and get this in the right forum section.

Am I right you have a 2002 Supercharged XJ8 four door and not an XK8 two door (either the Coupe like Paul's or the Convertible equivalent)?

Graham

 

Yes, it is the xj vanden Plas super 8.............I misread the info at the top. sorry about that.



2002 Super 8 103k.

 

I've moved your original question together with Paul's and my replies to a new thread in X308 section. You should get further help here from members with the same model.

Graham

 

Need to change the thermostat, immediately. The primary overflow reservoir is on the left hand side next to the throttlebody. The secondary is underneath the wheel well on the left-hand side if you follow one of the black hoses over to the left Side of the car you will see it disappear. Radiator Petcock is on the left side of the radiator engine side.

Most people replace the bypass hose, a little short hose, and the waterpump when ever they replace. the thermostat. Mostvalso will renew the belt, tensioner, and idler at the same time. Just about all parts were available at advance auto parts (not tensioner or idler). If no bolt breaks or fails to yield should take 2 - 3 hours.

Google any of these terms and you will find the threads on this forum, as well as some great youtube diy videos. Be very careful with those plastic pipes, both in routing and to preclude breakage at the nipples, very fragile.

 

Your thermostat might very well be bad, and I agree that the guage is not very good to tell the real temperature, but if your thermostat was held closed, ithe guage would show high. And You say that the car "never" ran the high speed fans previously. I would be suspect of an XJR that did not run fans in Sarasota in the middle of summer. If you know someone with an IR temperature guage, that can help. Look at the temperature of the ccolant resevoir.

So, change the thermosat to be sure, since it is not too expensive nor too hard to replace. It will make you feel better, it might just have a problem. Just don't be suprised if nothing changes.

As to flushing, the best way is with a garden hose, with the big hoses off and the thermostat out. Open the radiator petcock and squirt water in the radiator as well as the engine until it looks clean draining out. Since you want to change the thermostat anyway, you can use this flush method. Otherwise, yopu are faced with several empty / fill cycles with waits to allow the engine to return to temperature.

I have had two Jags with a plugged heater matrix. I blame the POs use of green standard coolant, and I now use DexCool. I have had no problems after many miles of DexCool. buit it iIS NOT the manufacturer's recommended formulation. If you want to be sure the fluid is "right" get the right stuff at the dealer.

Have a look at the drawing. Note that there are two #7s- one is the SC and the other is NA. Give special attention to the hose connections for # 4 and #7 at the expansion bottle. It is easy to convince yourself they should be swapped!

 

Thank you guys for your help.
The fans work it's just that they never really ran on like this. It was an obvious difference that I had not heard before. It was like they were roaring.
I am going to change out the thermostat and flush at the same time per your suggestion. What thermostat should I get? Is there a gasket/seal that I need as well? You are suggesting I buy the coolant fluid at Jaguar?

 

Oh, and the tubes are crossed as they are supposed to be.

 

Thank you for this in depth explanation. Now I need some technical product help.
I called a Jag dealership and they say I need 12 liters of coolant at $18 per Liter. That's about $230 for coolant. The thermostat is $75 and they only sell the one seal at $9. They don't sell the two seals separately for the outlet pipe and the thermostat housing. They only sell the one for the outlet pipe. This means the one seal will be reused.
They say I have to use this coolant because it's an aluminum engine. When I look online for replacement t-stat's they range from $12 to 40. So, the question is...can I use a t-stat from elsewhere and can I use a coolant from elsewhere as long as it's rated for an aluminum engine?



2002 Jag super 8 103k miles

 

Any orange coolant works. Advance Auto Parts had thermostats for XJ 8, probably for supercharged units, as well.

 

Curtiss:
I may have been too "exact" in my post. Many folks around here are **** about their Jag-u-wah! I said the DexCool was not the exact spec, but I also said that is what I use with no problems. If you want everything to be per Jag's spec, use their fluid and pay no heed to the cost. If you want to be more reasonable, then use what's available at reasonable cost for aluminum engines.
The aftermarket thermostat is fine , too. I have had good luck with RockAuto and PartsGeek for reasonable prices and quick delivery.
BTW, to test the thermostat, drop it in a pan of water, heat to boiling, and the thermostat should open just before the water boils.

 

FWIW, I use Dexcool also with no problems. It seems a few people have had problems when someone used green coolant and then it got mixed with orange at some point. This has been known to cause clogging problems in the heater matrix or Rad. Not good.

 

Curtiss,

You're getting good advice here from Jhartz, sparkenzap and JimmyL on coolant and thermostats.

The capacity of the cooling system is 12 Litres (12.7 US Quarts) BUT the strength required is 50% so it's diluted 50/50 with distilled water. In other words you need 6 Litres of Coolant for a refill.

The important thing is to use the right specification. The brand is not critical. Specification is WSS M97 B44-D Extended Life Coolant (usually coloured orange).

Graham

 

Yes and yes. T-stat is not 'just' a one-marque Jaguar part anyway. Few are.

And the dealer is being a bit HUTA on the coolant.

An ALL aluminium engine is actually not as fussy about coolant as a partly-aluminium, partly iron one, with 'white metal' (zinc-rich) bits in water-pump and heater-circuit valves, brass tank on copper-core rad .... far more galvanics about on MANY other marques.

Dexcool should be just fine.

Do flush well and keep it clean and unpolluted thereafter - EG; mixeth not with the green.

W/R Temp gauge.

Computer-driven off the ECM is it not? Placebo, then.

I have a set of vintage Veglia-Borletti's in the air already so as to add an independent 'second opinion' and save-yer-budget earlier-warning.

Earlier Jaguars, several BMC cars, as well as Italian ones used those, so finding sensors to mate-up to the motor with off-the-shelf fittings should be easier than some of the other choices out there.

 

..unless, of course, what one finds in-stock is the now very common 'pre-mixed' that is already diluted to 50-50. Handy stuff w/r not having to mix - or guess when the half-way point has arrived.

I shall refrain from 'recommending' this other option, as there ARE some downsides - minor disadvantages as to cooling efficiency, and freezing at a modestly HIGHER point than 50-50 does (albeit a 'gelling' rather than the rock-hard metal-cracking freeze of expanding water-ice)..

... but as I don't live in Hibbing, MN or the North Slope of Alaska, for around 50 years now I have had superb life out of mixed-metal cooling systems by using 100% coolant, (glycol until recently) with ZERO water.

JM2CW and YMMV, of course.

 

I am Going to go out on the limb here, Since it has been 50 years since I studied the chemistry of ethylene glycol. But, from memory, adding water actually lowers the freezing temperature and it also raises the boiling temperature.

I use the 50-50 solution right out of the bottle, works great. What is not debatable, the price your dealer quoted is highway robbery.