I know there are lots of threads on the low coolant light, but I can never find it for my model and year. So can a very knowledgeable member please answer my question. My 2003 XK8 had the low coolant light show up about 1.5 years ago. I filled it up with some generic "any make, any model" coolant, however recently it has occurred every other month or so. The dealership says there is no leak. So what could be the issue? Filling up the coolant this frequently seems too often to be normal.

 

I had a similar situation a couple of years ago, though not quite as frequent as yours, I would have to put a cup or so of coolant in about every three months. There was no evidence of a leak on the ground or dripping signs from any of the major hoses, but I could smell the faint scent of coolant on a regular basis. It turned out to be the "octopus" of heater hoses that were leaking at the flanges not through the hoses themselves. The leaks were tiny, almost like a mist, that would hit the hot manifold and sizzle into evaporation. I replaced them and have had little missing coolant since. There is still an occasional top off, but much less frequently and no smell.

 

I too had the low coolant greeting a while back, had it topped off at local lube shop only to return few months later. No evidence of a leak so very puzzling. Warning light became more frequent and one day I noticed a little coolant on underside of coolant filler/header tank. Asked around on forum, was advised this is common fault, small crack appears on underside of tank and needs replaced. Coolant would hit hot manifold and evaporate. Check for wetness under tank or rust stains on manifold underneath.

Bought one off of ebay and installed myself with some new hose clamps.

Hope this helps.

 

+1 on the other, but I can guarantee you there is a leak. When you do a search in the forum, most forum users have the year and model in their signature, and while there, add yours as well.

My advice is to get it sorted out asap, and I mean asap. You don't want to risk overheating the engine. If you do a search, you will get to the most common items for leaks.

 

On your model with the 4.2, it is very common to get microcracks in the plastic thermostat housing assembly, where the leak is too small to detect with a pressure test and simply evaporates.. For under $100 you can replace the whole plastic assembly, and it includes all new seals, a new sensor and a new thermostat. This is a good investment on a 10 year old car and there is a good likelihood it will cure your problem.

See 2003 JAGUAR XK8 Parts - Direct JPLV Porsche Parts.com

 

+1. It is a closed system. If you need to keep filling it up, it is leaking somewhere. You do not want to overheat these engines. Several common places to look regardless of year, such as expansion tank (especially at bottom as noted earlier), overflow hoses to expansion tank, and of course the radiator hoses themselves.

 

Filling up the coolant at all is not normal. These vehicles should not lose coolant. If the level is dropping, then you have a leak.

Generally, leaks from hoses have a higher loss rate than you report. It is more likely to be from the Thermostat Housing or Expansion Tank.

The Expansion Tank design has changed little from the first XK8's and is a regular problem area. The Thermostat Housing is much improved from those fitted to the earlier 4.0 litre model but is still not free from failures.

Graham

 

Thank you every one. I will fix this ASAP. Also I have added my signature, but apparently older posts don't update?

 

Found this aluminium thermostat housing for the XK8 on ebay. Any thoughts?

Jaguar XJ8 XK8 Aluminum Thermostat Housing KIT W Thermostat AJ82217 | eBay

 

Careful, that is for the 4.0 engine only, not your 4.2. The information is either wrong or Jaguar still shipped the 4.0 in 2003 to certain markets other than the US and UK.

 

Also check your heater feed lines on top of the engine, as WhiteXKR recommended to me this week as well. Mine are leaking. Although unlike the XK8, I'll be removing my supercharger to get at them this weekend on my XKR...

 

Thanks Steve, hadn't checked VIN suitability at time of writing last night but did like the possibility of the upgrade from plastic to aluminium! Looks like I'll be hitting Gaudin Jag for the OE housing (c/w all the other stuff:stat, sensor & o rings)

I have been closely following coolant/cooling issue threads, engine knock/ping threads as I have, surprise, a couple of issues to address on my XK.

All started with noticing excessive pinging under load. Also noticed the fan running, it is summer here (30's C)

Thought I'd try Seafoam, bought can of spray and with throttle assistance from my lovely wife put just over half a can in through TB. WARNING It gets really hot holding the can there! Went for drive after waiting the five minutes and pinging is gone! Great.

Poked around looking for thermostat housing as I thought it would be a good idea to change it it out, and do a coolant flush refill too. Found this orange goo seeping out of bottom of temp. sensor housing area (see pic). Felt hoses, all firm and hot so thinking t-stat operating but will need to replace housing as it doesn't look serviceable.

Funny, there's a lot of similar threads/issues on other guys cars on the forums right now, guess it's the age of the cars and the hot summer weather (not to mention underhood temps) that is taking its toll.....

Thanks to all contributors, all ideas, knowledge and experience is greatly appreciated and is what keeps our great cars running~affordably!

 

Called Gaudin Jaguar and they do not ship to Canada unfortunately, so went to local dealer, Kelowna Auto Sport and Terry in parts has ordered the same thermostat housing package for $133 CAD (no shipping fees) so I'm around the same cost and may even get the pieces sooner!

 

Reading the frequent threads this week regarding the various cooling system design flaws in these cars caused me to take a good look under the hood of my wife's 2006 XK8 yesterday evening when she returned home. I removed the plastic engine cover, got my trusty mini-flashlight in hand, and spent about ten minutes having a good look-see. Results were as follows:

The much-feared plastic overflow reservoir shows no visible signs of coolant leaks. Nor does the thermostat assembly. But what I immediately noticed is that one of the upper radiator hoses appears to have slipped back a bit from being snugged up against its mount. I attribute this to the quick-on / quick-off hose clamps that the factory used when these cars were built. I'll bet that hot, condensed coolant could escape through that currently not-so-tight seal as steam and never leave a trace of evidence. Like some other folks here, I've had to add a capful or so of coolant a couple of times since we purchased this car in February 2012 in order to bring the coolant level up to the top of the filler neck in the reservoir....

So this weekend I'll be replacing that suspect factory hose clamp with a good ol' worm-drive clamp that can be screwed down tight to evenly hold that hose end snug up against its mount. I'm hoping that will solve the mystery of the very slight coolant loss that I've experienced in this car during the past 18 months....

 

Picked up my new thermostat housing assembly from dealer yesterday. Looks great, all assembled and ready to install!

Question is, is the new housing assembled to correct torque specs and is thermostat installed correctly? Looking into housing I can see bleed hole is not quite at top more in 11 o'clock position.

Thanks

 

Did a coolant flush and replaced the thermostat housing assembly today, assembly was a breeze to install. Used Dex cool as per the decal on header tank (use only long life engine coolant ref.WSS-M97844-D colored orange)

Also, the instructions from MrTexasDan in the How to sticky were very helpful, thank you Mr Dan!

Thank you to all you guys once again for making this forum what it is-awesome!