Hello everyone,

I am new to the forum, apologies if I am posting in the wrong place or this thread has been started before.

I have a 2005 s type r.

The car struggles to warm up and has thrown a code for a thermostat, so I am replacing this weekend. The reason I am asking on the forum is that every 500 miles I have to top up the coolant as has fallen from max to min, I do not think this is thermostat related, and i can see no obvious signs of a leak. Could the forum point me in the right direction, for example, what hoses are prone to weeping/which ones to check or provide a logical explanation why I am having to top up once a week.

Many thanks all

Many

 

Your car is of an age that the coolant hose under the supercharger needs replacement if it hasn't been done already. On mine the coolant from the bad hose ran off the right side rear of the engine, the same area where the AC condensation drips down. While the supercharger is off some of the other hoses are easier to get to. It's good to change those too.

The procedure is here:

jaghelp.com: 2006 S-type supercharger removal

 

I was fearing the valley pipe, what is the best way to confirm - or is it a case of just looking in that area at the back for signs of water?

Excellent write up, can not decide if i should do myself or let a specialist at it (need to find one near braintree essex? (as an ex vehicle fitter, think I have the skills to do with your write up). Unfortunately it is the wrong time of year as the s type is too long for my garage, tempted to nurse it through winter and do in summer - but scared i would be tempting fate and causing damage.

So annoying as only had the car a month!

Many Thanks for your reply

 

Getting the front end under roof, use tarp's or drop cloths to block out most of the wind. A day or two, with all the parts in hand, should put you back on the road with one less worry this winter.

 

Guess that would work, does anyone know how long it would take....possible in a day? Would I need the pn off old hoses or would jaguar know? Just need to somehow confirm that that is Def where the problem lies, shone a torch down the back earlier and didn't see any dampness, unless it's evaporating hiding the evidence

 

For the first time give it 2 full days. Having done it once it might be done a second time in a long (12-14 hour) day. I've done the process multiple times and have always done it in 2, but........I'm retired and have the luxury of working at my own pace.

I buy my parts at Jaguar Reno - they have an online pictorial guide with part numbers:

https://www.jaguarlandroverrenoparts.com/

If your cooling system contains water only it might be evaporating on the exhaust or within the valley area without the unmistakable smell of burning anti-freeze.

 

That is an excellent site for exploded views, thanks. Have anti freeze in the cooling system, making me wonder if I should be looking elsewhere than valley as can not smell burning antifreeze, although no evidence of any other visible leaking hoses so thinking it must be under there. Def not the head gadget as oil looks and smells fine

 

Been doing a bit of research and read that the radiator shares it's gearbox cooling internally within the rad, and it can fail mixing coolant with gearbox oil. Does anyone know if this applies to the s type r and if there are any clues to look for to indicate this. Really lost as can not see or smell any indication of coolant loss any where....no signs of wetness down back of engine (from what I can see) no smell of antifreeze or indication of a leak anywhere. Although it is losing it slowly - from max to mine in 500 ish miles

 

any time I have slow hard to find coolant leaks using a pressure tester and leaving it pressurized for a time usually reveals slow leaks.

Have you tried this? I get a loaner from my local parts store.

 

I wouldn't pin the coolant leak on just one possibility. The cooling radiator and coolant expansion tank are fairly common sources of slow leaks. I had a slow leak on my V6 petrol and it was the radiator which also has the cooling section for the gearbox atf. Very hard to spot the leak which was on top of the rad but underneath the cover.
Mine was losing between 0.25 and 1 litre each run, but sometimes it didn't lose any.
I would suggest take the car on a run then when you stop, remove the radiator cover under the bonnet and have a good look using a decent torch to look down at the bottom of the rad and pipes. Check around the expansion tank especially the spigots.
A coolant leak will leave deposits somewhere.

My leak came from the right hand side top of the radiator and the coolant tracked across the top of the rad and then went down on the left hand side to appear as a small pool of water on the floor near the left hand seat footwell. The engine under tray can hide where the leak is. My mobile mechanic did a cold pressure test and it showed no leaks.

​​​​​​I got a pattern radiator with 2 year warranty although it wasn't easy finding the correct spec of rad from an independent supplier. Mine is a crossover year between the early model and the later model. With a 2005 car you shouldn't have that issue. However on the day of fitting the radiator the plastic connector to the top hose threw itself in bits all over the floor as the hose was disconnected. This connector has already been mentioned. But in my case it had been glued back together one too many times and it was time to replace. The connector only came with the new top hose complete which I was very surprised to find wasnt too expensive at all direct from Jaguar. The top hose including this plastic connector was about £120 which tbh was about normal. The top hose for my Ford Mondeo zetec engine was almost £90.

So just bear on mind there could be other costs.
Makes sure you use the correct Jaguar spec of coolant. I'm not sure about the STR but my V6 uses the orange coolant. I buy it premixed and keep a litre of top up in the boot. On older cars like these a regular fluids check is best adopted as the routine. It can save a lot of money in the long run! Mine still looses a fraction of coolant but not every month and even then only half a teacup. Sorry for my non engineering equivalent measure.

 

+1 on that. I’ve had several instances, on my Jag and other vehicles, exactly as described. When driving, the combination of heat and airflow quickly evaporates small leaks, leaving no obvious evidence, including that telltale scent. Same goes for just running the engine in your driveway. Airflow from the fan has the same effect as driving, just not quite as strong.

Meanwhile, using a pressure tester works very well. As mentioned, pressurize the system and wait a few hours. You may be surprised what you’ll find, without heat and airflow to hide the evidence. Run your finger on the bottom of each hose, since leaks will accumulate at low points.

 

Another consideration is that people often sell cars when faced with expense from a coolant leak and the possibility of having major works replacing parts like the radiator and hoses. For some people it is the last straw. From experience they use one of the addatives in the cooling system which can provide a temporary repair while they sell the car. Without naming any brand names which most of us know for these types of "fix".
But if it has been added by the previous owner you will need to flush the system through to remove any traces of that stuff once the leak had been fixed.
Those type of addatives are only for temporary use in an emergency.

 

+1 on pressurising the cooling system after a cold soak to check for leaks.

Be sure to use the correct coolant (OAT type), such as DEX-COOL.

 

Thank you everyone for your help, going to order a pressure tester as you guys feel that may help find the culprit. I am suspecting that this is the reason the previous owner decided to sell as only had the car a short time and noticed the dropping level after the first week.

 

I would check the reservoir for leaks as well.

 

As you've already heard, a true rarity an owner selling a car, or anything else, with NO ISSUES. I always figure on fixing a problem or three when you buy ANYTHING USED. Often miss an issue or two, that bites you in the backside, but hopefully not too hard, or often. Used has it's plus side of another taking the financial hit on the vehicle. Also the risks, buyer beware, don't overpay, no warranty, as well as more than a couple not mentioned. All that said still love both the big, & little Jag in the garage, & bang for the buck a really great car.

 

Agree with you there, got it for a lot less than I was going to spend so have reserves to fix and a lot of car for the money. Was initially chuffed as was the first second hand car I have purchased that drove home with no apparent faults. Hopefully the pressure tester I have just ordered will help identify the fault. Still pleased with the car, paid £5500 for the s type with full jaguar and specialist service history and no rust

 

I'm pleased for you because the S type is a superb drive and the comfort is excellent. But the STR is very special. A bit of a sleeper maybe? Unless people see the rear badge. But even so most people wouldn't know what it means.

Make sure the pressure tester has the correct adaptor to fit the expansion tank before you buy. They usually come with several different sized adaptors, but I'd just confirm.

 

Hello again everyone, pressure tester turned up this morning. Does any one know what pressure I need to pump it up to? (Don't want to overpressure it looking for leaks). Am I best leaving it overnight if leak still not apparent?

On another note, I am a little confused....replaced the thermostat at the weekend as had been sticking, went to do a water check earlier after a couple of hundred miles and it hasn't lost any like it normally does????? Really confused, as was no sign of leak on housing when I took off so don't think it's the new seal resulting in non loss of coolant. May sound a silly question but can a faulty thermostat cause misreading in expansion tank....I am thinking not as topped up coolant would go somewhere.

Going to put some miles on it this week and keep an eye on it.

Thanks in advance for your help

 

Unless the thermostat housing is leaking, the thermostat itself is not the cause of coolant loss.

Pressurise the system after it has cooled down overnight to 120 kPa, or 1.2 bar, and see if it loses pressure after an hour or so.