Over recent weeks I noticed leaking Coolant (red) which markedly increased last week - to a point where something just had to be done to fix it.

My first point of call was the local Jaguar Dealer(s) for pricing of new parts to replace the probable and likely culprit(s);
1. Coolant Expansion Tank: AUD$233.60
2. Coolant Pressure Cap: AUD$52.30
(shock horror)

I had read elsewhere on this Forum about places from where these Items could be obtained more economically - from several US eBay Sellers, despite the added US$50.00 shipping to AU.
The point here being I did not want to wait the 2-3 weeks for delivery (ex USA) and I was uncertain and most concerned how much worse this leak was going to get and the prospects of total failure - was unacceptable.

What I was able to do is locate Used Parts from a local Auto-wrecker and so obtained a replacement Tank and Cap (ex-2004 X-Type) for AUD$100.00 and this ensemble came with a 90-day warranty.
Having installed these Used Parts - I am pleased to advise the Coolant Leak/Loss problem is now fixed.

Having said all this the remaining issue I want to resolve here is I still did not know which of the two Parts (Tank or Cap) was indeed faulty.

My Query Here is;
Does anyone have Jaguar's Workshop method or procedure to test the Pressure Cap - for function and proper operation?

Does anyone know what is the normal 'operating pressure' - for the X-Type.
AND
At what pressure the Cap is supposed to trigger/open - to relieve excess pressure to atmosphere?

Now I have the faulty parts off the car I feel I should be able to determine if the Cap was Faulty?.... or if the Tank simply developed a crack/fracture - causing the leak?

Albeit my problem is currently resolved via the installation of Used Parts, I would still like to determine the actual fault - then replace that with a new Part.

Dunno how long these Used Parts will last - but they have given me breathing space and a good opportunity to determine the actual fault.

Also, this discussion may save someone else the uncertainty, hassle and potential waste of replacing Parts uneccassarily.

All help appreciated ......

 

Cooling System Parts: 2001-2008 X-Type

 

Booted..... can someone please contribute

 

G'day Lcgi: I'll attempt to help with an indirect answer to your question, since I don't know the direct answer to pressure testing the coolant tank and cap.

Take a look at this thread by LadyAce12 titled "Losing Coolant". I responded with pictures of my stress cracked, leaking reservoir and describe how to determine the origin of the leak.

https://www.jaguarforums.com/forum/x...oolant-115783/

Instead of fixing the stress cracks, I purchased a replacement reservoir on eBay from ImportPartsDepot for 38.45 USD. The seller will ship to Australia for an additional 46.41 USD. It's not Jaguar OEM, but it looks and feels identical to the original, including brass reinforcement inserts in the top two plastic nipples. Here's the eBay link:

Jaguar Coolant Recovery Reservoir Expansion Tank Cap Premium Quality C2S861 | eBay

One more suggestion from other posts: Rotate the top two hose clamps so the tabs point foward, not up. Some folks warn about sagging hood insulation that put pressure on, and eventually cracked the top two nipples because the hose clamp tabs faced up. Whether this is real or presumed, there's no harm rotating the clamps forward.

Cheerio!

 

LCGI, are you ready for answers? he he he he he.

As for the cap and its rating, if I am not mistaken, it is rated to relieve at 15 or 17 psi. The pressure will actually come out from under the cap and on to the top of the bottle.

Now, for testing this, here is where the Thermo ingeniuty comes in. The easiest way I see is to remove the rubber hose that comes off the back of the overflow bottle and what you are going to do is to cap the end of this hose with some sort of plastic rod or smooth metal pin and then use a hose clamp to make sure that the pin/rod remains in place. Next, you are going to attach a rubber hose to the newly exposed nipple and you are going to attach a low flow regulator to the hose along with a gauge to monitor pressure. Then, using an air source, slowly dial up the regulator to around 10 psi. This will pressurize the whole coolant system of your car. The regulator will maintain the system at 10 psi and if with the engine off, if you have any sort of air leak, you should be able to hear the hissing sound and/or see where the coolant may be leaking out at. Once you are done, you can back off on the pressure of the regulator and it will lower automatically (if your regulator is self venting) or you may need to pull the hose off of the overflow bottle and relieve the pressure that way.

I would recommend leaving the bottle vented for a few minutes as the coolant will be releasing some air that may have gotten forced into the coolant due to the higher pressure. But, after about 5 minutes, you can reconnect everything and be just fine.

 

Hi dwclapp,
Thank you for your summary of similar posts leading to causes
for Coolant Loss or leakage.... and sources for replacement parts.
Your interest and contribution to this discussion is appreciated.

 

Hi Chris,
Thank you for your take on this matter and for the welcome portion of your personal ingenuity.

You did not say where you obtained the value of 15-17psi relief pressure? but,
I bow to your knowledge and experience - if this is merely empirical.

As mentioned as far as the car is concerned - the Leak/Loss problem has been resolved by virtue of my fitting other (USED) parts..... To further validate this, I've been on a 100 mile round trip today and there is no sign of any leak or loss of coolant - so I'm very sure it was either Tank or Cap before.

With the benefit of your given numbers for both Operating Pressure (OP) and Pressure Relief (PR) It seems to me the most expedient way to test the Tank and Cap - is with these off the car.

Test 1. Tank OP Integrity:
We could pressurise the tank (AIR) to 5-10 psi then simply immerse the tank into a bath of water and look for any tell-tale bubbles. Just like we do when fixing a puncture on bicycle tyres. If bubbles are coming from the Cap only - then we've evidence of a faulty Cap.

Test 2. Cap PR Actuation:
With the tank still at 10 psi and submerged in Bath, if we slowly increase Tank Pressure (via the regulator & gauge) the actual Cap PR actuation can be validated - as we would see witness bubbles coming from around the Cap - as relief pressure is reached.

Your thoughts Thermo...?

 

LCGI, yes, you can submerge the tank and slowly raise the pressure till you start to see bubbles. I would possibly recommend having something that holds the tank under the water instead of your hands since you are questioning the integrity of the tank and I would hate to see the tank let go. While 15 psi is not a lot of pressure, with that much surface area, it will become quite the force.

As for the rating, this is fairly standard on most modern day cars. They operate under the principle of getting the coolant near the boiling point at the worst spot in the motor. This allows the coolant to absorb more heat without raising the temperature of the water (referred to as the latent heat of vaporization). If the coolant does boil slightly, this will cause the pressure in the system to rise and ultimately convert the steam back to water due to increased pressure. With the system up near the relief set point (15 psi), this would mean that the water would be up in the range of 250F. This is way hotter than you ever want your engine to be running under normal conditions.

 

It occurred to me that an alternate to submerging the pressurised tank in water - would be to apply soapy water to all the external joints and connections ? (Much easier -eh)

I have now concluded my testing of the suspect Tank and Cap and took a few pics/video of how I did this - to illustrate results and findings - to all those who may have interest.

I am processing those images now and will post these shortly.

What I found from my Tests - is as follows;

Test 1. Tank OP Integrity:
Above 5 psi there is evidence of a leak below the L/H upper hose connector. Therefore Tank Integrity is faulty and a NEW TANK will be required.

Test 2. Cap PR Actuation:
Increasing the air pressure setting to 15psi... as the tank pressure increased I was able see (and video) the Cap actuate its Pressure Relief mechanism - which occurred at around 13psi. Therefore the Cap is good and working properly.

Stay tuned for the images - coming soon.

(i'm happy now that I know & proven which of the two suspect parts had the actual fault)

 

Back Again,
Here are the photos and a couple of videos to show the set up I used to do the mentioned tests on both Tank and CAP.... using soapy water as the 'witness medium'

Of particular interest is the Pressure Relief Port located in the Neck of the Overflow Tank. (may not be apparent to some folks when Tank is installed and in situ)
Note: I have threaded Hi-Viz string through this port to better indicate the path and discharge point - which is beneath the Tank. (not sure I like that idea)

Anyways, if anyone needs further clarification on what was done - just let me know... by responding to this.

 

Just for everybody's edification, the pressure cap on the overflow bottle is 90kPa +/- 5%. Got it from the specs on my Land Rover, which takes the same cap.

 

Thank you for that wa3ra....

Therefore keeping things in the local (imperial) parlance;
your 90kPa = 13.5 psi

So, Thermo you were close to the money when you offered 15 psi

Thank you all for the contributions

 

Silly Me..... ??

If you look closely at the Pressure Cap (obviously I did not) you will see
that its rating is printed on it.

That being 100kPa (or 14.5 psi)

 

Looking at the catalog, they do have three, 90, 100, and 110.

 

Hi wa3ra,
The plot thickens.... so, are these variants designated/assigned to engine size?

i.e.; 2.0L, 2.5L & 3.0L?

Which Catalogue are you looking at ?

 

You can use all 3. Doesn't matter. Really, the question that you have to ask is how much stress are you willing to put on all your hoses and the tank during adverse conditions? Under normal situations, all 3 caps will see much less than they are rated for. it is only when you start overheating the engine that you will see a difference between the caps. This is for the basic fact that as long as you can keep the coolant in the liquid state, the motor is getting some cooling. It is when you start flashing the coolant to steam that you have real issues. The higher the cap rating, the higher you can raise the temp of the engine before you start flashing the coolant to steam. Please keep in mind that getting the engine say 20+ degrees above normal operating temp is not good on the engine. But, the temps rise dramatically when there is no liquid present, only water vapor.

 

Thermo,
I hear what you say about Pressure v Temperature.... and the practice used by racing engineers to opt for system designs that utilise higher Operating Pressure.
However, I think we've got off the track here, to assume that Jaguar facilitate such changes from their optimal engine design and anticipated operating conditions.

Yes, Jaguar do supply individual Pressure Caps sold separately for use with their generic Coolant Tank, but I believe that when these parts are married to a Vehicles VIN # then only one specific Pressure Cap would be nominated and supplied by Jaguar. Which is why I reckon the 3 variants mentioned - may well be related to engine size and nothing more.

As you say, when a Pressure Cap triggers at its rated value... it releases the lot to atmosphere and in doing so does bugger-all to improve or assist engine cooling.
Of course, aside from high temperature other mechanical factors may come into play that can create excess pressure conditions and thus requiring actuation of a Pressure Relief Valve. (in the Cap)

This has been a great and worthwhile discussion...... Thank you again Chris.

 

I see the 110 is spec'ed for high altitude on the 4.0 V8 that the Disco had, 90 was the stock.

I can't see that the actual altitude would make a big pressure difference in a sealed system, but I wonder if it might not be related to the thinner air not removing heat from the radiator as efficiently?

It's a big random scrapbook of oddball parts that was put together at a no-longer extant area LR dealer that I managed to get a few pages from for my (also departed) Disco II.

 

Simple Physics really....altitude does affect density and resultant BP of water - be it sealed or otherwise.
Also the density of Air (being thinner) but you won't be driving a car at the altitudes that affect a car. (its just that gravity thing)

Your mentioned 4.0L V8 is of course irrelevant to our X-Type discussion.

Could be your odds 'n' ends catalogue/scrapbook - covers several Jag's of old.

Have a great weekend....

 

wa3ra, like LCGI was mentioning, the cap works off of a "differential pressure" (ie, the pressure in the system compared to the pressure of the surrounding air). Since you are higher in altitude, the outside air pressure is less. Kinda like the reason for the cap is to build up pressure to raise the boiling point of the coolant temperature wise. Well, the same can be said about having the coolant at a lower pressure (ie, below that of sea level), the temperature of the water when it boils will be under 212F/100C. For example, at my work, we have systems that have water boiling at around 140F. That would not be good in your car. It is an extreme situations, but outside pressure has an effect on the coolant system.