Hi All, I have a 2004 Jaguar S-Type 3.0 Base Model. Not. "R"

I keep haven't to add coolant to It, Yet don't have any leaks. Pressure test On expansion tank, Pressure holds at 16lbs. for many hours. And again. after driving for a day or so, message " LOW Coolant" Remove cap, and sure enough it's low on coolant.

Would really appreciate any, and all help. Cause it has me puzzle. Thanks

 

Forward lower right of your engine bay. Either DCCV or radiator is leaking. I'd bet on the radiator. Could be the turret, but if so, one fine day it will become really big and you'll have no trouble seeing it.

 

Well, that's a good start. Was the pressure test done cold? Assuming (Danger! Danger!) it was, the next step would be to try it with the engine warm. Although rare, some leaks only appear with thermal expansion.

You have to be very careful doing a warm pressure test. The cap is your pressure relief for the cooling system, but it's replaced by the tester. You have to watch the tester gauge like a hawk to avoid exceeding the pressure limit for the system.

With that in mind, connect the tester with the engine cold. Start the engine and let it warm up. Do NOT pump up the pressure with the tester for now. Just let the normal thermal expansion slowly increase the system pressure. The tester gauge should gradually rise. You should not see any spikes or pulses, just a slow increase. If the pressure approaches the limit, shut off the engine and carefully vent the tester if needed. Remember, you are now the overpressure protection.

Once the engine is fully warm, shut it off. If the pressure is not near the normal upper limit yet, you can slowly pump up the tester. If you have any leaks that only open with heat, this is when they will show up.

If the pressure rapidly drops off now, you've got a problem somewhere. Keep in mind the pressure will slowly drop as the engine cools, so the pressure decay test will appear to fail, so don't be alarmed.

 

Thank you both very much for your very quick response, and great testing advise.

I'll tried this test later today and post the results. Again, Thank you both.

 

Many is the report of "low coolant level" followed immediately by "But it's not leaking..."

A pressure tester is not in my available arsenal, thus I've no experience with same, but based on the description given by Karl above, and the geometry of the system, I'm going to now change my Karnack-the-incredible assessment of your leak to the far more common nipple at the neck of the overflow reservoir fill port. I reckon the pressure tester seals off just below that, to the same surface as does the pressure cap. However, it doesn't allow flow-thru as would the pressure cap under sufficient pressure.

All of the leak points I've discussed so far in this thread have demonstrated the ability to dribble coolant out in a manner that results in a low coolant caution within a day or three of topping up, yet not leave any drips or puddles in the floor - on one or both of my cars. Part of this is owing to the undertray fitted to the car which allows drips getting to it a chance to spread out and dry before ever getting to earth if the leak is small enough. I recommend the "sniff test." If you have the car out and bring it to full operating temperature, then park up in the garage, pop the bonnet and sniff around for the sweet smell of glycol. Not sure you'll pick up the faint whiff if you are parked outside. If memory serves, I was sniffing the the 05's radiator failure a good 4 or 5 weeks before it set a low-coolant warning!

 

My 2.5 V6 lost coolant fairly soon after buying it.
I think the seller put that dreadfully Radweld in it prior to sale. The coolant leaking only happened when the engine was warmed up and it would lose 0.5 or up to 1 litre each time it was driven.
The cold and hot pressure test were fine and done by a local mobile technician.
So I kept an eye on it and eventually the loss got worse and then I could see the leak on the floor under the left hand side of the engine bay just infront of the footwell. The leak was from the radiator coming from the top right hand side and which tracked across the top of the rad dropping down the left hand side then across the belly pan to then spill out on the floor.

I got a new pattern radiator and at the same time replaced the DCCV as advised to here on the forum. All was good until the plastic connector in the top hose crumbled on removal. The plastic connector had been glued back together so many times it hadn't got much plastic left. So a new top hose from Jaguar was £105 which wasn't too bad.
I used the orange premixed coolant of the correct Jaguar spec for the refill after lots of flushing out. Radweld is not best for longterm protection.
I think the radiator is the area to look in your case, but there could be other things as well.

 

Hi all, I finally got a chance to do the pressure test,
I connected the pressure tester to the expansion tank and started the car,
allowed it to come to normal operating temperature,
allow it to run for a good 30min. I had already removed the engine bottom cover,
so that I would be able to see a leak If one was present. No viable leak.

After the car cooled down and I removed the tester, I realized that coolant fluid was low again.
I had top It off prior to starting the test.

Checked the oil, and there is no contamination, Of Oil and coolant. Also decided to do a Block test
to see If there was any exhaust fumes and the radiator, And none Is present.

Again completely puzzled, Why, Or where is the coolant going? Would appreciate any help and solving this problem. TY.

 

Have you checked your expansion tank? They are prone to leaks from the top bleed fitting

 

Yes I did, It's not leaking from there at all. But, Thanks for your help.

 

+1 pull the expansion tank and check the seams carefully (even cool) and look for cracks too. Try to check for leaks and cracks at temperature. Also look down the passenger side of your radiator for stress cracks as well.

 

Question, If coolant system had a leak, wouldn't car overheat cause the 16lbs. of radiator pressure wouldn't be achieved?

 

No. The elevated pressure just elevates the boiling temperature of the coolant. The overheating will result from the loss of coolant, not the lack of greater-than-atmospheric pressure.

On the other hand, if allowed to boil, the coolant would do an excellent job of cooling the engine...it is how your air-conditioner cools your cabin so rapidly......until it all evaporated...then, see above - Overheating.

Can you not smell coolant after a spirited run, if you raise the bonnet?

 

Thank you for that explanation.

I been running It with mainly water at this point.

Is there any kind of dye that can be used to make It easier to spot a leak? In the coolant system

 

My recollection is that the "pink" coolant your car was originally equipped with shows up quite brightly with a black-light, almost as good as the dye intended to be used with such lights.

 

I looked in the Drivers Handbook, and The coolant recommended Is Orange, Not Pink. ORANGE CONCENTRATED ANTIFREEZE/COOLANT - Ford (VC-3-B) Coolant specs. WSS M97B44

 

Yeah, my 03 and 05 had the same spec as your 04. Guess what? In contradistinction to title of the pop culture TV show...."Orange" is the new Pink!
At risk of plagiarizing Capt. Obvious here, but if you went from "Topped up" to "low" from just starting the engine and bringing it up to operating temp......I'd think dye-tracing might be overkill.

 

If I might ask you, Where do you think that my coolant is going? Being that there is no visible leak, and no oil/coolant mix. Plus it does not overheat at all, considering I'm running It on mostly water at this point. and Temperature here In Florida has been In the high 90's

enough to make me crazy, why I can't find this low coolant problem.

 

Misty coolant leaks in the engine bay that originate from pinholes in hoses or plastic nozzles and occur only when the vehicle is being driven often tend to almost instantly evaporate from the heat of the engine before the owner can spot the leak source. Bring your engine up to temperature, park your car, raise your hood, and have a buddy/spouse rev the engine up to a consistent 3,000 rpm or so while you look for coolant misting somewhere in the engine bay....

 

The only other possibility I can imagine, would be a leak in your heater core, which should either wet the carpet in the floorboard or else exit the HVAC condensation drain(s.) If that is the case, I'd think you'd have noticed the anti-freeze smell in the car, or that the condensate had a bit of color to it, previously. However, if you are now down to mostly pure water, this may escape notice, though with as much as you are losing, I'd think you'd notice a greater-than-normal amount of condensate.

 

Read all the comments, but my problem is the low coolant warning comes on usually when I start up the car and then goes out as I drive. I do notice some coolant around the radiator cap. But the coolant in the overflow tank is right where it should be. Recently had the car in for an oil change and check fluids. Could it be the cap? When I tried turning the cap it was tight.