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After spending time over the last three days bleeding the coolant system slowly (and it made a huge difference to jack the front left corner of the car up a good six inches), the car was running cooler than ever before. In fact, only reaching the 1/2 point on the needle after a good thirty minutes of driving (outside temp 29 Celsius). No leaks, no problems. What a dream to drive.
Today, I drive the car for the first time with the AC on since bleeding and bingo, leak city. (see attached photos). The leak seems to come from the center of the car. Is it a coincidence that the leak occurred when the AC was operational? I have experienced no leaks when driving without the AC over the past three days.
I am assuming you have gone around and retightened ALL the hose clamps since the work was completed??
If not, then that could well be the reason.
A/C or no A/C has no direct relation with the coolant, other than in some cases the A/C system can add some extra heat to that system, and that can sometimes, cause leaks. RARE.
Feeling around ALL teh hose joints, COLD engine of course, is a simple, wuick way of finding the culprit.
Middle of the car, and IF towards the front, my GUESS would be water pump hoses, the top short sucker from the cross pipe to the top if the pump has caused me grief many times. Then its simply a process of elimination.
Filler spout cap seal
Cross pipe hoses at the ends.
Bottom radiator hose AT the pump.
The 1/2" shaped hose from the top of the cross pipe to the header tank.
Remember, fluid leaking on the ground HERE, may have started its journey way over THERE.
your A/C will always drip melted ice out of the drain tubes.
In this case it does have a greenish coolant look to it, but not bright green like new coolant. There is always condensation dripping off AC systems, most cars leave puddles if they've been stopped with the AC on.
Charles
get the car on a ramp, then look under your car, level with the gearbox to engine join, to maybe about foot rearwards. peer carefully up into the gloom each side with a strong light. You will see a plastic tube, about 10mm OD coming down each side and stopping about 1/3 of the way down the side of the box. This is the aircon condensate drain. under the aircon unit is a tray with tow drains, and these tubes are they.
Your water may well be this condensate draining.
Alternatively, if you have fixed the atmospheric bottle in the wing cavity, this could have been over-filled and now is levelling itself off.
I would get the car warmed up, get a BRIGHT light, have the thing ticking over and look carefully around the engine bay as Grant suggests - keeping hands, neckties etc etc well clear! There is a coolant hose that feeds the heater from the A bank (RHS) rear water manifold to the heater tap on the bulkhead centre. This can leak from the water manifold outlet, hard to see but you CAN see any leaks from it. This is always a candidate because it is hard to get at and tighten. If you do see a weep, switch off the car and wait for it to cool and then tighten.
This is a photo of the RHS drain tube, they are not easy to see, but they are there! Poke a stiff bit of wire (eg coathanger wire) up them every so often to keep the inlets clear.
Last edited by Greg in France; 07-07-2021 at 07:25 AM.
Since Grant mentioned cap seals . . . are the header tank and the filler (cross pipe) caps the same?
I purchased two of the pressure expansion / header tank caps (CCC6707) when I had my mechanic replace the header tank with an aluminium along with a water pump and all hoses. He suggested that the pressure caps (header tank / expansion tank) and (cap on cross over pipe) were not interchangeable.
SNG and Jaguar/Land Rover seem to suggest they are exactly the same.
That cap fiasco is nearly as bad as "which oil is best".
The caps are IDENTICAL.
The header tank cap is the pressure cap for the entire system.
The filler spout cap has NO pressure related task at all, it is simply a seal to the outside world. The seal UNDER the metal top section (where you place your hand) is the 100% important item. If that seal fails tor seal, the coolant will leak out, and pressure will not rise as designed, and air will bleed in when it cools.
I use a CPC Blank Cap here, (2001) is their part number. Unipart had one back when these cars were new, and a lot of BL cars used them. Supply is NOT good, so any suitable TOP SEALED pressure cap to seal that spout at the very top is all that is needed.
The "lip" down inside that spout is too far down for any suitable cap to contact. Caps of the very old days, which were much longer, would possibly get to it, but they have NO top plate seal, so useless to us.
This what I use on the filler spout.
Last edited by Grant Francis; 07-07-2021 at 11:06 PM.
Apols if this is a red herring but I had a similar problem a few years ago on my 4 litre. When running aircon and with the temp then set to cold, the heater valve then moved to the closed position. And that was the point at which it leaked from the valve and dripped to the bottom of the car. As soon as the temp was set to anything which opened the valve, then the leak stopped. Apparently a common occurrence. I don't know if the V12s use the same type of lever-controlled valve, but if so, I'd definitely have a look there first.
Charles
FYI, if you look at the filler spout in the centre of the engine, you will see that between the cap top seal and the lower inner neck seal of the cap, is the spigot running off the filler spout that joins up via a thin hose to the radiator top purge system. Thus when the lower cap seal lifts, the coolant, and so the pressure,does not escape, it merely allows overflow into the radtop purge system.
Thus, as Grant so explained above, the system remains closed, by the cap top seal against the spout top flange, whatever the lower cap seal is doing. So an blanking cap, as Grant posted, will work just as well!
So in reply to your mechanic, as long as the cap on the wing tank is of the correct pressure rating, and is working properly, that is all that matters. The spout seal has NO effect at all on overall system pressure. In fact, Jaguar would have been better advised to place a screw-threaded cap on the spout, in my opinion...
Finally, I have found that Stant pressure caps with the lever pressure relief attachment are far more reliable than any other make. e.g.
Paul
Thank you. Indeed, if I had to eyeball where in the car the leak is from, it looks to be at the back of the engine bay, center, which is exactly where the heater valve is located. It was just replaced so that will be the first point of call. But, as Grant stated, just because a leak is showing at point A, doesn't mean it didn't start somewhere else.
Charles
After spending time over the last three days bleeding the coolant system slowly (and it made a huge difference to jack the front left corner of the car up a good six inches), the car was running cooler than ever before. In fact, only reaching the 1/2 point on the needle after a good thirty minutes of driving (outside temp 29 Celsius). No leaks, no problems. What a dream to drive.
Today, I drive the car for the first time with the AC on since bleeding and bingo, leak city. (see attached photos). The leak seems to come from the center of the car. Is it a coincidence that the leak occurred when the AC was operational? I have experienced no leaks when driving without the AC over the past three days.
07-07-2021, 05:33 AM
Post Bleeding Coolant leak only with AC running
