Mine has always used a bit since I’ve had it in 6 years, but then again assome of you know I’ve recently just suffered HGF so I’ve been closelymonitoring my levels
However after 3 months now of having my car back and after the settling downperiod I’ve noticed is still using some.
I mainly spend most of my time sat in traffic but the car approx. uses about100mm every 200 miles, however like I said the car is sat and getting hot intraffic and probably spends around 5/6 hours stood still to do these 200 miles.
I check the coolant levels when the engine is stone cold and although theres hardly much usage its still using some.

What you think small leak somewhere or completely normal?

 

It is not "normal" to leak coolant, although I have, like you, had long spells of leaks I could not find. Just for fun, are you SURE the two tubes connected to the front of the expansion tank are correct? (they should appear to cross). The top middle one leads to the recovery bottle in the fender well. I had that problem for years, and I was SURE, (well maybe), that I could not have gotten them swapped! Have you replaced the thermostat riser with the metal one? Look carefully there for leaks and along the plastic crossover pipe at the top of the engine. Good luck!

 

none. not a drop.

 

Just went a 200 round trip yesterday, I checked it after 100 miles it hadnt used any, did some drag racing and came home. Checked it again when cold this morning and a fair amount has gone (2cm of coolant tank). What could be causing this, am I filling it to full (up to the neck of the tank) or do I have a leak on a hose somewhere?

Will take it back to the garage next week I think, opinons welcome....

 

Hopefully not the hose under the SC...

 

Have the coolng system pressure tested...that will usually locate the leak.

 

Will do, and the S/C hoses where replaced when I had the headgasket done

 

The early cars before 2000 had issues with the buried heater connections -- so this is a known area of concern -- Jag has a TSB on it.

They also have a TSB regarding filling the system if you are having problems. Fill the tank with coolant -- start the car and wait for the fluid to drop once the thermostat opens and then fill the tank to the top and put the cap on it.

This overfills the system ........ causing the excess to flow into the tank in the fender.

They tell you to only do this once.

Mine has needed a top up once many years ago -- never uses any coolant.

 

Just took it out for a quick spin and then rechecked the level after an hour of getting back (engine still warmish) and the coolant level has gone back up to was where it was before I went on my long journey????????????

 

Up to one inch bellow the neck is the normal level, I always had the same level (OK, recently I had some trouble with the cooling but now it's back on the same level). If your level with cold engine is at the neck level,(after topping up), when the engine is hot, the coolant goes to the overflow tank and your level will be the same when cooled back. It's a good idea to have a temperature monitor, using a tester, for a few days, just to calm down.
I did it today and now I am more relaxed (90-91 C at 100 mph and 98 C driving in the city) as I suspected overheating and coolant loose few days ago.

 

Just a quick update to this as I'm still not completely happy.

Ive had the Jag garage do 2 pressure tests on the coolant system now, the last one lasting up to an hour with no visable leaks.

He told me the only problem he could see is me topping my coolant level up to far (up to the neck of the coolant tank). He said when the coolant gets hot it expands and is pushing it out the overflow at the top of the neck into the coolant expansion tank.

So I have stopped filling it up to the neck now and it seems to have settle a bit, however I still get the odd smell of coolant on a hot day and its still used a small amount since I last checked.

Is this cause my level is still on the high side and should settle completely soon? Looking in the tank the level appears to be between 2/3's - 3/4's full, not quite one inch below the neck I would guess

 

On mine, the low coolant warning came up on the dash back in March. I added maybe half a liter and resolved not to worry about it unless the warning came up again. Presumably, it would come on at the exact same level if lost any more. That's been 3,000 miles ago and the warning has not reappeared. Frequently opening the system and adding small amounts is probably not an accurate way to assess if there is a problem or certainly not gauge if its a big problem because its going to spit out whatever amount it doesn't want and you can't easily measure what's in the recovery tank.

Have you actually driven it till the warning comes on? Perhaps carry a measured amount of water with you. When or if the warning comes on, add a small measured amount, just enough to turn off the warning. Then continue driving and see how long or if the warning comes up again. Then you'll know how long or how many miles it took to actually lose that amount. On my old Corvette, if I fill it to the top of the radiator, it will spit out coolant until it settles about 3" below the cap. That's probably about 1 liter low and had me worried for years until I just got used to it, but that's where its happiest.

 

After spending a few months adding coolant on a regular basis, I decided to replace the thermostat tower (it was obviously leaking) and had the two heater hoses replaced as well as the two pipes going to the front of the car. No more leaking.

I concur with the dealership's comment about overfilling the reservoir -- although the instructions are to fill it to the bottom of the neck, that seems to be too high for my car. A bit (and just a bit) lower than that seems to be the ticket for me.

Remember that some coolant leaks will be small and will puddle in a place you can't see it and will burn off almost as fast as it leaks. This can cause the coolant smell that you're detecting. Coolant leaks don't always result in puddles or spots on the ground or anywhere else that you can see them.

Try filling the reservoir to about 1" below the bottom of the neck. Should work unless there's a leak.

 

Ok I'll give it a go thanks for the advice

 

I've had to replace the coolant filler stand on all three of my V8 Jags. Replace with the aftermarket aluminum type, they are cheaper and better. have also replaced the water pump on 99 Vanden Plas. The pump was actually not bad, it was the paper gasket, it has shrunk at the bottom and developed a very small almost undectable leak. The water pump on these is quite easy to change.

 

If you still have the original water pump, then replace it and the thermostat. I doubt the original lasted this long though. My coolant level stays about an inch below the bottom of the filler neck, always. My low coolant light works fine, but never comes on. It's sort of like my oil level. I can fill it every couple of days, but it's going to level off at about 1/2 way down the stick, whether I fill it every day or every six months.