Hey guys,

My XJ8 has always had a water leak. At first the feed pipe under the intake manifold had a hole. Enough to leak. After I sorted that, I replaced the thermostat housing wirh a metal one. Since then it is sealed. The front cross over pipe is new, as are the little hose between the pipe and thermostathousing and the twomradiator hoses. The octopus hose is new. The two little hoses on the TB are new. The hoses around the heater valve are still old but they aren't leaking...

I have to top up my water bottle every ~2000 km with about 0.5l of antifreeze.

There is never a puddle under the car, nor a smell of burnt or evaporating antifreeze...

Can it be that I am overfilling it all the time and that the engine pushes it out of the atmospheric bottle innthe front left?

 

Have you done a pressure test of the system. A small leak may boil off before you see it. Also have you tested/changed the cap? The cap may be allowing it to go to the expansion tank under pressure but isn't holding the vacuum necessary to return the coolant to the system.

 

There's nothing as effective as pressurizing the cooling system to say, 5 PSI above the Normal maximum. To do that you need a cooling system pressure tester, like my Mityvac.

My Land Rover V8 lost a little coolant, but could not see where. I brought it up to 25 PSI with the Mityvac, and found at least 3 leaks right away. Fixed those, no more coolant loss.

On two Jags so far I've had problems with the line to the expansion tank, where it was kinked. It thus lets coolant out, but will not let it return. The result is constant coolant loss.

 

Do you have the exhaust heat shield in place underneath the expansion tank? It was missing on my old XJ and it used to evaporate the coolant from the heat from the exhaust. I'd have to fill the coolant regularly. After I replaced the shield, the coolant would only need a top up every few months or so, as I'd expect.

 

That is fitted and installiert correctly. I think I'll see if I can overpressurize the system and see if I can find a leak.

A friend said it is the headgasket, but it lacks the typical emulsion in the engine, the smell of combustion in the Expansion tank as well as the smell of burnt coolant from the exhaust.

I know the octopus hose leak before I replaced it. But since... I don't know.

 

Pressure testing is way to go and the MityVac is fairly cheap and a good tool (not so for their brake fluid evacuator kit sold years ago; whereas their oil evacuator is superb and saves me tons on oil changes on my Range Rover).

You have seen all the threads on mis routed radiators lines, ney? If the head gasket is leaking to a combustion chamber you should see white smoke on acceleration . . .

When I had mine, it was my new waterpump: dumped it and installed an AC Delco . . .