Disco 2 Where are the sneaky places that coolant can leak

Greetings from an encumbered colony. I fumble through the maintenance of RRCs but my son's partner has a 2001 Disco. Which is nothing like a 3.9.

The beast is trickling coolant away. Slowly. A mechanic says it's a knackered head gasket, but no sign of goo in the oil.
Where should we look for sneaky leaks on that high tech system?

Heater matrix, water creeping under the carpet insulation, a head gasket can leak in many ways
Water into combustion chamber ( water goes out exhaust as steam) and if bad leak it will pressurised the cooling system, Head gasket can blow between cylinders giving loss of power, head gasket can leak to oil gallery causing
Crankcase pressure increase, and last but not least the oil can get into the cooling system causing what we call
Mayonnaise, white/ brown sludge in expansion tank and blocked radiators,

Head gasket can also leak to the outside, coolant will escape to the atmosphere, drip on to hot exhaust manifold etc and you'll never see it

Which engine is it?

1/ You can test the coolant for combustion gases with a cheapish kit.
2/ there was a thread on here in the last couple of days saying there was a pipe along the front with a pinhole in it, and that the pipe was wrapped in insulation which made it hard to find,
third post on here
https://www.landyzone.co.uk/land-ro...itted-bmw-expansion-tank.369163/#post-5118259

kermit_rr said:

Which engine is it?

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Thanks for the responses. It's a North American spec 3.9 petrol lump. Here's a pic.

Oh, I have another question. Did a 2001 SE come specced with 18 inch wheels?
Thanks again.

Western Slope Rover said:

Oh, I have another question. Did a 2001 SE come specced with 18 inch wheels?
Thanks again.

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So as all 4.0 D2s in the UK the 3.9 engine is the Thor with the Bosch engine management. In the UK the ES was fitted as standard with 18 inch Hurricane wheels in 2001 iirc as it a long while ago.

Check the throttle body heater (TBH) plate (#14 in picture) is leaking under the throttle body. It’s got 2 smaller coolant lines going to it.
That TBH is well known area that leaks on our Thor V8 engines.

Just wondrin, and i may well be wrong, but a lot of water pumps have a little hole where coolant bleeds out when the pump is on the way out. Have you looked for one?

Stanleysteamer said:

Just wondrin, and i may well be wrong, but a lot of water pumps have a little hole where coolant bleeds out when the pump is on the way out. Have you looked for one?

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I have. And no weird sounds from the pump either.

Western Slope Rover said:

I have. And no weird sounds from the pump either.

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Mine only leaked there sometimes, never made any noise either but when i took the belt off it was quite wobbly

kermit_rr said:

Mine only leaked there sometimes, never made any noise either but when i took the belt off it was quite wobbly

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Cheers for that.

Western Slope Rover said:

I have. And no weird sounds from the pump either.

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You wont if it happens its only the seal thats failed, but you will certainly know when the bearing fails.

Thanks for the advice. Hopefully it turns out to be something less than a bad head gasket.

Do you have a pressure tester? Much easier to spot leaks on a cold engine that's not running

You could also put some ultraviolet dye into the cooling system run it for a day then check with a UV light
When it’s dark, might point you in the right direction,

kermit_rr said:

Do you have a pressure tester? Much easier to spot leaks on a cold engine that's not running

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Nope.