02 Freelander SE Reservoir? Overheating

So! My rover started leaking coolant, actually pouring it out as I'd poor it in, after noticing the leak and having to fill it. FYI this was all spontaneous, I never had a coolant leak. Well it's the thermostat, and we find the elbow coolant pipe next to it, how they must reuse corks for this crap material, cracked, a big hole crack. We replace that and the whole housing. It still leaked, went back down and changed the straight coolant pipe with the special clips that you can't special order from the parts store, ended up getting some, replaced it and a few fittings and tightened up some stuff, also replaced manifold gaskets at the end of it all. Put it back together, should've been good. Also, no overheating occurred with the antifreeze leak, the gauge would barely go above the middle normal mark, it wasn't driven but to test it down the road after changing things. WELL. Now it's overheating, no leak, maybe a few drops but I tested it about 200ft and it went to the top of the temp gauge and I turned around, parked it, got home, popped the hood and the reservoir is boiling, bubbling, hissing, coming out of the cracks on the top it looked like so I assumed that was the few drops on the ground. Rising almost. I know!! Im going to replace the reservoir. And that is my question, does anyone think that now I replaced the main problem, also no oil in antifreeze or vise versa, no milkyness, no smoke or antifreeze on engine or in valley. So I think it's a coolant reservoir not pressurizing correctly kinda problem. But by now I'm getting a little discouraged after solving the problem to find another one. I love my rover though and feel that it's not a blown head gasket or water pump. Any thoughts or help is appreciated!

The KV6 (I'm assuming it's a KV6) is very fussy with coolant. The engine uses very thin head gaskets, that are damaged in seconds, if the engine is run without coolant. The thermostat assembly is well below the level of the HGs, so if the stat leaks, the HGs are left without coolant in no time.

It is also possible that there is air trapped in the system, as the KV6 is notoriously difficult to get all the air out.

First off replace the coolant tank, as the KV6 normal running temperature is over boiling point, so any leaks will allow it to boil over.

Next fill the new coolant tank with coolant to just over the maximum mark and allow the engine to warm up on the gauge, adding coolant if the level drops. Turn the engine off and allow to cool down, again adding coolant if needed.

Once cool, release the haater bleed screw 2 turns, until any air stops only coolant comes out, then tighten the bleed screw.

Top up the coolant, fit the cap and start the engine until the fans come on, making sure the coolant level in the tank doesn't drop below minimum, stopping the engine if it does.

The engine will only expel any trapped air, after many repeated hot and cold cycles, so you need to monitor the coolant level, and top up as often as is needed.

If you're lucky, the head gaskets are ok, but you can only prove that, if it maintains the coolant level without topping up.

Thank you, I'll definitely be doing this when the new reservoir comes in. And if that doesn't help. If it were the head gaskets, does that mean the coolant mixed with the oil? As theres no signs of mixture or vice versa. This is all new so learning as I go but know the basics somewhat. Not sure what other signs to look out for.

Cornella77 said:

If it were the head gaskets, does that mean the coolant mixed with the oil?

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Not necessarily. The KV6 is a wet liner engine, meaning the cylinder liners aren't closed at the top by the block. The head gasket closes the top face, and also presses the liner hard into the block on the bottom too, sealing the joint too.
However unless the oil feed up to the head , or the oil drain back down to the sump has been compromised, then there's no guarantee that coolant can get into the oil.
Normally when the HG fails, it looses compression to the coolant, so this results in the coolant being displaced very rapidly, with the cap unable to keep the pressure in. This would happen regardless of the engine being hot or cold.

Get a new tank in there, and see what that does first.

Ugh, just got the new reservoir to find out my coolant tank has been slowly leaking this past week and is almost empty and it's a slow drip down the front of the block is what it looks like from underneath. I feel were gonna have to take it apart again as replacing the reservoir isn't going to help a leak on the driver front side, right? Also no coolant that I can see in the valley or around the thermostat, it's all dry in there. I'm gonna still replace the reservoir but feel now it might not help.