Range Rover Vogue L322 overheating problem

My L322 Vogue V8 has started to overheat. After about ten minutes on the road the temperature needle starts to move away and goes into the red. If I turn the heaters up and the fan on, the needle comes back down and I can limp home.

This is the history to my radiator / cooling related problems:

- The car started to use water on long trips and needed topping up
- After a while this started to become more noticeable and on the advice of my garage I added K Seal (radiator sealant) and this worked for a bit
- The feeling was that there was a leak in the radiator so this would stop the leak and fix the problem
- The problem returned so I added a second dose of K Seal but didn't shake the bottle well enough and I noticed a dollop of K Seal went in
- Several weeks later the car overheated while towing a car on the motorway as described above and I managed to limp home
- The garage has done a pressure test and there is nothing wrong with the head / gasket
- After reading this / other threads I've replaced the thermostat and refilled the radiator system as described but the problem is still there

The good points are there are no noticeable leaks, the thermostat is new and the head gasket is holding pressure. So what could be the problem?

Before I fitted the new thermostat my garage felt the system may not be getting up to pressure and kicking it in. Their suggestion was to go for a lower temperature thermostat ... but I decided to fit a new / OEM one just in case the old one was faulty. Or I'd somehow blocked it up with the K Seal.

Now my concern is that by adding two doses of K Seal that I've blocked the radiator .. or significantly reduced it's efficiency. Is this likely and please can you let me know how to test this?

Alternatively please can you let me know what I should be looking to test in sequence to narrow down on what the problem is. The garage is great BTW .. I'm just trying to cut down on costs at the moment and have a bit of time for DIY.

K Seal can be death so some modern radiators, but check the viscous fan is working correctly and also check the the space between the aircon condensor and radiator is not chock full of rubbish.
I'd pull the RAD out, that will allow you to clean out the space between the rads and you can try flushing the rad. Check for splits in the header tank if it's using water and that the pressure cap is OK.

If a garage advised using K-Seal instead of finding the fault and fixing it correctly - I'd be finding a new garage fast.....

As Datatek says, K-Seal can kill modern rads, and with small orifice plates in modern systems, this can be the death knell for a cooling system.

Also, the system has the gearbox oil cooler plumbed into it, and these are known to clog up, K-Seal will only accelerate the issue.

If it is the M62 derived V8 (as you don't mention year - or if it is a later Diesel V8) then there is a manifold that runs across the back of the engine, this is prone to cracking and leaking - but it leaks on to the hot bell housing and rear of engine, meaning drips are unlikely.....also, the heater matrix is known to split and this leaks into the heater box, and drains through the AC drains either side of the gearbox again masking a leak.

Have you done a static pressure test to see if the cooling system hols pressure? if it does, and yet it still overheats - think air-lock (the M62 is prone to these if the correct bleed procedure is not followed), water pump impeller failure (not so common), blocked rad, head gasket.

What saint said.....K seal and a garage said use it.
If its the m62 engine
In no real order but off the top of my head common coolant issues are
Rad
Water pump
All hoses
Coolant transfer pipes leaking
Rear manifold
Plastic short hose rear of the engine
Valley pan
Thermostat electrical connection
Expansion bottle know to crack n leak

Think that covers it i hope you get it sorted at the least change the rad and flush out the K seal

Many thanks, I've been out today and started just with what I can see. The 'hot smell' looks like oil dripping from the bottom of the head and onto the exhaust manifold. Presumably from the rocker cover. You can just see the wet patch on the photo attached.

On the bulkhead there are a couple of silver (air conditioning?) pipes that are fixed with hex head bolts. If you look at the photo attached you can just see fluid seeping from the bottom of the black washer. The black sound deadening around that area is soaking wet.

There are also two disconnected sensors under the hood too. The first is at the back left corner of the engine and looks quite clean (like it just come off) and the other is forward of that on the inside of the drivers wing. But this one looks cruddy. Photos also attached.

The oil leak:
Hopefully just bolting the rocker covers down ... or replacing the gasket?

The water leak:
Could this leak be enough to keep the pressure in the system from rising, to heat the water enough for the thermostat to kick in?

The sensors:
Could you tell me what these are for?

Good to actually find something to start knocking off the list.

CambridgeL322 said:

Many thanks, I've been out today and started just with what I can see. The 'hot smell' looks like oil dripping from the bottom of the head and onto the exhaust manifold. Presumably from the rocker cover. You can just see the wet patch on the photo attached.

On the bulkhead there are a couple of silver (air conditioning?) pipes that are fixed with hex head bolts. If you look at the photo attached you can just see fluid seeping from the bottom of the black washer. The black sound deadening around that area is soaking wet.

There are also two disconnected sensors under the hood too. The first is at the back left corner of the engine and looks quite clean (like it just come off) and the other is forward of that on the inside of the drivers wing. But this one looks cruddy. Photos also attached.

The oil leak:
Hopefully just bolting the rocker covers down ... or replacing the gasket?

The water leak:
Could this leak be enough to keep the pressure in the system from rising, to heat the water enough for the thermostat to kick in?

The sensors:
Could you tell me what these are for?

Good to actually find something to start knocking off the list.

Click to expand...

The silver pipes look like gas pipes for the aircon,
Rocker cover may respond to tightening but a new gasket will probably be needed.
A leak will stop the pressure rising which will, if bad enough, lead to over heating. Pressure raises the boiling point of the coolant, lack of pressure will not stop the coolant getting hot but may lead to it boiling. It will not affect the operation of the thermostat.