Fan struggling to reduce temperature unless revved kv6

[racing green rover]

I have flushed and rebleeded it what it says on the instructions for bleeding about keeping the level topped up when you start the engine mine doesn't drop so it's still at the neck of the expansion tank. The fan was cutting in and out as normal both the bottom and top hoses were hot to touch however when I went for a drive the temperature was up and down in the 90s if I went faster the temperature would drop between 93-96 degrees if I was just going slowly with a light throttle it would be up in the late 90s sometimes 100 when I got home and parked up the fan came on and the temperature rose to 101-102 and then cooled down to 96 degrees but was just staying there and the bottom hose was just warm whilst the top hose was hot to the touch if I held the revs on at 2000rpm the temperature would drop to 85 degrees and when I turned the engine off I could hear crackling from where the thermostat is.
I have checked the water level 30 minute later and syphoned some out to Max level when I start the car with the cap off there is no coolant flow through the bleed hose the hole is clear in the expansion tank and if I rev it the water rises to the top of the tank within 30 seconds.

[SD1too]

Well done for your latest efforts Pete. Looking on the optimistic side, maybe you're getting somewhere. If you haven't done so already I'd be tempted to empty the cooling system completely, including the drain plug in the LH bank then start from scratch. You need that narrow cylinder head bleed hose to be delivering a stream of coolant, not air, into the expansion tank. Measure the total amount of coolant that you put in. The total capacity is 7.5 litres. If it's significantly less than that, it means that you still have problems. If you can bear to do more flushes they can only be beneficial but use an additive to help remove the K-Seal.

Simon

[racing green rover]

I have just run it now and the fan was struggling to cool it again with the top hose going soft and bottom hose just warm.i have followed the mg Rover bleeding procedure there is something seriously wrong with it.there was nothing coming through the bleed hose whatsoever with the engine running if I turned the off and squeezed the top hose they will be a few air bubbles from the bleed hole in the tank and then short sprays of coolant.

[SD1too]

The bottom hose being just warm usually means that the thermostat isn't properly open (reduced flow). On the other hand you've had temperatures as low as 85 which means that it's not closing when it should. Since K-Seal is designed to bridge small orifices, I've always feared for the health of a thermostat which is a delicate mechanical device.

Simon

[vitesse]

Funny isn’t it, that some KV6 engines are dead easy to re-fill others a nightmare. I’ve previously described my experiences with a car that defeated the old Rover dealer here, yet last month I did a cam belt change on my daughter’s V6 and when I refilled it I just poured coolant mixture in, didn’t bother with a raised tank and the car’s fine. Why? Just as an experiment after my nightmare V6.
One other thing I tried, was compressed air to try and get the coolant to circulate. I’ve owned a Saab V4, and Rover 820 and often used compressed air to pressurise the clutch hydraulics. Sometimes you’ve just got to think outside the box.

Good luck

[racing green rover]

When I bleed it both the top and bottom hose was red hot it's only when I took it for a drive it started having problems again anyway I've just lifted the expansion tank and opened the bleed screw there was a clear flow of water no air bubbles. If I put my ear close to the expansion tank I can hear water bubbling. I'm putting a new engine in anyway due to these problems and also that it makes a knocking noise