I'd asked this in another thread and never received a response so I'm starting a new thread. After replacing radiator # 3, I observed a new behaviour with the cooling system, the system's remaining pressurized even after sitting for days without use and the upper radiator hose's bulging a bit. I'd never had that happen prior to replacing the radiator and I'd replaced many pipes, hoses, pumps, etc over the last several years.

My question was if this was normal or was there something wrong? ECT's relatively steady at 210 F, front a rear heat are plenty hot on demand and I've done multiple vacuum fills and kept it under vacuum and I've not observed any loss of vacuum, hoses remain collapsed and the system fills with what appears to be the same amount of coolant which was removed for service. My concern when I originally asked the question and remains today, is it would seem keeping the circuit like this would put stress on the hoses, pipes and fittings.

The overfill tank has a new genuine Land Rover cap fitted since the radiator was replaced 2 months ago but when I unscrew it, there's a massive amount of air escaping rapidly and the tank goes from being nearly empty dry to nearly overflowing.

I asked a tech today if this was normal expected behaviour and he indicated NO, the system should self bleed air and definitely hoses should be soft after sitting for several hours or something may burst or leak eventually (what I've been seeing).

Can anyone here PLEASE confirm how their's behaves? As I said, prior to fitting radiator # 3, after cooling down the hoses would soften up and it had always been that was prior.

Many thanks.

 

Mine does not have this behavior.

 

Mine does the same thing, 2012 LR4 5.0

working through diagnosis

 

wonder if this could be a small head gasket leak pushing combustion gasses into coolant. could test coolant for exhaust gasses.

 

So your system remains pressurized even when cold and sitting for some time?

 

I've thought about that. I change my oil every 2 months/5K miles. just done last week and it was oil, just as always. Engine runs perfectly smoothly, in fact now I've done the new pipes on the front, the idle vibration it had for years, is gone. Super charger was removed 3 times prior by the main dealer, this was the first time I'd done it. ECTs appear normal and within proper range. First drive after replacing these pipes and after the exhaustive vacuum fill, ECT was all over the place from about 223 F to as low as 191 F bouncing up and down with continuous changes, though setting heat to max would bring the ECT to a relatively steady 206 F then switching back to cold would send the ECT up and down again. Now after a few days, ECT stays at 209-212 F.

The expansion, when cold, filled to the top fill line. After operation, expansion tank's nearly empty but unscrewing the cap, the tank fills up to overflowing and I quickly tighten it. There are bursts of bubbles, but only from the top overflow hose and only when I do this so the overflow's under coolant, I assume this's air from the pressure release as there are no bubble at any other time. There's no coolant loss either after several hundred miles of driving and since also had this same pressure issue after replacing the radiator, that was several thousand miles of driving again with no coolant loss.

A tech I spoke with suggested the thermostat's stuck closed with an air bubble in the thermostat and I should replace the thermostat. Unfortunately I had intended to do that when I replaced the radiator as preventative maintenance but thermostats've been on global back order with no ETA for a very long time and at around $100 for genuine, I'd prefer not to buy aftermarket and have something inferior.

Thoughts?