Coolant pressure.

Monkey13 · Nov 17, 2014

Just a quick question, I've been told before that the td5 engine runs a pressurized cooling system that's how it works, so when do you think it is over pressurized? For example the top hose in mine does go hard when up to temperature but it isn't bulging. I've read when they do over pressure they really balloon? Its just nice to know encase it ever happens

sierrafery · Nov 17, 2014

if it's harder than a softer tennis ball it's not good... first would be to replace the tank's cap(make sure it's completely tightened)... it's possible that the presure release valve in it is blocked, it must open at 1.4 Bar, if that doesnt help you might have a HG issue or even worst a crack in the head

Monkey13 · Nov 17, 2014

1.4bar, that's around 24psi so that'd be a lot harder than a tennis ball lol any idea on operating pressure?

sierrafery · Nov 17, 2014

1.4 bar

Monkey13 · Nov 17, 2014

Ok cheers I'll get a digital gauge from work and try and plum it in somehow and record the pressure

kharnsflair · Nov 17, 2014

My Td5 hoses were hard but almost straight away from start-up......and when my vehicle had been sat cold for a couple of days and the coolant cap was then removed, a few bubbles came up from the reservoir, along with a loud hiss of escaping air. I questioned the amount of pressure in the normal cooling system and changed the cap as you could also sometimes see coolant on the bonnet. No bulging hoses however, I would expect this to be just before they blow-off and leave you on the side of the road.

But in the end it turned out to be the head gasket I'm afraid (when the head was off you could see the leak). The coolant pressure was about the only symptom my Land Rover was showing. Since having the head done, the hoses are much softer, and when cold there is barely any pressure in the reservoir. Good luck!

http://www.landyzone.co.uk/lz/f50/coolant-system-pressure-vs-gagging-high-rotation-253811.html

Threads here and on other forums including:

http://www.aulro.com/afvb/technical-chatter/86981-coolant-leaking-expansion-tank-2.html
http://www.defender2.net/forum/topic24703.html

Monkey13 · Nov 17, 2014

Ok cheers for that, when it's cold or cooled right down their isn't any pressure

Discodevon · Nov 18, 2014

Hi whats the outcome of this as mine goes a little hard when up to temp. but still sqeezaeble mind you

Monkey13 · Nov 18, 2014

If the running pressure is 1.4 bar around 24psi it will be hard so I wouldn't worry about it

Shifty1962 · Nov 23, 2014

All car cooling systems run pressurised as it allows for higher temperatures before the water boils. Most run at between 1.2 - 1.5 bar and the pressure is controlled by the radiator filler cap which should have its opening pressure marked.

In an emergency you can remove the cap and run with virtually no pressure in the system but you will have to keep topping up after every 10 miles or so. This is useful if you repair a burst hose with gaffer tape and need to get somewhere for a proper repair.

Coolant pressure.

Monkey13

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sierrafery

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Monkey13

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sierrafery

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Monkey13

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kharnsflair

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Monkey13

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Discodevon

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Monkey13

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Shifty1962

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