cooling system psi

[RCN]

can anyone tell me the coolent pressure a 1.9 petrol waterboxer. i'm thinking about 25 psi. is this right?

[andisnewsyncro]

According to Mr Baxter's explanation on t'yard, it should be about 1 bar - 15psi if I remember rightly

[croc]

Would suggest that 15 psi would be max for this era of engine.
Any more an you'll be popping hoses and head gaskets I suspect!!

[billy739]

it should be written on the blue expansion tank cap!

[TeamSid]

So, how do you go about measuring the pressure in the system. Would it tell you how healthy the water pump is?

[California Dreamin]

So, how do you go about measuring the pressure in the system. Would it tell you how healthy the water pump is?

You don't
and
This tells you nothing about the condition of the pump....coolant circulation yes but pressure is down to coolant expansion and the pressure cap (Dalek type on later vans) holding that pressure up to it's designed release at which point excess pressure and coolant are released into the expansion bottle (the one behind the number plate.

Pressurising the cooling system is necessary to raise the coolants boiling point and so that the coolant itself can store more heat energy.

Martin

[Hacksawbob]

Never understood this... 15 psi = 1bar = 1 atmosphere so it should equal the outside pressure at 15psi but it is clearly not if you take the cap off it expands, so if internal pressure = external pressure it wouldn't leave the tank. ????

[tonytech]

Never understood this... 15 psi = 1bar = 1 atmosphere so it should equal the outside pressure at 15psi but it is clearly not if you take the cap off it expands, so if internal pressure = external pressure it wouldn't leave the tank. ????

I would imagine the 1bar refers to the pressure difference required to open the valve, ie 1bar outside and 2 bar inside = open.

T

[Plasticman]

best stay away from the hyperbaric industry
If your bothered about the internal system pressure then fit a water pressure gauge, be handy if you have a hose go or pump impeller..
mm

[kevtherev]

quack test the cap
change the cap for a quality one before any testing is done

[California Dreamin]

1 bar over atmospheric pressure innit....

Best to buy a genuine cap as some of the 'reproduction' ones are notoriously unreliable.

Martin

[Plasticman]

one of my other persuits is drawing up and building commisioning this stuff, so yep pressure is fun to work with

mm

[California Dreamin]

Latest common rail diesel injection systems work at 1600 bar

Martin

[AdrianC]

Latest common rail diesel injection systems work at 1600 bar

Scary, innit? And to think that mechanics have spent the last 50+ years being scared of Citroen hydraulics at "only" 100bar or so...

[Plasticman]

yes and the pressure itself isnt the worry, its the misuse, I work a bit with hp cutting stuff and the pressures far exceed that , the danger is selfpenetration the entry hole is neat but the internal damage is horrendous and thats with water, derv would be as bad again.
mm