Slight Coolant Loss V6

[mikeWalsall]

what s brilliant animated reply by .. widdowson2008 ..!!

Coolant pressure test is normally done cold / warm not when heat (hot) pressurised ... most car radiator suppliers / garages will do a (generally free) pressure test while you wait ...

[widdowson2008]

This diagram shows how the expansion tank cap works and what it does. There are basically 2 seals, the top one and the lower one.
What Ady is saying is that if you replace the cap with one that has the top seal only (no lower seal, spring and red valve), then the system is open to atmosphere via the little black tube (top left). By connecting a pump to this small black hose you can artificially pressurise the system.
Once you have reached a pressure of 1 bar, leave it fo a few minutes and note the pressure gauge. If the pressure drops, then you have a leak somewhere and it should be easy to spot.
As Ady has said, DON'T exceed 1 bar or you may damage hoses and cause additional leaks.
and DON'T forget to put the correct cap back when you have finished

And I'm guessing this is done cold

Ady is the bloke to ask regarding X/tank pressure testing and I think (hope) he will be along to advise. Watched him do it many times.
Having said that, I see no reason it can't be used cold and then left on while the engine warms up. (but I would defer to Adys input). Only potential danger I could see is that as the as the engine warms up, the pressure will increase and with the blank cap fitted, there is no release point. You would have to keep a very keen eye on the pressure gauge.

[teenmal]

Hi,

If you are carry out a pressure test,this should not be done with the engine running.

Cheers..

[Northern Bongolow]

This diagram shows how the expansion tank cap works and what it does. There are basically 2 seals, the top one and the lower one.
What Ady is saying is that if you replace the cap with one that has the top seal only (no lower seal, spring and red valve), then the system is open to atmosphere via the little black tube (top left). By connecting a pump to this small black hose you can artificially pressurise the system.
Once you have reached a pressure of 1 bar, leave it fo a few minutes and note the pressure gauge. If the pressure drops, then you have a leak somewhere and it should be easy to spot.
As Ady has said, DON'T exceed 1 bar or you may damage hoses and cause additional leaks.
and DON'T forget to put the correct cap back when you have finished

And I'm guessing this is done cold

Ady is the bloke to ask regarding X/tank pressure testing and I think (hope) he will be along to advise. Watched him do it many times.
Having said that, I see no reason it can't be used cold and then left on while the engine warms up. (but I would defer to Adys input). Only potential danger I could see is that as the as the engine warms up, the pressure will increase and with the blank cap fitted, there is no release point. You would have to keep a very keen eye on the pressure gauge.

absolutely spot on steve as usual, i was thinking how to explain things but gave up, but one of your animations speaks more than a thousand words of crap from me

[dandemann8]

Cheers chaps, I think I'll do it myself rather than spending £20+ at a garage, just one more thing where will I find the right flat cap to use

[widdowson2008]

Cheers chaps, I think I'll do it myself rather than spending £20+ at a garage, just one more thing where will I find the right flat cap to use

ADY!!!!

[dandemann8]

Cheers chaps, I think I'll do it myself rather than spending £20+ at a garage, just one more thing where will I find the right flat cap to use

ADY!!!!

[haydn callow]

Just get any old cap and "rip" the spring etc off.

A good way to pressurize it ...is to get a old racing bike innertube.......cut the valve off close to the tube with a hacksaw.......remove the short black vent tube from the tank outlet....you will find the valve will "self tap" it'self into the spigot.....then use a pump with a pressure gauge to put pressure into the system..

[Northern Bongolow]

nissan micra (old shape) caps, and other jap motors, just chop a slice off the end flat seal but not the pin through the centre, or the top seal.