Topic

Cooling system pressure testing is a good way of finding leaks in your cooling system.

The kit generally consists of a hand pump with a pressure gauge and various adapters to suit different size radiator and header tank/bottle filer necks.
The suitable adapter is screwed onto the filler neck in place of the radiator/ pressure cap and the hose of the pump is connected to it.
then you pump until the maximum recommended pressure for the vehicle being tester is indicated on the gauge.

(The maximum pressure can be found in the specifications section of the manual of the vehicle being tested)

The pressure should stay consistent at the recommended maximum pressure, if it pressure drops you have a leak in the system somewhere.
So whilst you have the system under pressure, have a god look around for the leak, if the pressure is dropping quickly you may have to re-pump up the pressure, or maybe you could enlist the services of a glamorous assistant.

First look over all the hoses, pipes and connections.
It may be something as easy to find and fix as a loose hose clamp.
Next inspect the the radiator for leaking coolant and check the water pump.
Also check all the welch/core plug in the engine block and head. (If so fitted)
Then you might have a look under the dash to see if the heater is leaking.
If the problem still cant be found it's probably a blown head gasket and or cracked head, and it's time for a compression and/or leak down test.

If suitable a suitable adapter is available, the tester can be used on the cap to test it's release pressure.

Some examples of cooling pressure test kits.




This one is a more basic type for older cars


This one is quite comprehensive and it also includes a pressure regulator to be used with a compressor as well as the manual pump.
This would be handy in the workshop, it would save you having to re-pump upto maintain pressure whist looking for coolant leaks.

Cobber

What's the diagnosis if the pressure increases rather than falls? Any idea?

Cheers

Robin

I had Russell and AA use this confirmed a inlet leak then no leaks.

cairnsys wrote: wrote:

Cobber

What's the diagnosis if the pressure increases rather than falls? Any idea?

Cheers

Robin

The diagnosis of increased pressure is that you've pumped it up too high
This diagnostic test is done without the engine running, like all diagnostic tests it's best done with the engine at operating temp.

Because you need to remove the pressure relief cap and replace it with the adapter to to this test there would be nothing to relive the normal pressure build up that would normally occur whist the engine is running.
This test is essentially a cooling system pressure leak down test.

Though I s'pose if you were to disable the car from starting and didn't pump it up, (just using the gauge function) whilst cranking the engine over an indicated rise in pressure might indicate a blown head gasket.