Combustion vs Pressure

[xiixvi]

Can anyone tell me the difference between combustion test and pressure test to see if head gasket blown? or is it the same thing?

 

[Major]

You want to do a pressure test. Combustion tests are done on the fuel itself, unless I'm mistaken.

 

[328ii]

IMHO

Combustion test - Usually called compression test - tests engine cylinder pressure (or leakage if lack thereof)
Pressure test - Engine coolant system pressure test (or leakage if lack thereof)

Should both show leakage (into each other) if head is warped / gasket blown

You might even see water in your engine oil depending on highest pressures

8?>

 

[Raybimmer]

Here is what you get for two cents :
Compression test done on warm engine , remove spark plugs and insert tester into spark plug no 1 hole ( has rubber end cap or screws in ) and crank engine , record reading and repeat for all cylinders . Can be redone after pouring about a teaspoon of oil into each plug hole , if readings increase due to better sealing then compression is higher due to oil sealing between rings and cylinder walls .
If a reading drops after a short while it shows a leak , two adjacent cylinders leaking would most likely be leaking head gasket .
Would expect pressure of about 1000 -1100 Kpa .

Pressure test on cooling system would most likely be an item similar to your radiator cap that is put on after removing your rad cap and it is pressurised . A drop in pressure indicates a cooling system leak , now you have to look for it , may be water being pushed into oil through leaking head gasket .
Would expect oil to get caramel/mustard colour if water is present .
Good luck