Is a compression test a conclusive way to check for a leaking head gasket? My 99 honda civic (D16Y7) Is losing coolant and ruining radiator caps from the coolant obviously getting too hot. I did a compression test on each cylinder, as well as a pressure test with each cylinder TDC with 180psi for approximately 1 minute with the engine at running temp. At the same time i had a cooling system pressure tester on with 25psi...there was no loss of pressure in any of the cylenders or cooling system, but it continues to loose antifreeze and ruin radiator cap seals, there are no visible leaks in the engine bay...Im am more than confused at this point...

Sounds like either a clogged radiator core or more likely a leaking engine cylinder head gasket.

I think you are right with the head gasket, You can find out easy, because you can check it by removing the radiator cap, then put your hand on it and feel if any pressure is building in the radiator while the motor is running. Please don't open the cap, when the motor is hot. ONLY TRY THIS ON A COLD MOTOR.

have a pressure test done on the coolant system to check for leaks. have a compression test done to check head gasket and cracks.. Have a flow test done on the radiator to check for blocked cores. Check that the fan is operating correctly. check the radiator cap for operation.

The radiator cap can be pressure tested but it may be easier to just replace it. This car is showing the symptoms of a blown head gasket so you should have it tested using an exhaust analyzer over the radiator.

have a coolant pressure system test done. have a compression test done to check for head gasket problems or cracked head. have the radiator cap tested for correct operation.

My civic did the same thing, twice, no over heating on the gauge, but the head gasket on both engines broke in the same place, #1 cyl. there is a TSB on the head gaskets, I replaced it with a felpro head gasket, had the head checked for cracks and decked, runs smooth and my wife gets 40 MPG
Pull the #1 spark plug and check for coolant on the plug. make sure you flush the cooling system.

Cracked Cylinder head or cylinder head gasket blown. Bet you filled it up with cold water when it was hot! Check your oil level, see if it is going up (water getting in) Remove the rad cap start your engine and if it blows the water out then i'm probably right.

Hi, its not good news im afraid by you describing that with the coolant cap off and revving the car causes the pressure to build up and push the water back out it sounds to me like the head gasket is on its way out, what you need to do is take it to a garage and dont have a compression test done you need to have a gasses test done, you can buy these yourself if you want to and what it does is this.

its a plastic tube with blue liquid inside it then you take the coolant cap off and place this in its place you then run the engine and rev it up then you squeeze the rubber at the end of the tube and it then sucks the air out of the coolant and through this liquid then if it detects gasses from the engine in the coolant then this turns the liquid green and this is then telling you that the head gasket needs changing.

please dont let it keep over heating as this will cause the cylinder head to warp and you would then need to get it skimmed to make sure its not warped, get the gasses test done as a compression test dont give you a true reading as the engine is not running when they do a compression test.

let me know how you get on or if you need further assistance ok

plz rate this solution as i have a whole page of unrated posts, thanks

Do the block chemical leak test and coolant pressure test to rule out blowning head gasket.
Check all freeze plugs to rule out coolant leak on the hot engine block.
Check for any hose leak.


Start monitor for coolant and oil lose.

COULD BE COOLANT SENSOR,HEAD GASKET,CHECK THE TIMING,THE PROPER MIXTURE OF COOLANT,WATER PUMP.DID YOU HAVE IT CHECKED OUT?ANY LEAKS?HEAT WORK WITH FAN?