e46 easy test to indicate blown head gasket

there should be no air in the system, expansion tank is filled to the brim with more water on top by using this jug. at the time i had a bad cylinder head gasket and those tiny little bubbles that you see (view fullscreen) are most likely an indication of this problem. i have not repeated the test with a good head gasket, so it's not 100% conclusive but it can be a promising indication :)

[@willk3807]

I'm hoping all I need to do is torque the head bolts down to spec. Should have done that when I replaced the valve cover gasket. How did yours do with the new head gasket? Did it continue to bubble?

[@BmwMe-uh9sy]

there can be air in the system but if you have exhaust gas in the cooling system then ye its blown

[@dallastxshadetree]

your right

[@hayabusa5306]

👍🏽

[@Ahmed-qf3wz]

Mine bubbles out like crazy, but i only loose coolant when i drive around.. no leak signs

[@petergibbons607]

in my case the head gasket was blown such that the high pressure combustion gases leaked into the coolant system, pushing the pressure past the limit where the coolant cap would vent the excess pressure in the form of steam, so that's where the water was going in my case. i fixed it but 2 head bolts pulled the threads out and i time-serted those and it was all good until a couple months later when i another head bolt came out so i gave up at that point. if you do this then my only advice is to time-sert all 14 bolts. it's a huge job though and that car just kept breaking non-stop, now i drive a toyota, no more problems :) either way, good luck.
in my case keeping the throttle and rpm low increased how long i could drive before enough coolant was lost that the car started overheating.

[@Ahmed-qf3wz]

​@@petergibbons607thanks, mine goes within 3/4 drives if i have the heater on, i`ve checked heater core and all the pipes, there isnt any leak while the car is running idle 😅 and its at 142000 miles as well,, so might be headgasket 😅

[@petergibbons607]

@@Ahmed-qf3wz you can buy the test kit with the blue fluid, it turns yellow if combustion gases get in there, that's what i ended up doing to confirm that's what it was

[@wyattybarra2236]

Couldn’t air get into the cooling system via coolant leak elsewhere in the system other than the head gasket

[@petergibbons607]

Yes, but first you bleed it, then also remaining air would get pushed out, especially when you rev it a bunch. In this case the little air bubbles keep coming, they never end. Later I bought the block tester kit with the blue fluid. It's a much better method and pretty cheap. I recommend that.