New coolant

[Foxhill]

Having replaced coolant and finally topped up I have about 55% antifreeze. The temperature guage remains the same as normal, just under halfway. If the engine got any hotter when running and replacing coolant could this cause head gaskit to leak or head to crack? I intend to drain radiator a little and top up with more water to lower % of antifreeze.
How would I know If there was an air lock in system and remove it. How do you know when the gaskit or heads gone, would engine sound any different??????

[Koi]

Having replaced coolant and finally topped up I have about 55% antifreeze. The temperature guage remains the same as normal, just under halfway. If the engine got any hotter when running and replacing coolant could this cause head gaskit to leak or head to crack? I intend to drain radiator a little and top up with more water to lower % of antifreeze.
How would I know If there was an air lock in system and remove it. How do you know when the gaskit or heads gone, would engine sound any different??????

Make sure both heaters are open and both getting hot, 55% antifreeze is a bit on the strong side, most use around 65 water to 35 antifreeze.
You can't tell for sure if its airlocked unless say the heaters were not working, run for a while and check often over the next few days to see if the level has dropped.
Tell tale signs of head or gasket failure are, loss of power, sauna from the exhaust, less mpg, expansion bottle overflowing, pressure in the cooling system. Don't rely on any of these with the surf, as my temo gauge new moved when my head went, never had the sauna and drove it for weeks with a duff head.
Only sure way to tell is to get it pressure tested.

[kitesurf_phil]

Having replaced coolant and finally topped up I have about 55% antifreeze. The temperature guage remains the same as normal, just under halfway. If the engine got any hotter when running and replacing coolant could this cause head gaskit to leak or head to crack? I intend to drain radiator a little and top up with more water to lower % of antifreeze.
How would I know If there was an air lock in system and remove it. How do you know when the gaskit or heads gone, would engine sound any different??????

I've had 50% de-ionised water/50% Anti-freeze in for over a year with no problems. My temp guage sits just to the low side of normal.