I have bubbles in my coolant reservoir. The engine was NOT overheated but I did accidentally restrict the flow in the hose to the muffs to the lower water pump and burn it up. It ran this way for about 3 minutes before I caught it. The temp gauge did not get above halfway on the closed system. However, the exhast riser and manifold and heat exchanger did get hot before I caught it. Replaced the lower water pump, flushed what I could see (there did not appear to be any debris on the outlet side of the pump)
Is it possible that air (exhaust) under pressure is getting into the closed cooling system in any way other than the head/ head gasket/block? I am 100% sure that I caught this before the engine got hot, but I did hear steam and popping from the riser/manifold area after I shut down.
Is there a way that a crack in the riser or manifold could pressure up the cooling system and cause the bubbles?
What should I look for, and where?
I am not getting any coolant into the oil, and in 1 hour or so of running I don't seem to be using any coolant. It leaks mostly at 1/2 throttle and above, not at idle.
It is a Mercruiser 470, cast iron manifold and riser.
Any and all help appreciated.
Thanks,
Greg
mbjeeper@aol.com
Is it possible that air (exhaust) under pressure is getting into the closed cooling system in any way other than the head/ head gasket/block? I am 100% sure that I caught this before the engine got hot, but I did hear steam and popping from the riser/manifold area after I shut down.
Is there a way that a crack in the riser or manifold could pressure up the cooling system and cause the bubbles?
What should I look for, and where?
I am not getting any coolant into the oil, and in 1 hour or so of running I don't seem to be using any coolant. It leaks mostly at 1/2 throttle and above, not at idle.
It is a Mercruiser 470, cast iron manifold and riser.
Any and all help appreciated.
Thanks,
Greg
mbjeeper@aol.com
