No flow

[Unregistered]

The last time I ran the engine the exhast water was less than normal but did not run long enuf to overheat. While doing acid flush today, the water flow stopped altogether. There was no flow to the exhaust box or thru the bypass hose. Water pump impeller appeared to be ok with visual check and hot water flowed out when the cover was removed. Where do I check next?

[Don Moyer]

It appears as though your pump has stopped functioning for some reason, although I don't know why it would have stopped in the middle of an acid flush. It's possible that you cavitated the pump while drawing the last bit of acid solution out of the bucket. Flexible impeller pumps don't prime very easily after losing their prime, unless you disconnect the discharge hose until it starts to pump.

I'm not sure where you separated your hoses to determine that no water was flowing through the bypass hose, but if you removed the hose from the inlet to the thermostat housing and there is no water from that hose, I'd remove the one coming directly from the pump and check there. If you can get the pump to work at that point, reconnect all hoses and see if it will continue to pump. If not, there must have been some scale that mobilized and is blocking the "T" fitting or diverter cap on the inside of the water jacket side plate, although I consider this to be rather unlikely.

Don