Sporadic cooling: 200+ down to 125, no thermostat or with thermostat. After flushing and checking every hose and fitting.
Good water floor then no water flow: Any ideas what this is caused by? I have now installed the new aftermarket thermostat so i will see if this persists.
Chain of events:
I change the exhaust last year from the engine manifold back. New exhaust flange, new brass fittings, new water lift muffler, new exhaust hose.
The system ran at 160 with the original thermostat and then started going up to 200 and the water flow shut down to a trickle. I stopped the engine, let it cool for 1 to 20 minutes and sometimes it would go back to 160 and water flow would be normal.
The problem can always be initiated by disconnecting the raw water and connecting to a bucket of water. After reconnecting the raw water the overheating persists. Sometimes running at idle but often a high RPM can initiate the failure to flow and then 200 F. Sometimes the flow is nothing and sometimes just 1/2 a cup every 10 seconds.
Ran with no thermostat and the check valve and restriction in place. Still the same problem. Replace water pump impeller and checked all parts. All water pump parts are OK, greased and fitting snugly. Checked every hose, every fitting and flushed the cooling system with 30 PSI water. Got a nice bucket of rust out of the water jacket side on reverse flush. Still the problem persisted.
Every time I disconnect the raw water and connect to a bucket of water there is no flow. I primed the hose with water, I tried pushing water into the intake hose with 30 PSI hose. No flow and no water moves in the intake hose. I check every opening in the system from the intake hose to exhaust exit on the transom. All seem very clear.
Reconnected the raw water, and sometimes it starts to work.
I Changed to new aftermarket thermostat with spacer. Seems to run fine at idle and under load (150-160 idle and 170/180 under full throttle maximum load). Ran out of time so I didn't repeat the use of a bucket of water.
I had been through every single hose and fitting to make sure there were no restrictions. The impellers have never had a chip off them and
I replace every 1-2 years since rebuild. What would cause this?
Is there some way a gas/steam pocket can form and block flow?
jimB
Good water floor then no water flow: Any ideas what this is caused by? I have now installed the new aftermarket thermostat so i will see if this persists.
Chain of events:
I change the exhaust last year from the engine manifold back. New exhaust flange, new brass fittings, new water lift muffler, new exhaust hose.
The system ran at 160 with the original thermostat and then started going up to 200 and the water flow shut down to a trickle. I stopped the engine, let it cool for 1 to 20 minutes and sometimes it would go back to 160 and water flow would be normal.
The problem can always be initiated by disconnecting the raw water and connecting to a bucket of water. After reconnecting the raw water the overheating persists. Sometimes running at idle but often a high RPM can initiate the failure to flow and then 200 F. Sometimes the flow is nothing and sometimes just 1/2 a cup every 10 seconds.
Ran with no thermostat and the check valve and restriction in place. Still the same problem. Replace water pump impeller and checked all parts. All water pump parts are OK, greased and fitting snugly. Checked every hose, every fitting and flushed the cooling system with 30 PSI water. Got a nice bucket of rust out of the water jacket side on reverse flush. Still the problem persisted.
Every time I disconnect the raw water and connect to a bucket of water there is no flow. I primed the hose with water, I tried pushing water into the intake hose with 30 PSI hose. No flow and no water moves in the intake hose. I check every opening in the system from the intake hose to exhaust exit on the transom. All seem very clear.
Reconnected the raw water, and sometimes it starts to work.
I Changed to new aftermarket thermostat with spacer. Seems to run fine at idle and under load (150-160 idle and 170/180 under full throttle maximum load). Ran out of time so I didn't repeat the use of a bucket of water.
I had been through every single hose and fitting to make sure there were no restrictions. The impellers have never had a chip off them and
I replace every 1-2 years since rebuild. What would cause this?
Is there some way a gas/steam pocket can form and block flow?
jimB
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