Have reciently installed a used A4 in my 30' Irwin. Had to combine parts from 3 engines but came up with a good strong replacement that starts, runs good and strong. Cooling problems became apparent first time out after running for about an hour. Up until that time temp remained normal. For no readly apparent reason temp started climbing to 250 and water ceased to flow out of the exhaust and started steaming. After a cool down, begin to trouble shoot from through hull, hose (good flow and can blow back) , water pump (new impeller and seals), thermostat (was open but removed anyway), inlet to manifold, outlet from manifold, hose to exhaust system, muffler (it is less than 2 years old) and exhaust hose. Found nothing amiss. Left hose from manifold outlet to muffler disconnected and started engine. After a moment or two water flow returned. It was hot to begin with but cooled after a few minutes to temp that was not to hot to run on my fingers. Hooked everything up and headed home. It took a while, had to run until temp got to high and then cool but made it.
Decided that first thing to do was an acid wash. Got set up per various published papers and spent most of one day pumping and flushing with good results. Pulled water jacket plate before and after and saw amazing results. Was sure that my problems were solved. No such luck.
I have had the boat out for our local Friday evening races 3 more times and have had the same experience each time. I have examined the whole system completly each time but have found nothing.
Today I dove on the inlet through hull and strainer an checked it out seems to be clear and the flow is very good. I have disasembled all elements once again to study on the problem.
My thoughts on the problem:
Pressure from pump to exhaust outlet seems to be low
Flow at manifold outlet weak
Temp seems to start climbing engine heats, heated engine builds preasure in water jacket slows flow, less flow, engine gets hotter, hotter engine makes steam, steam bubble developes in engine creates back pressure and slows flow even more, engine gets even hotter all incoming water slowed and what little gets into block turns to steam.
The only thing I have found today is upon checking the water pump it is very possible that when I rebuilt it I have installed the seals backward. Could this allow the pump to draw air in to the system and decrease flow and pressure?
Is there any kind of info or picture showing correct seal installation?
Thanks for any comments or ideas.
Jerry
Decided that first thing to do was an acid wash. Got set up per various published papers and spent most of one day pumping and flushing with good results. Pulled water jacket plate before and after and saw amazing results. Was sure that my problems were solved. No such luck.
I have had the boat out for our local Friday evening races 3 more times and have had the same experience each time. I have examined the whole system completly each time but have found nothing.
Today I dove on the inlet through hull and strainer an checked it out seems to be clear and the flow is very good. I have disasembled all elements once again to study on the problem.
My thoughts on the problem:
Pressure from pump to exhaust outlet seems to be low
Flow at manifold outlet weak
Temp seems to start climbing engine heats, heated engine builds preasure in water jacket slows flow, less flow, engine gets hotter, hotter engine makes steam, steam bubble developes in engine creates back pressure and slows flow even more, engine gets even hotter all incoming water slowed and what little gets into block turns to steam.
The only thing I have found today is upon checking the water pump it is very possible that when I rebuilt it I have installed the seals backward. Could this allow the pump to draw air in to the system and decrease flow and pressure?
Is there any kind of info or picture showing correct seal installation?
Thanks for any comments or ideas.
Jerry
Comment