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318 temp cycling

J

jcs707

New member
"79 318s, just replaced impell

"79 318s, just replaced impellers, (old ones were intact). Now I have the following issue with one engine: the temp cycles between 140 and 190 only at idle. It takes it about 3 minutes to complete the cycle and then it starts over again.

At any point during the cycle if I throttle up - temp will immediately decrease to 140/150 and stay there. If I return to idle it begins cycling again.

both upper and lower helm gauges do same thing. No temp issues prior to changing the impeller.

/Clint"
 
Double check your new impeller

Double check your new impeller. If you have the standard sherwood raw water pump and your intake is 1-1/4" the impeller should be the 10615. If it's 1" the impeller should be the 09959. If you have closed cooling (FWC) then you might have a dual pocket pump which takes one of each (10615 and 09959).
It's possible to put a 1" impeller in a 1-1/4" pump and it will pump at higher rpms but sporatically at idle.

It could also be a vacuum leak on the suction side of the pump or a sticky thermostat.
 
"I watched the mechanic put th

"I watched the mechanic put the impeller in and noted that there was no effort made to keep the fins going in the appropriate direction. At the time I assumed that it didn't matter, but Dave at Hurrikane.com said it absolutely matters. And since this problem didn't exist prior to the new impeller ...it would seem like a logical place to start.

Regarding intake size - good point. When I called emarine and ordered the impeller for 318/Sherwood, ...no question were asked about intake size ...so maybe that's an issue as well.

Thanks for the reply."
 
"Clint:
Dave knows a lot more

"Clint:
Dave knows a lot more than I ever will about marine Chryslers but my experiences suggest that it does not matter which way you initially install the impeller as long as you install the pump body correctly. I tested this on my sherwood G7 pumps by intentionally twisting the impellers into place with the wrong rotation. As soon as I rotated (by hand)the pump pulley in the correct direction, the impeller vanes flipped to the proper direction.

I suggest you remove the thermostat and run the engine to see if the problem persists. Better yet, swap the port and starboard t-stats to see if the problem follows the suspect t-stat."
 
I'm sure it was all over..

I'm sure it was all over....... I bled the air out through the bleeder above the thermostat bypass hose. I really am not sure what your question means tho.
 
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