12 vs 6 blade impellers

[rbruce63]

My 1969 Chrysler 20 HP with short of 30 hours of use, overheated after a 5 hour rally "climbing" a river in Costa Rica. The mechanic found that the 12 blade impeller had one blade almost torn out, now the impellers have only 6 blades for this motor and I feel that if it overheated with 1/12 of the blades not working, what would happen with 1/6 of the blades not working in the next rally. Please help!

 

[The Marine Doctor]

Re: 12 vs 6 blade impellers

Your engine will be fine.<br /><br />The older impellers were 12 fins...the new ones are only 6 and perform just as well.<br /><br />TMD

 

[JB]

Re: 12 vs 6 blade impellers

I agree with TMD. <br /><br />In fact, I believe that the 12 blade impellers performed poorly as displacement pumps at low rpm and not as well as the 6 blade impellers at any speed. Reason? The water volume of the pump is increased with fewer blades.<br /><br />In either case, impellers should be replaced annually and must be replaced at 2 years to maintain satisfactory performance. This is true whether they get 100 hours use annually or 10 hours use.<br /><br />You are better off with the 6 blade impeller, Bruce.<br /><br />Good luck.