Trojan Boat Forum

my question is in regard to the chrys. 318 - (i guess its probably the same for all engines though) how often should you change your impellar or water pump? the boat hasnt ran in two years until this past weekend, i was just wondering what the general opinion on the suggested length of you of the impellar or water pump. Thanks.

From an amatuer:

I inspect the impeller every spring and regardless of condition change it every 2 years. I winterize with antifreeze in the raw water side, so it seems to hold up pretty well - they usually foul when they dry out.

If the water pump isn't leaking, I leave it alone. They usually show signs of wearing out - I'll do a visual inspection while it is running at least once a month. If it leaks, I'll swap it out.

Just keep an eye on the raw water exiting the exhaust - over time, you will be able to recognize when you have a "weak stream"

Joe

You know ........... Impellers are CHEAP. I change my out every spring and keep new spares on the boat all the time. Impellers will set to memory over time and do not push as much water once that happens. It's just not worth the chance or money to me. As Joe says, they start to dry out with lack of use and get hard. That is when they shell, and now you are digging to find all the vains before you can run. Be safe....... By the way, be sure you buy a quality impeller. There are after markets that I have found just do not last.

I was replacing my thermostats and found that in the thermostat housing there were two pieces of old impeller blocking one of the hoses going to the manifold. Make sure if you find a broken impeller when replacing with a new one that you do all you can to locate the missing parts so they don't clog your hoses or manifold.

Hey Tad,

Our Trojan was laid up for two years from the time it ran last while we refurbished it. The impellers became 'set' as they were left in the Sherwood water pump all this time. One did crack in a couple of vanes, the other was ok but we're keeping that one as a spare.

Brand new impellers will have the vanes sticking straight out from the centre hub. If your impellers have become set, the vanes will likely be bent in the direction of rotation and may have become brittle, too.
We found that getting new impellers is fairly simple. They're made in the US, so your price shouldn't be too bad. Up here I paid close to $35 CND for each.

Be sure to fill the water pump and cooling system with water before running the engine. These impellers will shred pretty quickly. The ones I have (from Sherwood) are made of neoprene and are rated to a max temp of 130C. Not a problem when you have water in there, but without it gets hot quick!