I run a 1991 Mercury 135-horse motor. It's been very reliable since we bought the boat back in about 2003. I had to change the impeller last weekend because the motor would run a little too hot intermittently last time out on the water. When I removed the old impeller from the water pump housing, it was still in good shape as far as flexibility goes, but it had taken an obvious eccentric set and I could easily see why the water pump was not keeping the motor cool. I rebuiilt the water pump, changed out the poppet valve and both thermostats, and zipped it all up before adding a bit of lower unit oil. I ran it in the driveway a little while and all is well.

Then a while ago the idea popped into my head---why not just flip the impeller over and run it the other direction for a season or two? If the rubber is or seems to be in good condition, why not? Has anyone ever done that routinely? Has anyone tried it and wished they hadn't?

Bad idea, reverse direction will surely crack/break the fins. Best to change every 2 years regardless of use, very small price compared to engine replacement.

I agree with you in your belief, but I would like to find out what anyone KNOWS...as in, voice of experience.

i dunno. i kinda like that idea. only thing is that if you're taking it apart anyway, why not just put a new one in and relieve any doubt.

The impeller is designed to.seal off the top of the housing. Your key slot won't fit right and itll.just pour.water into.the.exhaust and not up.the water tube.

That's from experience.putting one upside down..

THIS.....

I haven't changed one on a Mercury, but the Yamaha impeller only goes on one way. But what bronco71 said is true, The chances of failure and a very expensive repair are not worth the price of a new impeller. Plus it will probably fail under load which means you are going to be stranded on the water, not in the driveway.

It would be really hard to reverse the bend and put it back into it's space. But if you could do it, and the rubber is still pliable, sure that would work. But let me tell you a story about a clutch I replaced when I was in college. It took me 6 hrs to unhook the transmission to replace the clutch. 1yr warranty was $50, lifetime warranty was $65. I saved $15, but had to replace it 1yr later. 6 more hrs and I paid $65 for the lifetime. Didn't have to mess with it again.

The moral is: if you took all that labor to get to it, spend the $20, or you'll have to do it again. Unless your time is worth less than $5/hr, spend the $20.
Tim

+1