johnsw":3hg46bqo said:
... just curious how long these things have actually lasted given the 'modern' materials available today ...
I haven't heard of any 'uninitiated' one in many years. Now, what I mean by that is, I've heard of 1 or 2 guys who admittedly 'beached' the boat on sandbars or ran through shallows and then had a water pump failure. Well ... duh :shock: !
I bet you that if not subject to abuse like above, then a good impeller could last maybe 5 seasons and many hours. It is tough to put an actual year or hour figure on them. I have taken impellers out of V6 motors when the owner couldn't remember when or if it was ever done (but clearly not in the last 3 or more years) and they were pliable and perfectly sound.
Now don't just worry about the impeller, as you inquired about, as that is just one of the critical parts crucial to a working cooling water system. The other key parts are the:
* Waterpump housing itself
* Thermostats
* Lower unit bolts
I perform a full waterpump and thermostat replacement every 3 seasons, which would be ~300 hours. Now if I was well over 200 hours in 2 seasons, then I'd most likely do it before the 3rd season. Conversely, let's say I didn't use it too much and my hours didn't clock over 160 hours for those 3 seasons (... now not that AIN'T gonna happen
), what I could do is 'skip' that year and do it after the 4th year.
But ... what I would darn well do is to
remove, clean and replace the lower unit bolts! I replace the t-stats anytime the waterpump gets a service and I would NEVER replace just the impeller on any V4 or V6 motor. I do, however, do this on smaller OBs. It is a judgement call, but only on small puppies.
Even when I repair old used OBs that have never had a waterpump or impleller replacement, when I get it out, the impeller is fine and the housing, specially the bottom plate the impeller runs against, is flat and not scored. But I have to drill out 1 or more lower unit bolts just to get the lower leg apart. I hate that - arrgghhhh! When I price out such a job (if doing for a friend) then I'll warn them beforehand that the 'estimated' price is subject to getting it apart and many times that 'heat hammer' (torch) and machine work will cost them twice as much or MORE to have the broken bolts drilled out and replaced than it did for the parts and service cost just to get to the waterpump.
If you get the chance, learn to do so yourself, as it takes me but ~30-minutes now to do so on most any of my brothers' motors or those of mine (I think we'll be running 12 or 13 OBs for the 2008 season). Not too bad for $50 for the kit and $2 coffee to consume during this work. And it sure beats the $90-$100 per hour fee the area shops are getting and I bet they rate it as a minimum 2-hour job.
There used to be an on-line DIY tutorial of 'how to' perform a waterpump service ... but I just checked it and the picture links are dead
. Oh well, if I do a service this season I'll try to take photos of the process.
