At 5 million hours on the T8 I'd be hitting Yamaha up for a new motor on them.

 

Great question! I recently had my 2010 T8 in the shop for annual service and they recommended to change out the water pump. I really didn't notice any low flow issue, but they still recommended it was time to replace it. To me this is one of those things that I need to work right when I want to use it. My time off is too valuable to have to waste it dealing with motor trouble so I went ahead and had them do the work. Haven't run the motor yet to see if it made a difference.

 

The OEM seems to say Annually or every 100 hours. Your User manual would likely say the same.

http://maintenance.yamahaoutboards.com/interval-maintenance/

 

I have a honda 50 that I run off the beach from Pacific City, not sure how comparable it is to your 115, but offer this anyway.

I called the company I purchased it from to ask about impeller replacement time frames. They said 3 years is a good time frame, regardless of how many hours you put on the motor, as the rubber eventually wears from both age and use.

So, two months back I decided to drop the lower unit and do the dastardly deed. By the way, I purchased the motor in February 2008 and probably have 700 hours on it. What I found was the impeller originally had 6 fins, two of which were totally gone. The motor still peed pretty well, but not nearly as well as it did after the replacement.

For my motor, it was a pretty easy job, total time 1 hour 15 minutes. And it was my first attempt doing something like this on an outboard.

From now on I probably will go with the 3 year time frame because it isn't terribly expensive, about $45. and I like tinkering with things.

Radke

 

It's a fairly easy job, so if in doubt fix it. That way it won't let you down when you need it,

 

I have twin F150's, 1400 hrs, all in the saltchuck. I change em about every 400-500 hrs, which equates to every other year for me. Not many folks who know these motors still do pumps each 100 hrs/annually, just not necessary. However, your shop won't argue with you if you choose to do so.

I don't know if my experience translates to your fresh water and power application, but that's what I do anyways.

fb

 

100 hours would be like changing your auto oil every 2000 miles-way too often.
500 hours is what I did and the impellers were fine. That was all salt use.

 

Honda says 200, Yamaha says 100, Mercury says 300, Suzuki says 200, Johnson says 300.

Ifish says 400 to 500 hours...............

How much does the Marketing department and COO play into the maintenance intervals????

 

I did my T9.9 at about the million hour mark (I actually don't know, it just seemed that long. Several years for sure). It was having trouble peeing.

The freakin' thing looked like new.

A little compressed air through the pee hose, it spit out a bit of corrosion from inside the motor, and it was peeing like a horse

 

Sorry. I posted pump but meant to say thermostat. I do my impellers every 3 seasons, and have a water pressure gauge to monitor its health. They are super cool. So, thermostat intervals?

 

Same interval IMO

 

Thanks everyone on the impeller info! Looks like change out end of this season for me
Great info

 

I change impeller and anodes at same time. Anodes are easy to see and when they start turning white and crusty, I do both. Some folks say to wait until 50% of anodes are gone but I just wait for them to get crusty: about every 2-3 years depending on how much salt I've been in.

 

I am going to change both thermostats since they are 16 years old, but one interesting note, the previous owner kept super good care of the boat as far as waxing, lower unit oil and engine oil every year, always covered, but had never done the impellers in 12 years. I did them immediately when I bought the boat, and both looked really good. They were still soft and showed very little wear. I know people who do them every 2 years which I think is excessive, which is why I put a pressure gauge on my main to monitor the pressure the pump is making and I?ve made note of what pressure it makes at what rpm. One would assume as the impeller ages, that pressure would decrease.

 

What all do you need to hook up a gauge?
I have a Yamaha 150 and 9.9

 

I do them at 500 hours as well, which is only a few years max. They always come out looking like they are ready for another 500. I believe using them is better than letting them sit. I think at 7-8 years it's time either way, but I know there are impellers that are much older than that still pumping away out there.

 

Besides wear and tear or the number of hours of operation there is another factor involved. The rubber in the impellers gets stiff and hard over time whether you run the engine or not. That makes it less efficient and prone failure. You don't want all those little pieces of rubber in your cooling system.

All the service techs have told me that the impeller is best changed every 3 years and on engines in "commercial" use with a lot of hours should be changed yearly. Don't let a $30 (or so) part ruin your engine or your fishing trip.

Thermostats in fresh water can go longer but in salt water they should also be changed every three years and check annually for salt build up and corrosion.

 

Here's a 4 year old, 600 hour Yamaha V6 water pump that I pulled out of my boat a day or two ago. It's just as pliable as the new Yamaha impeller, and really doesn't have any wear marks on it. There's some creases on the inside of the blades from flexing, but nothing that screams "replace me!" I'm sure this one could have easily made it to 1000 hours.

 

So a pressure gage will tell you if the water pump is working but what it won't tell you is if it is about to break up in little pieces and fail. I don't want that to happen on the big water or on a multi day trip so it feels better to replace them every 3 years.
One cause of failure is running the engine even for a few seconds without water in the pump. The impeller quickly over heats and is damaged but possibly doesn't failed right then. Some time down the road (or lake) it suddenly breaks up and you are in trouble.

 

I should really look at changing the impeller in my 2004 Yamaha, bet I'm going to have fun with the bolts since the lower unit has never been off. I know better but life happens I guess.

Sent from my Moto G (4) using Tapatalk

 

After reading this, I feel better and will quit worrying. Makes sense to me that if you never-ever move them without lubrication (water) that they will last a very long time. I have changed them every 3-5 years for peace of mind. Just hope I never have one go out.

 

If you left your boat parked with the summer sun baking your lower unit maybe more often! It no big deal to pull your lower unit every year and check impellers, clean, re-lube and paint new gunk on the lower unit bolts. Dosent mean you have to replace the impellers. same thing with the thermos.