Yamaha HPDI 150 Question

[A-dog]

I went to winterize my motor and noticed that the motor was not pumping the usual amount of water out when flushing. I ran it for a few minutes and it gradually got better. Then I shut it down and noticed that the lower unit was warm and steaming. I did not have the motor in gear during the flush. What could this indicate? The lower unit wasnt hot, but was definately warm. Any ideas?

[Bloom]

It's possible that you may not have had either enough water flow/pressure(kinked hose, bad fit with the muffs) or your impeller may be a bit worn.

If it got better as you said, I'm betting you didn't have a good fit with the muffs. Try squeezing them together before installing in order to get a tight fit. I noticed that this occured on my kicker until I tightened the muffs.If you have a body of water nearby, back it down and fire it up to see if it repeats what you described.

When did you last change out your impeller?How many hours on the motor?

[A-dog]

Thanks for the advice. I was wondering if the water was getting to the motor. The warm lower unit really worried me though.

The impeller has never been changed to the best of my knowledge, but I will have to go back through my maintenance receipts. I am now doing the maintenace myself as my warranty is up. Motor has 500 hours plus. How difficult is an impeller change?

[Bloom]

I believe if it's over three years in age and with more than 500 hrs, not a bad idea to change it out. You might refer to your manual, but that sounds about right. it's not a huge job, takes about an hour or so, unless you have some corossion issues.

There are some on-line sites that you can go to for assistance, just type in, Changing impeller on Yamaha and you'll find a number of sites.

[1pump]

I ran it for a few minutes and it gradually got better

Some outboards have thermostats, but I don't know about the Yamahas. Could be stuck or slowing down.
I got 20 years out of my original impeller in my Merc, but I'm sure it was way overdue for a change. A lot of mechanics will tell you to change the water pump out every 2 years, but that seems a bit excessive unless you're putting 100 hours a month on it.
At first glance my Merc impeller looked OK, but when I got the new one the difference was huge. The old one wore evenly with no damage, but when I matched it up with a new one the impeller blades were worn down about 1/4". Amazing it worked at all.

[MattPark]

With my habit of pulling up to a sandy beach and having a couple cold ones, or camping on occasion, I've sucked a bit of sand through impellers. 200 hours is pushing it doing that IMO.

The VP I/O will kill them in less than 300 hours if I'm not careful, the outboards I've had seem to be a bit more tolerable. I've got 250hours on the current impeller, and it's definitely a bit tired. They are so cheap and easy to change, there's no reason to not change them every 2 years/200 hours.

A warm and steaming lower unit is normal. Exhaust runs through there when the boat's out of the water, she will get a bit warm even at idle.

[packer]

were you looking at the water coming out of the hole in the bottom of the cowling or out of the exhaust , if the flow coming out of the cowling is reduced or dribling pull the hose going to it and blow out the fitting as it creates a restriction. They have a tendency to plug up with grit

[A-dog]

thanks for the input guys. I got the impellor changed out and put in new thormostats. Thing is running great!:meme: