Water pump issue?

[Slow Ride]

I took "Slow Ride" (31' fountain with twin yammy outbaords) out for a ride yesterday and ended up having the port engine over heat. The buzzer went off and I slowed to an idle to check it out. After letting it "rest" at idle the buzzer stopped. I assumed I picked up some grass or something like that and didn't think to much of it. I took off again and ran for about 20 minutes at 3500 rpms. No problem. When I stepped up to 3800, I got the buzzer again. I notice this time that there was no water coming from the tattle tale! I let it idle for about 3 minutes and the alarm went turned off again. I limped home and got it on the trailer. Today I changed the impeller on both engines and went for a ride. The other engine did great. There is a very strong stream of water from the tattle tail. The engine which ran hot did have a steam of water from the tail but it was not as strong as the other. It ran fine and I ran it at WOT for several short bursts and kept it at 4000-4200 for about 10-15 minutes. I think its ok but because it is different than the other, it has my attention. What do you think? Am I over reacting or should I be alarmed. As a starting point, the stream is much stronger than I have ever seen it on that motor. (I bought it used 2 over a year ago)

specs 1999 Yamaha 200hp saltwater series ox66. New (not rebuilt) powerhead with less than 50 hours. Left hand rotation. Max RPM at WOT 5400 with top speed of 53mph. Salt water use all the time. No other symptoms

 

[99yam40]

Re: Water pump issue?

Did you find any visible problems with the impellers?
Did you do kits or just impellers?
How did the housings look?
Both should be pumping the same, my thoughts are there is still something not right

 

[Slow Ride]

Re: Water pump issue?

I just did the impellers because I replaced the entire kit a year ago and the boat has had only minimal use this year. It went fising twice. Other than that it has been run for 20-30 minutes, in the bay every 4-6 weeks to keep the batteries charged, etc. The stainless housing was in good shape although it did have a little surface rust. There was no pitting or anything like that and 90% of it wiped of with a shop towel. The empellers looked OK when I took them out. As usual they were "formed" in the direction they turn but were not missing any pieces and still had some stiffness. The new ones diffenately made better water pressure but there is that noticeable difference in the two. If they weren't side by side I may not have noticed. I will go ahead and replace the stainless plate, housing, and gaskets just to be safe, but if that does not fix the issue, where else should I be looking? Also, when the water hose is hooked to engine in the driveway, there is almost no stream. But, when it is in the water, it has the stream we have been discussing. What the heck?

 

[vrodrig]

Re: Water pump issue?

Slow Ride, some times there are salt or aluminum deposits that collect in the small orifice where the water comes out of, I have removed the small hoses and or plastic orifice that make up the tattle tale and cleared them with compressed air and bingo the steady strong stream is restored. Give it a try!

 

[Slow Ride]

Re: Water pump issue?

vrodrig,

I did put some air through it today just after replacing the impeller. I'm thinking along the same lines, that salt deposits may be impeding the flow. However, its a new power head ordered from the manufacturer in Japan with very few hours on it! It is unlikely that there is very much build up actually in the engine. So, Im wondering if there is the possibility that there is an occlusion between the pump and the block. I'm considering running some kind or salt remover or other deposit remover through it to help get it out.

Thanks for the input!

 

[99yam40]

Re: Water pump issue?

did you make sure the cup was seated properly?
If it gets out of place just a little it can partially block the outlet of the pump.

If it overheated then there was a problem with something and sounds like you will not be sure if it is fixed until you give it a long run like you did before.

Are you sure it was an overheat alarm and not a low oil level?
I have heard of the remote tank in line filter restricting flow where it cannot keep up with the motors oil consumption at high RPM, but will fill up when RPM is lowered

 

[Slow Ride]

Re: Water pump issue?

99yam40,

Yes, the cup is in there properly. It had two small tabs in the bottom that forced it to fit only one way. As I stated in my first post, I have run it pretty hard after the impeller replacement and it does just fine. It's just the noticeable difference in the stream that caught my attention.

As for over heat alarm, I'm all but certain it was the temp alarm. The oil tanks an oil injection system were removed by the previous owner. On the dash, the low oil symbol is always on but the alarm does not sound. Its been that way as long as I have owned the boat. During this issue, the symbol on the Yammy multi gauge that looks like a thermometer was lit up as well as the one next to it. The other one looks like a red circle (dot) with the top 1/3 colored black. Not sure what it symbolizes but I assumed it was water pressure. Wrong?