SHO overheat alarm - low water pickup?

[Meleagris1]

I took my 250 SHO in for the annual service, and this year it was also due for a new water pump. This motor has run like a top for me since day one, never so much as a hiccup. First time out on the water after the service I noticed it was taking a long time to get a stream of water at idle. Eventually - 30 seconds -it starts spitting water, then a steady stream and appears fine. This is longer than it normally takes. I takeoff and all seems fine, water pressure is good.

Then while running later in the day when the lake got some 1-2 foot chop I hear an overheat alarm. I look at the water pressure gauge and it is at or near 0, so I take it off pad and shut it down, the restart and it starts sucking water again and all seems fine. After this I took it back to my mechanic and they thought it might have been a pinched seal in the water pump. They dropped the LU, checked everything, water test it and all seems fine. When I put it on the water again I am now getting the stream of water quickly like I used to but still occasionally lose water pressure, but only when the lake gets choppy. Running on flat water is fine, no alarm.

I just dropped it off at the dealer again so the they can give it a more thorough look. It never did this before the water pump was changed this year, and I've had the water pump changed before without issue. I'm no mechanic, but it seems that possibly the low water pickup isn't working as it should.

Since we have a wealth of educated individuals here, I was wondering if anyone had any ideas? I suspect that they will check the poppet valve, among other things. It's almost like it's an air lock in the system when there is less of the motor in the water (just to be clear, the water wasn't so rough that I was dealing with cavitation or the prop coming out of the water). Seems to only happen when the boat is bouncing around in the chop.

Any thoughts? Anyone ever experience anything like this?

[Big Orange Basser]

What kind of water pressure where you getting originally? After service work?

[Brianmoore25]

If you get an answer let us know. I've got 3 customer boats doing same thing. Normally happens in rough water but not always. I did have one do this, had bottom of boat slicked up by glass shop and fixed it haven't tried this on other ones yet. All of the ones doing it for me are on i class and fx skeeter. Don't know if its coincidence or not.

[Meleagris1]

What kind of water pressure where you getting originally? After service work?

No change there - water pressure fluctuates when running depending on RPM but at throttle I'm getting the same as before the service, 15-20 on the gauge.

[FrankWhoa]

Ok, maybe this is related. First time running my boat wot hard after its first impeller change I noticed my engine temp on my HB (nmea) rise steadily to 214ish. Water was choppy crossing Barataria Bay (salt water). I rarely run my motor wot for anything longer than a couple of minutes but this time I did for almost 5 mins after running in the lower 5000rpm range for about 15 mins. I let off the throttle quickly do to a boat in the distance. Once I did I heard my temp alarm. Not sure if it was already going off or did once I let off the throttle. Ive never watch my temp at wot before so I dont know what is normal or if it has something to do with something else (saltwater, service, etc).
Water pressure never dropped off more than usual so Im confused


Doesnt the engine shut down electronically prior to any damage occuring to the engine?

Thoughts?

[rzone]

5000 RPM at WOT seems really low, should be 5800-6000, this is not related to your temp problem, just an observation.


I don't know, but gotta believe something is screwed up with your water pump / impeller after the service. Way too coincidental to be not related to service.

I had mine services at 100 hours and It's the same as before service as far as temp and pressure.

Lots of knowledge in this forum, someone will likely have an idea to point you in right direction.

[FrankWhoa]

5000 RPM at WOT seems really low, should be 5800-6000, this is not related to your temp problem, just an observation.

Thanks for the response, just to clarify 5000 wasnt WOT just cruising through some two footers

I think it may be serviced related too.

[Brianmoore25]

I've had a few do this and fixed it by tightening up the intake screen screw a small amount. If the gear oil was changed it had to be removed and that is when I've seen this problem.

[FrankWhoa]

I've had a few do this and fixed it by tightening up the intake screen screw a small amount. If the gear oil was changed it had to be removed and that is when I've seen this problem.

wow really?

[Rich Z]

Yep, the water pickup screen needs to be flush and tight on leading edge of lower unit otherwise it can deflect the water and water pressure can suddenly drop and overheat the motor.

[falcooon]

P.S. SHO's do not have a poppet valve. They have two thermostats.

[FrankWhoa]

P.S. SHO's do not have a poppet valve. They have two thermostats.

Where are they? What do they measure?

[Haikt]

Wow, my boat did the same exact thing as you describe. Same identical thing. Got a new impeller, first time out got an overheat alarm took it back like 3 times, everything checks out perfect. Also next time look back at the water stream and you will notice that when you punch the throttle around 2500-3000 rpm you will lose water per for a sec and it will come right back, but you still have good psi.
I think I figured out the issue with my boat and have not had a problem again. I noticed that when in rough water you tend to trim in a little, for me half way on the gauge. Also the overheat will only happen when my tank were close to empty( 2-3 gal in each). What happened is back end of the skeeter comes out of the water due to trim and no gas or weight in the back, you hit a wave an it makes the back end pop up for a sec loosing water pressure and creating air lock. It will not get water pressure back until you slow down a little an force water in. I tested this theory extensively with very reputable results ( I may have a lite ocd :) ) . If you trim up and run in the chop never looses pressure. I think it may have to do with hull design. Also one Yamaha tech I spoke at a tournament told me that fxp props tend to aggravate this issue more. I hope it helps.

[Rob1138]

Did you ever figure our why the water flow changed following a new water pump? This exact thing happened to me today?

[falcooon]

According to the basic owner's manual, the audible alert can come from 3 things: overheat, low oil Pressure, or water in the fuel separator.

[Meleagris1]

Mine was overheat - confirmed by codes. I took it to the dealer and they took the pump out and reinstalled it and that corrected the problem. Still not 100% sure we knew what the issue was but I just got my water pump changed again so hopefully no issues this time.

[jgill6816]

found this thread after researching an issue i had over the weekend. I did service and changed my water pump 2 weeks ago and had the same issue as described above except the audible alarm which could have sounded but my hearing is kind of bad. Any updates on these issues since previous post?