at least the buzzer works...over temp condition... need advise...

[highpowerdad]

Four Winns with a 5.0GXI-e, SX drive, So, boat was FINE just a couple of days ago, all around the lake...but tonight, start it up and after a minute I get a little bit of what sounds like a belt squeak. Don't think much of it and figure it will go away in a minute...It has a similar noise every now and then...well it didn't and the engine overheated after a few minutes of no wake speed and a minute at 3000rpm, buzzer went off and it was at ~240F...I shut it down, checked for weeds etc, in the water intake - nothing - and let it cool for 15 min, started it back up and limped back to the dock...had to "rest" half way there when it hit 240F again. So...I assume the squeaking noise was the impeller running dry, so even though I will assume the impeller is shot, it probably was not the problem, just the fall out of another problem...so what should I look for...if I just put a new impeller in it, I will probably just burn it up... ALSO, I assume the buzzer sounds long before real damage is done...but it would be nice to hear that from one of the pros here...ah...this boat is being really difficult...
thanks
highpowerdad

 

[dypcdiver]

Check you have replaced the hoses the correct way after renewing the impeller, supply is the top hose, bottom hose goes to thermostat housing.

 

[Scott Danforth]

ALSO, I assume the buzzer sounds long before real damage is done...

you would assume wrong. your buzzer should have went off about 200F

lets hope your gauge is just off.

at 240 degrees, you had zero water flow for some time. 240 degrees coupled with zero water flow is the point where things go haywire. usually damage to the motor may result.

that means the exhaust gasses had zero water. you at a minimum burned up the rubber coupling hoses in the exhaust, and possibly the exhaust bellows. rubber starts to burn at about 250. your exhaust without water was at 1100-1300

hopefully you did not get the motor hot enough to collapse the pistons or warp the heads.

pull the impeller, and now look thru the cooling system until you find all the pieces
do a compression check to see how bad the motor is
pull the exhaust hoses and replace them (the insides are all burned up)
look at the inlet side of the raw water pump and check for debris or a cracked fitting at the drive (common )

 

[highpowerdad]

Scott,
"look at the inlet side of the raw water pump and check for debris or a cracked fitting at the drive (common )"

What is the fitting you are talking about, I am not sure where to look? Are you talking about the fitting between the transom and the drive itself...? ie, remove the drive?

Today, pulled the impeller, it was destroyed, found the pieces in the hose going to the thermostat housing, took the thermostat housing off, removed thermostat, nothing was above the thermostat, so I don't think any sizable pieces got up there. Back flushed the raw water supply line, flushed the thermostat to pump hose (big one), ran water backwards through the motor, not sure what that did, but it made me feel good...checked the exhaust coupling hoses, they look good and really undamaged...Will put it on a hose tomorrow and see what happens.

Still don't have a smoking gun, impeller destroyed itself on its own or impeller couldn't get water and destroyed itself. Maybe the garden hose connection on the supply side wasn't tight and it was sucking air...didn't seem right when I removed it today...or maybe there was something in the drive, my son said a "bunch of dirty water and black stuff" came out of the drive when I back flushed it. The impeller that was in there was not a factory part, what I replaced it with is, so maybe a bad part...still hopeful I have a working engine, with all that synthetic oil, as long as it didn't get TOO hot, I would like to think it is good to go.

 

[highpowerdad]

So, started it up this morning on the hose...fired up right away...let it warm up, took temp readings with a thermal gun, all seems good, shut down, checked the oil, all is good. Did the same thing down in the water and all seems good, and no odd noises. Took it out on the lake and ran it easy, all is good, then ran it HARD for 5 min and then went to WOT, after a minute at WOT, I got a HT buzzer, and the engine went into limp mod, but just for a second...The temp gauge was reading 175F...checked the engine over with the a thermal gun, the starboard manifold is running 40F hotter than the port...I had 180 or maybe a little more at the end of the riser and the elbow. Ran it around some more, again pretty hard and didn't have any issues, but that Starboard side exhaust is running hotter than the port (saw 200+ down by the elbow just past the riser. It could have always been this way, I never put a thermal gun on it before, or maybe some of the imploded impeller found its way into the manifold...

So I know I am understanding the temp warnings...
I assume the two temp sensor on each of the risers are what the buzzer uses - so when I got the buzzer, the riser was over temp?
I assume the temp sensor on the thermostat housing is what goes to the gauge - so the engine itself is getting good cooling at 160-175?

boat history...2005 VP 5.0GXI-E with SX drive, This boat started as a norther fresh water boat and then maybe saw 75 hours of salt use (2012-2017) before I bought it in 2018, it had 150 hours total...I am at 230ish hours now, I am only in fresh water. So, not knowing much about a salt water boating, is the 75 hours enough to need to take off the risers and all and check them. I think I already know the answer...I guess I just wanted to make sure that I understand what is sounding the buzzer vs the temp gauge reading which was good so I know where to start working...

Thanks
Scott R.