Uncommon overheat issue, please help!

[avi8or3117]

Hello and good evening Jetboaters. First of all, I would like to thank anyone that responds with any helpful information about my issue. Also I promise I searched the forums for my specific overheat issue and couldn’t find anything (promised I tried doing my research first)

Now for my overheat issue, my starboard motor would overheat after about 20 mins on plane running at about 7600-7800 RPM’s. I hooked it up to YDS and no codes, so I did the second obvious thing and replaced my thermostat. While doing so I also made sure the pisser line wasn’t clogged. I took the boat out this past weekend and she ran great all the way to the sandbar, both engines around 7700-7800 RPMs the whole way. The trip out there took about 30 mins and I had no issues, both of the pissers ports had good water flow, I checked often.

Great problem solved, nope. On the way back, after about 20 mins on plane (7700 RPMs) the same engine overheated and went into limp mode. I also checked and there was nothing stuck in the jet pump/impeller area. FYI I’m decent with a wrench and how an engine works, but some of you guys are freaking wizards when it comes to these boats. So I’m going to the pros. So here are a few of my questions.
1. Why did the boat run great for the 30ish min ride out there, but decide to take a dump on the ride back in?
2. I did notice a fairly large difference in temperature that was coming out of the pisser ports. The port engine pisser was warm to fairly warm, but the starboard (overheating engine) pisser was cool, basically the same temperature as the river water. Why the huge difference in temperature?
3. I thought overheat issues happen pretty quickly on these motors, just after a few mins. Why is mine overheating after such a long time?

Also a few more bits of information. While on the garden hose and at idle, both engines have water coming out of the exhaust waterbox hole and also the thermostat thru-hull fitting hole. The water temperature exiting those holes on both engine is the same. Both engine ran for about 5-6 minutes separately.

Any help, suggestions or guidance would be greatly appreciated.
Thanks again and happy boating!

 

[Cobra Jet Steering LLC]

Probably a bad heat sensor either on the engine or the exhaust I believe those have 3 of them and I had one . I used the non contact thermometer to check the engines and exhaust for any hot areas and found none. My engine that did that was a 2014 1800 NA so it is a good possibility .

 

[avi8or3117]

Thanks Cobra for the quick response. I thought the YDS software would tell me if there is a bad sensor. If one of those sensors were bad would hooking up my computer and running YDS detect it? Or am I a dummy and it’s s operator error? Haha

 

[Cobra Jet Steering LLC]

Good question I am not sure of that, perhaps someone else can answer that I have never used a Y D S myself I take it to the dealer for diagnosis.

 

[VitaminSea]

@avi8or3117 Sorry to hear of your troubles. Based upon your profile, it looks like you have a 2015 AR210 with the MR1 engines. Can you confirm?

What is baffling to me about your initial post is that you are getting an OH alarm, but not seeing evidence of it with YDS and that the water temp from that engine’s pisser is significantly cooler. Did I get the correct?

I see you mentioned you replaced the thermostat, how did the old one look? Have you checked the engine anodes? Any signs of corrosion build-up inside the engines?

The MR1 engines have the thermostat as you mentioned, and then 4 sensors that I am aware of…
1) Thermoswitch
2) Engine Thermosensor
3) Exhaust Thermosensor
4) Intake sensor

To your question about YDS - it will not necessarily tell you if a sensor is bad. In the service manual there are procedures to verify proper voltage/continuity at different temperatures using a pot of hot water.

Also, when you get the OH warning, it should be logged and you should see the fault and the engine hours at which is first occurred in YDS. From my experience a new fault will not override this data point until you clear it with YDS. Also with YDS, if you hook it up immediately after receiving the fault, there is a log of the last 90 or so seconds of the engine running in which it will capture RPMs, engine temp, intake temp, etc.

You should be able to compare the two engines to see if anything is drastically different.

Last March-May I was chasing an issue, turns out there was considerable build-up/corrosion in the water jackets of my engine AND my thermosener or thermo switch (don’t recall) was faulty. Here is some of my journey documented - https://jetboaters.net/threads/engine-temp-sensor-yds-code-15.41276/

Here are the sensors I am aware of… The two on the left #4/6 are under the exhaust manifold, and a bit challenging to get to, but possible with patience.