2021 SX190 - overheat warning but reality seems unlikely - suggestions?

[boldboater]

Ok. You are not alone. I have a 2017 SX190 with the same symptoms. My own over heat conditions usually happen about 25 minutes after the boat has been started and we are under way. I have been on a quest to solve the issue and it has been elusive. To begin with I don't believe there is a crushed or weak hose that is preventing adequate cooling water (but I will keep this in mind). The evidence for this is that the engine is by passing water properly and it's not steaming or overly hot when Limp Mode arrives. The dual battery scenario above intrigues me as my 2nd battery was on its way out and bad voltage has a way of triggering all kinds of sensor issues. By the way if the late model 190s' do not have a volt meter or it's buried deep in a menu, you might consider buying an aftermarket unit and installing it. Having installed a volt meter has saved my butt twice and it's a super easy DIY.

Moving on though:

I've pulled the T-Stat and found it stuck "Open" and it was replaced. Additionally I have pulled the "Thermoswitch" and bench tested it per the Manual and it tested correctly. This switch, per the Manual is what is supposed to trigger the Overheat condition. To be on the safe side I replaced it anyway. Next I removed and replaced 1 of the "Engine Temperature Sensors" there are at least 2 of these. It also bench tested correctly but it showed rust and corrosion where the electrical leads were attached. Since the replacing these sensors I have not had the overheat alarm. However, I have not been underway for more than 25 minutes since my destinations during the winter have only been to the sandbar and back. I posted the volt meter vid and the T-Stat change on YT (links below) and the other vids for the sensor changes are in the editing stage.

Good Luck on sorting this out and post back anything that you uncover.

T-Stat Replacement Link -

Volt Meter Link -

Thanks for the detailed post - and sorry you have a similar issue... Voltage seems fine - checked the battery directly, and the engine off voltage is 12.7V. Alternator is good as the voltage rises to 13.7V with engine running. I think I have a handle on where the temp sensors are and once guests are out tomorrow, will see bout pulling and testing them. Just pulled the boat from the water and cleaned it this afternoon - will crawl up under the keel to take another look inside the intake area and the hoses in there. I am (and my pretty savvy brother-in-law) leaning toward the thermostat as long as nothing underneath (including impeller) seems problematic. Thanks!

 

[boldboater]

On my IPad, this morning, so a different layout. Here is the page you inquired about.

Maybe I’ll bump into you one day on the flats. My folks keep their boat out at HB Marina. Been meaning to take the ski out that way. Are you familiar with the ramp at Jenkins creek? Really want to avoid launching at HB if possible, and Bayport is just too far from HB and has limited parking. Was wondering with tides how shallow the canal at Jenkins gets, and during high tide, what the clearance is under the pedestrian bridge.

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Have been to Jenkins Creek and seen the ramp, but have not yet launched there. I am guessing tides would be pretty much the same as the HB ramp just a bit south. Clearance... Hummm. that bridge has decent height, but not sure how decent... I may need to drive that way tomorrow and if do will stop and take a look,

 

[boldboater]

Quick update - did get the thermostat out this evening - was pretty clean and tested fine. Began opening at 140F and full open about 180F. Crud. That would have been the simplest fix by far... Does anyone know if you can get the fault codes from history off the screen...??? List of fault codes to an SX190??? Should have asked that right off...

 

[boldboater]

I did also look carefully at the intake and impeller - no apparent damage. clean, no nicks or dings at all on the blades.

 

[Farny]

Quick update - did get the thermostat out this evening - was pretty clean and tested fine. Began opening at 140F and full open about 180F. Crud. That would have been the simplest fix by far... Does anyone know if you can get the fault codes from history off the screen...??? List of fault codes to an SX190??? Should have asked that right off...

Press and hold the settings gear on the connext screen. Menu will come up. Press engine and it will sow codes. Aside from that your local dealer can run the yds on it.

 

[Farny]

Just wondering if you possibly have a little something caught in one of the engine block cooling passages. Where all the flow only goes thru 1/2 the engine, have you tried IR ? Maybe only part of the engine is hot?

 

[boldboater]

Just wondering if you possibly have a little something caught in one of the engine block cooling passages. Where all the flow only goes thru 1/2 the engine, have you tried IR ? Maybe only part of the engine is hot?

Having a hard time figuring out how anything would get in... There is a screen/filter in the impeller housing - some water being pulled through the impeller is directed through that screen/filter assembly and into the engine cooling loop. Nothing of any notable size can get through that.

 

[VitaminSea]

Have been to Jenkins Creek and seen the ramp, but have not yet launched there. I am guessing tides would be pretty much the same as the HB ramp just a bit south. Clearance... Hummm. that bridge has decent height, but not sure how decent... I may need to drive that way tomorrow and if do will stop and take a look,

At the HB ramp, from my recollection, you don’t need to worry about tides, as the majority of the canal is sufficiently deep (especially for Yami’s). I have heard Jenkins is significantly shallower, and very tidal as its a creek vs a canal and in due time the county plans on enhancing the ramp and dredging the canal. Looking forward to your feedback.

Wishing you luck on your OH issue. If you can remove the anode, that might help allow you to see more of the inside of the block to see if there is build up there.

 

[boldboater]

Press and hold the settings gear ⚙ on the connext screen. Menu will come up. Press engine and it will sow codes. Aside from that your local dealer can run the yds on it.

Did not show any codes, possibly because the battery had been shutoff. Will try with the boat running if we do run the boat again before I figure out the problem. Thanks...

 

[boldboater]

On my IPad, this morning, so a different layout. Here is the page you inquired about.

Maybe I’ll bump into you one day on the flats. My folks keep their boat out at HB Marina. Been meaning to take the ski out that way. Are you familiar with the ramp at Jenkins creek? Really want to avoid launching at HB if possible, and Bayport is just too far from HB and has limited parking. Was wondering with tides how shallow the canal at Jenkins gets, and during high tide, what the clearance is under the pedestrian bridge.

View attachment 199423View attachment 199424View attachment 199425

Hey, VitaminSea: Did stop by Jenkins Creek this afternoon - about an hour before full high tide. Today's tide is "high" (3.1 ft) but not "real high" (3.6 ft which we had last weekend). I would say at today's full high tide you would have roughly 5 ft and maybe a couple/three or so inches - I thought I left a 7 ft pole in the SUV, but did not, so best guestimates. A little narrow under that walkway as well - ~ 10ft, maybe a tad narrower on the ramp side than the outgoing side. The ramp seems a bit less angled than HB and the one we have in our neighborhood, so might have the trailer in more water/rear tires closer to water than those? Hope that helps! This Yamaha SX190 has 4ft 2in clearance and would make it fine even at high tide.

 

[VitaminSea]

Thanks for that feedback!
Sorry I hijacked part of your thread.

Good luck with your OH issue. Fingers crossed you get it figured out in short order so you can enjoy the water and your boat.

 

[14SX190]

Here was the cause of my overheating and gives you idea of what the sensor is.

https://jetboaters.net/threads/1-8-na-over-heat-gremlin.35681/

 

[boldboater]

Summary to date: Removed old T-Stat - a little "old" looking, but not really bad shape. Open started about 130 - 140F and was full open between 170 - 180F. Replaced anyway as it sounds like these should be near full open by 140 - 150. Checked water flow out of the water exit from the hull just above the jet with T-Stat removed - good flow/steady stream. Did same with new T-Stat. Very little flow until engine warmed to about 130-ish per infrared on the T-Stat housing, then strong steady stream. Should also prove no significant blockage anywhere. Removed and replaced the temp sensor at rear-starboard side of engine (relatively easy). Ran the boat and still get the overheat and check engine warnings with limp mode. Infared on the engine showed most temps between 138 - 145F with highest of 152F. Next step will be to R&R the temp "switch" near front starboard side of engine block. More difficult and requires some other removals to be able to access this. Definitely frustrating. The codes I have been able to view do not seem to indicate any specific fault - but, understand it is possible to connect a laptop with the right software and get data that way, so may be looking into that.

 

[boldboater]

Here was the cause of my overheating and gives you idea of what the sensor is.

https://jetboaters.net/threads/1-8-na-over-heat-gremlin.35681/

Ah - that is the "thermoswitch" I take it - starboard side near the front of the block - the dip-stick tube runs right past it and have to remove/move (it appears) some wiring and the intake to reach the two screws that hold it in? I just received a new one and hoping I have found a guy comfortable with doing what is needed to remove it. I am not...

 

[14SX190]

Ah - that is the "thermoswitch" I take it - starboard side near the front of the block - the dip-stick tube runs right past it and have to remove/move (it appears) some wiring and the intake to reach the two screws that hold it in? I just received a new one and hoping I have found a guy comfortable with doing what is needed to remove it. I am not...

Probably meant rear of block. Its #13. It's hard to get to put doable as its under intake manifold. Just take your time

 

[boldboater]

Probably meant rear of block. Its #13. It's hard to get to put doable as its under intake manifold. Just take your time

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I missed that in your thread - I did replace that one as it was fairly easy to get to - the old one actually looked fine, and the new one made no difference. #15 will be the target - I assumed it was more likely as it is a "switch" and could somewhat feasibly be some sort of conditional/intermittent failure. That one requires removal of some "stuff" to get to it...