2019 G23 Diagnostic Message "Stop Shutdown Engine"

[Ryan_2018_G23]

Hello,

Hoping someone can help me diagnose an issue. I have a 2019 G23 with 152 hours on it.

The boat has low hours and we do not get to use as frequently as desired. We took it out for Fathers Day & when we got about 5 minutes off dock from initial launch we got the attached Exhaust Riser Water Temperature & Engine cooling Temperature Error Codes (pictures attached). Boat went into limp mode and would not get out of trolling speed. Before we could get back to dock, within a few minutes, smoke was coming out of the engine bay (attached video). We did not get video when it was smoking really bad as reaching for fire extinguisher, so this was after it started to cool down a bit.

Any ideas what it can be? If it is just the sensors, which I did have go out on a previous g23 boat, I would not think it would ever get to the level of bad smoking. Engine is PCM H6 6.2L 450.

A few things we did:

• Cleaned strainer
• Boat was just filled so had fresh gas
• Inlet valve open & does not seem to be blocked
• Sensor plug connections checked & unplugged / plugged back in
• Exhaust sensors were clean
• Oil & transmission fluid levels are fine

Has anyone seen this or have solutions? ...closest Nautique Dealer is about 90 minutes away so would prefer to handle myself vs. towing in.

Thanks!

Ryan
queen.ryan@me.com
714-916-8769

[GMLIII]

Ryan_2018_G23 when was the last time you changed your impeller?

[Scooter G]

Cooling codes in all directions, Ryan_2018_G23, when is the last time you changed out your water pump impeller?

[Ryan_2018_G23]

Thank you GMLIII & Scooter G. I'll pull it apart this evening to see if it is frozen up / corroded. We were thinking no water was flushing through to cool so could very well be it! Fingers crossed & I will report back after checking it out.

[Scooter G]

Ryan_2018_G23 Any updates, what were you able to determine..?

[Ryan_2018_G23]

Scooter G Slight change of plans. I ended up just going ahead and ordered the impeller part kit yesterday so will hopefully get it today or tomorrow & then take apart / reinstall. I'll post a reply for sure when I figure out if that is the issue! I appreciate the help in trying to diagnose and hope this is it.

[Gregake@comcast.net]

Were you able to solve your problem? I am having similar issues. We changed impeller, cleaned trans cooler, found pieces of the impeller in there. checked thermostat, no debris. pulled 1/4" hoses from riser and all clear. pulled blue drain plugs, flushed, no real debris, just a little sand and scale in one of them. Sea strainer is clean intake below boat is clear.

We also pulled temp sensors from manifold and cleaned and re installed.

Does anyone else have any words of wisdom. We are at the end of our ideas. Boat has been very dependable over these hours but the overheat issue began about 100 hours ago and has gotten progressively worse.

Greg


2017 G23, 6.2L 850 hours

[Scooter G]

Ryan_2018_G23 went to silent running, it would be bonus points to see what he came up with.
Gregake@comcast.net you said you checked the thermostat, how did you check it?
Have you run a fake a lake or hose attachment to see what kind of flow you are drawing in and out?

[Gregake@comcast.net]

I meant to say I replaced the thermostat. However, I did pull the exhaust water temp skin sensors from their nesting spot and set them on top of the cool intake manifold. Was unable to get the boat to throw the code once I did that. This indicates bad sensors. I am going to replace them after a few more tests. After going through the entire cooling loop and inspecting everything, I had already concluded that I had a sensor problem, not a hot engine problem. Our lake is only 65 degrees f right now and risers barely get hot on top after full on running. Even the elbows that send the water and exhaust back down the hill are cool to the touch. No one should run their boat without these sensors in place and working as they prevent catastrophic overheat conditions. I do not have a hot motor. I only have a motor that thinks its hot because of the sensors. They are located at the rear side of the exhaust manifold risers with 2 wires going into a plug. 65-70 bucks apiece online. PN R02 0064.

G-

[Traveller]

I am having the exact same issue. My issue only happens when we are running at full ballast and seems to occur when engine temp gets higher than 171F and RPM's greater than 4250. It also normally happens when we are turning. If I hit Ignore and let engine cool down slightly we are able to start right back up and just modify rpm and ballast. I have a new impeller that I intend to change out to see if that helps. Any additional information on what you all discover would be helpful. If the impeller does not fix the issue my next move will be to change out the temp sensors. If someone could post a pic of where those are located that would be helpful.

[jpwhit]

Y'all are pretty brave... I wouldn't be clearing these and running any of my boats with these messages popping up until I found and fixed the root issue. Having these engines, and as importantly the exhaust systems, run hot is not good for the life of the engine and exhaust systems. The catalytic converters and many of these boats have fiberglass muffler boxes, deteriorate pretty quickly when the temps are high and are pretty expensive parts. Not to mention mostly aluminum engines don't stand up to heat that well.

Yeah, if it's truly just a sensor issue then you're right. But I wouldn't be comfortable with that assumption without comparing temp readings from a infrared temperature gun to the same engine running properly. I've recorded those reading for my boats already, so I have that reference info prior to any problems. But that's just me, I also have normal Rhinda Diacom recordings of all the ECM parameters to make future problem diagnosis easier as well.

I apologize if this sounds a little "preachy", but I work on a lot of boat beyond my own, and I guess I've replaced too many cylinder heads, melted exhaust systems hoses, deformed fiberglass muffler boxes, and chased down too many thermostats and cooling passages blocked by chunks of impeller in my past.

[Scooter G]

You brought out a thought jpwhit, a temperature gun, now there's something I don't have. They don't seem to be that expensive on the amazon, I'll have to do a little homework on a decent one that I don't use all the time. There are 101 uses, including wheel temperatures from brakes running hot, or potential bearing failure. I like it.

Good narrow down to the sensors Gregake@comcast.net, let us know if that is the problem solver...

Traveller, looks like you are throwing the identical code. Sensors? Not sure you mentioned your boat year, model?

[jpwhit]

Were you able to solve your problem? I am having similar issues. We changed impeller, cleaned trans cooler, found pieces of the impeller in there. checked thermostat, no debris. pulled 1/4" hoses from riser and all clear. pulled blue drain plugs, flushed, no real debris, just a little sand and scale in one of them. Sea strainer is clean intake below boat is clear.

We also pulled temp sensors from manifold and cleaned and re installed.

Does anyone else have any words of wisdom. We are at the end of our ideas. Boat has been very dependable over these hours but the overheat issue began about 100 hours ago and has gotten progressively worse.

Greg


2017 G23, 6.2L 850 hours

The recommended way to test these sensors, is to record the sensor reading in Diacom. Most often one sensor will be above the warning threshold level. If something very catastrophic is wrong, such as a bad impeller, both will be reading high. If it's just one, then swap them. If the high reading moves to the other side, then it's the sensor. If the high reading stays on the same side, then something isn't right and it's not the sensor itself.

These sensors are pretty sensitive and are meant as an early warning system to prevent a bigger issue. If you've had an impeller come apart, you can have parts of that stuck in the passageways in the catalytic converter and cause the temp to go up enough to set off the alarm. Disconnecting the sensor and placing it on something cooler will always prevent the alarm, but it does not prove that the sensors are bad. Actually, I think it tends to suggest the sensors are likely working because it means they are registering the cooler temp. Typically when these sensors fail, they just quit working all together and stop registering actual temp. They can fail by just being off on the temp, but that's rare in my experience.

[Scooter G]

I think it is interesting that we have 3 G's of different circa, all throwing the same code, on the same calendar?
Aliens, solar flare, Chiiinna? lol

[Traveller]

Just an update on the things I have done since last post. I changed the impeller, I switched the exhaust temp sensors, and I checked the exhaust hoses coming from the T into the manifold for debris or restriction(nothing found) and ran it yesterday afternoon and still got the same error message.

Here are a couple of questions if anyone knows the answers that would be helpful:

1) My engine temp runs around 155 to 160 when idling and when under a load runs closer to 169 to 171. Is that normal? Seems like most of my other inboard boats held a constant temp whether under load or not.

2) Does the boat have different thermostats for engine and exhaust or just one thermostat?

So puzzling.