Really weird issue need help. Engines overheating randomly Yamaha/Dealer says it’s not happening

[merlinjet]

I had an overheat last year and it turned out to be scissor grass wrapped around the impeller shaft. That stuff is a real pain in the Lake Havasu shallows. Definitely get a flashlight and take a good around the intake area.

 

[Gym]

Just took my boat out for the first time of the year and for the first 10 minutes the port engine was overheating. No tubing or anything going on just a casual ride from the dock back to my lift at the house. Do you guys think I should try replacing the overheat sensor for the port engine? Does anyone have any tips how to do that? Are there any threads for it? I’m not super mechanically inclined. Thanks!

I haven't read this entire thread going back to August 2018 so I apologize if I'm asking questions answered. Do you boat in salt water? If so do you flush religiously after each use. If you don't you may have salt buildup in the cooling passages. Does this overheat condition happen to both engines? Do you beach your boat? One of our members found fine sand blocking some cooling passages on the exhaust side causing his overheat.

To determine if this is a real overheat you can take the temp of the pee water during a normal run. If you get an overheat warning take the temp of the pee water again. If the water temp is significantly higher it's an actual overheat and not the sensors.

 

[NewBoater]

I boat in salt water only and flush 5 min on hose after each use. No salt away though.

 

[Scottintexas]

@NewBoater I'm sorry I didn't realize you were the originator of this thread and thought you were just posting about a new problem on an old thread not a holdover from last year,

Have you ever looked in the intake grate are or pulled the impellers?

I still think pulling the impellers, checking the grate and intake screen are easy/obvious first steps, as well as running on the hose to try to replicate the problem,

next I would get a cheap infra red thermometer to monitor actual engine temps and look for anomalies for when the overheat alarm goes,
A YDS would be a great tool to monitor the temps while actually on the water,

since you're in salt water I would think the next easiest thing would be to check the thermostat, even if you just pull it for exam to see if there is any build up on it,


.

 

[haknslash]

I boat in salt water only and flush 5 min on hose after each use. No salt away though.

Why not use salt away? All those salt crystals on the side of the boat don’t wash away just from water so imagine how the inside of your engine feels. I wonder if your cooling jackets are getting salt or scale buildup. I would for sure use some kind of salt away, terminator, vinegar, something better than just water.

 

[Gym]

I boat in salt water only and flush 5 min on hose after each use. No salt away though.

Fresh water alone will not remove all the salt and it will continue to build up. You can prove this by rinsing your boat exterrior after a trip. when it dries you will still find a lot of salt on the boat indicating that fresh water alone will not remove all of the salt. You might want to try flushing with Lime Away to clear your passages. It may take several flushes. When flushing use the no wake setting.

 

[swatski]

When flushing use the no wake setting.

I keep forgetting about it. It’s like hi-idle, lol.

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[MidnightRider]

Fresh water alone will not remove all the salt and it will continue to build up. You can prove this by rinsing your boat exterrior after a trip. when it dries you will still find a lot of salt on the boat indicating that fresh water alone will not remove all of the salt. You might want to try flushing with Lime Away to clear your passages. It may take several flushes. When flushing use the no wake setting.

Huh. Assuming the no wake setting is for the higher idle. Educate me. What would a higher idle do for flushing. Not like there is a water pump in there to rev up. Curious of the thought behind this.

 

[buckbuck]

I believe no wake would be counter productive. But I am willing to learn.
I have found on my boat I run the risk of an over temp while doing no wake mode while flushing.

@NewBoater you are going to have to spend some time going through each part of the cooling system. We will be here for you. It is not a difficult system to learn.

 

[buckbuck]

 

[NewBoater]

I appreciate all the help guys. I’m going to do some digging over next few days

 

[Gym]

I keep forgetting about it. It’s like hi-idle, lol.

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Yes @swatski it also forces more flushing solution into the upper cooling journals but, more importantly, if you have an overheat condition while flushing the ECU will immediately drop you into low idle. You would notice this allowing you to shut down before any damage.

 

[MidnightRider]

Yes @swatski it also forces more flushing solution into the upper cooling journals but, more importantly, if you have an overheat condition while flushing the ECU will immediately drop you into low idle. You would notice this allowing you to shut down before any damage.

I'm still curious for an explanation on how this helps. The ECU dropping the idle as an indication is interesting (although the high idle may contribute to that in the first place in my opinion while flushing), but what i don't understand is how a higher idle "forces more flushing solution into the upper cooling journals". I must be missing something and want to learn if I am.

 

[swatski]

I'm still curious for an explanation on how this helps. The ECU dropping the idle as an indication is interesting (although the high idle may contribute to that in the first place in my opinion while flushing), but what i don't understand is how a higher idle "forces more flushing solution into the upper cooling journals". I must be missing something and want to learn if I am.

Yeah, there is no dedicated water pump for circulating water in cooling passages like an outboard, other than the pump (w/intakes in the stator segment), but I like the idea of high idle for the engines to run a tad smoother - the first indent would do that. I find the throttle binnacles to be way to rough/imprecise, never occurred to me to just push the no wake in neutral without touching the throttles. Right?

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[NewBoater]

Well she’s at the dealership to be looked at. Flushed it out and rinsed it off, put the cover on, sent them all 3 videos I have proving the problem and said let me know when it’s fixed. Fingers crossed.

 

[NewBoater]

Alright guys need some more help/advice.

Dealership tested thermostats and all was well, pulled pumps and no obstructions anywhere.

They think there is corrosion in engines but would need to pull exhausts to check and that’s 3 hours of labor and $350 or so.

He said that’s not covered under my warranty and Yamaha also won’t cover corrosion on engines under warranty. Is there a phone number for Yamaha to fight this? The boat is 3 years old and I’m religious about flushing. 125 hours or so on the engines in salt water.

Do I start a fight with Yamaha now as I don’t want to eat $350 that’s something that they should be covering.

Thanks

 

[Scottintexas]

What makes them think there's corrosion in the engine for a $350 look-see ???

Do you trust this dealer?

I don't know what to tell you, they didn't even believe you when you first took the boat to them, now they want 350 to pull the exhaust manifold on a guess,

also, terminology can be confusing, by corrosion did he maybe actually mean sediment blockage?
I wouldn't doubt there might be some sediment obstruction in your manifold but paying somebody to guess.

If your going to do stuff out of warranty I think I'd try to find a PWC shop or somebody you have some faith in,

 

[NewBoater]

This was their write up on my service ticket


CHECKED FOR FAULT CODES BOTH HAVE HAD OVER TEMP FAULTS. PORT@193 AND STARB@157 RAN BOTH FOR 20-30 MIN AND TEMP WAS STABLE AT 175 DEG. IN NO WAKE MODE. CONFIRMED WITH TEMP GUN. REMOVED T-STATS TO TEST, FOUND A GOOD AMOUNT OF SALT BUILD UP BUT THEY OPENED UP OK. REMOVED BOTH JET PUMPS TO INSPECT, NO OBSTRUCTIONS. MOTOR ALMOST CERTAINLY HAS CORROSION BUILD UP IN COOLING SYSTEM, NEED TO REMOVE EXHAUST TO VERIFY AND DIAGNOSE.

 

[Scottintexas]

If the thermostat had salt then it's definitely possible
Look at this thread

https://jetboaters.net/threads/bad-thermosensor-intermittent-overheat.8032/[HASH=153]#post[/HASH]-138920

 

[Liveto99]

Salt away strait up? Salt buildup would prevent heat transfer. It may be worth a try they already said Yamaha’s not gonna cover corrosion anyway.