Overheating Warning - Temp Sensor Questions

[Bacchus_fl]

Hello All!

I continue to get an overheat warning sporadically on my port engine. It only happens after 30-45 min of riding if it happens at all. It does not go into limp mode but won’t clear without turning it off for about 5 min. I have checked with an IR heat gun and the effected engine is reading about 5 degrees cooler than the unedfected engine at all measuring points. Screens are clean, pee holes working great, and I’ve checked for blockage with no issues. So I believe it is a bad temp sensor? Would you agree? Is there a way to test the sensor? Clean/check them? I saw two in the manual do they both need to be replaced?

Any help with this would be greatly appreciated!

Thank you! Jason

 

[Ilmmct]

https://jetboaters.net/threads/rece...aler-for-overheating-alarm.16438/#post-282695

 

[Bacchus_fl]

Thanks for the reply. I read through that post but didn’t talk much about how to test, clean, or replace the sensors. I’m having a hard time finding anything in my searches. Find people saying the test, clean or replace but nothing about how and which sensors to replace. I’ll keep looking though.

 

[Ilmmct]

@Bacchus_fl I can't add more about the "how to" just that I had the dealer replace two thermostats under the YES warranty. I had similar intermittent over-heat situations and the dealer was having trouble reproducing the errors during both; (i) on-water and (ii) service-center/dry-land testing. After consulting Yamaha directly and after many reads of posts on this forum ... I pushed for the YES warranty replacement of the thermostats. I believe I read that @Cobra Jet Steering LLC has had success using salt-away (or some other type of salt removal agent) to clean the thermostats/heat-sensors. Sorry I could not be of more help on the location or the DIY procedure.

 

[Mainah]

There are three parts related temperature on the 1.8l engines. The thermo switch and the intake air temp sensor are located under the front two fuel injectors. The Engine temp sensor is located behind the back of the intake manifold. The service manual has detailed procedures for testing these parts by suspending in a vessel with water and a thermometer. Heat the water slowly and observe output resistance with a multimeter at certain temps. As far as cleaning I have no idea and would just replace if bad. If you are the type to diagnosis and repair yourself I do advise picking up a service manual.

 

[Bacchus_fl]

Thanks for the reply @Mainah! I have done all the service on it so far and 450 HRs later thankfully I have yet to need a service manual “knock on wood”

I’m having a hard time finding much detail on the sensors and/or a diagram of the system. If anybody has a pdf of the service manual for a 2013 SX210 please shoot me a PM.

 

[Mainah]

The pdfs that I have are secured. All of the 1.8l sensors are the same across the years from what I know and are standard 5v ref. Most of them work by employing a metal that conducts/resists at a known rate in a certain temperature band. The ecm sends 5v in and measures the volatge that comes back. Corrison, foreign object bulid up, etc will all affect sensors. In the case of an engine temp sensor they have less resistance at higher temperatures. Since your temp gun indicates the eninge is not over heating I would just swap the sensors between the two eninges and see if the issue moves to the other one. If not then something is clogged or the ecm is the issue.

If you attempt cleaning the sensor beware that reducing the mass of the metal will affect its resistance.

 

[Cobra Jet Steering LLC]

I has a similar issue and finally had the sensor replaced, it did the same thing even started doing it as soon as the engine was started dead cold. Yamaha sensors have a reputation for going bad so I would replace it especially when you know the engine is not hot.
I even tested the thermostat and found it to be ok and I inspected the water jackets for the possibility of sand in the engine cooling system.
Once the sensor was replaced the problem went away just as fast as it appeared.

 

[Bacchus_fl]

I have the standard MR1 1052cc motor and the service manual I saw for the HO seemed to be different.

I found a parts diagram which helped. I switched the two temp sensors that are located on the exhaust (#9 in the diagram) the sensor located near the intake (#6 on the diagram) would require me to remove the exhaust manifold which is a much larger job so I will leave them be until I see if switching the exhaust sensors makes a difference.

When I had them out there didn’t seem to be away to clean them. They are solid metal with a rubber boot near the top and were covered in some type of petroleum jelly or lubricant. I left them be and just did a simple switch.

If this doesn’t work would the next step be replacing the intake sensors? If I am going to remove the exhaust manifolds I would just replace them both since I would want that to be a one time job. If it comes to that I will be back asking for more tips and tricks

@Cobra Jet Steering LLC which sensor did you replace to fix your issue? Mine has yet to sound when it was cold but it has many times without actually overheating.

Thanks again guys!!

 

[Bacchus_fl]

Here is the diagram:

 

[Cobra Jet Steering LLC]

My issue was with a 1800 supercharged engine and the sensor was up on the front right of the engine.
I recall even the 2 stroke engines having so many issues that people soldered in resistors to bypass faulty sensors on the p w c s. my sensor did exactly what yours is doing alarm without a limp mode and for no obvious reason whenever it felt like it.

 

[Scottintexas]

Bacchus, I didn't realize you had an MR1, have you watched Buck's video of the cooling systems for the MR1, I believe he shows the sensor locations,
https://jetboaters.net/faq/how-does-the-cooling-water-flow-in-my-yamaha.101/

I agree with the others, since your temp readings don't indicate an overheat I would swap the sensors

If you have a question about a particular sensor I have a shop manual and can look it up for you,

 

[Bacchus_fl]

@Scottintexas i have watched the video which definitely helped me. Thanks!

I guess my question is that there are two sensors, one near the intake and another on the exhaust. Which one causes the overheat warning? Can both of them cause the issue? The one at the intake is going to be a pretty big job to replace so I’m hoping it is only the one on the exhaust which I already swapped

 

[Jon Gottschalk]

Did you ever figure out which sensor was the issue? I am having similar problem on 2014 sx210.....over heat alarm most the time and engine is operating at normal temp. Def. faulty sensor but would want to see how you sorted Bacchus

 

[Bacchus_fl]

I ended up doing several test. First i switched the top temp sensors between motors to see if the fault switched motors. It did at first but turned out to be a fluke. Next time it was still port and I had a temp gun with me to confirm. Turned out to be a thermostat which was an even easier and cheaper fix. If it’s a 2014 I would just replace them both for good measure first and then go for a test run. Good luck!

 

[JoeDranschak]

Hi all, I'm new here and new to Yamaha Jets. I'm in the same situation, I just bought a 2006 SX210 with 320 hours and first time out my port side motor is getting an overheat light shortly after opening the throttle from no wake to cruising speed. I checked that both pissers were outputting water and both were about the same temp. I immediately limped back to the dock and trailered it home to figure out why. The thermostat was pretty corroded so I cleaned it and tested it on the stove with a thermometer and it check out ok. I checked the strainers at the pump and they were both clean. The boat was a salt water boat from Florida so I flushed it 3 or 4 times with vinegar and Dawn dishwashing liquid and got a lot of crap out of it. Previously it would not overheat while running on the hose but it seems that after flushing it a few times it now overheats during flushing which is very confusing. I also watched the YouTube video outlining the cooling water flow through the motor and I found that on my boat for some reason someone has sealed the cooling holes on both motors at the transom by the pump where water exits from the rear of the exhaust pipe! Does anyone know why this would have been done? The only thing that I could think of was to increase the water pressure from the pissers?? The starboard motor runs fine so I'm not sure what steps to take next shy of taking it to a dealer which is a last resort. Any suggestions would be appreciated.

 

[Scottintexas]

Hi all, I'm new here and new to Yamaha Jets. I'm in the same situation, I just bought a 2006 SX210 with 320 hours and first time out my port side motor is getting an overheat light shortly after opening the throttle from no wake to cruising speed. I checked that both pissers were outputting water and both were about the same temp. I immediately limped back to the dock and trailered it home to figure out why. The thermostat was pretty corroded so I cleaned it and tested it on the stove with a thermometer and it check out ok. I checked the strainers at the pump and they were both clean. The boat was a salt water boat from Florida so I flushed it 3 or 4 times with vinegar and Dawn dishwashing liquid and got a lot of crap out of it. Previously it would not overheat while running on the hose but it seems that after flushing it a few times it now overheats during flushing which is very confusing. I also watched the YouTube video outlining the cooling water flow through the motor and I found that on my boat for some reason someone has sealed the cooling holes on both motors at the transom by the pump where water exits from the rear of the exhaust pipe! Does anyone know why this would have been done? The only thing that I could think of was to increase the water pressure from the pissers?? The starboard motor runs fine so I'm not sure what steps to take next shy of taking it to a dealer which is a last resort. Any suggestions would be appreciated.

glad to have you on board, update your profile with your location so we know where you're at,

The sealed exit holes at the transom could be because of the engines you have,
I can't remember for sure but maybe the non-HO engines those are blocked at the factory, so that may not be any issue,
take a picture and show us which one is plugged,

You should buy a YDS unit to see in real time what your engines are doing,

I would GUESS since it's an older salt water boat your cooling lines are blocked somewhere along the line, you may also pull the anode on the engine to see what it looks like,

You may want to look at CrankyGypsys closed loop flush to try to clean your engine out,


.

 

[JoeDranschak]

glad to have you on board, update your profile with your location so we know where you're at,

The sealed exit holes at the transom could be because of the engines you have,
I can't remember for sure but maybe the non-HO engines those are blocked at the factory, so that may not be any issue,
take a picture and show us which one is plugged,

You should buy a YDS unit to see in real time what your engines are doing,

I would GUESS since it's an older salt water boat your cooling lines are blocked somewhere along the line, you may also pull the anode on the engine to see what it looks like,

You may want to look at CrankyGypsys closed loop flush to try to clean your engine out,


.

I have YDS ordered and hopefully will be here today. Where is the anode you refer to?

 

[Scottintexas]

It's in the video at 7:11 mark

I would definitely consider the closed loop flush listed in the faq section since you have no history on the boat and already dislodged some debris

 

[JoeDranschak]

Attached is the pictures of the silicone sealing the outlet on the pump housings