Removing, Testing and Replacing a Thermostat & Why To Use A Salt Flush

[HawaiiBreeze]

Just finished replacing the thermostat on my 2017 SX190 n/a 1.8L motor. Turned out it was malfunctioning...stuck Open.

The YT video:

Most likely the result of shallow anchoring and running (sucking in silt), the 100% salt environment and 5 years of operation.

During the process I was able to peer into the cyl. head cavity of the T-Stat to get a glimpse of the water passages. Thank the maker for flushing and using a salt remover the passages looked clean. Of course the real test would be to remove the exhaust manifold and check those water passages but that operation is for some other year or decade.

Looking back it was an easy operation but in the beginning it was super tedious with very little room to maneuver. I learned a bit during the removal so that the re-install was faster.

Final verdict: 1. Flushing with a salt removal product after every outting is a must. 2. The operation is fairly easy and would be something to tackle during the off months. 3. The process affords you a glimpse into the motor that you might only be guessing at. 4. Those rusting Spring - Clamps need to be addressed all over the motor.

 

[FSH 210 Sport]

If that is the T stat that came out of the motor… well that is pretty phenomenal !

Perhaps liberal spraying with silicone spray all over the engine bay would have decreased the rust on the spring clamps?

What were the symptoms you were experiencing that made you check the T stat?

 

[fatboyroy]

Thanks for posting I probably need to do this in 4 years, let us know how you ended up changing it, engine temp running cold? You're lucky its stuck in open position, you can still use the boat probably consume more gas though.

 

[HawaiiBreeze]

If that is the T stat that came out of the motor… well that is pretty phenomenal !

Perhaps liberal spraying with silicone spray all over the engine bay would have decreased the rust on the spring clamps?

What were the symptoms you were experiencing that made you check the T stat?

That is the Million Dollar question... what symptoms prompted me to investigate?

A month ago I had just launched, was cruising at 5800 rpms in deep water, 20 odd minutes in I went full throttle and instantly got an OverHeat Alarm and the boat went into Limp Mode. Checked water bypass - all good. Shut boat off for less than 5 mins (drifting) started it back up and full power was restored. Got to my destination anchored all day. On the return at about 25 mins in the Overheat Alarm kicked in again and back in to Limp Mode. Waited a few minutes at idle and full power came back on.

That prompted the investigation and finding the defective T-stat. BUT it was stuck open so that should not be causing an Overheat Alarm. I've since pulled the two sensors and tested them (upcoming video). They tested "good" but I still received an Overheat Alarm/Limp Mode last weekend so the gremlins are still there. I will be pulling them again this weekend and testing them once again and probably replacing the unit that is supposedly, per the manual, directly responsible for the Overheat Alarm. More on that as things come together.

 

[HawaiiBreeze]

Thanks for posting I probably need to do this in 4 years, let us know how you ended up changing it, engine temp running cold? You're lucky its stuck in open position, you can still use the boat probably consume more gas though.

Aloha, it was an Overheat Alarm that happened and started this whole process. You are correct though, I did use the boat while the new T-stat was in transit.

 

[tdonoughue]

@HawaiiBreeze , how many hours did you have on it?

 

[rkim808]

Aloha kakou @HawaiiBreeze,

Very informative, and nice to see a fellow Yammy Jetboater in Hawaii.????