2008 Yamaha SX230 MR-1 Engine

[Mwawryk]

Good day all,
I have a Yamaha jet boat that has served me well over the years, but now I have one engine (port side) that is heating up on me from time to time. I blew out the two lines that run to the side of the hull, and still overheating after awhile. So looking for a few tips, see if anyone else has had the same problem. Maybe a water impeller issue? Partial clog in the motor. I do notice that that port side engine is not pissing as well as the starboard engine. thanks for your time.

 

[Scottintexas]

glad to have you on board !

where are you boating ?
salt or fresh water?
do you regularly flush the engines after use ?
how long have you owned the boat ?
how many hours are on the engines ?
do you have a lot of weeds or debris in the water ?

I would expect you have a clog or build up somewhere,
you may consider buying a YDS unit to read the engine in real time,
you could also get an infra red thermometer to read different points of the engine, compared to the good engine to see if you see any hotspots

I would start by removing the thermostat and seeing it's condition
if that was good I'd try the thermometer to narrow it down,
there are many cooling passages in the engine and in the exhaust system that could be blocked,

.

 

[Scottintexas]

watch this video from member buckbuck to get a good understanding of the cooling system,

 

[Beachbummer]

Thermostat is worth checking. Seal material getting loose on the tunnel/pump area can also cause cavitation that reduces cooling water pressure at speed.

Can you share your symptoms in detail? Best of luck!

 

[Scottintexas]

yes, many possibilities and your input will help us diagnose it,

does it over heat when you run the engines on the flush hose ?

 

[Mwawryk]

glad to have you on board !

where are you boating ?
salt or fresh water?
do you regularly flush the engines after use ?
how long have you owned the boat ?
how many hours are on the engines ?
do you have a lot of weeds or debris in the water ?

I would expect you have a clog or build up somewhere,
you may consider buying a YDS unit to read the engine in real time,
you could also get an infra red thermometer to read different points of the engine, compared to the good engine to see if you see any hotspots

I would start by removing the thermostat and seeing it's condition
if that was good I'd try the thermometer to narrow it down,
there are many cooling passages in the engine and in the exhaust system that could be blocked,

.

Thanks Scott, happy to be on board. I have owned it now for 13 years and there is less than 200 hours on the boat. Its usually in very clean fresh water in Northern Saskatchewan. Interested in that YDS unit, never heard about that tool before. Comparing the engine temps with infrared is a wonderful idea. Will definately try that. Yes I have viewed that there are many cooling passages and it all starts at the intake screen, which i am going to check when I head back up to the lake. The only thing I forgot to mention is that engine just starting changing its RPM from time to time. So when running at 8000, it will go down to 7000 for 30 seconds or so, then go back to 8000 - without touching the throttle. Engine light is not on when his is happening. Dont know if these two issues are connected.

 

[Mwawryk]

Thermostat is worth checking. Seal material getting loose on the tunnel/pump area can also cause cavitation that reduces cooling water pressure at speed.

Can you share your symptoms in detail? Best of luck!

After running the engine at medium speed 8000 RPM, the one engine will start flashing overheat. Had it happen also once when I was just idling for an extended period of time. Seems like it takes 10+ minutes for the light to flash when running around 8000 RPM. Also noticed recently that RPMs on that engine will move up and down (by approx 1000) without touching the throttle. Happens from time to time and will do it every minute or so. I dont know if there is a connection to the overheating light going on. Will check that and seal material. Thank you!

 

[Mwawryk]

yes, many possibilities and your input will help us diagnose it,

does it over heat when you run the engines on the flush hose ?

Have not tried that yet, but can definately give it a shot. Is there a max amount of time you can idle and engine while running with the flush hose? I ask because I think it will take some time to light up the overheat

 

[Beachbummer]

Do you have a California engine by any chance?

 

[zipper]

The surging issue could be a not seated plug wire/coil pack. That could also cause an overheat. I am in the same camp with Scott and Beachbummer about the thermostat. Take it out and try it. The cooling passage for the thermostat exits at the stern next to the exhaust outlet, circled in red. Do you see any white water vapor from that side that you do not see on the other? Some call it steam, but steam is invisible.

 

[VitaminSea]

You can also check/replace the engine anodes (#11 in diagram below)… when you remove them, you can see a bit inside the block and this will help determine if you have any build up.

A YDS can be picked up off of eBay for ~$50-70 last time I checked. Just need a laptop you can connect to run the diagnosis. From my experience you’ll also want to review and clear the existing faults, as the ECU will only log the 1st instance of a particular fault, not the most recent, or keep a running log of faults.

 

[Mwawryk]

Do you have a California engine by any chance?

Good day,
Motor label says made in Japan.

 

[Beachbummer]

Ok, I think if it has 3 stars emissions sticker and catalytic converter, along with extra temp sensor to the water routing it is a California emissions engine. Reason I ask is. There are extra sensors on that engine, and the exhaust temp sensor on that engine can also trigger a blinking light.

 

[Mwawryk]

Ok, I think if it has 3 stars emissions sticker and catalytic converter, along with extra temp sensor to the water routing it is a California emissions engine. Reason I ask is. There are extra sensors on that engine, and the exhaust temp sensor on that engine can also trigger a blinking light.

Thank you for the details on that, much appreciated. Will check that.

 

[itsdgm]

Have you changed the spark plugs recently?

 

[Mwawryk]

Have you changed the spark plugs recently?

Hi Dennis, no plugs have not been changed for some time. I assume the RPM change is where your headed with that question. thanks

 

[itsdgm]

Hi Dennis, no plugs have not been changed for some time. I assume the RPM change is where your headed with that question. thanks

Overheat warnings were common with your vintage boat running on old spark plugs. It’d be worth changing them and checking.

 

[Mwawryk]

Thanks Dennis, much appreciated!

 

[Mwawryk]

Dennis,
I put new plugs in the boat over the weekend and ran the boat on the water for a few hours. Overheating light issue - gone! Thank you so much for your insight, it is greatly appreciated!

 

[itsdgm]

Dennis,
I put new plugs in the boat over the weekend and ran the boat on the water for a few hours. Overheating light issue - gone! Thank you so much for your insight, it is greatly appreciated!

That’s awesome. Glad to hear. I’ve kept a spare set on the boat and replace them every season just to eliminate a lot of random issues that bad plugs were associated with on our engines. Hope you had a great trip out on the water.