MR-1 engine overheating

[2015 SX210]

View attachment 195892
Got the exhaust off and found the upper and lower right cooling passages in the head on cylinder #4 plugged up. I opened the top one partially before the picture was taken. Total pain getting the exhaust off with the engine in the boat so the next step is to pull the engine, remove the head and see what is going on.

So I’m in the middle of the same issue on my twin MR-1 engines. I’ve had the temp sensors replaced, oil change and plugs, now I have exhaust partially off but the holes seem clear enough. Any other ideas? It randomly overheats one engine to the next, but only while turning circles with a tube attached.

 

[Brad_Ct]

So I’m in the middle of the same issue on my twin MR-1 engines. I’ve had the temp sensors replaced, oil change and plugs, now I have exhaust partially off but the holes seem clear enough. Any other ideas? It randomly overheats one engine to the next, but only while turning circles with a tube attached.

Not sure about your issue but I wonder if you are cavitation going in circles and your cooling water pressure is dropping.

 

[2015 SX210]

Not sure about your issue but I wonder if you are cavitation going in circles and your cooling water pressure is dropping.

Anything that can be done other than no circles or another boat?

 

[tdonoughue]

Pull the pumps and check for smooth jet path and that the impellers are good (not all chewed up). Going in circles may make the issue worse, but may not be the sole cause... FAQ has directions on pulling it.

 

[finnrigged]

2015 SX.... Regarding your mystery overheat issue, we've seen it in the past where some of these motors pick up so much trash in the oil that it will clog the filter screen that is located inside of the oil pump itself. There are two filters in your way of getting free flow oil flow going through these motors. One of them is super easy to access by just removing the eight 8 mm head bolts on top of your oil reservoir. The seal on that lid is made by an o-ring that you can reuse so don't worry about that. You will need to siphon out the oil then and then you will be able to access three Allen head bolts that hold down a stainless steel plate that sits just slightly above bottom in that oil reservoir tank. Want to remove that you will be able to complete siphoning the remaining oil which will reveal an inverted dome screen at the bottom held on by 2 Allen head bolts. A lot of the time this dome screen gets compromised and will have a hole in it which would allow junk to pass through into the oil pump screen next in line. So the first indication of the possibility of your oil pump screen itself being clogged would be if this dome has a hole in it. (I'm uploading a YouTube video right now on one with that condition that I fixed a few days ago as well as a screen repair). What happens is people get too aggressive with whatever they are shoving down inside the oil tank to do the oil changes over the years and a band and or puncture that screen. Also find particulates can get through that screen and go down to a much finer screen on the oil pump itself clogging it up which prevents proper cooling oil to the system and hence an overheat condition.

I have another buddy right now with the MR1 motor who is struggling to resolve and overheat condition like that but he has cleaned out all of his screens. He finally figured out that it was a faulty thermostat. There is a reasonably easy test you can do by removing that thermostat and putting it in hot water with a multimeter on it in the service manual. If you use your boat in saltwater or if it's been in salt water quite a bit that would actually be my first guess at resolving your problem.

As with most of my postings, I apologize in advance for any wording or spelling grammar errors. I do all voice to text because they get long on this cell phone to type lol.

 

[buckbuck]

@finnrigged Please provide a link to your u tube video.

 

[2015 SX210]

2015 SX.... Regarding your mystery overheat issue, we've seen it in the past where some of these motors pick up so much trash in the oil that it will clog the filter screen that is located inside of the oil pump itself. There are two filters in your way of getting free flow oil flow going through these motors. One of them is super easy to access by just removing the eight 8 mm head bolts on top of your oil reservoir. The seal on that lid is made by an o-ring that you can reuse so don't worry about that. You will need to siphon out the oil then and then you will be able to access three Allen head bolts that hold down a stainless steel plate that sits just slightly above bottom in that oil reservoir tank. Want to remove that you will be able to complete siphoning the remaining oil which will reveal an inverted dome screen at the bottom held on by 2 Allen head bolts. A lot of the time this dome screen gets compromised and will have a hole in it which would allow junk to pass through into the oil pump screen next in line. So the first indication of the possibility of your oil pump screen itself being clogged would be if this dome has a hole in it. (I'm uploading a YouTube video right now on one with that condition that I fixed a few days ago as well as a screen repair). What happens is people get too aggressive with whatever they are shoving down inside the oil tank to do the oil changes over the years and a band and or puncture that screen. Also find particulates can get through that screen and go down to a much finer screen on the oil pump itself clogging it up which prevents proper cooling oil to the system and hence an overheat condition.

I have another buddy right now with the MR1 motor who is struggling to resolve and overheat condition like that but he has cleaned out all of his screens. He finally figured out that it was a faulty thermostat. There is a reasonably easy test you can do by removing that thermostat and putting it in hot water with a multimeter on it in the service manual. If you use your boat in saltwater or if it's been in salt water quite a bit that would actually be my first guess at resolving your problem.

As with most of my postings, I apologize in advance for any wording or spelling grammar errors. I do all voice to text because they get long on this cell phone to type lol.

Thanks. I have not looked at the thermostats yet. We’ve only been out on the boat three times this year! New oil, plugs, air filters, all temperature sensors replaced, checked exhaust cooling passages as best I could, pissers flow freely, screens on jets are clean, just looking up in grate and through nozzles both impellers look nice and shiny (no nicks, imperfections, caulk hanging) that I can see.

I’m thinking of just changing the thermostats anyway as another precaution. Just odd it only does it while pulling a tube in circles, and it randomly jumps between motors. No rhyme or reason.

 

[finnrigged]

Yeah to me it seems less likely that it would be the thermostats since it goes back and forth between the motors? Very very strange anomaly you got going on there. Did these motors ever get water in them that you are aware of?

 

[2015 SX210]

Yeah to me it seems less likely that it would be the thermostats since it goes back and forth between the motors? Very very strange anomaly you got going on there. Did these motors ever get water in them that you are aware of?

I don’t know. It’s a 2015, I bought it in 2019 with only 15hrs on it from a dealership. It doesn’t feel or sound like I ever get cavitation…

Yes, it is weird how it jumps between engines. Has to be something that effecting both when put under stress while turning hard circles with tube in tow.

 

[finnrigged]

Here is the video on removal of the oil reservoir cover in order to clean it out and extract as much oil as possible. Plus one way of doing a makeshift full oil change very similar in fashion to the way a person bleeds the brake lines on a vehicle and refills them while they are bleeding to replace all of the fluid with new fluid.

My apologies for the shaky camera work but it's just a cell phone and a guy who hates editing video lol.

The motor in this video is a Yamaha VX110 MR1 which is identical for the sake of this video purpose to the FXHO and the FX140 motors. There are some internal differences inside the head that have nothing to do with the purpose of this video though so it is the exact same on the SX230 boat motors.

 

[finnrigged]

The VX110 has the identical head cover, head cover gasket, cylinder head, valves, timing chain,, cylinders, Pistons, rod length, piston rings, wrist pins, cases, crankshaft, bearings and oil pan cover ... That the FXHO MR1 has. The only difference on the cases are that there are two stainless water line nipples on one side of the motor and one of those water pipes has a 90° bend on the VX versus a straight short pipe on the FXHO. Coming out of the cylinder head that big stainless pipe is also different shaped on the VX than it is on the FX but they are an easy swap. And on the oil reservoir, the shape of the reservoir cover is slightly different as well as the stainless nipples that come out of it point in different directions than the FXHO. They are however interchangeable if you just do a little fancy hose manipulation to make them plug in from an awkward direction. Then there is a small difference in some of the electronics that plug in on the side of the VX versus the FX but again none of this has anything to do with the oil change purpose of this video and they are identical in that.

 

[buckbuck]

@finnrigged It is interesting to see that indented screen at the bottom of the reservoir. I suspect that mine looks the same as I have jammed a small pick up tube down there trying to get as much oil as possible.
Is there any danger of losing a screw down a hole when removing the screen?
How much total oil can you extract by just going down the passageway that returns oil from the engine? That is, without starting the engine.
Thanks for the video. It is informative to see inside the reservoir.

 

[Scottintexas]

Here is the video on removal of the oil reservoir cover in order to clean it out and extract as much oil as possible. Plus one way of doing a makeshift full oil change very similar in fashion to the way a person bleeds the brake lines on a vehicle and refills them while they are bleeding to replace all of the fluid with new fluid.

My apologies for the shaky camera work but it's just a cell phone and a guy who hates editing video lol.

The motor in this video is a Yamaha VX110 MR1 which is identical for the sake of this video purpose to the FXHO and the FX140 motors. There are some internal differences inside the head that have nothing to do with the purpose of this video though so it is the exact same on the SX230 boat motors.

just curious if you know about the drain bolt on the back of the engine to extract all the oil ?

https://jetboaters.net/threads/oil-change-on-mr-1-how-to-perform-a-complete-drain.3805/

.

 

[finnrigged]

just curious if you know about the drain bolt on the back of the engine to extract all the oil ?



Yes but it's a PITA to get at in these waverunners without making a huge mess in the hull. I have often thought that it would be an awesome idea to install a 90° angle pipe out of that full oil change hole and put it at an angle so that you can just pull a screwed on cap out of it then shove a siphon tube down inside that hole to extract from the bottom. But again, all you have to do is actually take off the head cover and you can get your siphon tube down past the timing chain to the very bottom anyway so...

 

[finnrigged]

@finnrigged
How much total oil can you extract by just going down the passageway that returns oil from the engine? That is, without starting the engine.

Virtually no extra oil can be extracted through that port if you don't crank the motor over. It quickly drains back down into the motor.

 

[Scottintexas]

..
I have often thought that it would be an awesome idea to install a 90° angle pipe out of that full oil change hole and put it at an angle so that you can just pull a screwed on cap out of it then shove a siphon tube down inside that hole to extract from the bottom.

Riva used to sell a kit with a valve and up pipe to suck from, it was $150 ea. so I don't think we saw anyone ever install it and riva has discontinued it,
in that link and maybe another we had members add a fitting and elbow at that bolt for their own DIY version,

 

[finnrigged]

Riva used to sell a kit with a valve and up pipe to suck from, it was $150 ea. so I don't think we saw anyone ever install it and riva has discontinued it,
in that link and maybe another we had members add a fitting and elbow at that bolt for their own DIY version,

I remember seeing a blog on green hulk PWC repair forum where a guy did one many many years ago. Definitely would not be very hard to add

 

[Brad_Ct]

I believe 84rzv500r made up a hose assembly from that plug on the oil pump when he swapped MR1s into his boat.