242 Both Engines overheat New to me

[RelentlessWMD]

Hi all! been reading a while and this is my first post, sorry its asking for help.

Background:
I bought a 2012 Yamaha 242 Limited S from a guy in NE Florida. The boat has been kept in enclosed high rack storage since it was new and only has 65 hrs on it. The guy ran it frequent the first couple years until his health became an issue and it has sat up for the better part of 3 years. Aside from a layer of dust the boat looks immaculate.
I somewhat know the guy and believe him when he says he flushed with salt away each time he took it out. All the flushing stuff was in the boat as further proof.

I bring the boat home, rinse it off, new batteries, pump out 45+ gallons of old gas and fill up with 51.2 gallons of ethanol free. Crank the boat on the hose each engine idles for 30minutes. Everything works perfectly. I inspected the impellers, they look great, no dings or obstructions, white water strainers look good. Oil looks brand new but order a complete oil and plug kit to install later.
I am ready for the river . . .i thought

within 10 minutes of getting it on the water and working the throttles the starboard engine overheat alarm goes off. I cool it off and take the boat out.

do more forum reading and check the thermostat. sure enough it is crusty and stuck. New set of thermos on order for both engines. In mean time i put housing back together without it. run boat on hose again for 30 minutes each, no problems.

Get back on the water. boat acts fine so i start working the throttles and within 1/2 mile i get overheat alarms on both engines. i cool them off and back on the trailer it goes.

(fortunately i live on the river and have a landing at my house)
I removed port thermostat, it was crusty but i could get it to move, reinstalled housing without thermostat
I took the strainers off and inspected, they were clean.
pulled water hoses off of the thermo stat housing, oil cooler and rectifier regulator all of which had good flows of water. very little sign of salt build up the places i could see.
Ran the motors for an hour each alternatively reving them to 4000rpm for minutes at a time and never got an overheat.

I figured maybe they cleared themselves and put it back in the water. 1/2 mile later i got overtemp on both engines again within 30 seconds of each other, with no thermostats in either engine, tell tail water is luke warm at best if not considered cool.

I took some temp (F) reading before i took it out and on hose:
On the water at idle:
Starboard
Cyl #1: 130
Cyl #2: 157
Cyl #3: 124
Cyl #4: 104
Oil Cooler/Filter: 150

Port
Cyl #1: 142
Cyl #2: 105
Cyl #3: 100
Cyl #4: 91
Oil Cooler/Filter: 143

On the Hose at idle:
Starboard
Cyl #1: 113
Cyl #2: 143
Cyl #3: 110
Cyl #4: 92
Oil Cooler/Filter: 132

Port
Cyl #1: 129
Cyl #2: 95
Cyl #3: 95
Cyl #4: 85
Oil Cooler/Filter: 120

Given the elevated cylinder temps on Starboard #2 and Port #1, I'm guessing there is a blockage. Only thing i can figure is there is some salt (or white algea i read about) build up in the water passages around the cylinders. What is my best course of action? only thing I can think of is pull the exhaust manifold to access passages for cleaning. if they are not blocked what else can it be?

I tried reaching the water intake hose T but its below exhaust manifold and nearly impossinble to reach much less wrench on with it in place. Thus i havent been able to look directly into it for plastic flashing problem as described in another thread, plus guy before me had no problems and i see on gauge where he had it at 53mph.

BTW i have a YDS kit ordered, should arrive next week.

 

[RelentlessWMD]

Also-
I put in new NGK spark plugs before I put it in the water last time, no change in behavior observed.

 

[WREKS]

@RelentlessWMD, Where on the engine are you determining the water temperatures? Close to the cylinders in the location of the exhaust manifolds is the best place to determine them. If you can bump up the rpms while you are taking them, that would be helpful.

 

[RelentlessWMD]

Took Temps at within an inch of the top of the manifold where it meets the block (just off the bolt flange)

 

[WREKS]

The temps you recorded should not send alarms. As before, recording temps at a higher rpm may be helpful.

 

[RelentlessWMD]

I was by myself on boat before so i had to be quick taking temps but basically i was seeing 30-40 degrees higher across the board compared to temps at idle on the water.

I plan to pull exhaust manifold tomorrow. Does anyone have torque specs and sequence for reinstall. I plan to reuse gasket unless it distort on removal.

 

[RelentlessWMD]

I found the service manual for boat Soni have the torque values now. Plus I got the test values for the thermo sensors.
That's what i am doing today.

 

[Beachbummer]

Water pressure from the pump has a major effect on temperature at higher RPMs.

Do Check the pump sealant is not loose and not obstructing the flow. Loose sealant can cause cavitation.

I put a temperature probe on the water outlet going to the pisser and I monitor that. I also have a probe on the manifold. To monitor, but the manifold for me is always cooler than the pilot water. (When all is well)

If I catch a branch or leave, I can generally see it as increased temperature.

The greater spikes and open thermostat occur when reducing speed. The boat heat soaks and the boat does not make much water pressure at idle, so when reducing front high rpm down to idle, on the next 2 or 3 minutes I will see temps rise 10 degrees above normal and then start to come down. If i bump the throttle a little the cooling is faster.

Best of luck!

 

[FSH 210 Sport]

Great post with lots of info.

There is a possibility that the sensors are bad, but with crusty stuck thermostats that may write a different story.

Go to salt aways web page and have a look at the instructions, there is a procedure for removing heavily salted up engines. Basically it’s a daily flush with salt away and then you leave the salt away in the engines overnight repeatedly to remove the build up.

Did you pull the strainers in the jet pumps to check for debris in there ? How is the water flow out of these strainers while it’s on the hose?

 

[RelentlessWMD]

Update:
Partial Success-
I pulled both Exhaust manifolds completely out. Found pretty big build up of white stuff looked like calcium, some of it was still wet and mushy like a paste.
I scraped out the water passages and chased them with a piece of stainless wire to make sure i knocked out the blockages, then blew it out passages with air compressor and made sure i had flow through all of them.
I put it all back together and installed new thermostats.

Hooked it up to the water hoses and ran engines at idle and at 4k RPMS for 5minuets. See #s below-
On the hose at idle:
Starboard
Cyl #1: 120
Cyl #2: 120
Cyl #3: 120
Cyl #4: 97
Oil Cooler/Filter: 119

Port
Cyl #1: 109
Cyl #2: 107
Cyl #3: 109
Cyl #4: 90
Oil Cooler/Filter: 198
______________________________
On the hose at 4k RPMS:
Starboard
Cyl #1: 140
Cyl #2: 140
Cyl #3: 138
Cyl #4: 110
Oil Cooler/Filter: 138

Port
Cyl #1: 128
Cyl #2: 127
Cyl #3: 128
Cyl #4: 99
Oil Cooler/Filter: 121

Overall a drop and equalization of temperatures as I would expect if I am getting more even flow through passages. Starboard engine is still running hotter than port but it improved.

The Bad News:
Put the boat in the river, run it at mid mid and idle throttle positions for about 10 minutes all is well (motors are already warm from running on hose).
I put the throttle down and got half mile before the starboard over temp alarm comes on followed 20 seconds later by the Port over temp alarm.
I jumped back there as quick as i could (had to get boat to safe spot, by myself on boat) and got the following numbers:

Starboard
Cyl #1: 120
Cyl #2: 120
Cyl #3: 120
Cyl #4: 99
Oil Cooler/Filter: 165

Port
Cyl #1: 120
Cyl #2: 120
Cyl #3: 120
Cyl #4: 99
Oil Cooler/Filter: 165

So the cylinder temps are looking good but oil cooler temp is up. I did not clean it while doing work described above but did blow air through it and got decent flow.

So now my best guess is the oil cooler has too much restriction and is getting too hot and setting alarm.
Fortunately(ish) i have to change oil anyway so when i drain oil out, I will pull oil cooler and take it apart for a cleaning this week.
YDS cable is supposed to arrive tomorrow so i will try to get some info off it before i drain the oil.

Thoughts, theory's and pointers are appreciated.

 

[RelentlessWMD]

Great post with lots of info.

There is a possibility that the sensors are bad, but with crusty stuck thermostats that may write a different story.

Go to salt aways web page and have a look at the instructions, there is a procedure for removing heavily salted up engines. Basically it’s a daily flush with salt away and then you leave the salt away in the engines overnight repeatedly to remove the build up.

Did you pull the strainers in the jet pumps to check for debris in there ? How is the water flow out of these strainers while it’s on the hose?

I plan to treat it with salt away when i get a chance to pick some up, maybe improve the flow on starboard so temps match port.

Strainers looked good., water was definatly flowing steady out of them but not with any force/pressure, think of faucet at minimum steady stream. Should i see more flow/pressure?

 

[RelentlessWMD]

Water pressure from the pump has a major effect on temperature at higher RPMs.

Do Check the pump sealant is not loose and not obstructing the flow. Loose sealant can cause cavitation.

I put a temperature probe on the water outlet going to the pisser and I monitor that. I also have a probe on the manifold. To monitor, but the manifold for me is always cooler than the pilot water. (When all is well)

If I catch a branch or leave, I can generally see it as increased temperature.

The greater spikes and open thermostat occur when reducing speed. The boat heat soaks and the boat does not make much water pressure at idle, so when reducing front high rpm down to idle, on the next 2 or 3 minutes I will see temps rise 10 degrees above normal and then start to come down. If i bump the throttle a little the cooling is faster.

Best of luck!

When i looked in pump housing i didn't see any loose sealant. Would i be able to feel or hear it cavitating like a regular boat? This is my first jet boat.

Only other cavitation concern i have is where the front of the grate meets/bolts to the boat. all the rest of it has sealant but this spot on the front has a decent gap (1/2") between it and the hull. The great is evenly recessed in the hull so the hole bottom of boat is flush but there is a gap between these components. It is the same on both sides. Any idea if its supposed to be like this? I bought some silicone to fill in this gap but was concentrating on other things as u can see from my update post.

 

[WREKS]

The holes by the arrows are the only passageways between the exhaust manifold and the cylinder head. At least that is how it is on my 2007 SX 230.

 

[RelentlessWMD]

Update 2:
YDS came in today So i tested both motors. At idle and at 4k RPMs everything checks out. All sensors are working consistently.
So it seams to me that it only has cooling problems on the top end of the throttle. Im not comfortable running it that high on the hose for any usable length of time so it will have to wait until I can put it back in the water.
I pulled the DTCs on it and @43 hours they both show an overheat warning. The boat has 72 hours on it now, I bought it with 68.
The engine running hours read:
0000-2000 : 33.03hr
2000-4000 : 17.23hr
4000-6000 : 18.79hr
6000-8000 : 4.13hr
8000-10000 : 0.0hr

I find it kind of strange he that the boat has very few hours over mid throttle. Coincidence or related to my over mid throttle overheat issue, cause or effect?

At any rate I drained the oil while engines were warm in preparation for pulling and cleaning oil coolers later this week. I managed to get 3.5 qts of the 4qts of oil out with suction hose which I understand is pretty good. The oil I pulled out looked a lot dirtier than what i was seeing on the dipstick.

Fingers crossed that oil cooler cleaning and oil/filter change will put this overheating thing to bed. Im ready to enjoy my new boat!

edit: spelling

 

[Dixemon]

By chance have you pulled the engine anodes? I have done this and pulled the thermostat then ran on the hose for a few minutes to flush from those two points. Shot in the dark, but it fixed an issue i was having with overheating. Similarly with your situation, it would take 1/2mile or so of running before alarm would sound. On the hose i would never overheat. Things like salt, sand or simply a swollen anode get hung up in the anode passage and do not allow proper water flow.

 

[VitaminSea]

@RelentlessWMD - Welcome to the forum. Sorry to hear that your new to you boat has led you in this direction, however from reading your post, it seems like you’re determined and knowledgeable enough to remedy the issue.

I find it kind of strange he thatvthe boat has very few hours over mid throttle.

You mentioned the boat was kept at a marina, there is a good chance there was a considerable no-wake zone on the way to the sandbar, so potentially the prior owner only had the opportunity to cruise at 5.5-6k for a short while before they reached their destination. When I think about my typical sandbar outing, one way it takes ~30 minutes, however only ~10 minutes is at cruising speed, the balance of the ride is no-wake.

I also agree with your assessment of the intake grate, where the front of it meets the hull. Maybe someone else who has the same hull can share pictures as to how their grate sits, however silicone is easy enough to try, but it might not hold long term and you may need something more like 3M 4200.

Lastly, I hope that cleaning of the oil cooler gets you back on the water. I will venture to say that based on your findings of the exhaust manifold, I wouldn’t be surprised that you have blockage in the block, and may need to remove the head to clean those passages. Fingers crossed for you that you’re able to remedy the issue for now with the oil cooler and can take a deeper dive in the off season.

 

[FSH 210 Sport]

I plan to treat it with salt away when i get a chance to pick some up, maybe improve the flow on starboard so temps match port.

Strainers looked good., water was definatly flowing steady out of them but not with any force/pressure, think of faucet at minimum steady stream. Should i see more flow/pressure?

You should be getting a lot more water flow through the engine while on the water. And it is quite normal for the oil coolers to have gotten a lot warmer after hard running.

If it was me I’d be getting to the store and picking up some salt away and use their procedure for a heavily salted up engine.

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[WREKS]

@RelentlessWMD Please, post pictures of disassembled oil cooler before cleaning!

 

[RelentlessWMD]

Update 3:

Pulled the oil coolers they could pass for new. The brown you see in photos is just oil.

The anodes on the other hand . . . Well there is the smoking gun.

Starboard anode half of it broke off in block and is caked with white calcium lookinstuff and salt crystals. See photo

The port I can't even get out, the bolt came out but the rest is still stuck and I have beat on it pretty hard to the point I'm worried I may damage the block if I go any harder.
I'm sure many of you know these anodes are not easy to get to with tools.

I kind of feel like this is the worse case scenario.

I feel my best course of action is to pull the intake manifolds off to gain better access to the anodes so that I can then drill/bore them out. If that doesn't work I may be forced to pull the engines.

Only other options I can think of but feel like they are unlikely to work:
1. Flush for days with salt away hoping it will free up
2. Cap off water port on low end of engine and pour muriatic acid down the thermostat housing to fill the block and hopefully eat away the build up.(I have done this on radiators and works great for removing build up inside those)

 

[RelentlessWMD]

By chance have you pulled the engine anodes? I have done this and pulled the thermostat then ran on the hose for a few minutes to flush from those two points. Shot in the dark, but it fixed an issue i was having with overheating. Similarly with your situation, it would take 1/2mile or so of running before alarm would sound. On the hose i would never overheat. Things like salt, sand or simply a swollen anode get hung up in the anode passage and do not allow proper water flow.

Seems you called it. Anodes are so far gone they wont even come out of the block. Now i get to tear apart the other side of the engine