2013 Yamaha 242 limited S overheat one engine, pics included, please help with next steps

[DenisRecchia]

Hello all,

Had an overheat issue on my 242 limited S last season near the end of it up here in New England, decided that was a problem for Spring me. Well here it is Spring. My Starboard engine has developed an overheat and I fear I have a blocked up engine block from reading these forums and trying to troubleshoot the best I can. I was hoping for a clogged line or blocked strainer but I am having the same results on the hose or on the water. Posted are pics of cylinder temps before I shut the boat down on the hose in my yard.

I have already replaced both thermostats, blown out the pisser lines, and cleaned the strainers on the jet drives. What is my next step here? Is it pulling off the exhaust manifold or just cutting to the chase and breaking the block down? I am relatively handy and fear this might be above my pay grade, but if I bring it to a local dealer I know I will lose my entire season waiting.

 

[FSH 210 Sport]

Have you verified there is no blockage in the main cooling from the engine back to the pump?

 

[DenisRecchia]

Ok I believe I have, I took apart the screen at the jet pump and there is pressure in the hoses that lead to the block / exhaust. When on the water some exhaust water gets out the pisser but not at the same intensity, and when on the hose water is escaping from the jet pump and the boat exhaust.

Attaching a diagram of the cooling system, where can I disconnect to see what the flow is like? Im a little hesitant to start it up and start popping hoses off to see if cooling water shoots out. For example, could I take it apart at #12 or #15 at the diagram? Or #30?

Is anyone able to show me how the water flows through this?

Thanks as always in advance, trying to avoid a lost season and thousands probably

 

[anmut]

Not sure on this method, but you could try some SaltAway to see if you can unclog it.

 

[Hot2Go]

T piece #12 is what I would pull off and check. That’s where it would get blocked if anything did happen to get into your cooling system.

 

[DenisRecchia]

Ok so I got my T piece out this weekend and it looked pristine. Unfortunately that doesn't seem to be it. Would it be next steps to just keep popping hoses? Im assuming it goes Oil Cooler, then up to that next square box, then into the exhaust. Tough to figure out where the water flows and I dont want to flood the engine by trying to trace flow without it running.

Thanks in advance

 

[RelentlessWMD]

Unfortunately, it sounds like you are having a similar issue when I got my boat. I am sure you already saw my saga in this post 242 Both Engines overheat New to me

Before you go pulling your heads I would check the following-
1. pull all the little hoses off and run a wire down them to make sure they are clear, then push a wire down the fittings the go into and see if you find any crud built up.
2. pull your engine anodes and look for buildup (might as well replaced them if you haven't already done so in past few years).
3. Flush with white vinegar. Pour it into the fittings and let it sit for 10-20 minutes, repeat this several times. This can loosen up some hard deposits. try to get as much in the exhaust ports manifold (hose #23 on your parts diagram), ideally until you see it running out elsewhere. After all this run it on the hose and check your thermostat again, some broken loose debris may get caught in them.

Honestly you may want to leave your thermostat out until you get this issue resolved. Personally, I never put mine back in, I just make sure I give the boat a solid 5min to warm up before I really gas on it. However, you may want it back in before the end of summer being your in NE.


I really hope you dont have to pull the heads. Its doable but its a lot of work. The disassembly and reassembly is relatively straight forward, its the scraping/cleaning out all the little passages that is so time consuming and tedious. 1.5 hr disassembly, 3.5 hr cleaning, 2.5 hr reassembly, 2hr looking for tools and retrieving from bottom of boat when they fall under engine.

if you go this route, order a couple extra air and exhaust manifold bolts when you order seals & gaskets.

 

[FSH 210 Sport]

Hello all,

Had an overheat issue on my 242 limited S last season near the end of it up here in New England, decided that was a problem for Spring me. Well here it is Spring. My Starboard engine has developed an overheat and I fear I have a blocked up engine block from reading these forums and trying to troubleshoot the best I can. I was hoping for a clogged line or blocked strainer but I am having the same results on the hose or on the water. Posted are pics of cylinder temps before I shut the boat down on the hose in my yard.

I have already replaced both thermostats, blown out the pisser lines, and cleaned the strainers on the jet drives. What is my next step here? Is it pulling off the exhaust manifold or just cutting to the chase and breaking the block down? I am relatively handy and fear this might be above my pay grade, but if I bring it to a local dealer I know I will lose my entire season waiting.

View attachment 234546

I should have asked this straight away;

Are you boating in salt or fresh water? If salt have you been flushing with salt away?
Are you getting any flow out of the pilot water from the oil cooler? How about from the main thermostat discharge?
Are you wet slipping the boat?
How many hours are on the boat?

 

[FSH 210 Sport]

Unfortunately, it sounds like you are having a similar issue when I got my boat. I am sure you already saw my saga in this post 242 Both Engines overheat New to me

Before you go pulling your heads I would check the following-
1. pull all the little hoses off and run a wire down them to make sure they are clear, then push a wire down the fittings the go into and see if you find any crud built up.
2. pull your engine anodes and look for buildup (might as well replaced them if you haven't already done so in past few years).
3. Flush with white vinegar. Pour it into the fittings and let it sit for 10-20 minutes, repeat this several times. This can loosen up some hard deposits. try to get as much in the exhaust ports manifold (hose #23 on your parts diagram), ideally until you see it running out elsewhere. After all this run it on the hose and check your thermostat again, some broken loose debris may get caught in them.

Honestly you may want to leave your thermostat out until you get this issue resolved. Personally, I never put mine back in, I just make sure I give the boat a solid 5min to warm up before I really gas on it. However, you may want it back in before the end of summer being your in NE.


I really hope you dont have to pull the heads. Its doable but its a lot of work. The disassembly and reassembly is relatively straight forward, its the scraping/cleaning out all the little passages that is so time consuming and tedious. 1.5 hr disassembly, 3.5 hr cleaning, 2.5 hr reassembly, 2hr looking for tools and retrieving from bottom of boat when they fall under engine.

if you go this route, order a couple extra air and exhaust manifold bolts when you order seals & gaskets.

You should be running your thermostats. They keep proper water temp, ideally 185* on the water jacket around the cylinders, in the water jackets whilst running. Its good you let it warm up before taking off, but your engine is running cold while underway, this inhibits the ability of the rings to seal on the cylinder wall among other things.