Engine over heat after tow rope caught

[Julian]

Then this morning it over heated..

Are you sure it is overheating? Did you use a temp gauge to test the engine to see if it was running hot in comparison to the other engine?

 

[Jmpicking]

I felt it and it’s definitely hotter on the tube that the water is supposed to go through after the temperature regulator.

Worked great for 15 minutes of idle, 6500 rpms for about 5-10. Minutes, then stopped and idled for about 5 minutes and it overheated. The overheat turns off after I get the rpms up a bit, but then overheats after another minute and 6500 rpms now

 

[Jmpicking]

What’s strange is that if it’s a water restriction cooling issues, it still shouldn’t overheat because no water flows out of the other one while it’s idling just like no water flows out at idle of the one I’m having issues with. They both flow the same.

 

[swatski]

What’s strange is that if it’s a water restriction cooling issues, it still shouldn’t overheat because no water flows out of the other one while it’s idling just like no water flows out at idle of the one I’m having issues with. They both flow the same.

Flow rates on the pissers are not necessarily reflective of flow rates through cooling passages. There is a video posted by @buckbuck on the MR1 cooling system, it is very similar in 1.8, also posted in service manual pages.
Some parts of cooling passages may be obstructed with minimal effect on pisser flow.

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[Jmpicking]

Flow rates on the pissers are not necessarily reflective of flow rates through cooling passages. There is a video posted by @buckbuck on the MR1 cooling system, it is very similar in 1.8, also posted in service manual pages.
Some parts of cooling passages may be obstructed with minimal effect on pisser flow.

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How could a rope get in there to obstruct it?

 

[Jmpicking]

Could the cooling intake grate be blocked if the water is pissing fine?

 

[swatski]

Could the cooling intake grate be blocked if the water is pissing fine?

On the hose - yes, but in the water - no, or at least that's seems unlikely. However, an internal passage might be obstructed leading to an overheat alarm, without effecting the pisser stream.

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[buckbuck]

It would be helpful to know what is throwing the overtemp signal. Connecting the YDS will let you see the data. Using a cheap infrared gun can help compare temps between two engines and possibly locate the problem. Use a thermometer to measure the temp of the pee steams can also help.

 

[Cambo]

Tip for extracting the bolt shaft if it’s soft enough center punch then drill an 1/8 hole about 1/4 deep take an Allen key that fits snug tap it in then try to extract. If it spins go to the next size between metric and American Allen keys you can always find a good fit snug fit. You could even start smaller I’m not sure of the shaft size . They have been going loctite crazy was that why it snapped ?

 

[Jmpicking]

Got the bolt out white crate is clear mr1 cooling video says water should come out of here. And on my boat it’s filled with silicone. Why might it be filled .. the red one is my boat with the silicone on both engines good and bad

 

[buckbuck]

That video was made in reference to the HO MR-1 engine producing 160hp. Your boat has the 140 hp MR-1 and does not use that port thus Yamaha filled it with silicone.

 

[Jmpicking]

Ok running on a hose bypasses the water intake portion of the jet pump, however if you run on the hose and do not see water exiting the pump itself or only a small amount as opposed to what you usually see, you probably have a clogged water port on the side of the pump.
Follow the hose to the raised portion of the pump where it attaches, this is where the cooling water flows to the engine ,as for cavitation any small piece of rope up in between the impellers where you can not see it can cause this problem. out of the water the air is in no way going to have the same effect or resistance that water has so unless it is catastrophic damage it probably won't be visible that way. Picture shows a square raised section on the main pump housing this is where the water is forced from the pump to the engine.

This port was clean

 

[Jmpicking]

That video was made in reference to the HO MR-1 engine producing 160hp. Your boat has the 140 hp MR-1 and does not use that port thus Yamaha filled it with silicone.

Thank you

 

[Jmpicking]

The cooling intake grate was completely clear. Any other ideas

 

[swatski]

Maybe check this thread, too, for ideas...
I think @buckbuck found a Y-fitting miss-molded from factory that was throttling down cooling lines, stuff like that might be exaggerated by a rope incident?

Cranky, have you checked the cooling lines and the plastic fittings? The oil cooler fitting and the exhaust manifold both have substantial restrictions in them. The Y-fittings also may have plastic flash in them from the factory due to improper manufacturing.
A couple years ago OperationROL had some overheat issues that were resolved by flushing. This was during a Shelbyville trip.

 

[Jmpicking]

Could the rope being stuck cause a blown head gasket?

 

[Julian]

OK, I can't remember if this was already raised...but did you check the thermostat? Perhaps it went bad as part of the rope overheat?

 

[Gym]

Could the rope being stuck cause a blown head gasket?

A blown head gasket would be caused by an overheat severe enough to warp the head. It would be fairly easy to detect. Either you would be leaking water externally, which you would be able to see. Or you would be leaking water internally which would either be seen as steam in your exhaust or water in your oil. You could do a compression or leakdown test to prove it. I wouldn't think you would have left the motor running long enough at idle, after getting an overheat indication, to cause that kind of damage

 

[Jmpicking]

OK, I can't remember if this was already raised...but did you check the thermostat? Perhaps it went bad as part of the rope overheat?

That’s what I thought but I swapped thermostats with my working engine, and still didn’t fix the issue

 

[Jmpicking]

A blown head gasket would be caused by an overheat severe enough to warp the head. It would be fairly easy to detect. Either you would be leaking water externally, which you would be able to see. Or you would be leaking water internally which would either be seen as steam in your exhaust or water in your oil. You could do a compression or leakdown test to prove it. I wouldn't think you would have left the motor running long enough at idle, after getting an overheat indication, to cause that kind of damage

I didn’t leave it running too long after, I would retry it but turn the engine off at least within 15 seconds of overheats warning