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Limp Mode


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Pull the engine temp sensor, heat it up real good with a Bic lighter, then reinstall quickly.  That ought to do it.  Out of curiosity. why would they want to put the engine into limp mode for 'testing'?

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The water hose from the lake that supplies the water for the boat has come off twice because the rudder (tiller arm) hits the hose. Hose pops off and no water gets to the motor. Both times it's happened the boat continued to run as if nothing happened. The motor was run dry of water and things started to melt. When they opened up the motor hatch the boat looked like it was on fire. It was from all plastic pieces on the motor melting and the motor getting so hot. Of course the dealership says it didn't over heat and it wont go into limp mode for over temp.  

None of his family will go in the boat anymore. 

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2 minutes ago, malibu2004 said:

The water hose from the lake that supplies the water for the boat has come off twice because the rudder (tiller arm) hits the hose. Hose pops off and no water gets to the motor. Both times it's happened the boat continued to run as if nothing happened. The motor was run dry of water and things started to melt. When they opened up the motor hatch the boat looked like it was on fire. It was from all plastic pieces on the motor melting and the motor getting so hot. Of course the dealership says it didn't over heat and it wont go into limp mode for over temp.  

None of his family will go in the boat anymore. 

Huh?  No hose clamp on the hose?  And the boat wasn't alarming from the over temp?

 

The hose that goes from the hull fitting to the v-drive has got to be one of the hardest hoses to get loose on my boat, something is seriously wrong if the tiller arm is capable of hitting it.  Also seems odd that it runs anywhere near the tiller arm, pretty sure mine doesn't.

Edited by oldjeep
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Just now, oldjeep said:

Huh?  No hose clamp on the hose?  And the boat wasn't alarming from the over temp?

Clamp is on and checked by a few people. The dealership said the routing of the hose was wrong and rerouted the hose so the tiller can't touch it anymore. They had a few other boats 2015 LSV boats have the same problem with the hose getting knocked off. No alarms either time. 

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Just now, malibu2004 said:

Clamp is on and checked by a few people. The dealership said the routing of the hose was wrong and rerouted the hose so the tiller can't touch it anymore. They had a few other boats 2015 LSV boats have the same problem with the hose getting knocked off. No alarms either time. 

Guessing the hose must have been the one that feeds the raw water pump then and not the one right on the hull fitting.  Odd that the hose clamp isn't holding it on unless it was installed on top the barb rather than behind it.

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Just now, oldjeep said:

Guessing the hose must have been the one that feeds the raw water pump then and not the one right on the hull fitting.  Odd that the hose clamp isn't holding it on unless it was installed on top the barb rather than behind it.

Yes it's the connection that feeds the raw water pump. Malibu and the dealership don't know why it keeps coming off even though it gets hit. They did agree that it shouldn't get hit so they rerouted it. I would assume the dealership would know how to install and make sure it was tight. 

 

My biggest issue is the no limp mode or alarms going off.

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The coolant temperature sensor needs to be immersed in water for it to be able to detect an overheat. If there is no water in the block, there is nothing to measure.

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@Engine Nut that's very useful information, but it seems that the temp sensor really only detects a failed thermostat, right?  Since losing coolant either via a failed impeller (for raw water cooled engines) or a hose failure (for closed cooling engines) are both likely scenarios, isn't this a "miss"? This situation seems to call for some sensor that would be able to detect a "running dry" situation. I'm interested to hear your view and if you have any thoughts on how the lack of a sensor detecting coolant presence could be addressed.

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2 minutes ago, mikeo said:

@Engine Nut that's very useful information, but it seems that the temp sensor really only detects a failed thermostat, right?  Since losing coolant either via a failed impeller (for raw water cooled engines) or a hose failure (for closed cooling engines) are both likely scenarios, isn't this a "miss"? This situation seems to call for some sensor that would be able to detect a "running dry" situation. I'm interested to hear your view and if you have any thoughts on how the lack of a sensor detecting coolant presence could be addressed.

It would be yet another sensor, but some outboards handle this issue with a pressure sensor on the output side of the impeller.  My folks have a water pressure gauge on the dash of the pontoon

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@The Hulk went thru this with his engine and went down the same road trying to find a solution to no water in the engine.  Not sure if he came up with a solution or sensor to add other than the different tone of the exhaust.  

 

2 minutes ago, oldjeep said:

It would be yet another sensor, but some outboards handle this issue with a pressure sensor on the output side of the impeller.  My folks have a water pressure gauge on the dash of the pontoon

True, most outboards do have water pressure gauge and/or a "pee hole", could add either if you wanted too.

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@oldjeep I agree, my thought is that a temp sensor that can't tell if there is coolant isn't very useful. This makes me want to add a pressure sensor like you describe to my engine, but I'd rather find one that could trip the same circuit as the temp sensor if pressure is below a threshold. Hopefully @The Hulk chimes in and tells us that he found a magic sensor.

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1 hour ago, Engine Nut said:

The coolant temperature sensor needs to be immersed in water for it to be able to detect an overheat. If there is no water in the block, there is nothing to measure.

That makes sense but what happens to the motor when you run it dry a couple of times? I would assume a few years down the road they are going to start having warping issues. 

 

My boat went into limp mode this weekend for High Temp because I didn't get a water hose tight enough. It still had water just not enough when I was WOT. 

 

One thing I would do is check the hose and make sure nothing is hitting it. 

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If the hose came completely off, I would think the bilge would fill w water. Then the warning message would come on  the dash possibly giving ample warning something was up before things got too hot.  

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1 minute ago, Web said:

If the hose came completely off, I would think the bilge would fill w water. Then the warning message would come on  the dash possibly giving ample warning something was up before things got too hot.  

It wouldn't as long as the pump end of the hose stayed relatively high (above the water level)and it is a pretty stiff hose.

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Just now, Web said:

If the hose came completely off, I would think the bilge would fill w water. Then the warning message would come on  the dash possibly giving ample warning something was up before things got too hot.  

Hose was totally off and no warnings. From the time he went from no wake to oh that's not good 2 minutes tops and it was a straight line. 

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We have addressed the "dry cooling passages" in two ways on our current 6.2L Ford based product. The Fords have a cylinder head temperature sensor that monitors the temp of the head itself, not the coolant so if the engine is dry the system will still measure the temperature. We have also installed a water flow sensor on those engines to let the operator know that there is reduced or no water flow in the system.

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Reminds me of the time we passed a Malibu wake board boat that was clearly smoking. They were wake boarding and continued to do so for another 10 minutes or longer and we passed near them several times while skiing ourself. Finally we pass by and they are dead in the water.  I pull up to assist and it was clear the impeller had gone and because there was no alarm, they continued to use th boat (even though there was clearly smoke coming from the boat for quite a while before it shut down). I towed them to their dock and had to wonder just how much damage they had done to the boat.  I suspect it took an engine replacement along with new exhaust hoses, etc.. It had melted quite a bit back in the engine compartment. 

The owner was in shock when I explained that the engine temp never got high because there was no water to make it register. It was a totally foreign concept to them.  I felt bad for them.  It was a costly lesson to learn. 

Edited by sic0048
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3 hours ago, Engine Nut said:

We have addressed the "dry cooling passages" in two ways on our current 6.2L Ford based product. The Fords have a cylinder head temperature sensor that monitors the temp of the head itself, not the coolant so if the engine is dry the system will still measure the temperature. We have also installed a water flow sensor on those engines to let the operator know that there is reduced or no water flow in the system.

It good to hear that this has been addressed in the new product. Is there anything someone with a GM based engine ('15 and prior) can do easily? I doubt there is a "retrofit" kit since this is two different blocks, but maybe you have a suggestion for an aftermarket way to monitor the head temp or water pressure.

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