Bad Overheating Problem

[pat656]

I have a 2006 Moomba Outback direct drive with 100hrs and it has a bad overheating problem.
The engine kept reaching 190 degrees and went into the protection mode where you can only idle until it gets below 180.
I had the impeller and thermostat replaced and i took off every water hose and inspected them for leaves/twigs etc since we spend a lot of time in the river.
We went back out and it still ran at 180 degrees and cut off many times at 190.
Then after a full day on the lake we parked the boat at the dock and had dinner. After about an hour we tried to start the boat and now it wont even start. We had to be towed to out trailer.

What might be causing this problem?

[ToddXLV]

I have a 2006 Moomba Outback direct drive with 100hrs and it has a bad overheating problem.
The engine kept reaching 190 degrees and went into the protection mode where you can only idle until it gets below 180.
I had the impeller and thermostat replaced and i took off every water hose and inspected them for leaves/twigs etc since we spend a lot of time in the river.
We went back out and it still ran at 180 degrees and cut off many times at 190.
Then after a full day on the lake we parked the boat at the dock and had dinner. After about an hour we tried to start the boat and now it wont even start. We had to be towed to out trailer.

What might be causing this problem?

May be a blockage in your fresh water cooling system. Do you have a fake a lake where you can hook up the hose in your driveway? When the boat is idling in the water do you see water bubbling under your swim ramp?

[pat656]

i have checked the fresh water cooling system and there is no blockage.
I have never noticed if there were bubbles but now i cant check because it wont start

Oh and I forgot to add this:
It only overheats at idle, at speed the temperature goes down.

[ToddXLV]

i have checked the fresh water cooling system and there is no blockage.
I have never noticed if there were bubbles but now i cant check because it wont start

Oh and I forgot to add this:
It only overheats at idle, at speed the temperature goes down.

Ok, I would check your impeller AGAIN. You may have sucked up some garbage and your impeller is shredded again. Did you idle your boat out of water for any extended amount of time? Anytime you have overheating problems at idle it usually means the impeller is shredded. The reason why you don't overheat when moving is because the water is being pushed thru the cooling system by pressure. I could almost put money on it that your impeller is chewed up. Go to your boat now and take off the plate to the impeller housing, pull out the impeller with a needle nose and inspect it.

[LSM]

May be a blockage in your fresh water cooling system. Do you have a fake a lake where you can hook up the hose in your driveway? When the boat is idling in the water do you see water bubbling under your swim ramp?

Can you tell if it is really running hot? It may be a temperature sensor issue indicating a false temp. If it thinks its too hot it probably won't let you crank it.

When you had the impeller replaced, did they give you the old one? Was it missing any blades? I've seen those break off and go inside the engine block and get hung up in the Exhaust Manifolds. That will limit water flow through the engine as it can't escape through the exhaust.

Take your board off the back and have someone drive as you watch the exhaust ports coming out the back. You should be able to see equal amounts of water coming out each pipe along with the exhaust. Its not going to be a full pipe of water or anything like that but you can see water coming out. That is how I new I had something plugged on my old Malibu. In my case it was getting so hot it was melting the exhaust hose coming off the manifolds, but I had zero water flow out of one pipe....

[ToddXLV]

Can you tell if it is really running hot? It may be a temperature sensor issue indicating a false temp. If it thinks its too hot it probably won't let you crank it.

When you had the impeller replaced, did they give you the old one? Was it missing any blades? I've seen those break off and go inside the engine block and get hung up in the Exhaust Manifolds. That will limit water flow through the engine as it can't escape through the exhaust.

Take your board off the back and have someone drive as you watch the exhaust ports coming out the back. You should be able to see equal amounts of water coming out each pipe along with the exhaust. Its not going to be a full pipe of water or anything like that but you can see water coming out. That is how I new I had something plugged on my old Malibu. In my case it was getting so hot it was melting the exhaust hose coming off the manifolds, but I had zero water flow out of one pipe....

Excellent advice LSM.

[pat656]

Ok, I would check your impeller AGAIN. You may have sucked up some garbage and your impeller is shredded again. Did you idle your boat out of water for any extended amount of time? Anytime you have overheating problems at idle it usually means the impeller is shredded. The reason why you don't overheat when moving is because the water is being pushed thru the cooling system by pressure. I could almost put money on it that your impeller is chewed up. Go to your boat now and take off the plate to the impeller housing, pull out the impeller with a needle nose and inspect it.

The boat has not been turned on while out of the water. I checked the impeller and its fine.


Can you tell if it is really running hot? It may be a temperature sensor issue indicating a false temp. If it thinks its too hot it probably won't let you crank it.

When you had the impeller replaced, did they give you the old one? Was it missing any blades? I've seen those break off and go inside the engine block and get hung up in the Exhaust Manifolds. That will limit water flow through the engine as it can't escape through the exhaust.

Take your board off the back and have someone drive as you watch the exhaust ports coming out the back. You should be able to see equal amounts of water coming out each pipe along with the exhaust. Its not going to be a full pipe of water or anything like that but you can see water coming out. That is how I new I had something plugged on my old Malibu. In my case it was getting so hot it was melting the exhaust hose coming off the manifolds, but I had zero water flow out of one pipe....

i could tell it was hot because all of the hoses were burning hot and had scalding water in them (took them off while in the water) and I took the one off the water pump and cool water sprayed out but there is no blockage in any of the pipes, i checked.
I tried to start the boat when the temp read 135 degrees, it was not hot at the time. we cut if on and off while at 200 degrees and it started right up
i did get the old impeller and it was not broken or torn.

[LSM]

The boat has not been turned on while out of the water. I checked the impeller and its fine.



i could tell it was hot because all of the hoses were burning hot and had scalding water in them (took them off while in the water) and I took the one off the water pump and cool water sprayed out but there is no blockage in any of the pipes, i checked.
I tried to start the boat when the temp read 135 degrees, it was not hot at the time. we cut if on and off while at 200 degrees and it started right up
i did get the old impeller and it was not broken or torn.

Sounds like it may need to go back to the dealer or a dealer.

You mentioned after dinner that it would not start. Did it attempt to start? Was it spinning over or did it make any sound at all? Starter clicking or anything?

As for the cooling, if you've found nothing plugged and you know it is actually hot then it could be that the circulator pump has failed. From what I understand the circulation water pump either works or it does not. I don't think you can do much with it except replace it.

But, if it won't start you need to have that checked first......so probably dealer is the best bet.

[ToddXLV]

The boat has not been turned on while out of the water. I checked the impeller and its fine.



i could tell it was hot because all of the hoses were burning hot and had scalding water in them (took them off while in the water) and I took the one off the water pump and cool water sprayed out but there is no blockage in any of the pipes, i checked.
I tried to start the boat when the temp read 135 degrees, it was not hot at the time. we cut if on and off while at 200 degrees and it started right up
i did get the old impeller and it was not broken or torn.

Just by saying your old impeller was not broken or torn pretty much tells you that you have a blockage in the cooling system.

[pat656]

Sounds like it may need to go back to the dealer or a dealer.

You mentioned after dinner that it would not start. Did it attempt to start? Was it spinning over or did it make any sound at all? Starter clicking or anything?

As for the cooling, if you've found nothing plugged and you know it is actually hot then it could be that the circulator pump has failed. From what I understand the circulation water pump either works or it does not. I don't think you can do much with it except replace it.

But, if it won't start you need to have that checked first......so probably dealer is the best bet.

It fired but never started and finally tried to start and would not stay on, and then it sounded like it wasnt firing at all. I waited thinking it was flooded but still wouldnt start

[Engine Nut]

I have a 2006 Moomba Outback direct drive with 100hrs and it has a bad overheating problem.
The engine kept reaching 190 degrees and went into the protection mode where you can only idle until it gets below 180.
I had the impeller and thermostat replaced and i took off every water hose and inspected them for leaves/twigs etc since we spend a lot of time in the river.
We went back out and it still ran at 180 degrees and cut off many times at 190.
Then after a full day on the lake we parked the boat at the dock and had dinner. After about an hour we tried to start the boat and now it wont even start. We had to be towed to out trailer.

What might be causing this problem?

Did you check the transmision cooler? Sometimes they get packed with debris and restrict water flow through the system. Take the 1 1/4" hoses off each end of the cooler and flush from the top (outlet end) of the cooler.

I suspect your no-start issue may be vapor lock ... the fuel has vaporized in the system, probably between the tank and fuel pump and the engine will probably start once the fuel turns back to liquid.

[pat656]

Did you check the transmision cooler? Sometimes they get packed with debris and restrict water flow through the system. Take the 1 1/4" hoses off each end of the cooler and flush from the top (outlet end) of the cooler.

I suspect your no-start issue may be vapor lock ... the fuel has vaporized in the system, probably between the tank and fuel pump and the engine will probably start once the fuel turns back to liquid.

I did take the transmission cooler off when i inspected the hoses and cleaned the debris out (took off the hoses, pluged the holes where the trans fluid enters/exits and washed it out, no trash entered the hoses after cleaning)

We have had a problem with vapor lock before and took the gas cap off, waited a while, put it back on and i cranked right up but that didnt work this time

[buzcoats]

I have the exact same problem. Let me know if you get it resolved. I've checked everything and the only thing I can come with is the circulating pump. I even took it off but there's not much to it and it seems ok. Does anyone know how much water it should be pumping out at idle? (Mine pumps none at idle). thanks

[K_E_N]

pat, if you run hot at idle and not at speed, I would strongly suspect your circulating pump. With that pump, there are several possible problems.
Be absolutely sure that your accessory belt is on correctly. I've seen the belt on some cars that has been put on so that the water pump is turning backwards. This will allow a slow flow of water. Check the impeller on this pump. Don't just look at it and assume that since it looks good that it is. Sometimes the impeller can spin on the shaft. Hold the impellar while trying to turn the shaft by hand to assure that it's still tight. It's a pressed fit and can corrode, thus becoming loose.
One other thing is a faulty thermostat. I would completely remove it and see if that helps, just to rule it out.
Keep us informed when you finally find the problem.

[pat656]

I have the exact same problem. Let me know if you get it resolved. I've checked everything and the only thing I can come with is the circulating pump. I even took it off but there's not much to it and it seems ok. Does anyone know how much water it should be pumping out at idle? (Mine pumps none at idle). thanks

I will let everyone know. We took it from augusta, ga to charlotte, nc to a person to work on it and he spent a whole day and cannot find the problem.


pat, if you run hot at idle and not at speed, I would strongly suspect your circulating pump. With that pump, there are several possible problems.
Be absolutely sure that your accessory belt is on correctly. I've seen the belt on some cars that has been put on so that the water pump is turning backwards. This will allow a slow flow of water. Check the impeller on this pump. Don't just look at it and assume that since it looks good that it is. Sometimes the impeller can spin on the shaft. Hold the impellar while trying to turn the shaft by hand to assure that it's still tight. It's a pressed fit and can corrode, thus becoming loose.
One other thing is a faulty thermostat. I would completely remove it and see if that helps, just to rule it out.
Keep us informed when you finally find the problem.

The thermostat is fine and the impeller is fine.
I will ask the guy to check the circulating pump and belt

[mcdye]

thanks for the update, i like to follow threads and see resolution....you will get it fixed.

[buzcoats]

Yes, please let us know. I'm having similar issues.

[K_E_N]

Pat, did you ever get this issue resolved?

[gcnettl]

You may also try pulling the drain plugs on the block and observe if water comes out, and what the water looks like. If it looks like the water that you are in, then it should be good. If it looks rusty or muddy, then the water sleeves are clogged or gummed up. If you crank the motor, in water or on fake a lake, then you should get water streaming from these drain plugs. Running on rivers a lot you could have some dirt buildup in the water sleeves next to the cylinders, restricting flow at idle.

I assume that timing was not messed with with the spark plug changing. Improperly advanced timing will cause an engine to overheat.

I assume that the plug wires were reinstalled using the correct firing order, a misfiring may cause an overheating problem, and the misfire may not be easily noted under normal operating conditions on an EFI.

Some water pumps have a bypass valve, that opens under pressure, to ensure that the cylinders heat up evenly and do not develop "hot spots". When the thermostat opens, the pressure drops, and the bypass valve closes, and the water no longer is recirculated but rather goes through the thermostat and on the radiator/exhaust system. If this valve sticks, then most of the water will continuously circulate the block, never running through the thermostat and out of the engine block.

[pat656]

so we fixed it!!!! 1 MONTH LATER!!!!!

it was silicon in the thermostat from where the guy made a seal instead of buying a gasket and it needed a new salt water impeller

all fixed!!!!