2011 Nautique 200 ZR409 6.0 overheat issue

[skifan]

I need some help with my 2011 200 6.0 overheating. It was only doing it when pulling barefooters at 39 mph for a long pass but did it this morning to me while skiing the course at 34 mph on the 4th pass of our 3rd set.

 

I will try to give some background of the boat without boring you guys. This is my third season with boat. I bought it with 1250 hours on it, guessing it was a ski school boat, it now has about 1450. The first season it did it overheated and went into limp mode a couple of times. The second season I changed the impeller, temp sensor and gauge because it read over while 100 it was cold. The gauge seams more accurate. This year I installed a new thermostat, when I took it apart I found there was not one there. It does have a closed cooling system and the coolant level is fine.

 

I'm just curious where to look next. I have not pulled the caps off of the heat exchanger yet, not sure if that's the next step. I'm also not sure if the exhaust hose can collapse and restrict flow. Or if the engine water pump can have impeller issues.

 

Any suggestions would be great. Thanks for your help.

[Kelvin]

I have the same boat as you with a similar histsory. First off, I hope you didn't install a thermostat in the traditional position when you realized one wasn't there. The thermostat on that engine is back near the heat exchanger. Also, when you check or add coolant, there is a process outlined in the owners manual that needs to be followed to ensure that all of the air is removed from the system. It essentially involves burping the system a few times during the coolant filling process. Those would be the areas where I would start.

 

Good Luck

Kelvin

[oldjeep]

Since it started overheating when you installed the thermostat, it seems like maybe you put the wrong temperature thermostat in there.

 

Also I would replace the impeller and check the trans cooler and heat exchanger for chunks of old impeller

[skifan]

Thanks for the comments. So the thermostat goes by the heat exchanger? Is there anything special that needs to be done to look inside the heat exchanger?

[skifan]

So I removed the thermostat from the automotive spot and replaced the thermostat in the heat exchanger. I replaced the impeller, it wasn't bad but was worn. I pulled the end caps off of the heat exchanger and the gaskets where all swelled up and broken apart. I tried to clean the heat exchanger the best I could and replaced the gaskets.

I was able to bleed the cooling system and when I drive it at 27 mph it runs fine at 175. When I try to run it at 36 mph the temp creeps up and climbs over 200 and causes the lights to come on.

Is there a better way to clean any debris from the heat exchanger? I removed the fresh water outlet hose and there seems to be good flow when the engine idles. Just not sure if there is enough flow when the engine is at speed.

The only other thing I can think of is that the short piece of exhaust tube after the manifold may be collapsed. Is there a way to confirm that?

Thanks for the help.

[oldjeep]

Did you check the trans cooler for debris?

[skifan]

Yes Trans cooler is clear.

[oldjeep]

Another less fun option is that the circulating pump impeller is damaged. Your 6.0 is different, but gm recalled a whole bunch of 5.7l engine water pumps in 2012 model year engines a few years back due to impellers that were cracking in half.

[Jody_Seal]

Is this a cat engine?

[skifan]

Yes it is.

[Jody_Seal]

You have an air pocket and air is trapped in the circ pump. The early cat 6.0 engines were a bitch to purge all the air out after a over heat. the last generation of 6.0 has a plug on the very top of each manifold to release air at it's highest point.

The trick is to hook engine up to a water source. then jack the trailer up as high as one can get it, we actually stand them up on the drag/prop guard. then run engine until warm, let stand for 20 min bleed off air at the plastic degas bottle where now is the highest point in the system and where you pour in the coolant. do this about three or four times and it should run as expected after that. The trick to not over heating these engines is to go ahead and bite the bullet and replace the impeller every 100 hours or once a year.

[unksskis]

Any additional tips @Jody_Seal , or if don't have ability to hook engine up to water source? Would being on a boat ramp help?

[skihacker]

So a bit of a long shot but do you know any auto techs? There is a gizmo in our world that uses compressed air to create a vacuum in the cooling system to fill it, mine is branded airlift. Minivans have heater cores that sit higher than any other part of the cooling system, might work for this.