Horrible weekend

[tmb]

I was just getting up on my new wakeboard when the boat stopped and a bunch of smoke started coming from the exhaust. Turns out the impellard burnt up. Went to the local nautique dealership, bought a new impellar, then spent 2 hours disconnecting hoses and thermastat to make sure all impellar pieces were out. Once I finished it started to rain so boarding was put off until Sunday morning. I get pulled up on Sunday (slaloming) and the boat stops again. It turns out there is now water pouring from my heater. The **** heater core cracked! I spent 1.5 hours trying to remove the heater and create a loop with the hoses so I could finally ski. Go out to ski at 2 this afternoon and find the waterpump is leaking! At least it hasn't been expensive.

[bkhallpass]

Well, the good news is your water systems should be in good shape for a while Yellow_Flash_Colorz:

BKH

[jthooker]

Overheating

tmb:
I hate to be the bearer of bad news, but I don’t think your problems are over yet.
When you lost water flow to the engine you also lost water flow through the exhaust system. That water flow keeps the exhaust manifolds, exhaust hoses, muffler, and through-hull fittings cooled during normal operation. Check your exhaust hoses by squeezing along the entire length of both of them. If they are hard, or if you can feel or hear them cracking inside then they are cooked. The same goes if they have obvious soft spots. If they are damaged, it may only be a short time before one or both of them split open and you will have dirty, rusty exhaust water spraying around inside the engine compartment. What happens is that the burnt interior lining peels off, blocks the exhaust flow, and you get a rather explosive rupture of an already heat-damaged hose.
It’s even possible that the smoke you saw coming out of the exhaust was from the interior linings of the hoses being burnt. It only takes a brief time for 1000 degree exhaust gas to burn those rubber hoses. Hopefully your over-temp sensor shut the engine down before the muffler and other fittings were also damaged.

[SGY]

RE: Overheating

Jt is right. The first thing that goes is the impeller. The second are the exhaust hoses. Check them out so you don't have another bad day.

[DavidF]

RE: Overheating

I concur. Even if the hoses do not rupture, they can be partially blocking the exhaust which leads to poor engine performance and fuel economy. Happened to me.

[tmb]

RE: Overheating

Thanks for the input. I will check this weekend and keep my finger's crossed.

[kingbriana]

RE: Overheating

I have a questions regarding this thread. We were boarding yesterday for several hours. The boat was working hard with a lot of people and ballast weight. We stopped the boat for fifteen minutes to take a break. When we started the boat back up and started to idle out to start again, the temperature guage went up to over 220. I immediately shut off the engine and heard a gurgling like what you hear from the launch control system when it is either filling or emptying. I turned it back on and ran it in neutral and the temp immediately came down to 160.

I have a hypothesis that when the boat was turned off hot, the water boiled off or evaporated leaving an air pocket that blocked the water flow from the impeller to the water pump. It was only idling for less than a minute until I realized the hot temperature.

I have two questions:

1. What does anyone think about my hypothesis or what could have caused this?
2. I checked the hoses and don't feel any soft spots. The boat ran fine the rest of the day and this morning. Is there any other damage that could have happened that I am not seeing?

Thanks.

[jthooker]

kingbriana's overheat

kingbriana,

Let's assume that everything about your cooling system is functioning properly and that this is the first time this has happened.

If those assumptions are correct, then what happened was that you sucked a piece of material up against the water intake under the hull when you restarted the engine after your break. Something like a plastic sandwich wrapper or even a heavy tree leaf could block off the water inflow. The pump suction held it in place as you idled back out, but when you shut the engine off the suction released and the water flowing under the hull swept the material away.

If the problem is actually with your cooling system then the most likely cause is a worn impeller in your raw water pump. They can cause intermittent cooling problems as they wear out. If you haven't replaced that in two seasons of skiing then I would go ahead and replace it anyway just as a matter of good preventive maintenance. Especially now that it may have been run dry during this recent overheating episode.

The gurgling you heard was residual water boiling in the engine block and heads. That is normal in an engine overheat situation.

As to an air pocket blocking the water flow, that is very unlikely since the cooling system is "open" in the sense that there is nothing to stop air from flowing through the system any more than the water.

Exhaust hose damage? If you flexed the exterior casings and they feel okay then they were probably not damaged enough to cause problems.

Other possible damage? Whenever an engine gets seriously overheated there is always the potential for subsequent head gasket leakage. Pull your dipstick frequently for a few weeks to check for water contamination in the oil. (Milky color).

I hope everything turns out okay.
Keep us posted.

[OldFart]

RE: kingbriana

tmb, have to reinforce a concern about the muffler. EXTREME heat will actually melt resin & fiberglass can be hanging down, restricting water flow. Disconnect the hoses & look inside the muffler.

[inboardsonly]

Something I did right from the start is put ball valves on the engine block
where the heater hoses connect.
If for some strange reason the heater core lets go on me, I can just shut off the valves on the block, and no worries.
And since they are on the block, if a hose should chafe through you're covered there as well.

When I'm on holidays, I want to make sure that nothing can keep me off the lake.

My engine overheated this year because I was in a rush to get it out of storage and onto the lake. I didn't run it on the trailer like I normally do, and didn't see that the strainer was loose.... That strainer has got to be the no. 1 source of impeller failure. Luckily, I had my tools in the boat with me, and a spare impeller kit, and had it up and running in 10 (oh-crap-there-goes-my-vacation) minutes.

Changed the oil after the overheat, and new thermostat, and it seems to be ok.

[EchoLodge]

Six years ago I put my fresh water pump on upside down. The pump now was sucking all the water out of my engine. Things got hot fast. So hot that the resin muffler had a few small pin holes. After I flipped the pump around and resined up the pin holes I was back in action. That was about 600 hours of run time ago. Now with over a 1000 hours my engine does not burn a drop of oil between 50 hour changes. Although I have replacement hoses, I am still running with my 15 year old original one. Point being... I think you would really have to cook your hoses for them to fail. I just replaced the original thermostat this season and the hose is still in good shape. I too run ball valves on my heater and shower.

[tmb]

thanks for everyone's input. I checked the exhaust this weekend and everything is good. The temp in my boat never exceeded 180 and hasn't run over 145 or so since. I have run into another problem though. My waterpump is dripping. I replaced the gasket twice but it still drips. The local dealer told me to get some gasket seal to stop it.

What are these ball valves you guys are talking about? Sounds like a good idea.

[EchoLodge]

http://www.planetnautique.com/index....pic&pic_id=396[url]

[jedgell]

Where can you get these ball valves? Sounds like a great idea to keep the boat going if you have any problems with heater/shower.

[ag4ever]

Home Depot, Lowes, Plumbing Supply, etc...