Engine Overheated Today

[No Hurry]

I got my boat out of the boat yard today after adding trimtabs and changing the pitch in my props.

As I pulled away from the yard, I let the engines idle along while they got up to operating temp. I have 6BTA's 250hp, with 175ish running temp. As I increased the throttle, I smelled something that smelled like hot brakes on a car, or burning rubber. I immediately noticed the temp climbing to about 230, The guage goes to 250 and it didn't get that far. I pulled down to idle and looked in the engine compartment (I had the hatch open). The belt was still on, which was my first thought. Then ran back and looked at the exhaust.. no water coming out. So I cut the engine. The engine was at 230 or so for about 2 minutes max (while running) and most of that was at idle after I pulled it back down. Obviously it stayed hot until it cooled down naturally.

I was only about a 1/4 mile from my dock so I limped the rest of the way on just the starboard.

I assume I either sucked something up the intake or the impeller just came apart.

I had to get back to work, so I couldn't do anything else then, but I'm going to pull the impeller housing tonight.

I hope that it wasn't hot enough to do any damage to the engine. Any recommemdations of things to check or do before I start it back up would be appreciated.

Basicly I hoping for some moral support that I didn't screw anything up. My biggest fear is screwing up an engine. I'd hate to tell my wife that. Any observations are appreciated.

Benjy

 

[Avenger]

It's not a wet liner engine.... come to think of it, it's not an any kind of liner engine, so it should have survived with no issues.

I had an unplanned shutdown on my dad's boat (363 Ford diesels) when running hard and the gauge got to about 260 before I could get it restarted and get cooland flowing again. The engine never noticed.

Just on the off chance that you hurt a head gasket, bar it by hand or crank it with the shutdown pulled before you start it next time. If there's any issues you'll figure it out soon enough.

 

[REBrueckner]

This is why I strongly recommend raw water flow meters which sound an alarm the instant raw water is lost. And listening to your exhaust sound when underway.

No real way to tell if you did damage right now; after fixing the problem, run the engine and if it works you were lucky. Chances are it will work ok but you never know when something is now stressed and may fail due to premature wear in the future.

As noted above, initial cranking after repair with the engine shutdown button activated (in shutdown mode) is a good idea just to be sure the engine turns normally.

 

[Pascal]

out an aqualarm exhaust temp sensor,... about $100 for both will react faster than the coolant temp gauge.

 

[No Hurry]

Thanks for the replys. I pulled the impeller last night and it was totally chewed up. I have a guy thats going under the boat today to see if anything is blocking the intake. I smelled it when it happened and the engines didn't run long after that. So hopefully no damage. I will look into the raw water flow meter. Do you have a name brand you could recommend.

Thanks again,

Benjy

 

[Pascal]

aqualarm

they have both flow meters and exhaust temp alarm, I prefer the exhaust temp, it's easier to install and no moving parts

 

[StratPlan61]

Benjy, you have probably already thought of this, IF the impellor was missing any pieces or vanes, you might want to track them all down and recover them before heading out.

 

[MikeP]

Yep...the pieces are now residing in the intercooler or heat exchanger, depending on which is first after the pump in the flow chain. Reverse flushing will flush them out of hiding. No pun intended...

Well, OK, the pun was intended.

 

[No Hurry]

Thanks guys, I did think of that, and I will back -flush today before re-installing the the impeller. There was no obstruction on the intake to cause this failure, just an air lock in the system.

Lessons Learned: Any time you haul and relaunch, make sure the intake hose and strainer are full (even though they should be self priming). After talking with a friend/marine mechanic, it sounds like this is not that uncommon if proper care is not taken handling the shutoffs before take out. I did not close them before take out and obviously alot of the water drained out.

Next time I will close the shutoffs before haul out and then inspect and top off the hoses form the impeller down before restarting the engines on the re-splash. In retrospect this seems like a common sense kind of thing to do, but like alot of things with boats, we learn form our mistakes.

thanks,
Benjy