Comodave
Moderator Emeritus
- Joined
- Jul 2, 2015
- Messages
- 21,283
- Location
- Au Gres, MI
- Vessel Name
- Black Dog
- Vessel Make
- Formula 41PC
Did the overheating start at the end of the 5 hour run or when you increased power at the end of the 5 hour run?
Did the overheating start at the end of the 5 hour run or when you increased power at the end of the 5 hour run?
There is only one way to find out for sure, pull it out and see if the vanes are curved and stiffYeah but I find it hard to believe they would take a set towards the end of a 5 hr trip.
Ski, are these impellers like the impellers of an outboard motor in the respect that if the engine is not run for a long period of time the impellers will get stiff causing the vanes to not straighten out when they get to the wider part of the volute causing it to not pull the correct amount of water with. Especially at higher RPMs?
One thing I didn't mention is that it is possible for even a relatively new impeller to fail because the rubber breaks away from the bronze hub. The impeller may look fine buts its essentially "slipping". This isn't common, but it does happen.
Ken
More common than you think and probably the easiest to check. It would be what I would look at 1st.
That looks like a pretty heathy flow to me. You still could have some type of restriction. When I first bought my boat the port engine would get dangerously hot if I pushed it over 1800. It turned out to be heavy scaling on the main heat exchanger on that engine. If yours are scaled, and then for some reason one got a little extra crap in it or if there are lots of bits of old zincs in it, it could be just clogged enough to cause overheat when pushed above a certain level. In any case, I think a look inside the leading ends of the first heat exchanger in the line (is it the oil cooler?) and inside the leading end of the main heat exchanger is in order.
Have you checked the antifreeze level INSIDE the coolant tank (The one with the pressure cap on it)? The level in the overflow tank may not be telling the story.
Ken
Crap, post #4 asked you that very question. Coolant level ok?? Ans: yep, ok.
So you have a leak somewhere, look for it. Hoses shrink in cold and leak, go around, look and snug up clamps.
Yep. I feel like an idiot. In my defense the overflow had coolant. We even added to it to get it above the minimum when cold mark. Today was the first time I’ve been back to the boat since it happened and I’m sans kinds so I had time to really check things out.
There are no coolant leaks that I can see. I ran the engine for a total of about 30 minutes today.
Idk, maybe it’s been low from the PO and it finally got to a level that it started sucking air. I’ll know more on Friday after a 2 hour drive.
Sorry guys
A faulty radiator cap is a common cause for an expansion tank not working. Lesson learned here. Start with the simple stuff.If it does end up dropping and you can find no leak it's possible to be the main heat exchanger
Once you fix the leak you will have to fix the clogged or otherwise malfunctioning expansion bottle circuit.
And verify the other engine's expansion bottle circuit is working and that engine is full of coolant. (Level in bottle should rise an inch or 2 when engine is fully warmed up and go back to exactly where it was when engine is fully cooled down)
When I bought my boat neither expansion bottle circuit worked but both bottles had coolant. If I hadn't watched them carefully and pulled the pressure caps off I never would have known.
Ken