Raw Water Cooling Loss: Overheating!

[knottybuoyz]

So I'm guessin' that loosin' the RWC for about 5 mins (no idiot light) isn't a good thing eh? Boat won't turn over now just Clunk! She's done right? Bent crank? Bent valves?

[Event_Horizon]

Heyo, your situation is not good. Overheating the engine causes serious problems. First you need to take off the distributor cap and see if your engine will still turn. If it does turn then you could have:

a) broken timing belt leaving piston valves open (zero compression)
b) blown head gasket (zero compression)

If the timing belt is broken you may also have additional problems depending on piston design. Since I donno your engine make and model I really cant be sure. Basically there are two types of engines, free and interference. In a free engine the piston is capable of damaging mis-timed vales on the upstroke, on the free it is not. Basically if you have an interference engine you could have bent valves, connecting rods, broken shaft bearing, among other very expensive things.

When checking the distributor, also check the oil and coolant for things that dont belong (like a bunch of metal or parts of your piston/piston rings). Also look for a white film on the dipstick or radiator cap.

If your engine doesn't turn (seized) then grab a beer, you might have accidently welded your engine block together and it could be time for a new engine.

Reguardless this sounds like fairly serious fix. HOPE for a broken timing belt and that you have a free piston design, in that scenario all you will need to do is replace the stupid belt

[knottybuoyz]

Originally Posted by Event_Horizon

If your engine doesn't turn (seized) then grab a beer, you might have accidently welded your engine block together and it could be time for a new engine.

That's the most likely outcome for this engine. It's an '87 Volvo Penta AQ271A which is a GM 350 w/duoprop outdrive. No timing belt on this vintage.

Originally Posted by Event_Horizon

Reguardless this sounds like fairly serious fix. HOPE for a broken timing belt and that you have a free piston design, in that scenario all you will need to do is replace the stupid belt

I'd never be so lucky. I'm pretty sure there's something in there that's twisted out of shape. A long block is $1650 Cdn so it's well within reach to change it out myself. Just need a case of beer and some brawny buddies to heft it out!

[Jesse]

You probably have a piston seized in its cylinder bore. If that is the case easy solutions are slim to none and it may be time to pull it out and rebuild or replace it, what engine is it? If you are lucky the head, or heads are not damaged and should allow you to go with a short block and save a bit of money. Sorry to hear of your misfortune and hope your luck improves.
Jesse

[Charlie]

Sorry to hear about that Knotty. $1650 Canadian is not money to sneeze at but at least it is something you can afford. My cousin has a saying, "Anything that you can right a check for and take care of isn't really a problem." I like her saying and find a fair bit of truth in it.

[knottybuoyz]

it's a Volvo Penta AQ271A (GM 350). I'll pull the plugs tomorrow and see what comes out if it'll turn over. Might of split a head gasket and hydrolocked. The heads have already been decked at least once so I don't know if they can be done again.

[knottybuoyz]

It runs. Pulled the plugs. Pumped out the water. Sprayed 'em all good with WD40 (didn't know what else to use.) Pulled the impeller. It's only 2 yrs old. I had to have pulled something through it to do this much damage.



New plugs, put it all back together. Started right up. No noises. A lil' rough idle. Next (when it cools down) I'll change the oil and set the timing. Let's hope it hangs together.

[Charlie]

Great News Knotty!! I am very happy for you.

Did you flush out the heat exchanger in reverse to get the parts or the impeller out. I was told that you should do that to try and get ail the pieces out. In fact the mechanic I worked went so far as to say that you should try and reassemble the impeller to make sure that you have all the parts. My impeller looked much worse than that when it ran dry for a few minutes. The impeller was dry because of an air leak in the raw water strainer. It is happening again so I need to either buy a new stariner or buy a new pacakge of gaskets.

Once again glad to hear no real damage was done.

[knottybuoyz]

Thnx Charlie

This is a fresh water cooled model. No heat exchanger and no strainer. Cooling water comes in through the outdrive leg (DuoProp) right into the raw water pump. I backflushed everything from the top of the engine by pulling off the thermostat housing. The only place I couldn't really get to are the risers on the exhaust manifolds. I'm thinking I'll be pulling the heads this winter anyways. We'll just see how it goes. If it gives me problems I'll just put it on the trailer for the year.

I still have to change the oil & set the timing b4 we go anywhere. My confidence is a little shaken at the moment so we won't be going very far.

Standby.....

[knottybuoyz]

Originally Posted by knottybuoyz

Standby.....

Everything appears to be fine. Boat runs well. Jumps right up on plane. Idles perfectly. Might just have dodged a bullet this time.

[svjobeth]

Yep, as Charlie said, be sure to flush the system well to remove the little bits of impeller that remain...

I wouldn't be so sure that you had a specific external event (i.e. pulling something through) the raw water intakes to cause the damages you saw to the impeller. Like zincs, impellers have a 'time' based working life in addition to an operational working life. An impeller sitting in an infrequently used engine can develop problems that can lead to failure as if it had been run-dry. Most commonly, unused impellers will develop a set to the vanes, which can lead to poor performance and diminished water flow, or cracks in the vane root will form, causing a complete failure of the impeller.

I usually (read: try) change my impeller every 100 hours or once per year - whichever happens first - to keep things flowing.

Glad to know you're up and running -

[Charlie]

Good to hear KB. That is really great news!!!!