My engine has frozen up

[Miker]

The engine is a Volvo Penta 2010. I came to start it the other day but no luck, so as I am clueless in engine matters (I must attend a course) I got my local service engineer to look at it. He showed me a metal tube with rods through it, from somewhere in the exhaust system between the engine and the exhaust box I think, which was solid with ice.
Can anyone tell me its purpose and what it and the rubber tube I assume it fits in are called? Also, how did the water get there in the first place (from the combustion process?) and what I should have done to prevent it accumulating when I laid the boat up? I changed the oil and oil filter, and ran the engine for a few minutes feeding water and antfreeze through the engine. Fortunately, it was just this exhaust thingy that was frozen up. I am wondering whether running the engine longer at lay up would have heated it more and so dissipated the water in the exhaust?

 

[rhumlady]

It sound like the heat exchanger which has fresh water circulating through it and back through the engine. This is cooled by raw sea water which circulates around the tube matrix taking away the heat and discharging via the exhaust hose. It depends how you fed the antifreeze into the system where it went. I don't have a heat exchanger as my engine is raw water cooled and I would always try to ensure the sea water is drained from the engine. I would think that would be the best thing for the raw water side of your system While the anti freeze should deal with the fresh water side.

 

[Salty John]

It's your heat exchanger. It is a bundle of tubes through which the freshwater that cools your engine circulates. These tubes are located in a larger outer case through which sea water circulates. The fresh water is cooled by this indirect contact with the sea water. Hence the term heat exchanger - the heat in the fresh water is taken away by the cool seawater.
The sea water enters through a seacock and strainer, a coarse filter, circulates through the heat exchanger cooling the fresh water and is then ejected through the exhaust system. The fresh water continues to circulate through the engine.
Think of the heat exchanger as the radiator in your car. If you didn't put antifreeze in your car radiator you would get the same effect as you have seen in your heat exchanger - the water freezes.

 

[Miker]

Thanks for the replies. Next question, how do I prevent it happening next winter?

 

[brianrunyard]

To prevent it happening again:
Either drain down both fresh water and raw water systems or:
1. Use Anti-freeze in the fresh water system as you would in a car.
2. Drain down the raw water system

 

[Miker]

Thanks for the replies. But I'm puzzled. Why would a frozen heat exchanger block up the exhaust system and so prevent the engine from starting?

 

[FAITIRA]

[ QUOTE ]
To prevent it happening again:
Either drain down both fresh water and raw water systems or:
1. Use Anti-freeze in the fresh water system as you would in a car.
2. Drain down the raw water system

[/ QUOTE ]

Good advice, re. drain down the RAW WATER SYSTEM I had, a few years ago in Scotland, a problem, where the RAW WATER froze, destroying the "BOWMAN" heat exchanger.

 

[chrishelen]

If the H/E is a frozen block chances the rest of the cooling system is also frozen,there could be a possibility of futher damage to the engine which needs a more detailed investigation.

 

[uforea]

If you have a "wet" exhaust system it will be fitted with some sort of anti-syphon device which will have water in it if you have'nt removed the plug to drain it down for winter. This water will have frozen, blocking the exhaust system. Fingers crossed there is no damage to the engine, which you won't know until it all thaws out.

Ted

 

[Miker]

The service engineer has checked over the engine and says that nothing is damaged. I have to buy a new exhaust hose thingy and pay for the labour. Still with the hard frost at night it could have been worse.

 

[FAITIRA]

[ QUOTE ]
The service engineer has checked over the engine and says that nothing is damaged. I have to buy a new exhaust hose thingy and pay for the labour. Still with the hard frost at night it could have been worse.

[/ QUOTE ]
Pleased for you that all is well!

 

[wotayottie]

For your own safety, get to know how an engine works and what the various bits are. You dont need to turn yourself into a mechanic, but you do need to know more than you do at the moment if only to avoid unnecessary bills and to deal with simple problems when no m,echanic is available..

If your "thingy" is indeed the heat exchanger it means that your engine has 2 cooling circuits. One is the main circuit that runs through the engine block and which should be filled with an anti freeze solution. This circuit is cooled by the sea water flowing through the heat exchanger thingy. Its that sea water that has frozen - a bit surprising t b h. You're not moored on the Lakes are you?

Anyway, you cant put antifreeze in that side of the circuit but if you are not going to use your boat it is usually possible to shut all seacocks and drain that part of the circuit. Failing that, an electric greehouse heater in the boat should prevent freezing.

Dont see why the heat exchanger freezing would stop your engine from starting - though it may well cause damage if you did start up.. Either you misunderstood what the mech said, or we've guessed the wrong component is the "thingy".

 

[Miker]

The engineer confirmed that the thingy was the heat exchanger which was frozen. He also said that there was frozen water in the exhaust hose. The boat was out of the water on chocks. To winterise, I had flushed out the sea water system with tap water and added anti freeze to the last of the water in the bucket, a procedure that I have carried out for a good few years. This winter, however, it has been exceptionally cold on the Fylde coast.