Loss of coolant from fresh water cooled Volvo Penta 2002B

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Chuckle54

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I have a VP 2002 in my GK29. A week or so ago we left the mooring and within a few yards the overheat alarm sounded. Limped back to the mooring and discovered that the coolant from the sealed circuit seemed to have gone. There was no trace of coolant in the bilge. Refilled and so far the problem hasn't re-occurred and the engine runs as smoothly as ever.
From research on the internet it seems the issue could have been caused by a cracked head/faulty head gasket or corroded heat exchanger? The oil level is constant and clean so possibly not a cracked head or gasket?
Which leaves the heat exchanger. I've been advised that the internals of the exchanger could be corroded and allowing coolant to mix with the raw water and then be expelled from the exhaust.
I had a good stare at the heat exchanger and noticed white deposits on the body and around the rear rubber cap. I've ordered new gaskets and will attempt to replace everything.
If the internals are corroded could I get away with covering the brass tubes with silicon tubing of the correct diameter. A bit of a bodge I know but the price of a replacement heat exchanger is ludricous. Also wondering why it hasn't reoccurred. We were recently motoring into a 36 knot head wind against the tide and the engine behaved impeccably with no loss of coolant whatsoever.
 
Chuckle54 said:
From research on the internet it seems the issue could have been caused by a cracked head/faulty head gasket or corroded heat exchanger? The oil level is constant and clean so possibly not a cracked head or gasket?
Click to expand...

Cracked heads usually allow water to enter the cylinders, not always, but mostly.

Head gaskets can allow oil to get in the water, water to get in the oil, compression to leak between cylinders, compression to get into the water jacket, water to get in the cylinder, water or oil to leak externally. Any, all, or any combination thereof i'm afraid.

You could have a small crack or small leak from the head gasket between the water jacket and the cylinder/s. This would normally lead to excess pressure in the coolant, ultimately leading to coolant being expelled from the pressure cap. Does the heat exchanger have an overflow pipe leading to a bottle or something, where the coolant could have gone ?

You could get a "block test" kit from Ebay to confirm it isn't the head/head gasket.
 
Mark which way the end caps go on

The water flow is a labyrinth along across back along etc
Get it wrong and you loose cooling area!
 
Chuckle54 said:
Also wondering why it hasn't reoccurred. We were recently motoring into a 36 knot head wind against the tide and the engine behaved impeccably with no loss of coolant whatsoever.
Click to expand...

Perhaps there isn't a major problem. If the symptoms don't recur, maybe you leave things alone.
 
pvb said:
Perhaps there isn't a major problem. If the symptoms don't recur, maybe you leave things alone.
Click to expand...

Hopefully you're right. Had to move the yacht today and with absolutely no wind ended up motoring for over 3 hours. (I did have a drum of 50/50 antifreeze on hand. ) Not the most relaxing trip as I was expecting the overheat alarm to sound. Arrived safely in our winter quarters and on checking the coolant level discovered it was once again unchanged????
She's coming out at the end of this month so I may check every thing just in case.
 
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It is not clear just how sudden your fluid loss was–between your pre-start engine check and the alarm sounding or between the last engine check which may have been prior to your pushing into the 36knot wind and adverse tide and the alarm sounding? Could the hard work/high revs have caused fluid loss which normal running does not?
Try working it hard and see if it happens again.
 
Cardinal said:
It is not clear just how sudden your fluid loss was–between your pre-start engine check and the alarm sounding or between the last engine check which may have been prior to your pushing into the 36knot wind and adverse tide and the alarm sounding? Could the hard work/high revs have caused fluid loss which normal running does not?
Try working it hard and see if it happens again.
Click to expand...
The fluid loss came about as we left the mooring and within 50 yards. After replenishing the coolant we went for a short sail and were caught out in high winds (not forecasted!) and turned around and motored back in. The engine was working very hard against a head wind and the tide. We were averaging less than 2 knots. Despite that the coolant level didnt budge. As was the case today when we motor sailed for over 3 hours. Again the coolant level was spot on.
 
I have the same engine. Twice in five years I've experienced a drop in coolant level, but it only took about half a litre to replenish it. I've no idea why but have speculated that lt was some sort of airlock somewhere. Did you measure how much you put in?
 
Familiar scenario

Two options, based on my experience

1 Check the cap on the header tank. Had endless problems with loss of liquid - bought a new header tank cap and the problem went away.
2 The last straw was the occasional vanishing of some liquid - turned out to be a micro leak that when the pressure built up as the water in the sealed side warmed up and the new cap [see 1] did its job then fluid was forced out of the heat exchanger via the sea water side.
Spent an age cleaning the heat exchanger and a fortune on those little rubber bits that the Volvo heat exchanger need - did not solve the problem. In fact it made matters worse because all the crud removed just made the leak worse. Re rubber bits, PM me if you'd like a load in an envelope.
Changed the heat exchanger for an alternative make and never looked back. ASAP were very helpful with the replacement part.
 
StormNorm said:
I have the same engine. Twice in five years I've experienced a drop in coolant level, but it only took about half a litre to replenish it. I've no idea why but have speculated that lt was some sort of airlock somewhere. Did you measure how much you put in?
Click to expand...

An airlock sounds plausible though I lost just under 2 litres in as many minutes
 
Gwylan said:
Familiar scenario

Two options, based on my experience

1 Check the cap on the header tank. Had endless problems with loss of liquid - bought a new header tank cap and the problem went away.
2 The last straw was the occasional vanishing of some liquid - turned out to be a micro leak that when the pressure built up as the water in the sealed side warmed up and the new cap [see 1] did its job then fluid was forced out of the heat exchanger via the sea water side.
Spent an age cleaning the heat exchanger and a fortune on those little rubber bits that the Volvo heat exchanger need - did not solve the problem. In fact it made matters worse because all the crud removed just made the leak worse. Re rubber bits, PM me if you'd like a load in an envelope.
Changed the heat exchanger for an alternative make and never looked back. ASAP were very helpful with the replacement part.
Click to expand...

given the crud on the outside of the end cap of the heat exchanger, I suspect something is going on in the internals. Have sent pm re rubber bits! Can you provide more details on the alternative heat exchanger.
Many thanks
 
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