VOLVO PENTA MD2030D Loss of coolant

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Aug 29, 2013
4
Bavaria 38 Cruiser DENIA
Hi everybody.
The other nearly no wind day when cruising on my Bavaria 38C with a 2005 VOLVO PENTA MD2030D diesel engine I got an overheat warning and shut it down immediately. I found the coolant expansian tank empty and added 4.5l of coolant which strangely enough dissappeared completely without leaving any visible trace. I took me hours to return to the marina on sail only. Then I refilled the expansion tank once again, restarted the engine for a few minutes to enter my berth and it ran smoothly. I suspected, dismounted and checked the fresh/sea water heat exchanger but found no leaks. The other theoretical possibility would be a deficient head gasket, but there is no water in the oil, and a loss of more than 4.5l (1 gallon) of coolant in a few minutes seems a lot to me. Before starting any serious and possibly costly repairs, has anyone any idea where all this coolant has gone...???
Thanks for your attention.
 

RichH

.
Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
Find a mechanic who can perform a 'black light' testijng of your cooling water (both sides of the heat exchange). and if the fluorescent dye shows that you have carbon monoxide present in your water, then an engine pressure leak down test (of cooling water circuit AND combustion chambers) to ascertain either a blown head gasket OR 'pin hole' in your exhaust manifold, etc. Have the mechanic or yourself do a pressure leak down test on the fresh water side of the cooling circuit first ... with the injectors removed so you can see evidence of water IN the cylinders.
If the cooling water is escaping from a blown head gasket and the gasket is also leaking between cylinders ... the water will be escaping as 'steam' and is usually not visually noticeable in the exhaust unless the cylinder is overwhelmed by the water/steam. If the head gasket is found/assayed to be intact, then remove and evaluate the exhaust manifold.
 
Aug 29, 2013
4
Bavaria 38 Cruiser DENIA
Thanks RichH. But is it possible for 1 gallon of coolant dissappearing like that when the engine isn't running. I also noticed when the engine was shut down and the heat exchanger still in place that the coolant ran down the exhaust manifold, but afterwards I found no leak in the heat exchanger What could be happening in that case?
 

cbsura

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Jun 7, 2004
27
Bavaria 32 Branford, CT
Another area to check could be the coolant loop to the hot water heater.
 
Aug 29, 2013
4
Bavaria 38 Cruiser DENIA
Hi everybody,

Finally I dismounted half of the engine and found a 1/2 inch hole in the aluminum heat exchanger housing near the iron cast exhaust elbow. That solves the mystery but carries a $1000 price tag for an original replacement part (a lot of money if you consider the price tag of a whole refitted engine). Anyway it would be unwise and unsafe to try to repair this as there probably are other corroded places in the housing just waiting to go south as well. The previous owner apparently didn't look well after his engine...
Nevertheless there seems to be no other damage, which is quite fortunate given the circumstances .
Thanks to all of you for your help and attention.
 
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