MD22 Diesel Heat Exchanger problems

[whiteshythe]

Having said what I have said, one of your points, the fresh water pump isnt running says that it isnt the calorifier, only other thing is the head gasket or the exhaust elbow is blocked
Stu

Boatone, in my case, there was no noticeable running of the fresh water pump, just a minute pinhole in the calorifier coil which pressurized the coolant system.

Why not turn your water pump off, allow the cylinder to depressurize, then check for coolant leak.

Regards,

Steve.

 

[boatone]

Having said what I have said, one of your points, the fresh water pump isnt running says that it isnt the calorifier, only other thing is the head gasket or the exhaust elbow is blocked
Stu

Ran the immersion heater for several hours yesterday whilst moored up and engine not running. No evidence of anything abnormal - certainly no change in coolant level or any water expelled thru pressure cap so I guess that rules out the calorifier.

Stu - I appreciate what you say re a blocked or restricted exhaust elbow and can understand that would increase the pressure in the raw water side. But surely there would still need to be a leak for raw water to actually cross over into the coolant?

 

[VicS]

Ran the immersion heater for several hours yesterday whilst moored up and engine not running. No evidence of anything abnormal - certainly no change in coolant level or any water expelled thru pressure cap so I guess that rules out the calorifier.

Stu - I appreciate what you say re a blocked or restricted exhaust elbow and can understand that would increase the pressure in the raw water side. But surely there would still need to be a leak for raw water to actually cross over into the coolant?

Yes there would but normally the higher pressure would be the engine coolant, at least when up to full working temp, so you would simply lose coolant. For the flow to be from the raw water inwrads someting must be making the raw water pressure higher than the coolant pressure!

Check the end caps AND the injection into the exhaust

 

[Heckler]

Yes there would but normally the higher pressure would be the engine coolant, at least when up to full working temp, so you would simply lose coolant. For the flow to be from the raw water inwrads someting must be making the raw water pressure higher than the coolant pressure!

Check the end caps AND the injection into the exhaust

If the end caps are a bit loose then a blockage in the exhaust elbow could then force water past the lands. Go with what Vic says
Stu

 

[Ruffles]

If the end caps are a bit loose then a blockage in the exhaust elbow could then force water past the lands. Go with what Vic says
Stu

If the end cap on the IN side is leaking then you will see it balloon slightly when you rev the engine. Particularly if the ultimate cause is a corroded manifold causing excess pressure in the system.

 

[boatone]

If the end cap on the IN side is leaking then you will see it balloon slightly when you rev the engine. Particularly if the ultimate cause is a corroded manifold causing excess pressure in the system.

Thats very helpful - something I can actually look for !

 

[boatone]

Talking about the rubber 'end caps' does anyone know if they have a recommended service life? My engines are circa 1997 so 13 years old now and probably the original caps.

My engineer tells me that he ensured the jubilee clips at each end were tight and all seemed ok - is it possible for there to be a wear and tear issue inside and invisible that would not be just a case of the jubilees needing tightening up?

These issues are a pain to resolve especially when no-one holds the spares in stock and it takes typically 7 days to get them. On my boat gaining full access to the engines means stripping furniture out of the saloon/wheelhouse so having likely needed spares available is a good idea before one starts! However, those end caps are about £120 a pair (best price I can find) so getting them and finding they are not needed is equally painful !

 

[boatone]

Progress update

With kind assistance from another forumite we removed the end caps from the heat exchanger this morning and extracted the tube stack. No signs of any damage to the stack at all - a bit of a clean up and looks pretty nigh perfect.

However ..... a rubber sleeve locating the forward end of the stack within the housing was completely knackered - split and broken up - item 9 in the diagram. No spare available at any of the suppliers within sensible range so it will need to be ordered on Monday.

 

[oldgit]

God,that chap looks so intelligent ,no wonder he has to fight the girls off with a pointy stick and all at only £500 pounds per hour + VAT and a few trifling expenses such as the jet and personal bikini clad lifestyle trainer..