retsina
Well-Known Member
The boat engine is a Volvo MD11C; the boat is out of the water for winter. The engine is sea water cooled; do I have to drain the water so it does nor freeze during winter?. Where are the drain plugs? Many Thanks.
Volvo MD11C water drain for winter?
- Thread starter retsina
- Start date
albineer
Well-Known Member
There are three drain cocks on the right hand side under the exhaust manifold. Make sure the water runs out when you open the cock. if it doesn't remove the whole thing and clear out the crud. Replacement drain cocks are probably still available, at a price. Our gear box (MSB2 I think) is also water cooled and drained by removing the LARGER of the two plugs underneath. The other releases the oil - nasty!
HTH
N
HTH
N
Grajan
Well-Known Member
Be sure to soak them with WD 40 or similar as they have a nasty habit of shearing off!
VicS
Well-Known Member
[ QUOTE ]
There are three drain cocks on the right hand side under the exhaust manifold
[/ QUOTE ]
One is on the underside of the exhaust manifold, the other two are low down on the cylinder blocks. The front one is hidden by the alternator.
They may have been replaced with plugs.
You may have to remove them and poke about with a bit of wire before you can get the water to drain out
Having drained off the salt water, Run the engine for a good while on a supply of fresh water, long enough to open the thermostat. Drain it again because you will have transferred all the salt water from the inlet pipework and the gearbox cooler to the engine! Then fill it with an antifreeze mixture. Don't just leave it empty and wet because that is the recipe for maximum corrosion.
If the pump impeller is due for change do it at the end of the winter because antifreeze is not too good on impellers. For that reason don't use a super strong antifreeze mixture if you intend keeping the old impeller in service. Ideally you should check that you are getting antifreeze out from the cylinder drain cocks if you crack them open.
I have never tried draining the cooling water from the gearbox due to complete inaccessibility but if possible that's a good idea, as it gets rid of a reservoir of salt water.
BTW the first thing to go for when you get signs of overheating are the two small passages in the exhaust manifold that carry the incoming water to the cylinder heads.
There are three drain cocks on the right hand side under the exhaust manifold
[/ QUOTE ]
One is on the underside of the exhaust manifold, the other two are low down on the cylinder blocks. The front one is hidden by the alternator.
They may have been replaced with plugs.
You may have to remove them and poke about with a bit of wire before you can get the water to drain out
Having drained off the salt water, Run the engine for a good while on a supply of fresh water, long enough to open the thermostat. Drain it again because you will have transferred all the salt water from the inlet pipework and the gearbox cooler to the engine! Then fill it with an antifreeze mixture. Don't just leave it empty and wet because that is the recipe for maximum corrosion.
If the pump impeller is due for change do it at the end of the winter because antifreeze is not too good on impellers. For that reason don't use a super strong antifreeze mixture if you intend keeping the old impeller in service. Ideally you should check that you are getting antifreeze out from the cylinder drain cocks if you crack them open.
I have never tried draining the cooling water from the gearbox due to complete inaccessibility but if possible that's a good idea, as it gets rid of a reservoir of salt water.
BTW the first thing to go for when you get signs of overheating are the two small passages in the exhaust manifold that carry the incoming water to the cylinder heads.
Saddletramp
Well-Known Member
Vic - speaking as one who has just ripped out the brass drain plug on my morris minor radiator (rather than do the sensible thing and just undo the bottom hose), I wonder if the drain plugs are not best left alone. If worried about getting the seawater out it may be easier to remove the thermostat.
On a related matter, I do not appear to be getting as much water out of the exhaust as is coming out of the pump. Sounds illogical but if I take off the pipe from the pump outlet there is good pressure which is not matched at the exhaust. I have trap and a large swan neck. Any ideas?
Sorry forgot to mention it is an MD2b
On a related matter, I do not appear to be getting as much water out of the exhaust as is coming out of the pump. Sounds illogical but if I take off the pipe from the pump outlet there is good pressure which is not matched at the exhaust. I have trap and a large swan neck. Any ideas?
Sorry forgot to mention it is an MD2b
VicS
Well-Known Member
[ QUOTE ]
If worried about getting the seawater out it may be easier to remove the thermostat. [ QUOTE ]
No that won't get the water out of the cylinder water jackets. It'll let some of the water out from the manifold and the heads depending on how much the engine is tilted backwards that's all. Just flushing with fresh water is no good either because there is not a forced flow through the cylinder jackets they are just cooled by convection. It'll take a long run in fresh water, several hours I would think, to flush out all the salt. [ QUOTE ]
I do not appear to be getting as much water out of the exhaust as is coming out of the pump. Sounds illogical
[/ QUOTE ] Sounds illogical at first but you are comparing the flow directly from the pump with no restriction with what it manages to force through the system. That's always going to be a bit less. but not that much perhaps. (Ive never compared them!)
Things to check are the pump impeller and body for wear but if you really are getting a good pressure that may be OK.
Check all hoses for possible collapse of the inner wall.
Check the bypass. In the MD11 that's a hole in the thermostat cover but there are some differences between the MD11 and the earlier MD2 (I have the manuals for the MD11 but I don't have them for the MD2 although its here: http://www.bluemoment.com/downloads.html if you need it.)
Most importantly check the water injection point into the exhaust manifold outlet bend. If that is getting choked up it'll restrict the flow.
Traps vary. We had an ""Elastomuffler" until it blew its self apart. We replaced that with a bit of plain exhaust hose but subsequently added a Vetus water trap immediately after the engine.
Swan neck is normal. Where space allows it should go up to just under the deck then down to the tail pipe.
If worried about getting the seawater out it may be easier to remove the thermostat. [ QUOTE ]
No that won't get the water out of the cylinder water jackets. It'll let some of the water out from the manifold and the heads depending on how much the engine is tilted backwards that's all. Just flushing with fresh water is no good either because there is not a forced flow through the cylinder jackets they are just cooled by convection. It'll take a long run in fresh water, several hours I would think, to flush out all the salt. [ QUOTE ]
I do not appear to be getting as much water out of the exhaust as is coming out of the pump. Sounds illogical
[/ QUOTE ] Sounds illogical at first but you are comparing the flow directly from the pump with no restriction with what it manages to force through the system. That's always going to be a bit less. but not that much perhaps. (Ive never compared them!)
Things to check are the pump impeller and body for wear but if you really are getting a good pressure that may be OK.
Check all hoses for possible collapse of the inner wall.
Check the bypass. In the MD11 that's a hole in the thermostat cover but there are some differences between the MD11 and the earlier MD2 (I have the manuals for the MD11 but I don't have them for the MD2 although its here: http://www.bluemoment.com/downloads.html if you need it.)
Most importantly check the water injection point into the exhaust manifold outlet bend. If that is getting choked up it'll restrict the flow.
Traps vary. We had an ""Elastomuffler" until it blew its self apart. We replaced that with a bit of plain exhaust hose but subsequently added a Vetus water trap immediately after the engine.
Swan neck is normal. Where space allows it should go up to just under the deck then down to the tail pipe.
Saddletramp
Well-Known Member
(quote) Most importantly check the water injection point into the exhaust manifold outlet bend. If that is getting choked up it'll restrict the flow. (quote)
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Good point Vic. I noticed it from cold so the thermostat should be closed and the water going straight into the manifold bend.
It has a new hose but there could be some gasket gunk in the way. I have the manuals from blue moment thanks.
Happy new year all!
/forums/images/graemlins/smile.gif
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Good point Vic. I noticed it from cold so the thermostat should be closed and the water going straight into the manifold bend.
It has a new hose but there could be some gasket gunk in the way. I have the manuals from blue moment thanks.
Happy new year all!
/forums/images/graemlins/smile.gif
