Md11 md28

[rib]

Hi.. I'm trying to help out a lady stuck here in Turkey with a couple problems.. Firstly her husband who has recently died did a fresh water conversion md11/md28 hybrid several thousand hours ago.. He recently did a rebuild four years ago but got ill and died with out really testing this rebuild.. When she came to remove the boat from the boat yard by sea. She over heated... Or I think she may of had a water/ airlock.. So I'm trying to work out how much freshwater would I expect to fill this hybrid cooling system..?. There are other problems which need sorting but this is my starting point

 

[VicS]

You mean MD2B presumably.

First check the seawater system:-
Pump impeller ~ replace if necessary. Lubricate with glycerine when fitting/refitting . (will also help the pump to prime)
Check strainer
Open seacock.
When the engine is running check water flow from the exhaust.

Re Fresh water circuit.
Dont know if VP system or other
But check coolant level... Expect an expansion vessel/ header tank to be around half full ..... It may have a level mark. ( It should be filled with an antifreeze mixture for corrosion protection.)
If no expansion tank and filler is directly on top of the heat exchanger ensure coolant covers the HE tubes and a bit. but leave a bit below the filler neck.
Re-check coolant level after the engine has been run and top up if necessary.
If seawater flow is good but overheats check thermostat. I should open at 76 C for freshwater cooling ( 62C for seawater)

It's an old engine and if been running for around 50 years on seawater may have a clagged up cooling system unless cleaned as part of the conversion to fresh water cooling.

 

[rib]

You mean MD2B presumably.

First check the seawater system:-
Pump impeller ~ replace if necessary. Lubricate with glycerine when fitting/refitting . (will also help the pump to prime)
Check strainer
Open seacock.
When the engine is running check water flow from the exhaust.

Re Fresh water circuit.
Dont know if VP system or other
But check coolant level... Expect an expansion vessel/ header tank to be around half full ..... It may have a level mark. ( It should be filled with an antifreeze mixture for corrosion protection.)
If no expansion tank and filler is directly on top of the heat exchanger ensure coolant covers the HE tubes and a bit. but leave a bit below the filler neck.
Re-check coolant level after the engine has been run and top up if necessary.
If seawater flow is good but overheats check thermostat. I should open at 76 C for freshwater cooling ( 62C for seawater)

It's an old engine and if been running for around 50 years on seawater may have a clagged up cooling system unless cleaned as part of the conversion to fresh water cooling.

Yes thanks for that.. I know that bit.. It is apparently a md11 sea water cooled but with a md28 freshwater cooling added . On the trouble shooting side I would like to know how much freshwater would be in the freshwater side approximately. It has done less than 17 hrs since the late husbands rebuild

 

[rib]

Don't mean to read being ungrateful

 

[rib]

Full story..she has come to move her late husbands boat.. She has her own in the south Pacific some where. She is in her 70s.on leaving the marina. She very shortly over heated. And replaced about 1 to 1 and a half litres of neat coolant ( I know) on restarting the engine made a horrible noise. So she shut down and got a tow back to the marina.. She has been advised to replace engine with out any one looking at it or spend a fortune just for a check... I offered to help thinking it was just a over heating problem. Ran the engine up. It sounded fine and she agreed that the noise has gone.. It was running for about 15 mins or more showing just a very small weep from a feed pipe to / from heat exchanger.. So I was thinking that the first over heat was probably a water / air lock in the system as that stayed at same level in the expansion tank. Though may be the engine didn't get hot enough in that time. The engine then just stopped. All the engine was warm to touch. But..... It has had the engine oil replaced with a unmarked oil can ( does seem a bit clear and thin to touch) and had been standing for a year or two unused without a new oil filter being used. ( so a possibility of a degraded oil filter thrown in as well) she may well have to replace the engine if she can afford it. Or get some useful engineer in.. But in the mean time I'm trying to see if I can A help her. B make sure she does not get taken for a ride..

 

[Bilgediver]

Yes thanks for that.. I know that bit.. It is apparently a md11 sea water cooled but with a md28 freshwater cooling added . On the trouble shooting side I would like to know how much freshwater would be in the freshwater side approximately. It has done less than 17 hrs since the late husbands rebuild

Some of the old Volvo's had a requirement to drill out the blocked port adjacent to the lower bulge on the thermostat housing. The outline of the port is visible and must not be drilled out if the engine is run as designed on sea water. Drilling out increases the flow through the heat exchanger.

If your engine has an expansion tank piped up correctly then you should only need to keep the expansion tank no more than half full . The filler cap on the heat exchanger should be a bi directional type if there is a wee hose from the cap neck to the expansion tank and a seat for the valve in the neck below the small outlet. When under high pressure excess water will flow to the expansion tank from the engine circuit. When the engine cools down after stopping the reduced pressure in the engine system will draw water back from the expansion tank. If this system is working correctly there may be no air space above the water in the heat exchanger and you just top up the expansion tank which operates at atmospheric pressure and will have a plastic cap.

Some systems are slightly different and the cap on the heat exchanger reservoir is just a plain cap with only a seal on the cap and no spring loaded valve and no seat for one in the neck below the cap. On these systems the cap on the expansion tank has the spring loaded pressure relief valve. The cooling system on heating up expels water to the expansion tank and some of this water returns to the engine on cooling down . The expansion tank operates at the cooling water pressure.

See if you can confirm if the correct components are fitted for your system . The radiator caps are all identical to types on cars . Just have to fit the correct type. The spring loaded valves have a pressure rating and 5-7 psi or 0 .5 bar would probably be fine.

If your expansion t

 

[VicS]

I think you will find the cap is this type

Turned upside down looks like this at least if it is the VP system which has been added

 

[rib]

I think you will find the cap is this type

View attachment 146996 Turned upside down looks like this View attachment 146997 at least if it is the VP system which has been added

Yes it does... Any idea of the water capacity.?