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marji

Water circulation problem.

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I have a BMC 1.8D engine, and the water no longer seems to be pumping, what could cause this, do these engines have an impella or just a water pump.

 

 

 

engine one.jpeg

engine 2.jpeg

engine 3.jpeg

Edited by marji

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1 minute ago, marji said:

I have a BMC 1.8D engine, and the water no longer seems to be pumping, what could cause this, do these engines have an impella or just a water pump.

 

 

What sort of cooling system do you have ?

 

Is it raw water cooled  (using river / canal water) ?

Do you have a heat exchanger ?

If it is a steel NB do you have 'cooling' tank(s) built into the side of the swim ?

What sort of boat is it ?

 

Pictures would help if you are not sure.

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I am sorry if these pictures are to big, I did not seem to have any control over that.

 

In picture 2 would that blue pully play a part in water circulation? 

 

River cooled yes to heat exchanger and a Norman boat.

Edited by marji

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It looks as if you have several cooling parts missing, hoses, cap etc.

 

I'd suggest that yes it will have an 'external' impellor pump between the hull fitting (water inlet) and the heat exchanger.

 

You may have a 'mud-box' or a filter that is blocked (they need fairly regular cleaning) and that could be the reason the pump is not pumping as it is not getting any water,

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5 minutes ago, Alan de Enfield said:

It looks as if you have several cooling parts missing, hoses, cap etc.

 

I'd suggest that yes it will have an 'external' impellor pump between the hull fitting (water inlet) and the heat exchanger.

 

You may have a 'mud-box' or a filter that is blocked (they need fairly regular cleaning) and that could be the reason the pump is not pumping as it is not getting any water,

Can you see where the mud box and filter might be from these pics, I do have other photos I can upload. Thxs

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4 minutes ago, Alan de Enfield said:

It looks as if you have several cooling parts missing, hoses, cap etc.

 

I'd suggest that yes it will have an 'external' impellor pump between the hull fitting (water inlet) and the heat exchanger.

 

You may have a 'mud-box' or a filter that is blocked (they need fairly regular cleaning) and that could be the reason the pump is not pumping as it is not getting any water,

When water stops ciculating,the first check with raw water cooling is the water inlet.There will probably be a mesh strainer in the seacock inlet,leading to a Vetus type water filter.There may or may not be a mudbox.Filters of course must be clear of weed and debris.

Another rare blockage can occur if the feed pipe to the water pump has a 90 degree junction on it,a build up of sludge here will block the water flow.

This happened on my last boat.Took me ages to diagnose the blockage.+

 

 

 

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The photos show no thermostat housing (fits on the three vertical studs), pipe connecting it to the heat exchanger, or a pressure cap on the heat exchanger. What is the reason for them being removed? The engine would overheat very quickly without them there.

Jen

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10 minutes ago, marji said:

Can you see where the mud box and filter might be from these pics, I do have other photos I can upload. Thxs

The mud-box could simply be a 'small steel box' with the water from 'outside' going into it a filter mesh inside, and a pipe going out to the pump.

 

If it is a filter (most GRP boats would use one rather than a mud-box) it will look something like this :

 

New Boat Raw Sea Water Strainer/Filter Replacement Fits for Hose 1" & 1.5"

 

If you find where the sea-cock is (where the water comes into the boat) the filter will be very close, maybe just 2 feet away. The outlet of the filter will go to the pump, the outlet of the pump will then go into the heat exchanger,

 

Assuming you do have an impellor pump, if you have bee running the engine dry(no water flow) it is quite possible that you have 'burnt' the vanes off the impellor, so even when the filter is clean it will no longer pump. You will need to strip the pump down and extract the impellor, ensuring you get all of the little bits of rubber out (as they can block pipes) and fit an new impellor

 

 

You will have a second pump which will circulate the water around your engine - this will be a 'built in' pump. This may be at fault.

 

 

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3 minutes ago, Jen-in-Wellies said:

The photos show no thermostat housing (fits on the three vertical studs), pipe connecting it to the heat exchanger, or a pressure cap on the heat exchanger. What is the reason for them being removed? The engine would overheat very quickly without them there.

Jen

I too noticed this,but assumed the OP had removed them to check water circulation,(I hope he has) otherwise as you understate the engine will of course overheat almost at once.

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Just to clear things up I have taken off the thermostat to test, it was fine I took these photos while doing that job hence the lack of stat cover and pipes and cap missing.

 

I would like to offer a more focused response to some of the suggestions mentioned, please allow me some time.

 

Thanks to all that have posted so far.

 

Alan de Enfield

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1 hour ago, marji said:

Can you see where the mud box and filter might be from these pics, I do have other photos I can upload. Thxs

 

I know that you asked for time so when you are ready locate your raw water pump. Its driven by the belt right at the front of the engine with just two pulleys in it. The larger pulley drives the raw water pump. That pump has two hose/pipe connections. One should run up to the rubber end cap on the exhaust manifold. that's the pump outlet. The other one, the inlet, probably runs back towards the back of the boat. Follow this pipe/hose and you should find any strainer and the raw water inlet. What you have could be a number of devices but it/they will be at the end of that pipe/hose.

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It looks like you have a circulation in the engine with antifreeze, sealed with the "radiator" cap on the heat exchanger cum header tank and exhaust manifold which is pumped by the engine water pump driven by the belt that also runs the alternator,  And  also a fresh water system which is pumped by the pump on the port side of the engine which draws water for outside the hull through a mud box or plastic filter as has been posted, passing through the heat exchanger matrix which is inside the header tank between the black rubber ends and exits through the exhaust.

 

It is likely this fresh water circuit that is either blocked somewhere ( Likely the mud box or strainer, )  or the fresh water pump has shredded its rubber impeller.

Marine Power Solutions - Marine diesel Engines 

Hope this diagram helps, Your expansion tank and heat exchanger are one unit. The thermostat is in the engine closed system. Heat from the engine system is cooled in the heat exchanger matrix by the fresh water running through and dumped overboard.

 

TD'

 

 

 

 

Edited by Tracy D'arth

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13 minutes ago, Tracy D'arth said:

 

Marine Power Solutions - Marine diesel Engines 

Hope this diagram helps, Your expansion tank and heat exchanger are one unit. The thermostat is in the engine closed system. Heat from the engine system is cooled in the heat exchanger matrix by the fresh water running through and dumped overboard.

 

I think that diagram is wrong for the BMCs and probably a lot of other engines. The engine coolant goes to the outside of the tube stack and the raw water through the tubes in the stack.

 

This one is no better in that respect because it does not show the water paths through the heat exchanger.

 

Hexcool.gif

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15 minutes ago, Tony Brooks said:

I think that diagram is wrong for the BMCs and probably a lot of other engines. The engine coolant goes to the outside of the tube stack and the raw water through the tubes in the stack.

 

This one is no better in that respect because it does not show the water paths through the heat exchanger.

 

Hexcool.gif

 True Tony, it depends how you look at the drawing, its ambiguous if a drawing can be! I could not find a better drawing quickly.

The fresh water in the BMC goes through the small tubes in the matrix, hence the extra hose clamps on the rubber end caps where the matrix ends are. The antifreeze  primary engine circuit then fills the header tank preventing the aluminium corroding away.

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Pic one shows the hose from the river connector,  pic 2 shows the hose coming in from rear of my boat into the tube connector from pic 1, there is a filter in the water just hanging off the end of the hose.

 

The tube thing has wire mesh each side of it and there was a small bit of green plant on the first entry point where the hose is connected in pic2, but the other side of that tube had the same mesh but there was no green stuff.

1.JPG

2.JPG

The tube thing

3.JPG

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1: Water Pump?

 

2: Diesel Pump?

 

3: Impella Pump?

 

Is this correct and is it easy to change a water pump?

123.jpg

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The "tube " thing is an engine oil cooler, it has a tube stack of small copper tubes inside through which the engine oil passes vie the 2 flexible hoses, the cooling water from outside goes through via the 2 end connections taking the heat away.

 

You didn't have to take the engine out for the pix but thanks!

 

TD'

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To me that "Tube Thing" looks like the oil cooler for the gearbox - the engine cooling water should be going into the big 'red' tank with the rubber caps on each end of it.

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It seems, as is all too often the case, that the raw water pump draws raw water through the gearbox oil cooler. The copper pipe seems to pass through a bulkhead unless it fits directly into the back of the hull. If its the former then the strainer/sea inlet is behind the bulkhead. If its the latter then no wonder it wont pump water. The gearbox oil cooler core and/or the heat exchanger core are probably full of rubbish  from the water.

 

Any even slightly loose hose between raw water inlet and the raw water pump will reduce or stop the raw water pump output.

 

We still need to see where the raw water is drawn into the boat

  • Greenie 1

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2 minutes ago, marji said:

1: Water Pump?

 

2: Diesel Pump?

 

3: Impella Pump?

 

1) Yes (engine cooling water pump)

 

2) No

 

3) Yes (Raw water pump)

 

You have (and need) two different water pumps

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1 minute ago, marji said:

1: Water Pump?

 

2: Diesel Pump?

 

3: Impella Pump?

 

Is this correct and is it easy to change a water pump?

123.jpg

  1 engine circ pump, sealed circuit. Unlikely to be duff unless there is play in the bearings with the belt off or you can see a leak under it.

2 Crankshaft, the diesel injector pump is under the alternator drive by the chain in the front case.

3 Fresh water pump, the stuff from outside that exits through the exhaust. Were you getting water discharging? If not it could be a blockage or the inpeller in this pump shredded.

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4 minutes ago, marji said:

1: Water Pump?

 

2: Diesel Pump?

 

3: Impella Pump?

 

Is this correct and is it easy to change a water pump?

123.jpg

 

1.  Engine circulating pump pulley, often just called the water pump.

2. Crauncshat pulley

3. raw water pump pulley. that pump does have a rubber impeller in it.

 

Answer - you probably don't need to change any water pump but we do need to know what water is not being pumped so we can advise accordingly. Engine coolant put in via the radiator type cap or raw water that probably leaves the boat via the exhaust.

 

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5 minutes ago, Alan de Enfield said:

To me that "Tube Thing" looks like the oil cooler for the gearbox - the engine cooling water should be going into the big 'red' tank with the rubber caps on each end of it.

No, its engine oil cooler. Lets not confuse the guy please. The flex hoses carry oil from the port side  relief valve to the starboard side oil gallery.

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1 minute ago, Tracy D'arth said:

No, its engine oil cooler. Lets not confuse the guy please.

 

Tony seems to be of the same opinion as me, we must both be wrong.

 

 

8 minutes ago, Tony Brooks said:

.........raw water through the gearbox oil cooler.

 

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3 minutes ago, Alan de Enfield said:

 

Tony seems to be of the same opinion as me, we must both be wrong.

 

 

 

Yes we are, engine oil coolers are so rare on inland boats  did not check the hoe connections. However if there is no strainer on the sea inlet it is still likely to be blocked.

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