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no cooling of BMC 1500 with Lancing direct cooled manifold


Frank30
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Now that's one weird cooling system set up!

 

Once the OP figures out WTF to do about what looks like a right bodge up job by the previous donkey owner, I would recommend doing a job I might try tomorrow, using a bottle of this nasty stuff after removing the thermostat housing, as I'm removing the thermostat anyway, as it seems to be a good idea according to Tony IF you have keel cooling.

Prestone Cooling System Flush Eliminates Scale Corrosion & Oil Contamination 1L 5010218007208 | eBay

 

Plan is to pour it in neat and top up until it comes out of the lowest point in the system and leave in place for half an hour before flushing out with a hose. Then I will fill with rain water and anti freeze mix, but will add a small amount of soluble oil, (Light machine oil), that is the best way of preventing rust, although it does turn the coolant light brown:

soluble machine oil | eBay

Edited by TNLI
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Tony never ever said removing the thermostat on a keel cooled boat was a good idea. It is, in my view, a good idea on DIRECT RAW WATER cooled BMC 1.5s. A keel cooled boat is little different operationally to a car/van with radiator so a thermostat is important for efficiency and the ability to use waste engine heat for other things.

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38 minutes ago, Tony Brooks said:

Tony never ever said removing the thermostat on a keel cooled boat was a good idea. It is, in my view, a good idea on DIRECT RAW WATER cooled BMC 1.5s. A keel cooled boat is little different operationally to a car/van with radiator so a thermostat is important for efficiency and the ability to use waste engine heat for other things.

Thanks, and it would be good if you could explain why there is a difference, other than a different higher coolant initial temperature for a keel cooled engine. It might be that the coolant flow rate is slower for a keel cooled system, so perhaps they tend to run a tad hotter at full chat along a river.

Edited by TNLI
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33 minutes ago, TNLI said:

Thanks, and it would be good if you could explain why there is a difference, other than a different start temperature for a keel cooled engine which is how I'm going to install my Ferrari red donkey, even if it might have been direct canal water cooled when it was installed in a steel barge that was scrapped. The pump the initial engine rebuilder said the barge had fitted near the donkey would probably have been for the hot water system coil or heat exchanger unit.

 

Don't you understand the different cooling systems operations? Certain internal parts in automotive engines have far more heat directed into them than others. In fact with so much heat needs to be dissipated given half a chance it will cause the coolant to boil at those points, especially at high speeds and loads.This known as localized boiling and is typically around the exhaust valve seats, injector holes and pre-combustion chambers. This is prevented by pressurizing the cooling system so the boiling point of the coolant goes up. (Hence you will often see me say that in canal use most engines will happily run un-pressurized).

 

As soon as you get close to boiling the water starts to deposit any salt or lime dissolved in it so those hot spots fur up. This thermally insulates them so the underlying metal gets even hotter and will eventually crack. On 1.5s it was normally the valve seats.

 

Now, with heat exchanger (indirect raw water), keel, or tank cooling you can pressurize the system to raise the boiling point, just like a vehicle, and the cooling liquid basically stays in the engine circuit so even if you get localized boiling the dissolved chemicals get deposited just once and then the coolant has lost them so no more depositing can take place. With direct raw water cooling not only can you not easily pressurize it but you keep supplying more and more dissolved chemicals to be deposited.

 

The only thing you can do on direct raw water cooled engines is to lower the running temperature so more heat is transferred between metal and water and thus it can't boil. The amount of heat transferred depends upon the relative temperature difference between the metal and water so by lowering the water temperature more heat will transfer.

 

On wet exhaust sea boats this depositing effect can be seen in the exhaust mixing elbows when they fur up with salt and cause overheating.

Edited by Tony Brooks
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Thanks Tony, that was a very informative reply, although the first sentence should have said, "Don't you understand the advanced aspects of a donkey cooling system", to which I would have replied, not as regards the BMC 1500.

  I'm fully aware of how dubious direct sea or canal water cooling is, although I didn't know that using tap water could be rather bad news for the exhaust valves in the long term. It's the fact that my Ferrari diesel has not been cleaned up too well internally, that added to my job list over the next few days, as I need to clean out the entire block of many years of crud. Hope a yellow bottle of Prestone drain cleaner will do the job, as hot spots result in a distortion of the adjacent bearings, rings or other parts like the valve seats as you listed. It will be interesting to see what emerges when I flush the crud and rust out,  as it looks like rust as far as I can see through the pressure caps hole.

 

  

Edited by TNLI
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43 minutes ago, TNLI said:

although I didn't know that using tap water could be rather bad news for the exhaust valves in the long term.

 

That is NOT what I said. I said using raw water causes the problem. That is unless you are continually feeding water from a tap through a direct raw water cooled system and even that it would not be a major problem in a very soft water area. s

 

On any cooling system where you fill the system just once and then only top up as required and dissolved solids will come out and fur the hot spots the first time the coolant gets to a typical running temperature. Then there are no more solids to  come out. It is the continuous provision of more dissolved solids with a direct raw water system that cases the damage. However there are those who advocate filling tank/keel/heat exchanger systems and cars with  distilled water but I feel it does not make a significant difference on our types of engines.

 

I also did not say the valves got damaged. I said the valve SEATS cracked.

 

I just hope that your acidic cleaner does not find too many rusted core plugs. If it is not acidic I can't say I would expect it to do much than maybe remove and oil film.

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Prestone is slightly acidic, as is any chemical I can think of that dissolves calcium carbonate or rust. It was designed for car or truck diesels and i seem to remember they have core plugs to prevent serious damage to the block if the coolant freezes solid. Also i would much rather find out the only thing holding those round plugs in place is the rust and paint before the engine is installed. The crank company are going to pressure test it anyway as part of the test I'm asking them to do. They are fully used to restoring an old donkey, cos they are also a classic car engine rebuilder, although they only seem to do the more serious main block jobs, furnace welding in particular. So if something really serios has failed, my beloved BMC is going to the right company. 

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