Corrosion pedia explains it all to do with ph, etc.
https://www.corrosionpedia.com/definition/407/distilled-waterK2
https://www.corrosionpedia.com/definition/407/distilled-waterK2
Looking for input on a cylinder block corrosion issue.
- Thread starter Eccentric
- Start date
Help Support Home Model Engine Machinist Forum:
Reporting Back on the Cylinder block de-rusting.
The engine is back together and I am using Prestone 50/50 premixed coolant and I am sure the corrosion issue has been dealt with. I have a few other issues I need to work on before I can go for longer runs. In the photo below I have indicated an oil leak. This is where the oil pump meets the timing case. There is a gasket between the oil pump and the oil pump cover and no leak occurred there. I am not sure why I didn't use a gasket also at the timing cover. Easy fix.
I did have some air bubbles at the coolant pump, this is a little aquarium 12V pump. I put both the inlet and outlet of the radiator at the bottom, then had a hard time filling it with coolant and getting the air out. I will turn it on its side and pull coolant from the bottom and return to the top.
I was surprised how quickly the coolant got hot and how hot the radiator got. I thought I could get away without a fan, now I am planning to add a 12 Volt fan blowing through the radiator. It would be interesting to put a few thermal sensors on the engine.
The distributor worked a dream. Should there be a grounding lug on the head for a current return from the spark plugs? I have the ground lug located on the base and the current needs to run across several part interfaces.
OK, back to it. I have a few changes to make to the engine test bed.
The engine is back together and I am using Prestone 50/50 premixed coolant and I am sure the corrosion issue has been dealt with. I have a few other issues I need to work on before I can go for longer runs. In the photo below I have indicated an oil leak. This is where the oil pump meets the timing case. There is a gasket between the oil pump and the oil pump cover and no leak occurred there. I am not sure why I didn't use a gasket also at the timing cover. Easy fix.
I did have some air bubbles at the coolant pump, this is a little aquarium 12V pump. I put both the inlet and outlet of the radiator at the bottom, then had a hard time filling it with coolant and getting the air out. I will turn it on its side and pull coolant from the bottom and return to the top.
I was surprised how quickly the coolant got hot and how hot the radiator got. I thought I could get away without a fan, now I am planning to add a 12 Volt fan blowing through the radiator. It would be interesting to put a few thermal sensors on the engine.
The distributor worked a dream. Should there be a grounding lug on the head for a current return from the spark plugs? I have the ground lug located on the base and the current needs to run across several part interfaces.
OK, back to it. I have a few changes to make to the engine test bed.
As long as there is good continuity the earth location is irrelevant. Check with a meter from head to earth lead and see if you have more than an ohm of resistance?
K2
K2
Just thinking out loud. Shouldn’t the coolant be coming from the top of the radiator to the engine ?? As is, the coolant is only circulating in the bottom portion of the radiator.
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Distilled water is pure water, De-ionized water is hungry water. Nothing there but H2 O. And it's corrosive as you can't believe it! Ph can be 7 but it's ion hungry so any transferable ions are eaten up.
kf2qd
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Get some pieces of zinc and fasten it to the inside of the cover. Zinc will act as a sacrificial anode and help reduce corrosion. All those different metals in close proximity, and who knows what is in your water, and to pure water will actually encourage corrosion. Never use DI water.
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La France,
My thinking regarding whether the coolant should flow from top to bottom or bottom to top is as follows: I want to minimize the amount of air in the block and try to insure it is full of coolant. Do a thought experiment with me and imagine we have a fish aquarium we want to keep filled with a flow of clean water. The aquarium has an open top and has a drain hole at the bottom. If we fill from the top, the water flows out the bottom and in the steady state condition is filled mostly with air. But if we fill from the bottom, the tank fills to the top and in the steady state condition is filled mostly with water. I think if we flow the coolant from top to bottom it could be difficult to insure we don't have too much air in the block.
My thinking regarding whether the coolant should flow from top to bottom or bottom to top is as follows: I want to minimize the amount of air in the block and try to insure it is full of coolant. Do a thought experiment with me and imagine we have a fish aquarium we want to keep filled with a flow of clean water. The aquarium has an open top and has a drain hole at the bottom. If we fill from the top, the water flows out the bottom and in the steady state condition is filled mostly with air. But if we fill from the bottom, the tank fills to the top and in the steady state condition is filled mostly with water. I think if we flow the coolant from top to bottom it could be difficult to insure we don't have too much air in the block.
Many car radiators are bottom fed, and top drained. But there are also top to top, top to bottom and bottom to bottom. And the pressure relief valve (usually in the radiator cap) also acts as a vent valve. When a cooling system has some air entrained, the plumbing is arranged so it can vent the radiator when the system is cold (start-up) before pressure rises and closes the 'vacuum relief" valve. But when the system has been shut-down (engine stopped) this valve opens to permit coolant from the reservoir to enter the system and avoid a vacuum forming that would collapse hoses, and potentially damage thin-walled radiators and any pressure directional seals. (Water pump?, O-rings?). This vented of air expels the dissolved air that comes out of solution in the water in the coolant mix, until there is no air in the system. Of course careful engine development tests that the flow of coolant is adequate to carry away the heat from all areas to where it can be used or thrown away (cabin heater, recycled during warm-up to speed the warming, or main radiator to warm the globe).
Actually, the key is the high capacity of the water pump. The high flow developed by the turbine causes swirling in all chambers, for good heat pick-up avoiding hot spot steam creation, but also generating swirl that entrap small bubbles of air from odd chambers and carries them to the radiator, where they can be collected and vented over time. I guess your pump is simply too small? Make a crank-driven water turbine. Driven by a belt off the flywheel? Using a small - 1mm? - O-ring or drive belt? Works well on a friend"s models. He uses clear acrylic water pump housings so he can monitor flow. Delrin turbine rotors. And his flows are high, but "semi-scale" radiators are always too small, and overheat after 10 mins or so of idling. Disproportionately large radiators and fans are needed.
Enjoy.
K2
Actually, the key is the high capacity of the water pump. The high flow developed by the turbine causes swirling in all chambers, for good heat pick-up avoiding hot spot steam creation, but also generating swirl that entrap small bubbles of air from odd chambers and carries them to the radiator, where they can be collected and vented over time. I guess your pump is simply too small? Make a crank-driven water turbine. Driven by a belt off the flywheel? Using a small - 1mm? - O-ring or drive belt? Works well on a friend"s models. He uses clear acrylic water pump housings so he can monitor flow. Delrin turbine rotors. And his flows are high, but "semi-scale" radiators are always too small, and overheat after 10 mins or so of idling. Disproportionately large radiators and fans are needed.
Enjoy.
K2
Badhippie
Well-Known Member
Not only does filling the radiator from the bottom help reduce air locks in the cooling system (if the system is plumbed correctly)
By filling the radiator from the bottom the coolant actually stays in the radiator longer to aid In cooling. If you filled the radiator from the top it would run straight out the bottom. But by filling from the bottom the coolant stays in the radiator longer thus giving the air being forced or drawn thru the fins of the radiator more time to remove excess heat. This is without getting in to the thermostat discussion or the bypass discussion.
By filling the radiator from the bottom the coolant actually stays in the radiator longer to aid In cooling. If you filled the radiator from the top it would run straight out the bottom. But by filling from the bottom the coolant stays in the radiator longer thus giving the air being forced or drawn thru the fins of the radiator more time to remove excess heat. This is without getting in to the thermostat discussion or the bypass discussion.
Incidentally, I worked on a thermostat that needed a small vent relief valve for an engine, where air could have been trapped in the thermostat housing and engiine, but when flow stopped, if the thermostat was closed, a small valve could let air pass into the top hose to the radiator to vent to the radiator header and to atmosphere. As soon as the engine started, the pressure from the water pump closed the vent valve, and the thermostat was the only active valve to permit flow, but contrary to the way the air was vented when the engine had stopped and was cooling, thus closing the thermostat.
Did you know that on first fill in the factory, the cooling system is evacuated, and checked for leaks before filling with Long Life Coolant? (3 year service interval is because the anti-corrosion elements in the coolant have been ci0onsumed, permitting engiine corrosion to happen from around 4 years onwards with the old LLC! Worth changing, as per manufacturers service intervals, with proper LLC, not just a Glycol top-up!
K2
Did you know that on first fill in the factory, the cooling system is evacuated, and checked for leaks before filling with Long Life Coolant? (3 year service interval is because the anti-corrosion elements in the coolant have been ci0onsumed, permitting engiine corrosion to happen from around 4 years onwards with the old LLC! Worth changing, as per manufacturers service intervals, with proper LLC, not just a Glycol top-up!
K2
Thanks Badhippie: On your comment "If you filled the radiator from the top it would run straight out the bottom":
I guess that when the system is full, there is nowhere for the coolant to flow "out the bottom"? - so correct filling is required first?
I have not made a model radiator myself, just worked on cooling systems for cars. They use every possible scheme. But base all the cooling on full systems, using 30% or 50% Glycol mix in water (with the fraction of % of anticorrosives in the LLC). The evacuation of air is always at the radiator cap, whether top or bottom fed, and top or bottom out, and many modern systems have a coolant flow from side-to-side! They all rely on high flow rates from the water pump to carry the heat away. And they all rely upon filling in the factory after sucking a vacuum in the cooling system, so minimising air entrapment. Not quite so easy in your garage with your model! But to allow for "garage" servicing and routine replacement of coolant, they incorporate such devices to vent the air after it has been carried to the radiator and allowed to separate in the "top" chamber". Apart from the high flow of the water pump to carry micro-bubbles of air to the radiator, the "daily" cycling of cold to hot to cold and atmospheric to system pressure (usually around 1 barg) tends to encourage bubbles to be vented from any entrapment air-lock points. And the dissolved air usually "boils out" after a few hot runs and becomes micro-bubbles that flow to the highest point anywhere - usually in the radiator.
But on an unpressurised system, e.g. a model, with reduced water flow, I can see this being more problematic. Air bubbles entrapped in the engine will expand, forcing coolant to overflow out of the vent, instead of being reduced in volume by the increased pressure of the system pressure in a capped and pressurised system.
Food for thought...
K2
I guess that when the system is full, there is nowhere for the coolant to flow "out the bottom"? - so correct filling is required first?
I have not made a model radiator myself, just worked on cooling systems for cars. They use every possible scheme. But base all the cooling on full systems, using 30% or 50% Glycol mix in water (with the fraction of % of anticorrosives in the LLC). The evacuation of air is always at the radiator cap, whether top or bottom fed, and top or bottom out, and many modern systems have a coolant flow from side-to-side! They all rely on high flow rates from the water pump to carry the heat away. And they all rely upon filling in the factory after sucking a vacuum in the cooling system, so minimising air entrapment. Not quite so easy in your garage with your model! But to allow for "garage" servicing and routine replacement of coolant, they incorporate such devices to vent the air after it has been carried to the radiator and allowed to separate in the "top" chamber". Apart from the high flow of the water pump to carry micro-bubbles of air to the radiator, the "daily" cycling of cold to hot to cold and atmospheric to system pressure (usually around 1 barg) tends to encourage bubbles to be vented from any entrapment air-lock points. And the dissolved air usually "boils out" after a few hot runs and becomes micro-bubbles that flow to the highest point anywhere - usually in the radiator.
But on an unpressurised system, e.g. a model, with reduced water flow, I can see this being more problematic. Air bubbles entrapped in the engine will expand, forcing coolant to overflow out of the vent, instead of being reduced in volume by the increased pressure of the system pressure in a capped and pressurised system.
Food for thought...
K2
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Eccentric,
It appears you are using a radiator designed for computer processor cooling. Unlike engine radiators they were designed to handle very low delta T (approx. 10⁰ F) across the radiator. Indoors a model engine can use a radiator with a 90-100⁰ F Delta T so they are very effective at engine cooling model engines operating at 160-180⁰F. Their main application issues are the multi pass cores, coolant connections are never in the right place, no coolant fill port, and don’t normally have any coolant expansion space. Hence they don’t easily adapt to a conventional engine cooling arrangement.
My models run at 160⁰F and all of the above are needed. You can take a 2 pass radiator with both coolant connections at the bottom and cut an opening in the opposite crossover end of the radiator and solder in a fill port and cap. The crossover will become your top mounted expansion tank with a fill fitting and cap in place. With the connections at the bottom you have satisfied the expansion space and the fill port issues. The fill port must be the highest point in the cooling system and when running your engine, always loosen the fill cap to prevent coolant leaks at rubber or vinyl connections. Plumbing routing issues that entrap air can easily be resolved by using a positive displacement style pump like a gear or vane pump. Always include a coolant drain fitting in a convenient location.
As for the proper coolant to use in model engines I would definitely use a corrosion inhibited coolant where dissimilar metals and fixing chemicals are used. I use a 50/50 mix of glycol antifreeze since I do fill the radiators of my engines when I go to Cabin Fever. However, I rarely store my engines long term anymore with coolant in them ever since I went to the automotive parts store and there were 6 different types of antifreeze available specific to different auto manufacturers. In my tank cooled engines like Water Wetter. I have had a piece of 12L14 soaking in it for over a year without any sign of rust.
Jeff
It appears you are using a radiator designed for computer processor cooling. Unlike engine radiators they were designed to handle very low delta T (approx. 10⁰ F) across the radiator. Indoors a model engine can use a radiator with a 90-100⁰ F Delta T so they are very effective at engine cooling model engines operating at 160-180⁰F. Their main application issues are the multi pass cores, coolant connections are never in the right place, no coolant fill port, and don’t normally have any coolant expansion space. Hence they don’t easily adapt to a conventional engine cooling arrangement.
My models run at 160⁰F and all of the above are needed. You can take a 2 pass radiator with both coolant connections at the bottom and cut an opening in the opposite crossover end of the radiator and solder in a fill port and cap. The crossover will become your top mounted expansion tank with a fill fitting and cap in place. With the connections at the bottom you have satisfied the expansion space and the fill port issues. The fill port must be the highest point in the cooling system and when running your engine, always loosen the fill cap to prevent coolant leaks at rubber or vinyl connections. Plumbing routing issues that entrap air can easily be resolved by using a positive displacement style pump like a gear or vane pump. Always include a coolant drain fitting in a convenient location.
As for the proper coolant to use in model engines I would definitely use a corrosion inhibited coolant where dissimilar metals and fixing chemicals are used. I use a 50/50 mix of glycol antifreeze since I do fill the radiators of my engines when I go to Cabin Fever. However, I rarely store my engines long term anymore with coolant in them ever since I went to the automotive parts store and there were 6 different types of antifreeze available specific to different auto manufacturers. In my tank cooled engines like Water Wetter. I have had a piece of 12L14 soaking in it for over a year without any sign of rust.
Jeff
ALL motor manufacturers have basically the same chemistry of corrosion inhibitors (as I was taught by the LLC chemist!), as that is dictated by the common (cheap) metals used. (30+) Years ago, the exception was Norway - I can't remember their particular environmental reason for a different coolant corrosion package, but in the 1990s they changed to accept what the rest of Europe uses. I guess "chemistry" in Japan and USA - and all other countries - are the same?
K2
I too have used the computer type radiators with success. I buy the more expensive brass ones instead of the aluminum ones so it's easy to move ports, add a filler at the top, etc. by soldering. Coolant recovery works well with a port in the filler neck that goes to a separate reservoir just like your car, plus looks cool.
Badhippie
Well-Known Member
One other thing to mention it sounds like a dumb question but it’s really not. Are you sure your water pump is turning the right direction???
Hi Eccentric, I have just been reading #27 again, as I replied to Badhippie about filling from top or bottom, but may have confused others as I definitely woke in the night (for other reasons) and pondered what was really happening...? - So, take it that I am confused...?
In your thought experiment (My middle of the night insomnia hobby!) I reckon you have a drain on the outlet. In the model you have a tank - the engine, etc. - presumably with top and bottom connections, and a water pump to make it flow (Thermo-syphon needs a large head to work - Models do not have enough height to create a useful density related pressure difference to develop the flow required...).
Hence, with a "second tank" attached to your fish tank - probably closed, not open to atmosphere, and maybe below the fish tank, I guess you will simply fill from the top connection until all the air is expelled from the bottom (closed) tank through the top tank (as a vent) until the top tank fills to the required level?
Does that help resolve the confusion? (Or maybe I'm the only one who is confused?).
Can you post a phot of your model - and a cooling-circuit diagram perhaps?
Ta,
K2
In your thought experiment (My middle of the night insomnia hobby!) I reckon you have a drain on the outlet. In the model you have a tank - the engine, etc. - presumably with top and bottom connections, and a water pump to make it flow (Thermo-syphon needs a large head to work - Models do not have enough height to create a useful density related pressure difference to develop the flow required...).
Hence, with a "second tank" attached to your fish tank - probably closed, not open to atmosphere, and maybe below the fish tank, I guess you will simply fill from the top connection until all the air is expelled from the bottom (closed) tank through the top tank (as a vent) until the top tank fills to the required level?
Does that help resolve the confusion? (Or maybe I'm the only one who is confused?).
Can you post a phot of your model - and a cooling-circuit diagram perhaps?
Ta,
K2
K2,
Find my latest configuration of the cooling system in the last post of this page:
https://www.homemodelenginemachinis...ngine-based-on-westburys-wallaby.33191/page-5
The little aquarium pump works great and provides good flow, and the clear tubing allows one to see all is good. There is one exception--when the engine is running!!! The problem I have now is the "DC brushless" aquarium pump quits running when the spark plugs are firing. I posit that the ignition system is producing EMI (electromagnetic interference) that is messing with the DC brushless controller in the little pump. Uggg, if it is not one thing it is another.
With the radiator/cooler oriented the way I have it, flow in to the top and out the bottom of the cooler and in at the bottom of the engine, I get good coolant flow. The fan on the cooler really helps and I am getting rid of a lot of heat. Amazing how much heat this little 30cc engine generates.
This is just an engine test stand and not the final engine mount. I guess I could try a "brushed" motor pump, or design up an engine driven pump.
Find my latest configuration of the cooling system in the last post of this page:
https://www.homemodelenginemachinis...ngine-based-on-westburys-wallaby.33191/page-5
The little aquarium pump works great and provides good flow, and the clear tubing allows one to see all is good. There is one exception--when the engine is running!!! The problem I have now is the "DC brushless" aquarium pump quits running when the spark plugs are firing. I posit that the ignition system is producing EMI (electromagnetic interference) that is messing with the DC brushless controller in the little pump. Uggg, if it is not one thing it is another.
With the radiator/cooler oriented the way I have it, flow in to the top and out the bottom of the cooler and in at the bottom of the engine, I get good coolant flow. The fan on the cooler really helps and I am getting rid of a lot of heat. Amazing how much heat this little 30cc engine generates.
This is just an engine test stand and not the final engine mount. I guess I could try a "brushed" motor pump, or design up an engine driven pump.
Obvious issue with obvious solutions. Don't go inventing causes here. Loctite products are petro plastics and do not induce corrosion. You need to use engine coolant over cast iron and/ or steel cylinder liners. You can spay paint the cylinders in contact with the coolant.
Badhippie
Well-Known Member
Try wrapping some aluminum foil around the pump controller this is a sure way to tell if it’s EMI causing the problem
Ta for video link: I understand the system now.
Personally, I would prefer to see a crank driven water pump. - maybe by a simple belt? Eliminates "EMF" issues?
But I like the computer radiator and fan!
Just thinking of "waste heat" from IC engines: When you get the pump working properly, I guess you can guestimate the heat discharged from the radiator - from flow (pump speed?) and Inlet - outlet temperature of the coolant? - The rest of the heat will be discharged (mostly) in exhaust gas, and also radiated from the hot metal (Not a lot).
K2
Personally, I would prefer to see a crank driven water pump. - maybe by a simple belt? Eliminates "EMF" issues?
But I like the computer radiator and fan!
Just thinking of "waste heat" from IC engines: When you get the pump working properly, I guess you can guestimate the heat discharged from the radiator - from flow (pump speed?) and Inlet - outlet temperature of the coolant? - The rest of the heat will be discharged (mostly) in exhaust gas, and also radiated from the hot metal (Not a lot).
K2
