Lister Engine Forum
How to / DIY => Engines => Topic started by: xyzer on March 20, 2009, 07:08:36 PM
-
I was thinking(???) the other day while my oid was warming up what if we used a larger air bleed hole in the thermostat. I watched as the temp gauge it climbs up to 190 or so then it opens and gets a shot of cold water and drops back down to 100 or less. This cycle repeats over and over until the cooling system gets warm then it will stay at 200 or so. If we used a larger hole in the thermostat it would allow more flow and it would eliminate some of the cold shock. Do I make any sense?
Dave
-
Can see where your coming from , try it and see. Worst case is a new stat if it doesn't work.
-
That would also slow down the warm-up. Perhaps it would be best to place a gate valve on the outlet and adjust it so the the engine has just enough flow to cool under full load. Then when the thermostat opens there might not be as big a gulp of cold water.
Best would be a housing that bolts to the outlet with recalculation to inlet. Could be a new product???
I felt the temp changes you describe on mine too. I have an 1/8" hole in my thermostat. I wonder if there are any slower reacting thermostats out there?
-
compig,
I agree no big deal! I'm going to try it and see what happens. I have data on the time it takes to get to full operating temp so I can compare.
Tom,
My thinking is it will take about the about the same time to reach full operating tempeture without the hot cold cycles. A more constant rise instead of 200 open 40 in (on a cold day) close heat er up again. Basicly the hole is the gate valve and if it is a bit to much of a restriction the stat will open to allow more circulation.
-
The only reason to have a hole in the thermostat valve, NOT the outer flat plate, is to release the air in the system while filling it up for the first time. In theory, once you have run it the first time, there should be no air in the system anymore. (unless you have it bolted to Vancouver Island ;D
Stan
-
I was thinking(???) the other day while my oid was warming up what if we used a larger air bleed hole in the thermostat. I watched as the temp gauge it climbs up to 190 or so then it opens and gets a shot of cold water and drops back down to 100 or less. This cycle repeats over and over until the cooling system gets warm then it will stay at 200 or so. If we used a larger hole in the thermostat it would allow more flow and it would eliminate some of the cold shock. Do I make any sense?
Dave
Dave
I don't recall what you are using for a cooling system? A larger thermostat hole should ease the severity of the temperature swings by allowing a steady flow of cool water to enter the engine. It may actually shorten warmup time. Warmup time is a factor of BTU generated, coolant mass, BTU dissipated and temp difference. By allowing a steady flow of cooler water into the cylinders, you maintain a greater temp difference between cylinder wall and coolant, and have a higher heat transfer rate.
The flow will be dependent on how much heat you are putting into the fluid, and how big the hole is. I agree that if it is too small, the temp will rise, and the thermostat will open and cycle to take up the slack. The area of the hole could be as large as the thermostat opening at normal operating temp and a very light/no load. The thermostat would open and regulate the temperature at any greater heat input.
-
I was just teasing you Jens...good to know you're still paying attention ::)
Actually, if the thermostat is installed the correct way, that is with the bimetal spring on the hot side, as the water cools just below the temperature of the bimetal spring activation, it will start to close very slowly, thereby throttling back on the flow but never quite stopping it. I would advise xyzer to take his thermostat out and put it in a pot of water on the stove and watch it while it boils. (yes, a watched pot will still boil!). You will then see the action that it uses. These things don't "snap" shut, they move at the pace of a Galapagos tortoise! There's no way it should act as described if it's functioning normally.
Stan
-
ronmar,
I thermo siphon with a metro radiator on one oid, and a Saturn on the other. They both exhibit this trait. My thoughts were as you explained but you did a better job!
Stan,
Yes I could have a defective stat......But I see this behavior on both of my oids....also I have heard of others observing this behavior. If I put the stat in a pan and wait for it to open then throw in a cold pan I bet it shuts. Wait for that pan to hit 190 it opens then throw it in another cold pan it will shut until I run out of cold water. Now if it had a pump and a bypass we would have another story. Like I said I was just thinking
Dave
-
Thermostat "gulping" s a common occurrence in lots of automotive systems.
FWIW, lots of Subaru cooling systems (and maybe other manufacturers) have the thermostat on the *inlet* side of the engine instead of on the outlet...
-
I took out the 195° thermostat and put in a 180° with a 3/16 bleed hole. If it wasn't such a pain to drain and refill I would take it back out and make the bleed hole even bigger but it does work much better. I'm tempted to take the thermostat out all together and regulate with the fan and temp switch, it may take more time to warm up but it would be a more even heat up.
Speaking of inlet thermostats. Another form of cooling is reverse flow cooling, where coolant flows through the head first and down through the block. For gas engines this means cooler heads so higher compression ratios and more spark advance can be used and the cylinder to head temps are more even. Maybe this would be an advantage for diesel also. Of course you couldn't do this with thermosiphon.
-
NoSpark,
When I have it apart I'll try a .225 and see how it does!
Dave
-
Nospark, Why did you opt for the lower temp thermostat?
-
I put in the lower temp thermostat with a bigger bleed hole to get the whole system up to temperature faster. With 20F ambient temps the engine temp swings were huge until it ran for a long time, even with a 3000+ watt load. At the same time I installed a much smaller radiator and 50/50 antifreeze. It still takes a while to heat up but warmer weather will be here soon I hope. I have a 120v fan mounted behind the radiator, I just need to find a safe place for the 120f snap switch to keep the fan off until the engine gets up to temp. I found out that a plastic radiator tank does not transfer heat to a snap switch very well, even with thermal grease.
-
Not sure wher Stan gets his 'bimetal sping thermostats' from - mine have been wax operated for as long as I remember, and I am old.
Not one has adressed/mentioned the other possible problem of a faster warm up. Reduce the water volume to the minimum required and the heat required will be at the minimum. If yours is way oversized with metres of extra tubing that might be a much better place to start.
Jens point about the 'stat not getting hot was just a little off beam - who else would put a stat at a lower level than the engine outlet and expect it to work properly? If it is elevated, the hot water will rise and operate it correctly.
If you have a pump and a 'stat there should be a bypass, or the pump will be pumping into a closed head which is not so good for it - even an impellor pump.
Maybe a smaller 'stat might be beneficial, instead of one designed for a 60HP engine. Big pipes were OK for thermosyphon in 1920s with sediment, no antifreeze/corrosion additives etc. Designs have moved on a pace since then. Apply a little mathematics to the well documented design requirements for the cooling system and come up with the minimum flow needed for the worst case scenario and I would think the flow rate can be reduced by quite a percentage of what you are experiencing now. Think hottest day, highest load - thermostat should remain open and temperature might rise a few degrees above that opening temperature, but engine should not overheat - and you will close to the optimum for the design parts you cannot change.
Me? Let it thermosyphon. I don't run mine long/often enough to worry about it. KISS.
Regards, RAB
-
Speaking of inlet thermostats. Another form of cooling is reverse flow cooling, where coolant flows through the head first and down through the block. For gas engines this means cooler heads so higher compression ratios and more spark advance can be used and the cylinder to head temps are more even. Maybe this would be an advantage for diesel also. Of course you couldn't do this with thermosiphon.
Mitsubishi used this method on their Evo from version 6 onwards. Quite a critical application though with almost 300 BHP from a 2 Ltr 4 cylinder , and this is before people like me start fiddling with them to obtain obscene amounts of power , currently 450'ish on mine !! The engines still bullet proof though ,even at this power and much higher !!
-
Not sure wher Stan gets his 'bimetal sping thermostats' from - mine have been wax operated for as long as I remember, and I am old.
We saved that one just for you RAB. LOL
Not one has adressed/mentioned the other possible problem of a faster warm up. Reduce the water volume to the minimum required and the heat required will be at the minimum. If yours is way oversized with metres of extra tubing that might be a much better place to start.
My system might contain 3 gallons of coolant, a far cry from say a 55 gallon barrel, its just to damn cold. When everything is warmed up I get a nice constant flow of warm air from the radiator. Once the inside of my garage hits 80f I'll be trying to get the thing to run cooler.
This summer I plan on cooling my house in the evenings with WVO. This will help me get the kinks out to run it more seriously next winter.
-
Nospark
If the radiator fan was running all the time, that was probably your biggest issue as far as warm up. On a 6/1, anything much larger than a metro rad is overkill, so in 20F air, even a little airflow can dissipate way more than the 17KBTU/hr that the engine can put into the cooling system at full load. Basically, like hooking it up to a swimming pool sized cooling tank, you gave it a nearly inexhaustable supply of very cold water from the bottom of the radiator. You could also run into this situation with a metro radiator and a good flow of 20F air. The 180F thermo probably is still cycling also, but with the slightly lower opening temp and a bleed hole to allow constant flow, I am sure the swings are not as extreme. Big semi trucks also run into this problem in winter. They have a simple solution. They put a cloth cover over the radiator inlet with a zipper on it to block a great deal of the airflow from the front of the radiator. They unzip this cover as neded to control the airflow and match the radiators cooling ability to the engine output.
Personally I would put the 195 thermostat back in with an even larger bleed hole. I bet it will work just as well in dealing with the swings as the 180 has. The biggest fix though will be to get that fan control working so the fan dosn't run untill the system is warm, and can shut off so it dosn't remove too much heat from the coolant. The thermal switch controlling the fan can also give you an idea of how well the cooling capacity is matched to the heat load. If the fan switches on and off at a fairly fast rate, it is moving too much air and overcooling the rad which causes the short cycling. If it comes on and stays on all the time, it is probably not moving quite enough air. Observing the fan cycling as well as the temps around the system will help you to match the cooling system to the engine. IMO, ideally, you would want the fan to just stay on all the time at maximum load, and occasionally cycle off, say staying on 90% of the time at lesser loads. In winter, use something to block airflow thru the radiator to maintain theis same relationship in the much cooler air. Your goal is to be able to remove enough heat that the cooling capacity is within the thermostats ability to control without fully opening or fully closing. You might find a much smaller fan or two, such as a 4" computer case box fan setting on the radiator face, can move enough air to maintain control.
Another good reason for the 195 thermostat is combustion efficiency. That 180F thrmo limits the upper operating temp. I noticed a significant difference between a warm engine and a cooler one during my fuel consumption testing. It does make a difference in how much fuel you will burn, and hotter(below boiling) is better IMO. This may also make a difference when running alternative fuels as it will probably cut down on carbon buildup from the heavier oils.
Good luck.
-
Jens, if you put 2 thermostats on with the heat sensor portion poking into the block, before the manifold, it would work much better. I didn't realize you twin guys were putting the thermostat way up there a good 6 or 8 inches away from the block. When the themostat is poking into the block itself, it heats up right away!
Stan
-
Ronmar
I think the radiator setup I have right now is almost perfect, the radiator isn't much bigger than a metro radiator but a lot smaller than the big heavy duty truck radiator I had before. I currently plug the fan in after the temp gauge stops swinging, Ive got to get that switch hooked up. The 195 thermostat may have been defective, because it allowed the coolant to go over 200 before opening. I'm not sure if I'll try another 195 stat or not, the temp control is so much better now. Today I started it at 50f and it warmed up pretty fast so thing are going to change.
-
The difference between the two thermostats was probably the bleed hole you put on the second. It allowed the heat to reach the thermostat sooner, allowing it to open befor the temp peaked so high. Even so, 200+F isn't really a problem as long as it isn't boiling at any point. I think you will see some better performance if you partially block the airflow thru the rad when it is really cold. and of course get that switch hooked up:)
-
The difference between the two thermostats was probably the bleed hole you put on the second. It allowed the heat to reach the thermostat sooner, allowing it to open befor the temp peaked so high. Even so, 200+F isn't really a problem as long as it isn't boiling at any point. I think you will see some better performance if you partially block the airflow thru the rad when it is really cold. and of course get that switch hooked up:)
My temp gauge is after the thermostat, so if it was reading 200+ before the thermostat opened something was wrong. Now under a steady load she holds 180. In the old thermostat I had ground the original bleed notch in the valve bigger, this one I drilled. That could of had something to do with it. My biggest concern was not really the running temp but how long it took to get the return hose warm. I would rather have a 195.
-
A thermostat with a bleed hole usually has a pin and ball, this is to allow air to escape during system fill but to prevent hot water bleeding away to the radiator during warm up. The most common cause of temperature surge is too large a volume of coolant. Modern car engines produce masses of heat but only have a few pints of coolant.
I’m not yet a CS owner but I will be one day, my intention is not to use a thermostat at all, but a restrictor, this being just a plate in place of a thermostat, and experiment with hole size until the ideal temperature is achieved.
It might work, it might not. :)
Rob
-
my intention is not to use a thermostat at all, but a restrictor, this being just a plate in place of a thermostat, and experiment with hole size until the ideal temperature is achieved.
It might work, it might not. :)
Rob, no need to re-invent the wheel. A thermostat is a tried and proven system to keep the coolant at a constant temperature. If you are REALLY concerned about heating the engine up quickly then put in a bypass system where coolant is circulated only through the engine until the thermostat opens. Even if you run into a thermal cycling issue from cold water entering it will stabilize itself quickly. Your restrictor method is bound to fail in many ways. There will only be one temperature point when all is well. The cold start and cycling might be bad and you might have it for 15 minutes or more but then you will stabilize. I fixed hole will over cool when the engine is cold and undercool when the engine is hot - it will never be stable.
Jens
But did Lister use a thermostat???????
-
Did anyone use a thermostat in the 1920s?
Regards, RAB
-
The Dursley Lister recommended a valve in the hot line that could be almost closed when starteup occured, and then gradually opened to maintain a heated condition. This, however requires constant monitoring, and failure to monitor correctly could lead to an over heated condition. They did eventually (don't know when, maybe Peter could shed light on this date?) start mentioning a thermostat in the line.
Stan
-
Was in all of this cases the radiator fan was running all the time?
Then, get the fan on the termostat switch. Vehicles with electric fans didn't run at all till temp is reached then is switched on.
Small hole in the thermostat is good especially for lister to have little of heated water trickling into the cold side of cooling system.
Cheers, Wizard
-
Thermostats are listed in a 1940's parts list that I have. It appears to be an in line hose mounted type.
-
My research shows they were first mentioned in the radiator models. It would make sense! The tank models were easier to control heatwise, with the much larger volume of liquid. 45 gal in temperate climates, double that in the tropics.
Stan
-
compig
Thermostats are listed in a 1940's parts list that I have.
With respect, that COULD be thirty years later.
One of my tractors came without a 'stat in 1948 but was soon field modded to use one (I have both water distribution maniflods for the tractor).
The point was: were there thermostats in the 1920s (or before)? Were probably bi-metallic strip ones if there were. :)
Your 1940s list might be 1940 or even late '49. A great deal of technology advancement went on over such a long period. Like pneumatic tyres being one development which advanced sufficiently to alter the direction/rate of agriculture.
The switched electric fan is now almost universal on smaller motor vehicles as it is the most efficient option available.
Regards, RAB
-
It's a 1948 publication and the thermostat is listed in the water tank & fittings section. There are two sizes , for 1-1/4" hose and 1-5/8" hose.
-
I seem to have opened a can of worms here so let me explain.
I've no intention of re-inventing the wheel, it's just something I want to do and as I said, it might work it might not. I'm not sure running a CS at such high temperatures is such a good idea and I favour running one a bit lower, about 65-70*C
My plan is to run the coolant through a domestic heating radiator, or into a hot water tank, or maybe both. But in the circuit I intend to fit a car radiator with an electric fan as a safe guard against melt down. The car radiator will be insulated to prevent unwanted heat loss and have air flow operated flaps to allow the fan to work.
So there you are, that's my plan. ;D ;D
Rob
-
No problem Rob....Vermiculture is a well respected art form ;D
I really don't care when thermostats were introduced by Lister. I use one and it's butt is firmly planted in the block where it's supposed to be.
Stan
-
No problem Rob....Vermiculture is a well respected art form ;D
Stan
Now! oddly enough, I'm having a go at this, just getting back into veg growing and I quite fancy a little worm factory next to my compost heaps. :) :)
Rob.
-
Well, if you do start a colony inside, and then set it out on the deck for just a minute at -8 deg C, and then forget it overnight, don't expect them little wigglers to survive.
Ask me how I know ???
Stan