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Thread: Trying to understand my cooling system

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    Jedi Warrior Drone Dog's Avatar
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    Trying to understand my cooling system

    as some of you may have read, i have been a bit concerned about my engine temps. weather is cool and it is running hotter than i expected for the temp of the thermostat. (160*)
    i have tried a few different things. the latest one was installing a sleeved thermostat. while i did notice what may be a little improvement, i did not see a big change. my gauge showed around 185 to 190 most of the time driving and a little hotter if sitting after a decent drive.

    this morning i got to thinking about how the gauge reads. when i start the car the gauge will climb steadily at a pretty even rate up to about 190 and then drop back about 10*. then it will go up a litlle and back down a little. but stay right about the 180-190 mark. it has acted the same way with either thermostat.

    So this morning when i started it, i let it run and just held on to the top radiator hose. as soon as i felt hot coolant coming thru it, i went and checked the gauge. yup it read 190. i know, a simple test i should have done in the beginning.

    i am now going to assume either my gauge is off or there are some air pockets in the system. (from draining and refilling) probably the first option is more likely. if it is some air, the more i run it the better it should get.

    the next test will be to see how it acts as the ambient temp rises.... if it ever does around here.
    Last edited by Editor_Reid; 04-20-2018 at 05:14 PM.

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    Yoda
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    Re: trying to understand my cooling system...

    FWIW, 190degF or thereabouts is considered the ideal running temp for a car. Less than that and you may not get the oil hot enough to boil off water contamination. Of course, an oil temp gauge would be best, but not usually installed in road-only cars.

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    Darth Vader John Turney's Avatar
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    Re: trying to understand my cooling system...

    The Healey cooling system isn't prone to trapping air pockets since the radiator cap it the high point of the system. So, the temperature gauge or thermostat are the most likely suspects. If you have an infrared thermometer, measure the temperature at the entrance to the radiator head tank next to the inlet. If not, and they aren't that expensive, you can use a small cooking thermometer in the top of the radiator fins. Next option is to remove the temperature gauge sensor and put it in boiling water.
    John, BN4

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    Yoda tahoe healey's Avatar
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    Re: trying to understand my cooling system...

    Harbor Freight sells them for about $30 when not on sale(sometimes $20 when they are). I don't think 190 is out of the ordinary range.

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    Re: trying to understand my cooling system...

    190 Degrees is a good running temp for the Healey sic cylinder engine,

    However, if you want to upgrade the engine performance it will require the addition of :

    1 a six bladed fan
    2 a fan shroud
    3 an upgraded serpentine radiator

    All of these modifications are readily available for reasonable costs.
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    Re: trying to understand my cooling system...

    Are you routing the coolant through the heater core? Block valve open and dash lever to the right?

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    Re: Trying to understand my cooling system

    Drone Dog,

    Okay, so did you test the thermostat on the stove before you installed it?? Its pretty mandatory now days with all the Chinese parts available. I had purchased a sleeved thermostat also, tested it and found it sticking severely such that I sent it back. I since just put a gasket on the water pump that blocked the recirculating hole, and put a 3/16 hole in the more modern thermostat to bleed air/circulate a little when warming up.

    Also, on the gage, anyone who has read gauges for a living knows that before you take a read, you tap the gauge lightly with your knuckle to take the internal friction out of the equation. If the gauge moves a little then you know that the gauge may need lubrication (or just simply tap it before you believe it).

    As for the temp, assuming the gauge is right, can you give us some history on the radiator? and the engine? Overhauled last? problems? coolant used? etc.
    Jerry Rude
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    Darth Vader Michael Oritt's Avatar
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    Re: trying to understand my cooling system...

    DD--

    The thermostat's rating determines the minimum operating temperature, not the maximum.

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    Re: trying to understand my cooling system...

    the stat temp no, is the "start to open" temp. put it in heated water and check it out. LeT

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    Re: Trying to understand my cooling system

    It is a common misperception that a 160 thermostat will maintain the coolant temp at 160. It doesn't work that way. The thermostat responds to the temperature of the coolant, it doesn't control it. Once a 160 thermostat is wide open, it has no ability to control the temperature, which is determined by several factors -- including the velocity of the air flow and the ability of the system to transfer heat from the engine to the coolant. If these factors mean the temp of the coolant is going to be 190, then a 160 thermostat is out of the loop once it is wide open because it can't open any further. I found that a 160 thermostat for my BJ8 was not the solution because it allowed the engine to run too cool in winter (I actually had to block part of the radiator to get the temp up above 160. The solution was a modern core with more tubes and fins combined with a sleeved 190 thermostat. My car now typically runs between 170 and 185 even in summer in the South. It normal for the temp gauge to go to 212 when the engine is thoroughly warmed up and then shut off. The cycling of the sleeved thermostat is also normal. This morning, I watched my temp gauge cycle from 180 to 190 and back several times until the temp stabilized at 180.
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    Re: Trying to understand my cooling system

    i will try to answer all above at one time. hope this does not get too long.

    i really don't mind if it runs at 190 either. As long as it stays there in warmer weather and does not run hotter.

    but i wonder if i am even running at 190. i have put two brand new thermostats in this car and both have had the same result. i would figure if you start the car cold and it begins to heat up, as the temp reaches 160, or there about, the thermostat is going to open and hot coolant is going to come thru that top hose. it is easy to tell when it opens. if the car ran up to 160 and the coolant started coming thru the upper hose, the car leveled out and then started getting hotter to 190, then i would assume it is running 190. but this goes right up to 190. so i am thinking something must be off with the gauge.

    i did test the gauge in boiling water before i installed it to see if it still had any ether in it. it seemed pretty close at that time. so i wondered if something else has affected it since i put it in the car. i also tested the thermostats to see they opened at the 160 temp. some of my drain downs. my wife thinks i bought stock in the gasket company....

    i do have a thermal gun and have shot the engine in a number of places. while the thermostat housing/cap can go up to 190 or so. the engine block where the sensor goes in.... i don't believe i have ever seen it go higher than maybe 170-174. So i am not sure what i am running.

    i do have a 6 bladed fan and my own fan shroud. never had the car running without it so i can't speak to how well it works or does not. this is rebuilt engine i just got back together. at this point, guessing maybe run all of 5 hours. the radiator is a stock with a new core in it by the previous owner. it was flushed and my radiator man said it had great flow. i bought the car in boxes so this is my first time having the car run. probably being too overly cautious.

    i believe i have the block heater valve open. the handle is parallel to the block and i have slid the heater handle to the right. but i have also almost completely drained the coolant to change thermostats, fix leaks, different tests, etc. several times. so it has the chance to have some air in there almost each day i have started it in the last week or so. changes to my cooling system were most of the questions i have been chasing down.

    you know i do not remember if this thermostat had a hole in it or not. i know the first non-sleeved one did not. but for some reason i think this one did.

    i do realize the thermostat does not control the final temp in the engine. but it should open and let coolant thru the upper hose at the proper temp when the car is warming up. and that should happen before 190*. i would think anyway.

    i have also noticed the cycling on some start ups. seemed a bit confusing to me but it does level out once i get to driving. i assumed most of that was air in the system working it's way out after coolant refills.

    from all i have read here, it looks like i have checked all i can short of sending the gauge off to be checked; or maybe trying a different temp thermostat; or buying another mechanincal gauge and see what it reads. i think i will just drive it and keep an eye on it. as long as it stays close to that 190 number, i will not worry about it. if it starts running hotter then i will look for another gauge to try.

    as always thanks for the suggestions and information.

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    Re: Trying to understand my cooling system

    The purpose of the thermostat is to allow the engine to heat up to operating temperature as quickly as possible. To do that it prevents coolant flow to the radiator until the thermostat control temp is reached. When cars were run all year round it was common practise to change thermostats. A 190 in winter and say a 160 in summer. As Michael said these do not affect the temperature that your engine will run at when it is at operating temperature.

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    Re: Trying to understand my cooling system

    I'm still looking for an explanation as to why both my BJ8 and BN2 will run at below thermostat setpoint temps on cool/moderate days. Both have 180degF thermostats, but will run at 160 or so unless it's warm or the engine is really working. This with several thermostats and, yes, I have tested at least one of them on the stove.

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    Jedi Knight DerekJ's Avatar
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    Re: Trying to understand my cooling system

    Something not right there Bob. That shouldn't happen unless its very cold weather.

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    Re: Trying to understand my cooling system

    Why not just start the car cold with the rad cap off , allow the car to idle and heat up , once you see flow in the rad that means the thermostat has opened .
    Drop in a five dollar meat thermometer and check the temperature . Compare to gauge reading ....Done .
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    Re: Trying to understand my cooling system

    Quote Originally Posted by Healey Nut View Post
    Why not just start the car cold with the rad cap off , allow the car to idle and heat up , once you see flow in the rad that means the thermostat has opened .
    Drop in a five dollar meat thermometer and check the temperature . Compare to gauge reading ....Done .
    Good idea. I'll do that next chance I get. I do think the thermostat is opening, as on a warm day or with a load the temp will stabilize at 180, at least until I get stuck in traffic. I had a Ford Ranger that would usually barely move the gauge needle off the peg, then read somewhere that it was a common problem with their quality German-engineered thermostats. Put a Stant in and it behaves like it should.

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    Darth Vader steveg's Avatar
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    Re: Trying to understand my cooling system

    Quote Originally Posted by Healey Nut View Post
    Why not just start the car cold with the rad cap off , allow the car to idle and heat up , once you see flow in the rad that means the thermostat has opened .
    Drop in a five dollar meat thermometer and check the temperature . Compare to gauge reading ....Done .
    I did a version of that: undid the housing, removed the thermostat, and rotated the radiator hose up so as to not lose coolant. Then inserted 2 meat thermometers adjacent to the gauge bulb and idled the car for a few minutes. My gauge showed 20+ degrees hotter than the thermometers. I moved the pin on the gauge to correspond to the thermometers.
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    Yoda Randy Forbes's Avatar
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    Re: Trying to understand my cooling system

    A new, low-hour engine is bound to be tighter and run hotter than a well seasoned one (so much talk about meat thermometers, I'm thinking about cooking) and since you're nowhere near a critical temp yet, why not just let it work itself out

    In the good old days of daily driving these cars, we didn't have time to worry about such things; did it start? Yes, then onto work! Did the car get us home? Yes, then time to do chores around the house! Being retired allows too much time to worry about things that don't need worrying about (I wouldn't know about that yet, just speculation on my part ).
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    Re: Trying to understand my cooling system

    Quote Originally Posted by Randy Forbes View Post
    In the good old days of daily driving these cars, we didn't have time to worry about such things; did it start? Yes, then onto work! Did the car get us home? Yes, then time to do chores around the house! Being retired allows too much time to worry about things that don't need worrying about (I wouldn't know about that yet, just speculation on my part ).
    Yeah, as I've gotten older, I too have perfected the fine art of over-thinking just about any job! Back then when a British car was my only transportation, I carried water, oil, tools, the old ignition parts, gasket material and Permatex. The few times I did have a breakdown, it never seemed to be a problem to just fix it and get on to where I was going. Now, I seem to worry about everything...but once I actually start to work, it usually turns out just fine.

    Back to the subject (if no one has already mentioned it): I bought an inexpensive IR thermometer for about $20. I can look at different areas on the engine, radiator and hoses. What I've found so far is the gauges in two cars read between 10 and 20 degrees too hot. I think it's a good sanity check, plus the engine can be run under pressure, and at full temperature.

    EDIT: DD, I see you did use an IR gun. I would trust those readings more than the car's temp. gauge. From what you wrote, it LOOKS like the temperature is not a problem.

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    Darth Vader steveg's Avatar
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    Re: Trying to understand my cooling system

    Quote Originally Posted by Randy Forbes View Post
    A new, low-hour engine is bound to be tighter and run hotter than a well seasoned one (so much talk about meat thermometers, I'm thinking about cooking) and since you're nowhere near a critical temp yet, why not just let it work itself out

    In the good old days of daily driving these cars, we didn't have time to worry about such things; did it start? Yes, then onto work! Did the car get us home? Yes, then time to do chores around the house! Being retired allows too much time to worry about things that don't need worrying about (I wouldn't know about that yet, just speculation on my part ).
    Being retired allows more time for "science projects". Ask me how I know.
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