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engine runs cool

Roberte

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I have a BJ7, 1963. I am planning to install a 160 degree thermostat due to summer heat and engine overheating. I have read that it might make the engine run too cool.

What effect does this have on the engine & on performance.

Can it damage the engine?

What should be the average temperature of the coolant?

Robert
 

TimK

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I have a newly re-cored high fin count (14/inch) radiator, a BCS 6 blade fan, and a BCS shroud with a 160 degree thermostat with the original design sliding cover for the recirculation port. The engine temp averages about 175 on a 75-80 degree day. A cooler engine is less efficient than a warmer engine within a certain range. You cannot hurt an engine with a 160 thermostat, but if your cooling system is functioning well, a 180 thermostat with the original design would be better for efficiency (fuel economy and power). If the system is tending to overheat, a 160 thermostat won't fix the problem. (BCS=British Car Specialists) If you have overheating at highway speeds (above 210-220), you have a radiator problem. If overheating only in traffic (idle/slow crawl) it's likely the fan/shroud. Also make sure you have a long neck radiator cap with 7 lbs. pressure to give you protection up to about 230 degrees without boiling over in extreme conditions.
 

vette

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Robert, The degree of the thermostat is the approx temp that the thermostat opens wide. After that the ability of your engine to stay cool is based on the cooling capacity of your complete cooling system. So a 180* thermo will just allow your engine to warm faster than a 160* thermo because it will stay in its closed position until 180*. If your cooling system is capable of keeping your engine at 170* then when starting to run the car with the thermostat closed, a 180 degree stat would allow it to heat to 180* then the wide open and efficient cooling capacity would cool it to 170 and the stat would close and the engine would then heat again to about the 180 mark where-by the stat would open again and the very capable cooling system would then cool it to 170* and it would just keep cycling like that while you are
driving. In reality, on most of our Healeys, the cooling system has trouble keeping it under 180*. So the engine will heat to what ever temp you have for a stat, the stat will open and then the temp will keep going up because the cooling system really doesn't have the capacity that we need. So the only way to get the engine to run cooler is to increase the capacity of the cooling system.
It sounds like Tim has it pretty well dialed in for all the enhansements we can do.
TIM, I am interested in a fan shroud. And I have looked on BCS web site. Do you have a pic of what their shroud looks like? Dave.
 

Patrick67BJ8

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Robert, The degree of the thermostat is the approx temp that the thermostat opens wide. After that the ability of your engine to stay cool is based on the cooling capacity of your complete cooling system. So a 180* thermo will just allow your engine to warm faster than a 160* thermo because it will stay in its closed position until 180*. If your cooling system is capable of keeping your engine at 170* then when starting to run the car with the thermostat closed, a 180 degree stat would allow it to heat to 180* then the wide open and efficient cooling capacity would cool it to 170 and the stat would close and the engine would then heat again to about the 180 mark where-by the stat would open again and the very capable cooling system would then cool it to 170* and it would just keep cycling like that while you are
driving. In reality, on most of our Healeys, the cooling system has trouble keeping it under 180*. So the engine will heat to what ever temp you have for a stat, the stat will open and then the temp will keep going up because the cooling system really doesn't have the capacity that we need. So the only way to get the engine to run cooler is to increase the capacity of the cooling system.
It sounds like Tim has it pretty well dialed in for all the enhansements we can do.
TIM, I am interested in a fan shroud. And I have looked on BCS web site. Do you have a pic of what their shroud looks like? Dave.
These are pics of my Kilmartin Fan Shroud installed on my BJ8 with Texas Cooler. Care should be taken when lining up the curve of the Fan Shroud with the radiator shroud because you don't want to stress any soldered joints on the radiator shroud. I bent the Kilmarting Shroud a little bit to make a smoother fit to the radiator shroud and used 10-32 screws to attach it.
 

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peteatgr

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Robert, I've just finished installing a new Wizard Cooling aluminum radiator as my '67 BJ8 always ran hot. After installing a 6 blade fan and a new water pump with only modest success at lowering the temperature I decided to go for the complete new radiator. The drive teperature dropped right away and has become quite stable at around 180-185 degrees (at 80 degrees plus outside temp). It goes higher when idling but comes back down nicely within about 3-5 minutes of driving.

What I have been amazed at is how much rust and junk I'm getting out of my engine block. I've never done anything much to the cooling system since I've owned it (39 years). But I'm now draining the new radiator and engine block after every 30-60 minutes of drive time. I've drained it at least 7 times now and I'm still getting quite rusty water with every darin. I'd get discouaged except every bit of rust that is removed gives more space for cooled water to move through the system and cool the engine so in the end the process is all working in the right direction.

All the info above is great and right on the money, but if you've still got an original radiator it's likely to be pretty clogged just as mine was. And you probably have an engine block that isn't near as open to coolant flow as it was when it left the factory. I don't know how many times it's going to take but I'm going to continue to flush my block until the water comes out "clear" - or at least close to it.
 

steveg

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Robert, I've just finished installing a new Wizard Cooling aluminum radiator as my '67 BJ8 always ran hot. After installing a 6 blade fan and a new water pump with only modest success at lowering the temperature I decided to go for the complete new radiator. The drive teperature dropped right away and has become quite stable at around 180-185 degrees (at 80 degrees plus outside temp). It goes higher when idling but comes back down nicely within about 3-5 minutes of driving.

What I have been amazed at is how much rust and junk I'm getting out of my engine block. I've never done anything much to the cooling system since I've owned it (39 years). But I'm now draining the new radiator and engine block after every 30-60 minutes of drive time. I've drained it at least 7 times now and I'm still getting quite rusty water with every darin. I'd get discouaged except every bit of rust that is removed gives more space for cooled water to move through the system and cool the engine so in the end the process is all working in the right direction.

All the info above is great and right on the money, but if you've still got an original radiator it's likely to be pretty clogged just as mine was. And you probably have an engine block that isn't near as open to coolant flow as it was when it left the factory. I don't know how many times it's going to take but I'm going to continue to flush my block until the water comes out "clear" - or at least close to it.

Suggest you backflush your block. I made a simple hose fitting, did this and removed tons of muck. See: https://www.pbase.com/stevegerow/coolingsysupgrade

Also installed a Tefba cooling system filter but it has captured very few rust bits due to the thoroughness of the backflush.
 

Lotuswins

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Robert,

If you're wanting to check for blocked tubes in the radiator, an old mechanic told me once to bring the car up to temp and mist the radiator with water. The front of the radiator should dry off evenly, if there are sections that don't then those are the blocked tubes.

Another couple of thoughts on the 160 thermostat is that the under hood temps at speed are cooler, causing a denser air into the engine, making slightly better power. Also, if the underhood temps are less, then the trans tunnel is cooler making the interior a nicer place.

Note that OEM thermostat was 160 degrees intially until the BJ8......but I'm no expert on healeyology......8^)

good luck
 

steveg

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I used a sheet-steel 'stretcher' to hold the tops in place by pushing the tops of the Kilmartin shrouds outward against the radiator shroud as well as adding blanking plates to the parts of the shrouds that are outside the radiator:
modshroud.jpgapologies for the drawing - am sans car right now.
When I get back from vacation will post closeup pics of mods.
 

TimK

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Robert, have the capacity that we need. So the only way to get the engine to run cooler is to increase the capacity of the cooling system.
It sounds like Tim has it pretty well dialed in for all the enhansements we can do.
TIM, I am interested in a fan shroud. And I have looked on BCS web site. Do you have a pic of what their shroud looks like? Dave.
Sorry, Dave I don't have a handy photo. It's raining, but I'll try to get the car out in the next few days and get a photo. The photos of the Kilmartin shroud look similar to the BCS shroud -- it is two pieces.
 

steveg

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Sorry, Dave I don't have a handy photo. It's raining, but I'll try to get the car out in the next few days and get a photo. The photos of the Kilmartin shroud look similar to the BCS shroud -- it is two pieces.

FWIW the BCS shroud is Kilmartin - BCS is a Kilmartin dealer.
 

TimK

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This is the photo of the BCS shield, I painted the left side red, the right side is black. I didn't know the BCS shroud came from Kilmartin, but it is well made and well designed. It attaches with a bracket at the bottom of each half to the lower radiator bolts. I added one screw at the top of the left side, but nothing else was needed on the right side. It goes over the radiator inlet hose but the bracket at the bottom keeps it very secure in place.
This pic also shows the BCS 6 bladed stainless fan which is not a flex fan. It works very well at idle or any speed.
 
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Looks like a flex fan to me (though not as extreme as the Hayden BCS used to sell). You can tell if you note the thickness of the fan 'disk' at idle, then rev it up. If the 'disk'--basically, the blur made by the blades--gets thinner then it's a flex fan.
 

steveg

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I have this BCS fan, too and you'd have to hit the blades with a heavy hammer to flex them. Having said that, will observe the fan when running in a few days when home per Bob's test.

Seems to me the flex fans 30 years ago were flimsy like venetian-blind airfoils.
 
5

57_BN4

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Seems to me the flex fans 30 years ago were flimsy like venetian-blind airfoils.

Those old flex fans also bend forwards about half an inch at high rpm and cut a neat round swath out of the radiator fins like somebody parked a lawnmower on it.
 

steveg

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Pictures of modified shrouds:
LeftOuterUpper.JPG closing the gap to the radiator.
LeftInner.jpg Inside left view
StretchBarInPlace.JPG Stretcher bar pushes top edges against radiator shroud
StretchBarEndDetail.JPG Detail of stretcher bar end
UpperShield.JPG Upper front shroud (homemade - not kilmartin)
 

TimK

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Steve, your mods make a maximum efficiency setup good for a long drive through Death Valley. I don't have those mods and don't get above 175-180, but I don't drive if the air temp is above 80 because I can't take the heat even though the car can.
 

EV2239

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Originally the cars were fitted with a lower temperature Thermostat, but North Americans complained that the heater was useless in cold weather, so BMC put a hotter one in, which meant you cooked in the summer!

Use whatever you like, it doesn't matter as long as the block and rad are clear and the water pump has all its vanes. In other words, first make sure the cooling system is 100%.

When I was a lad and thermostats were less reliable, it was quite common for different ones to be used for different seasons. Oil too, 20 grade in the winter and 30 in the summer.
 
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