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Topic Review (Newest First)
01-08-2011 09:41 AM
kc8oye I think people may be missing the point of the electric fans. If your fans are running while you are moving, either your fan temp is set too low, or your radiator isn't big enough.. the fans are only there to keep the engine cool while the car is NOT moving. Once you get moving, the fans should be turning off so they don't restrict air flow. (if you don't use a controller, then it's different)

i have a 160 t-stat in my car, but I have my electric fans set to turn on at 200.
and the big fan switches to high speed at 220. This way they aren't constantly running. and I can stop briefly w/o the fans cycling on and off.
I set them up this way back when I had a little 80A alternator, and the electric fans would drag the voltage down. now that I have a 110A CS130, it doesn't make much difference

my one fan controller that turns both fans on together (with the big fan being on low) has an extra wire to turn the fans on when the A/C is on.. I don't have AC so I ran that wire into the car to a toggle switch.. so when I'm sitting in the staging lanes at the track, I can force the fans to run anyway to keep the engine temp down so I'm not trying to launch with the engine temps up near 200
01-04-2011 12:36 PM
oldbogie
Quote:
Originally Posted by Sweet-34
Can someone enlighten me as to drill or not to drill holes in the 180 degree thermostat on a 327 Chevy Engine. Been running a 195 degree thermostat and it runs too hot. I'm running a manifold fan sensor that turns on my fan at 200 degrees and cools to 185 before shutting off. Most people tell me to drill 3 small holes in the stat before installing.

If so......what size holes? Also, what is the benefit of doing this?

Thank you
The hole, not holes, needs only to be 1/8 inch it is there to help vent air when filling the system making life a little easier. It is not large enough to affect operating temperature, especially given the Chevy already has two bypasses the heater circuit and a flow balance return in the right head and block.

You should expect that the engine will run from 10 to 15 degrees warmer than the stamped temp on the thermostat, the reason for that is the stamped temp is the opening temperature where the thermostat's valve just cracks open, it takes another 5 to 10 degrees or so to achieve full opening.

200 degrees on a 195 thermostat is what I'd consider inside the normal range of operation. If the electric fans can pull the operating temp to 185, I say they're pretty good as at this temp the thermostat is again closed and has to recycle to open again.

If everything else is doing its job, a 185 thermostat should get you a running temp between 190 to 200 degrees.

Don't forget these things are mass produced, their functional range is probably on the order of +/- 10 to 15 degrees. To a large extent the actual operating temp say 220 to 230 as a max isn't as important as keeping the insides of the cooling jackets wet. That's to say a running loss of coolant will be far more destructive than a wet though high operating temperature, with-in reason of course.

Bogie
01-04-2011 09:48 AM
Centerline
Quote:
Originally Posted by scrot
......So the fact that the manufactures aren't doing it should tell us something.
Yes. It tells us that with a complete factory setup in most cases the holes aren't needed. However, most of us don't run a factory setup. Just about all of us have a non stock engine which creates more heat and in many cases have a complete aftermarket cooling system. Drilling holes in the thermostat is done mainly to keep air pockets out of the system which is a common cause of overheating problems in custom cooling setups. They don't really help with cooling, but do help the system to operate properly.

I always drill 3 1/8" holes in any thermostat that's going in a custom cooling system. Its cheap insurance against air pockets which WILL lead to premature failure of critical (and expensive) engine components.

Centerline
HotRodsAndHemis.com

"Aerodynamics are for people who canít build engines." Ė Enzo Ferrari
01-04-2011 04:47 AM
Sweet-34
Quote:
Originally Posted by Buzzard II
You're in Florida, try a 165 or 180 thermostat. Check your radiator cap to make sure it is good and of the correct lbs. Run a 50-50 anti freeze-water mix. Set your fan to come on earlier, maybe 185-190 max. Are you running a fan shroud? They do work! I would not waste time drilling holes, once the thermostat opens, after warm up, they don't serve any purpose. Good luck! Bob
When running a 195 degree thermostat.....Correct me if I'm wrong.......But once the vehicle is up to operating temperature and running around 200 degrees and the fan come on and cools it down to 195 degrees doesn't the thermostat start to close and holds the temp so it doesn't go any lower than the 195 degrees?

I pretty much proved that the other day.....when I took out the 195 and replaced it with a 180 thermostat. With the 195, I was running around 203 degrees with the fan on. Put in the 180 (fan on) and it dropped to 188-189 degrees same road, same time and same conditions. I was taught the same way....after it opens it doesn't have anything to do with the running temperature. I have changed my line of thinking after doing the 180 switch and talked to a certified GM mechanic the other day. He says that the degree does determine how low it will cool before the thermostat starts closing and will hold the temperature so it goes no lower than the stated degree for that particular thermostat.

I do appreciated everyone's replies~~~~~~Ron
01-04-2011 03:22 AM
Buzzard II
running hot

You're in Florida, try a 165 or 180 thermostat. Check your radiator cap to make sure it is good and of the correct lbs. Run a 50-50 anti freeze-water mix. Set your fan to come on earlier, maybe 185-190 max. Are you running a fan shroud? They do work! I would not waste time drilling holes, once the thermostat opens, after warm up, they don't serve any purpose. Good luck! Bob
01-03-2011 06:16 PM
eloc431962 Stewart performance does it has the holes in the thermostat they sell.
And i read somewhere where ford did it in the windstar van also.


Cole
01-03-2011 05:04 PM
scrot If drilling a hole or holes in a thermostat was a good idea, why don't the manufactures do it, and advertise it as "new and improved," "high performance", or some other bs?
They could charge a higher price for it if it were a good idea.
Some have a very small hole around 1/16" with a loose rivet in it to restrict the flow of air even more.

So the fact that the manufactures aren't doing it should tell us something.
01-03-2011 02:49 PM
machine shop tom
Quote:
Originally Posted by F-BIRD'88
Some things that will make it run hotter than you'd like:

Not enough fan air flow thru the rad.

Not enough airflow thru the rad at hiway speeds.
Not enough idle spark timing.

Defective vacuum advance.
Are the heater hoses hooked up?
Add some Water Wetter to the coolant.
Collapsing lower rad hose. (missing hose spring)
Air trapped in the coolant system.
Add to that a radiator too small for the application or one that is getting plugged up.

tom
01-03-2011 12:28 PM
kc8oye
Quote:
Originally Posted by ap72
I always drill one 3/16" hole when I install a t-stat, any more than that and you're defeatting the purpose of a t-stat, anyless and you can get air pockets.

High system pressure, high flow, about 30% antifreeze has always worked very well for me.
30% antifreeze will get you a cracked block in Michigan :>
01-03-2011 10:03 AM
XNTRCI-T I drilled my stat, too. My understanding is this is mainly to allow air to escape the block when filling the system. I would think the amount of coolant flow through such a small hole would be insignificant.
01-03-2011 08:41 AM
ap72 I always drill one 3/16" hole when I install a t-stat, any more than that and you're defeatting the purpose of a t-stat, anyless and you can get air pockets.

High system pressure, high flow, about 30% antifreeze has always worked very well for me.
01-03-2011 07:16 AM
Irelands child This is copied and pasted directly from Stewarts Water Pumps website: http://www.stewartcomponents.com/index.html

"Tech Tip #3 - Thermostats & Restrictors

Thermostats & Restrictors
We strongly recommend NEVER using a restrictor: they decrease coolant flow and ultimately inhibit cooling.

For applications requiring a thermostat to keep the engine at operating temperature, we recommend using a Stewart/Robertshaw high flow thermostat. This thermostat does not restrict flow when open. The Stewart/ Robertshaw thermostat enhances the performance of the cooling system, using any style of water pump. However, the Stewart Stage 1 high-flow water pump may require this thermostat to operate properly, and Stewart Stage 2, 3, and 4 water pumps simply will NOT operate with a regular thermostat because these pumps have no internal bypasses.

Stewart further modifies its thermostat by machining three 3/16" bypass holes directly in the poppet valve, which allows some coolant to bypass the thermostat even when closed. This modification does result in the engine taking slightly longer to reach operating temperature in cold weather, but it allows the thermostat to function properly when using a high flow water pump at high engine RPM.

A common misconception is that if coolant flows too quickly through the system, that it will not have time to cool properly. However the cooling system is a closed loop, so if you are keeping the coolant in the radiator longer to allow it to cool, you are also allowing it to stay in the engine longer, which increases coolant temperatures. Coolant in the engine will actually boil away from critical heat areas within the cooling system if not forced through the cooling system at a sufficiently high velocity. This situation is a common cause of so-called "hot spots", which can lead to failures.

Years ago, cars used low pressure radiator caps with upright-style radiators. At high RPM, the water pump pressure would overcome the radiator cap's rating and force coolant out, resulting in an overheated engine. Many enthusiasts mistakenly believed that these situations were caused because the coolant was flowing through the radiator so quickly, that it did not have time to cool. Using restrictors or slowing water pump speed prevented the coolant from being forced out, and allowed the engine to run cooler. However, cars built in the past thirty years have used cross flow radiators that position the radiator cap on the low pressure (suction) side of the system. This type of system does not subject the radiator cap to pressure from the water pump, so it benefits from maximizing coolant flow, not restricting it."

I'm using one of their pumps and have done this mod to my thermostat. With a 190* stat seldom does the195* fan setting ever turn it on unless the car has idled for quite a while.

Dave W
01-03-2011 06:56 AM
Bryan59EC A lot of vehicles shut the heater flow off when not actually wnating heat.
Prety sure all AC cars do this.

If there is no valve hooked up the the heater core to shut off the water flow, a bypass should not be needed.

Not having a bypass can create some strange temp patterns util the car fully warms up-----even if there are a couple of holes drilled into the t-stat.
01-03-2011 01:25 AM
kc8oye if you have a heater core hooked up, will the holes really help? since the heater core acts as a bypass around the t-stat anyway?
01-02-2011 09:08 PM
larryf
Quote:
Originally Posted by Sweet-34
Can someone enlighten me as to drill or not to drill holes in the 180 degree thermostat on a 327 Chevy Engine. Been running a 195 degree thermostat and it runs too hot. I'm running a manifold fan sensor that turns on my fan at 200 degrees and cools to 185 before shutting off. Most people tell me to drill 3 small holes in the stat before installing.

If so......what size holes? Also, what is the benefit of doing this?

Thank you
as was suggested,a good fan shroud forces air to be pulled thru radiator.larry nice rod
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