CAMARO82

Does anyone know if drilling holes is the thermostat helps keep it cool in the summer if so can someone show a diagram of where to drill it thanks.

Danno

Drilling holes will help to run it a little cooler, and also eliminates the so called hot pockets that develop or so they say. I think it's a waste of time and energy. If you are that concerned and if you run a 195 stat drop down to a 180. Go to the tech article section on the site and read Bill Weissman's article about cooling fan operation. While I disagree with most of the objectives, it is well written and very informative.

CAMARO82

I run a 160 thermostat, because I live in the middle of the desert. I have tried Various thermostats and the only one that has worked decent is the 160. Does anyone know where I should drill the holes

GKK

Here's a picture; the holes are 1/8" diameter.

MdFormula350

i never tired it on any of my t-stat's, looks like a nice tip i might have to try it sometime.

Mark W. Winning

It has help both of my cars. It lets a bit of water still flow through the system as the motor comes up to temp. I think the extra water flow early, helps with hot spot. Its not a night and day difference, but it is there.

CAMARO82

Cool Thanks!

fast86z28

yea i drilled 3 1/8" holes in my 195 stat and it stays at 195-200 during the 120* summer heat

CAMARO82

FAST86Z28,,, What did it run before you put the thermostat with the holes in it?? WHat fan setup do you run???? Is yours a 350?

brodyscamaro

i have two 1/4" holes in my 160*. still warms up fast in the summer, not in the winter though.....

fast86z28

Before the holes it run at least 220ish...I have dual electric fans, aluminum 3row radiator, new water pump...yes the engine is a 350 the block is .060 over too, so the cylinder walls are pretty thin

FreeLoader

you know, as long as you have your own fan switch, and make sure your upper and lower hoses are doin good, you can run it without a thermostat at all and it will keep your car at its absolute coolest. I use my air conditioner as a fan switch, but i generally dont need it. I have a totally stock radiator and fan and so on, but all i did was remove that slinky thing that connects the exhaust manifold to the air intake assembly and removed my thermostat and i can run at an average of 160 or less at noon in Florida, and on a winter night i could run all across town without it going over 110, without the fan ever going on, i think ima just get a real fan switch and never use a thermostat again

Drakar

With out a thermostat in the car you un more of a risk of overheating then over cooling, as it does not allow the coolant enought time in the radiator for it to cool.

So no T-stat is a broken on the side of the road fix. Not something I would do permanetly.

1MEAN92RS

I have one 1/8" hole in my thermostat. I did this because I did the heater valve bypass (now have only 2 hoses, one from the back of the manifold to the heater core and the other from the heater core to the radiator with a manual heater valve in-line that I shut off in the summer) and still wanted some water to run through all the time to eliminate hot spots on warmup. It doesn't really keep my car any cooler in the summer, but in the winter it takes twice as long to warm up and almost never goes above 165* unless I'm sitting still.

brodyscamaro

realfast89

i tryed run with out one and it keep over heating i even tryeed useing a restrictor like they run in late model race cars but evertime i stop even with the fan on it would over heat and that was when i was running a 305 i wouldnt even think about it with my 350

Danno

You have a problem. I run a zz-4 block with all stock cooling and it runs just like the standard engine. Many people try to get around problems with mods. A properly functioning cooling system these cars run just like any other.

jcurrieirocz

i got a simple thought..........
How does a thermostat work is it really on the temp or the amount of pressure????

I always thought or guessed it was on pressure (because of the temp). Wouldnt drilling holes in it hinder when the thermostat actually opens, because it cant build up as much pressure to open it up. Like makeing a 160 therm. actualy open when temps get to 170-180??

If its operation is run purely on temp then wouldnt a 170 therm. w/ holes equal a 160 or so therm. w/o holes.

1MEAN92RS

It has to be based on temperature. How else would a reverse poppet (the kind that stick open when they fail) thermostat open?

Tremo

I have one of those Mr. Gasket "hi-flo" tstats (180 deg.), and I drilled two 1/8 inch holes in it. The holes slow engine warmup a bit. I tried 3 holes earlier, but on a cold night the engine would not come up to temperature, so I went to 2 holes.

In the summer, when stopped in traffic, the temp still shoots thru the roof until the fans turn on.

Danno

A thermostat has what is called a wax motor in it. It does not care about pressure, only temp. As the coolant heats up the wax motor moves the piston to open it up. System pressure is controlled by the rad cap(typ 15-16psi) and the overall integrity of the cooling system components. Drilling holes in the stat does not affect the temp which it opens, only how long it takes. Also it affects the temp at which the engine actually operates at since there is always coolant flow through it. For instance drilling holes in a 170 stat may cause the engine in highway driving to run anywhere from 5-15 degrees cooler than the stat rating. You are right on that score. Keeping the average operating temp as close to a target range is more important. That's why I don't recommend anything less than a 180. Drilling holes only delays warmup and serves no real practical purpose. Large temp swings to the engine are counterproductive and only serve to reduce fuel economy especially on fuel injection.

Tremo

The only time a couple small holes will result in the engine running too cold is if it's cold as hell outside. My engine runs at normal temps unless it's REAL cold outside, or unless I'm on a long downgrade.

Catchen22

So you live in Arizona too huh. Does it really make that big of a difference?

TRAXION

Back from the dead. I disagree ... but in specific applications.

I have no heater or AC system in my car. Thus, I do NOT have the 5/8" or 3/4" nipple on the front of my intake manifold that sends coolant from the intake to the heater core and then back to the radiator (or intake to diverter valve, etc.). In stock applications this actually means there is a constant flow of coolant through the engine (intake nipple -> heater core -> radiator). In order to maintain this same flow due to the fact that I don't have this routing anymore, I drilled three 3/16" holes in my thermostat.

Tim

Motor City Mike

The drilled thermostat idea was originally meant to be used when the thermostat by-pass port and the heater hose ports were plugged off. This was done so coolant could still circulate when the thermostat was closed to prevent localized overheating within the engine.

TransAm12sec

Running without a T-stat is not a good idea. The part that confused me is the fat that the motor runs either too cold or too hot. How does it determine which one?


You do not want the motor to run too cool. 110 would be a good example. One reason would be when the oil is not heated enough, there is not enough lubrication because the oil it too thick.

Nate86

Wouldn't the car be stuck in open loop if it ran that cold?

Cadillac

The answer to this question helps me decide what I would do.

I believe the open loop condition would be met when the engine "came up to temp" with a sensor in the ECU. Closed loop ensues?

Difference between closed and open is engine efficiency versus rich start up?

I'll go with the 180* stat (UNDrilled) and get back to you on this.

xlwhellraiser

iTrader: (1)

Ait, I will tell you this. I drilled one small hole in it and it makes a lot of difference. For example, the car now runs two to three notches from the middle, instead of hanging around 220 (which I hate). My heat is not effected that much, and mind it I am running 180 thermo with the hole in the winter!! Some of you might say thats crazy but I know that it works for me. Also, I took a girl out in the car and we drove for about 3hours, and the temp was just staying in the same spot. At one point I wasnt even using the fan and the tem was a notch and a half away from 220. Than I turned the fan on and it cooled down. It was pretty damn cold in Colorado too, the cars had ice on them and stuff. So, I guess it all depends on your cooling system, but I know that I replaced mine totally and I got that drilled thermo and I know that I will be running a lot cooler.
I just have to wait untill it gets pretty cold to see how the thermo performs.
Also, I fixed my leaking problem with some RTV, its working now, went out in cold and washed my car and engine, it looked pretty. Than the lady wanted t-tops off, so we did it with the heat on and T-tops out. It was an auxilirating experience!!
Ya, and I wanted to mention that I saw many cooling systems that do not go to a certain temp and than drop down, after I did the hole in the thermo, my car has been doing the same thing!!! Something to think about. A lot of cars do have some kind of bypass and restrictors on the stats and stuff!!

Nate86

I thought about doing it as well when I decide to change out my coolant again, but after reading what Danno has said, I think it would be unwise of me to do so.

Right now I have a 180° thermostat in the T/A with a belt-driven fan. It comes up to operating temperature quickly but I can't give you an exact temperature because the gauge's intervals are quite goofy if you ask me. Let's just say that it sits a little past the second mark on the temperature gauge.

Not only that, but the temperature is extremely consistent. It doesn't fluctuate up or down once it comes up to "OT," it happily sits at the same place during every driving session. I've heard constant fluctuations in temperatures can cause small cracks in metal, but I'm not too worried about that since a car's engine is constant going from hot to cold throughout its lifetime. Still, it does give me a little peice of mind I guess.

Anywho, open loop basically means that the car runs on predetermined values on the computer until it reaches its operating temperature, when it then switches to closed loop. Closed loops means that the car is making adjustments based on various sensors' imputs, such at the O2 sensor or CTS.

Still not too sure on what "hot pockets" are though. I thought they were a frozen snack food?

Nitsuj86Iroc

Im making an assumption that those hot pockets arnt food, but an air bubble or pocket someplace in the cooling passages? And that part of the engine gets quite hot, then as coolant all the suddent hits that spot when the thermostat opens, it shocks the steel and can possibly weaken it. Thats what i always thought people meant when they say that.

if thats the case, a small hole in the thermostat that will always let coolant trickle through might get rid of the pockets. I think it would be bad to put too big of holes in the thermostat, atleast thats what i would think for a stock engine.

Nate86

Beats me. I never even heard of them until this thread.

Stekman

Basically, these hot pockets can be gotten while adding coolant. Also, they can be created by normal use. Due to the design and flow of the cooling system, little pockets of steam can be created. These steam pockets in turn create little air bubbles. Air, being in a fluid, finds it's way to the highest point in the engine. That being right under the thermostat. Because the thermostat takes a temp reading from what it directly contacts, it measures the air pocket temperature then. And since that doesn't heat up as fast as the coolant, the coolant may be well past the thermostat temp, but the air pocket (what the stat itself measures) may still have 10 or so degrees before it hits the stats temperature, so the stat will remain shut while the engine heats up, moreso than normal.

Nate86

Mine doesn't seem to have a problem without holes.

I can see GM being a company to overlook this sort of problem, but this is seriously the first time I have ever heard of anything like this since I started getting into f-bodies and cars in general.

Stekman

Some people have it, others don't. My Camaro never had an issue like that. However, my Caprice does. Consider it a flaw of design in the conventional cooling system where coolant hits the block, then goes to the heads with already heated coolant.

I can watch my Caprice's gauge climb up to 220-230 before it will drop and I have a 180° thermostat in it.

I gave the Camaro a surge tank to alleviate those air bubbles, so we'll see how that turns out.

xlwhellraiser

iTrader: (1)

Defenetly true. It does take a while to warm up with the hole, but if you just make a tiny little hole on the side it should be enough!!! Also, the guage climbs up to 180 and stays there, without the hole my temp gets up to 220 and than drops to 190. So, I can not stress enough how important it is to have some kind of flow, just so your thermostat is not being fooled by air. And yes, the air will heat up the block faster, but it will not be registered by the thermostat due to coolant. So, thats why our cars drop after the stat opens.
Heres an idea. If you are still doubting that this is not a right thing to do, go buy 180stat, drill the smallest hole you can and check it out. It does work!!!
Good luck.

Cadillac

That's my plan. Get the 180* stat installed: Observe temp. If it doesn't cool to my expectations I will try with one hole. Repeat observation.

Spring time...

xlwhellraiser

iTrader: (1)

Already did it dude. I put a non drilled one took the car for a spin. Went up to 220 droped to 190. Than I installed the drilled 180 in there. Drove the car, went up to 180-190 and stayed there. No drop. Throughout driving I can tell you that even on the coldest days the hole is not a problem when its small. The one I made is tiny just so it lets air out. On the highway going up the hill at over 90mph my temp was at about 200 or 210 at the most. It was for about 50min that I drove uphill passing everybody. Than as soon as I slowed down it droped to 190 and stayed in 180-190 area. I am a firm beliver now that a little hole in the system will help a lot!! Especially for our cars since the cooling system was Crap!:hail:

xlwhellraiser

iTrader: (1)

by the way, I have a winter one and a summer one. The winter one has a lill tiny hole, and the summer one currently has one small hole. When summer rolls around i will add another hole on the other side. This will keep the beast at bay!!! I did not belive that the drilling was right, but when I talked to a hot rod dude, he changed my mind. Every single one of his cars has it and he usually buys them with the holes in them. I belive they call them restrictors or sumtin like that.
Defenetly try it NOW!

Cadillac

I'm sold. Again... this Spring. 180* drilled.

Merry Christmas,

JPrevost

Couldn't have said it any better.
Oh, and if the temp of your engine is getting high before dropping you should look at the different brands. Some take as long as 10 degrees to open and even then their rate is slow, others will do it in just a few degrees (robertshaw design).
I recommend the Robertshaw 180 for just about everything.

Cadillac

Any parts store will carry that or is it a special order?

JPrevost

www.stewartcomponents.com is highly recommended, they also don't charge an arm and a leg like companies like BeCool . BeCool wants $20 for the same stat from stewartcomponents.com ... go figure.
Hypertech stats are the design to avoid. When they fail they fail closed overheating your engine. The robertshaw design will fail (if you can get it too) in the open state.
Jet and Summit brands are also like the hypercrap stats.
Miloden, Mr.Gasket, Steward, Robertshaw, and BeCool all sell the better stats. They're all made by the same company, the only difference will be the number and size of the bypass holes.

Cadillac

I'm guessing this is right one?
Robert Shaw Stat

It mentions the following:

"...must be used with Stewart Stage 2, 3, or 4 water pumps.

Non-issue with a stock water pump?
Good info.

Thanks Jon!

96Iroc

bla, bla ,bla.
Stay cool man...

camarojustin

My engine builder; who is also my old boss, always drills a hole in the t-stat on new engines. It is mostly to safeguard against a possible faulty thermostat which could be castrophic when breaking in a new engine especially since many people are running new guages with their new combos
I still have the hole in mine, Why wouldn't you ?

TransAm12sec

With the extra time it takes for the motor to warm up, the oil will take even longer to warm up. When the oil is not at operating temperature, it is not thin enough to properly lubricate the engine, therefore causing more wear.

jagevileye21

iTrader: (3)

Those 1/8 holes that you drill in the thermostat are to purge air from the cooling system while the engine is filling up.

Jay

Wishmaster's87IROC

iTrader: (4)

so is this good or bad to do? cause Ive got a 180 in there right now and I drilled 3 small holes ..I have not started the motor yet as Im still in the process of swaping the motor out...but the water neck is all sealed up....should I remove it and just install a normal 180?

Cadillac

It won't hurt anything but I have to say that I haven't seen this thread in a long while. I never drilled anything in my t-stat and just went with a 180* and the Jet fan switch (goes on the block). The lower than stock stat is keeping the engine cool when operational and the fan switch kicks in when in traffic to make sure it gets the air it needs when it's not rolling.

No complaints here.