running without a thermostat. educate me

So I am working on a buddies 305 and pulled the filler neck and there is now thermostat. I asked the guy what happened and he said that he was told that since he wasn't running a heater and it was not running a hood that he should pull the thermostat.

I had never heard this....So whats the scoop. I know older motors run without them but never a SBC. is there any drawbacks/problem running it as a constant flow system?

 

When I put the 327 in my chevy it didn't have a thermostat in it and it was running hot all the time. I put a 185 degree t-stat in it and now it runs much cooler. I'm guessing it did not get the chance to stay in the radiator long enough to cool down...just my thoughts.

 

We drilled out the thermostat on our 409 to see if it would run cooler- and it did. As long as you have the ring to slow the coolant but without the guts it should be okay. It worked for us anyways.

 

A thermostat regulates the flow of coolant to the radiator from the engine. The engine needs to run at 180 or so....running cooler sludges up the oil and also the oil does NOT lubricate as well at a lower temperature.

Nascar engine dyno tests prove that a SBC makes the most HP at 205 to 215 degrees. Street engines also pollute less at warmer temps.....my new Silverado runs at 210..from General Motors.

When no thermostat is installed............the coolant goes to the radiator and back to the engine so fast...........it does not have time to cool down.....

IMHO.......

.

 

The oil needs to get above 210F to drive off any condensation,
that means the water needs to be,at least,185 consistantly.
The motor will last longer,without developing sludge.

A motor that is 30 degrees too cool actually has more friction
than one that is 30 degrees too hot.


Doesn't matter if you run a hood or a heater.That's just Bullshit.

 

Thermostats do two things. 1. when the engine is cold they stay closed to help the engine reach opperating temp quicker. They also cycle in cold weather to prevent radiator freeze up. 2.. When open the housing also acts as a restriction to slow the coolant flow. This allows the coolant to stay in the radiator long enough for it to do it's job. Running without a thermostat causes the temp to slowly climb untill it overheats. Their are Exceptions::
If the cooling system is restricted in some way, (deposites in raidiator, slightly collapsed hoses, deposits in engine,ect) The restriction will act as the thremostat would and the system would function normaly. Adding a thermostat to this set up would cause overheating. Bottom line is run a thermostat, the factory put it there for a reason.

 

Duece Roadster and Unkl Ian....SO it is actually a good thing to run without the thermo?

He says it runs hot 210-220 but he says it runs better without it then with it...

If the water is not cooling down should there be more coolant or less?

 

i have a 383 i run at 160 degree thermostat. It runs fine and i notice no sludge. Should there be a 180 degree one in there?

 

Try running water wetter or whatever it's called.

 

Oh ya sorry to be a hijacker but anyone know what a good operating temp should be for a built 409 high compression roller motor? It was stuck at 220 all the time even in the cold until we changed the AFB's for edelbrocks and drilled the thermostat. It's now running 190.

 

No only will the coolant/water not have enough time to cool in the radiator, the water wont have enough time in the block to pull the heat out of it. The gauge will show that it "runs cooler" for this very reason, since the sending unit measures the temp of the water and not the block.

 

Hell with all the metalurgy and physics, I'll Splain this the easy way, the way that makes cents, dollars and cents.
Do you think for one minute that the auto makers would spend actually millions of dollars, that otherwise would be profit, putting a part in an engine that it didn't need?

 

What do you mean by drilling the thermostat??

 

Yeah - what size bit do you use ?? I have a 400 - 30 over and it can't keep cool to save it's ass, the top hose is hard as a rock, with a 16psi cap?

Thanks for the hi-jack

 

either drill the guts out of it and keep the outter ring like graverobber did or drill small holes in the outter ring and keep the guts

 

well 400s have a problem running hot to begin with and since its 30 over you're decreasing the cylinder wall which causes the block to heat up faster and run hotter

use a bit the size of a drinking straw

 

I do this stuff for a livin, so please bear with me...

the 'stat is there to regulate water temps. An engine is designed to run at a specific coolant temp - give or take 20 degrees. Aside from the oil sludge comment mentioned earlier, the piston/cylinder clearance is a function of differentials in coefficients of thermal expansion; design clearances are for an engine AT OPERATING TEMPERATURE. If you run the engine below operating temp - pistons rock in the bore, and rings don't seal like they should. 160 degrees is the lower limit, IMHO, for proper operation.

As for time in the engine or radiator - horsepuckey. the 'U' value (thermodynamic efficiency of heat transfer) is better when water velocity goes up. What ACTUALLY happens is the loss of the pressure drop of the T-stat in the system causes the water pump to cavitate at higher RPMS; cavitation causes loss of coolant flow and subsequent overheating.

Heat rejection is a really simple formula:

Q = GPM X delta T X 500

where GPM is the fluid flow in gallons per minute (design on a car water pump is typically 55 GPM) and delta T is the temp of the water going in/out of the radiator. Q is heat, measured in BTU's.

You can measure the system's capacity with an infrared pyrometer - they sell these little bastards now at Radio Shack for 50 bux. great tool for diagnostic stuff, BTW - you can pinpoint probs in no time - if you understand heat flow.

Anyway - you CAN run with no T-stat AS LONG AS you replicate the pressure drop of the stat in the pumping system. The solution is called an orifice plate, and a 5/8" hole has *about* the same pressure drop as a thermostat.

Do keep in mind, tho - the carb relies on some heat from the engine for vaporization, and runnin' no stat will increase warmup time on motors with carbs.

okay (pant,pant) I'm done ranting. thanks for tuning in...

 

Hmmmm...Dr.J. You mean like catalytic converters and air pumps? I thought an engine didn't need those things.

Just joking a little.

But seriously. An engine NEEDS a t-stat. period. Its already been explained.
...Operating temperatures etc etc.


I would think the only time a person should run without a T-stat is in a case of an emergency.
I once had an engine blow a head gasket. It wasn't burning antifreeze, but just pumping it out the overflow tank. The coolant system was super pressurized by the combustion of the engine. I was losing coolant like crazy.
I also had a few more miles to go to make it home, so I pulled over and pulled out the T-stat. I made it home.

Put a 180º T-stat in that engine.

If it has overheating issues, then find the problem. But the T-stat isn't the problem.

TINGLER

 

Ok, here's my 2 cents. I've had alot of old cars and hot rods in my time ont his planet and have run with and without thermostats, 160's, 180's, blah-blah-blah. All my experiences resulted in not much difference in operation temps. In each case I was hunting down cooling problems only to end up with what was REALLY wrong (Water pump, fan spacing, timing, etc.). The thermostat change just never made a huge difference.

 

You need a thermostat in a street car.

A restrictor orifice will work but has no variability to conform to differing engine requirements...why reinvent the wheel?

This isn't a confusing subject...but it can be if you try hard enough!

QUOTE... Dixiedog.....
Yeah - what size bit do you use ?? I have a 400 - 30 over and it can't keep cool to save it's ass, the top hose is hard as a rock, with a 16psi cap?


Once the cap senses 16 lbs it will open and bleed pressure into the overflow bottle. At full operating temp the rad hose will be hard...thats normal. The pressure allows the water to heat beyond atmospheric boiling point.
Drilling out a thermostat isn't a miracle cure. Chevy used a bigger rad in cars with 400's... I believe the thermostat remained the same.
Perhaps they were on to something.

My ONE experience with a car with no thermostat went like this...
The car took forever to reach operating temp...in our climate it was full of sludge in a month. To the point where you couldn't even check the oil properly.
When it finally reached full temp it was very likely to overheat at a stop light and spew water everywhere, to the point that the temp gauge dropped to zero from lack of water and the engine cooked. Always had to carry water in the trunk to get me home.
Others I know who tried it had the same problems.

It isn't a smart way to deal with overheating issues. It's a bandaid solution at best.

 

does it have steam holes in the heads? are the head gaskets sealing properly? is the radiator big enough? (they were extra big with these engines originally). is the fan big enough and well shrouded to pull enough air thru the radiator?

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I'm not running a thermostat in my bulldozer (1940s IH TD-9 diesel 4 cyl) because it didn't have one in it when I got it last month...it ran very hot too. Once I discovered that the water pump driver was missing, and got the pump to actually function, it runs too cool. So I'm putting a T stat in it.

 

Not to hijack but this may be relevant. What lb. radiator caps are you guys running. I just replaced my 16lb. with a 13lb. because that's all they had at the time. Just curious.

 

Hmm...that reminds me:

WAAY back - like early brass T era back - many water cooled motors ran thermosiphon systems. Hot water rises; cold water falls - toss a rad and a motor into the mix, and the system WILL circulate! Water pumps were a later addition. In fact, the old stationary gas motors simply ran a water reservoir, and relied on the latent heat of vaporization to maintain cylinder temps at 212 degrees.

Cooling issues are usually a function of fouling - either the radiator or the block. Steam holes are relief vents drilled between the block and heads to insure no vapor pockets form in the cooling circuit; where there's vapor - there's no cooling.

While on the subject - a good rule of thumb is the 1/3rd rule. 1/3rd of the available heat goes inta (g'zinta) power, 1/3rd g'zinta the tailpipe, and a third g'zinta frictional lossed in the form of heat. When you double the output of yer hotrod - you need double the surface area to dissipate the additional thermal energy rejected to the cooling system.

Sorry, guys - Can't help myself. I'm an inveterate tech weenie.

 

I've pretty much learned to shut up on this issue, because WAAAAAYYYYY too many folk have it in their minds that cooler = better with engines.

Never mind that they have a 195º therm in their new car.

Never mind that Kawasaki, having a spate of complaints of overheating (on the guage) when the 900 Ninja first came out, put in a resistor in the temp gauge circuit, rather than compromise their own research.

The sludge aspect I had never thought about. Makes perfect sense.

FWIW, I run 195 thermostats. I believe that the thermal efficiency has been more thoroughly researched by the factories, than by the backyard mechanics. And I've not seen a new car with even a 180º thermostat.

Overheating is NOT over 180º. Overheating is when the radiator boils over, and may not be the fault of the thermostat.

When in doubt, look at a factory automobile. Trust me, they design these things to last a long time, make as much power as possible, and be as efficient as possible. Witness that of all the "chip" replacement tests that I have seen, very, very few have made more power, while almost all have compromised driveability to some extent.

Bottom line: a thermostat is absolutely necessary in all street applications, no exceptions. Further, the hotter, the better, use that 195º or 210º thermostat, your engine will make more power and last longer.

Cosmo

 

Ok, but how hot is TOO hot? I have a fresh 427 Ford that likes to go 225 or better idling. When does engine damage occur, 240,250?

 

240 is probably getting close to too hot, but only because the coolant boils somewhere around there....and that's what you need to avoid.

On the issue of pressure caps, the higher the pressure=the higher the boiling point. But you have to watch it with the rads from the 50s, they have big tanks that cannot take more than 4 to 7 psi they were designed to hold. Ever seen an early radiator with the tank bulged out because someone put a 16 psi cap on it?

 

where/how is your temp gage sender attatched?