Gutting or Removing the Thermostat

Phoenix7 · 10-15-2008, 05:19 PM

Well, I asked before and I didn't really get a reasonable response.

Why are you NOT supposed to gut or remove the thermostat?

It seems to me that if there was no Thermostat the water will continually go through the radiator at all times. Mate it with an aftermarket thermo switch and you would turn the Efans ON at any temperature range and ensure that the car is being cooled properly. Right?

The only problem is that everyone says don't do it but they never say WHY. I trust you all (which is why I haven't done it) but is there more to the reasoning besides just "no, don't do it?"

10-15-2008, 08:40 PM

IMO the theory is that if you don't have a thermostat it wont build up the appropriate amount of heat in order to get warm air out of the vents to keep u warm in the cold or to defrost your windows.

Another things is some people says it wont let the engine get warm enough to get up to temp to put it into the open loop (or is is closed lol I get them mixed up)

RotaryProphet · 10-15-2008, 08:59 PM

The engine requires a restriction in order to build up water pressure, which helps eliminate hot spots in the engine; and serves to hurry along water vapor that will have a tendency to sit over the hot spot where it formed instead of allowing water through.

If you remove the thermostat, install a restrictor in it's place to allow the pump to build up some pressure. The exact size of the restrictor hole needed depends on the size of the engine, water pump flow rate, water pump RPM, heat load, and a ton of other things, but a 1/2" or 5/8" hole would be a good start for a rotary.

My5ABaby · 10-16-2008, 06:49 AM

The way I see it, the thermostat is there to regulate the temperature within a set amount of degrees. Without that regulator, your temperature is whatever your system allows. Running too cold (which could likely happen) is not a good thing. Unless you're pushing a ton of hp and creating a lot of heat or something, I see no point in removing it. Hell, I just replaced my presumably original one after 22 years on the car and prior to replacement the presumably original system was cooling the car adequately in most situations.

10-16-2008, 06:57 AM

IMO its just a replace deal.. not remove.

88turboii · 10-20-2008, 11:28 AM

i drove my old TII for a while on a stuck open t-stat, it would take forever to warm up, and temps usually be around 1/8th onthe gauge. The coolant seals went out a little while after.. food for thought

djmtsu · 10-20-2008, 11:44 AM

If the engine never reaches operating temperature (t-stat removed), it will not go into closed loop mode and will run rich all the time.

At least that is what I was told.

Cp1 · 10-21-2008, 06:19 AM

the real reason:

Ive operated a supra race built car for a long time without a thermostat with no ill effect on the motor however the reason it is there is allow proper heating of the motor. the colder the motor is the poorer gas mileage and greater amounts of hydrocarbons are released effectively make the t-stat an emissions control, and quite possibly the best emissions control on your car. i have a number of graphs showing engine operating temperature and emissions, so companies strive to get the motor running as hot as possible without the risk of damage to meet emissions and mileage requirements. the other main factor or result of this is that because the tolerances used to build your motor are derived directly from the desired operating temperature, ie: thermal expansion, if your car is constantly running too cold the tolerances are too far out to ensure smooth operation and transversely if you are consistently too hot... well you know what happens!

RETed · 10-25-2008, 09:51 AM

I've run my FC with a gutted thermostat and NO thermostat.
For day-to-day street driving, it just takes a little longer to warm up.
Mind you, I live in Hawaii with relatively warmer ambients.
It just takes a few more minutes to get to temp (above 160F).
I would NOT recommend this if you see anything close to freezing temps.

For racing, when the engine sees sustained revs, you need the restriction to minimize hot spots, as others have mentioned.
For street driving, you just eat up more gas due to the engine staying colder longer.

-Ted

retaliate1st · 11-17-2008, 10:32 AM

and your add coolant warning light will stay on...

11-17-2008, 10:40 AM

Quote:

Originally Posted by retaliate1st

and your add coolant warning light will stay on...

I think if the system is properly full and no air pockets this will not happen.

Signal 2 · 11-17-2008, 02:11 PM

IIRC, there is also a route that allows coolant to bypass the radiator and return directly to the motor. Isn't it always be open without the t-stat?

retaliate1st · 11-20-2008, 12:35 PM

Quote:

Originally Posted by SpooledupRacing

I think if the system is properly full and no air pockets this will not happen.

From experience, I beg to differ. I had my engine rebuilt by what I later realized to be an inexperienced shmuck. When I picked up the car the add coolant alarm/light stayed on constantly. It was completely full w/ no air pockets. (I drained and refilled it 3 times...)

800 miles later: coolant in the engine; rebuild. I discovered my lack of thermostat, put one in, and ever since the alarm / light has been off.

just my $0.02

staticpat · 11-21-2008, 08:13 AM

Even the mazdamotorsports tech section recommends this.

Quote:

Originally Posted by mazdaspeed

Water Pump
Water Pump/Thermostat
If you are using a stock (cast-iron) water pump, we recommend "gutting" the stock thermostat, leaving just the thermostat casing. Because some "restriction" is helpful, generally removing the thermostat is not as effective as using a gutted thermostat or restrictor. It is also important to plug the thermostat housing's water bypass. This can be done very easily by tapping the hole (1/2" pipe tap) and installing a plug

11-21-2008, 08:42 AM

Quote:

Originally Posted by retaliate1st

From experience, I beg to differ. I had my engine rebuilt by what I later realized to be an inexperienced shmuck. When I picked up the car the add coolant alarm/light stayed on constantly. It was completely full w/ no air pockets. (I drained and refilled it 3 times...)

800 miles later: coolant in the engine; rebuild. I discovered my lack of thermostat, put one in, and ever since the alarm / light has been off.

just my $0.02

when I bought my rx7 it had no t-stat in it. no buzzer ever came on. So I know from experience that the buzzer wont go off without one.
Also dont u think reted would have mentioned that since he just said that he has run one with a gutted one and without one all together.

10-16-2008, 06:49 AM	#4
My5ABaby Sigh..... Join Date: Feb 2008 Location: Murfreesboro, TN Posts: 2,377 Rep Power: 20	The way I see it, the thermostat is there to regulate the temperature within a set amount of degrees. Without that regulator, your temperature is whatever your system allows. Running too cold (which could likely happen) is not a good thing. Unless you're pushing a ton of hp and creating a lot of heat or something, I see no point in removing it. Hell, I just replaced my presumably original one after 22 years on the car and prior to replacement the presumably original system was cooling the car adequately in most situations. __________________ 1986 Sport: 132k miles, 5A (Sapphire Blue Metallic), Tokico Blues, Racing Beat Springs, Custom LED tailights (only S4 LED tails in the world), SSR Mark II, Racing Beat exhaust, S5 black interior, Rotary Resurrection rebuild at 120k miles Community Service Manual RotorWiki "Imagination costs nothing; we could build square locomotives or fly to Mars" - Felix Wankel Yesterday is history, tomorrow is a mystery, but today is a gift. That is why it is called the "present."

10-20-2008, 11:44 AM	#7
djmtsu My minds tellin' me no... Join Date: Feb 2008 Location: Murfreesboro, TN Posts: 4,043 Rep Power: 22	If the engine never reaches operating temperature (t-stat removed), it will not go into closed loop mode and will run rich all the time. At least that is what I was told. __________________ 1976 Mazda Cosmo RX-5 1976 Mazda Cosmo RX-5 2003 Toyota Tundra TRD 2015 Toyota 4Runner SR5

11-17-2008, 02:11 PM	#12
Signal 2 Viable Fossil Join Date: Mar 2008 Location: Mid-West Posts: 199 Rep Power: 18	IIRC, there is also a route that allows coolant to bypass the radiator and return directly to the motor. Isn't it always be open without the t-stat? __________________ Jim VR R1 FD

10-15-2008, 08:40 PM	#2
SpooledupRacing Guest Posts: n/a	IMO the theory is that if you don't have a thermostat it wont build up the appropriate amount of heat in order to get warm air out of the vents to keep u warm in the cold or to defrost your windows. Another things is some people says it wont let the engine get warm enough to get up to temp to put it into the open loop (or is is closed lol I get them mixed up)

10-15-2008, 08:59 PM	#3
RotaryProphet Rotary Fanatic Join Date: Sep 2008 Posts: 147 Rep Power: 18	The engine requires a restriction in order to build up water pressure, which helps eliminate hot spots in the engine; and serves to hurry along water vapor that will have a tendency to sit over the hot spot where it formed instead of allowing water through. If you remove the thermostat, install a restrictor in it's place to allow the pump to build up some pressure. The exact size of the restrictor hole needed depends on the size of the engine, water pump flow rate, water pump RPM, heat load, and a ton of other things, but a 1/2" or 5/8" hole would be a good start for a rotary.

10-16-2008, 06:57 AM	#5
SpooledupRacing Guest Posts: n/a	IMO its just a replace deal.. not remove.

10-20-2008, 11:28 AM	#6
88turboii destroy, rebuild, repeat Join Date: Feb 2008 Location: Charleston, SC Posts: 395 Rep Power: 18	i drove my old TII for a while on a stuck open t-stat, it would take forever to warm up, and temps usually be around 1/8th onthe gauge. The coolant seals went out a little while after.. food for thought

11-17-2008, 10:32 AM	#10
retaliate1st The Newbie Join Date: Nov 2008 Posts: 21 Rep Power: 0	and your add coolant warning light will stay on...