Spectator

iTrader: (1)

The car never runs in winter, why would I want a thermostat? What are the consequences?

jgrewe

iTrader: (1)

It helps the car reach operating temp faster and it also slows down the flow of coolant through the engine(which is a good thing, gives it more time absorb heat)

Spectator

iTrader: (1)

I would had thought the opposite.

Since the coolant goes faster it absords more heat because it cools faster.

Aaron Cake

iTrader: (1)

If you are insistent on running with no thermostat, you need to at least plug the bypass hole in the water pump housing. Without the thermostat there to close it, a lot of coolant actually bypasses the radiator.

Really though, a thermostat is about $20 at the dealer. Just replace it. The thermostat is there to regulate the engine into operating at a specific temperature, and maintaining that temperature. If you don't run the thermostat you will find that your engine temp will fluctuate wildly leading to poor mileage and performance.

SpeedOfLife

iTrader: (16)

Not to mention that on a 7 overheating is often lethal to the motor. Don't take that risk. ESPECIALLY since it's a summer car. Having free flowing coolant will make the motor stay very cool, and fuel apparently atomizes better when you have a warm block (but cool air is good so it compresses well), not a cold one. You would most likely get terrible mileage and it might not even run well. These cars do better when they get a little time to warm up compared to piston engines, right? If anything EVER happens to your coolant (well, you may have the coolant level buzzer still) like if it gets contaminated or really dirty it could make things bad by raising the temperature dangerously and you would never know it while driving because you'd have nothing to drive your temp gauge.

slpin

iTrader: (9)

you are an idiot

CyberPitz

I had this question too....does the thermostat attach to the bottom of the radiator? I'm thinking that it does, due to the fact down there is a little thing dangling...looks like it snapped off the radiator....if that IS the thermostat, how would I go about reconnecting that? IT's not like it can snap on..looks like it needs welded?

Spectator

iTrader: (1)

tHE THERMOSTAT IS JUST ABOVE THE WATER PUMP.

sry for caps..

My5ABaby

iTrader: (7)

The thermostat is inside the water pump neck. FSM.

Aaron Cake

iTrader: (1)

Actually, in a way what he said is true. A more accurate way of saying it is that the thermostat regulates the flow of coolant through the radiator so the coolant flow is proportional to engine temperature.

And next time, don't reply with an insult.

slpin

iTrader: (9)

he is true to an extent

but what he is forgetting is that, even if each oz of water isnt doing as much cooling, there are many oz of water that flows through it that will....
not sure if that make sense...

think of it like a fan on a heatsink for your CPU. a higher cfm will always yield a closer temperature with ambient - even though each air molecule doesnt stay on the heatsink 'long enough to pick up the heat'

anewconvert

iTrader: (1)

He's right in the fact that it helps the car reach operating temp faster, but he is completely wrong in the part that slpin quoted.

A given volume of water that hasn't absorbed heat (energy) will absorb more heat than the same volume of water that has already absorbed heat. You will get greater cooling by movign the water through there quickly than you will by slowing it down.

That doesnt mean you WANT that though. In the case of the engine operating temp is better than a cooler engine.

BC

SPIRITED_DRIVER07

if madza didnt want to use a thermistat in the rx-7, they wouldnt have put it there.

my $0.02

jgrewe

iTrader: (1)

Its OK, I've been called worse by better.

I came to this thinking after a race car was doing strange things in the cooling area. I thought about how you can run your finger through a flame quickly and it doesn't burn you but if you do it slowly it will hurt. It may be a function of our body and feeling pain but it made sense after staring at the car holding a beer( OK maybe a few beers) and we made the hole in our blanking plate smaller and the car quit overheating.

SpeedOfLife

iTrader: (16)

Let me try to clear this up for everybody.

When the coolant is at its lowest temperature it will absorb heat at a higher rate, however, as soon as it starts absorbing heat that rate at which it absorbs heat decreases. Now, if you didn't cycle coolant at all, the coolant in the motor would absorb about all the heat it could manage, BUT since that maximum absorbed heat is less than the motor puts out, the whole motor will overheat. So that's a rough case for when there's no pump or the thermostat is stuck completely shut.

The other case is where there's no thermostat or it's stuck all the way open. Coolant rushes through the veins, absorbing heat at a very fast rate and dissipates it through the radiator as it flows quite easily. It certainly won't cool the engine to anywhere near the outside temperature, but it will be much lower than desired. Don't think of it as a finger over a flame, I'll give you a better example. Gases are fluids, too, so fluid thermodynamics apply to both liquids and gases. So, you're outside on a warm day wearing shorts and a t-shirt. Forget what temperature exactly, just think of it as your ideal temperature plus 5 degrees Fahrenheit. A cool breeze would be really nice, because it's 5 over your comfort zone. A strong wind could make it cold because even though that air isn't resting around you as long as with no breeze or a slight breeze, it's robbing you of your heat very quickly. Each particle you would come in contact with MIGHT not take quite as much heat than if it was traveling slower, but you're coming in contact with many more particles, and the harder molecules collide the more thermal energy they can transfer.

Any questions?

jgrewe

iTrader: (1)

Thanks for the eloquent explanation. Are you sure you don't want to throw an insult around to fit in?

I've long forgotten which car this was an issue on but thinking more about it it was probably a water pump cavitation problem. I've always run a blanking plate since then and have never had the same problem show up on any other car.

SpeedOfLife

iTrader: (16)

I looked this up because firefox was telling me I was wrong, but it turns out I was right. Yet another word to add to its dictionary. So when I looked it up I discovered it can also mean pitting of a solid surface, but I assume you meant the first definition.

cavitate:
1. The sudden formation and collapse of low-pressure bubbles in liquids by means of mechanical forces, such as those resulting from rotation of a marine propeller.
2. The pitting of a solid surface.
3. Medicine The formation of cavities in a body tissue or an organ, especially those formed in the lung as a result of tuberculosis.


Anyway, if the pump is cavitating in the first sense I would think something's very wrong with the pump (like it might be the wrong pump altogether).

jgrewe

iTrader: (1)

Number 1, water pumps on RX-7's with the stock pulley set-up cavitate at around 6500rpm. It can actually show up on dyno runs as a loss in HP from the drag. It also will stop the flow of coolant.

SpeedOfLife

iTrader: (16)

Well that sucks, I can't believe they didn't engineer a fix for that before selling the car. So what are some fixes for that? I'd hate for engine temps to spike if I was running at 6500-7000 RPM for 30 or so.

jgrewe

iTrader: (1)

Actually most engines will have this problem at some high RPM. Its all on how much the water pump is over driven from the crank/eshaft speed.
A smaller eshaft pulley is the first thing then with the extra room you get from that you go with a bigger waterpump pulley. Mazdaspeed sells both, Mazdatrix will sell them to you if you aren't a racer.

SpeedOfLife

iTrader: (16)

If you aren't a racer? What do you mean?

xfeastonarsex

iTrader: (5)

I dont know if anyone said it yet or not but the thermostat will actually cool your engine more evenly by slowing down the water and allowing it to absorb the heat from the engine.

jgrewe

iTrader: (1)

Mazdaspeed is the factory parts support connection. If you race your car in just about any organized group like SCCA, NASA, NHRA etc. they will sell you parts directly at dealer cost.

Careful xfeastonarex, slpin will call you an idiot...

SpeedOfLife

iTrader: (16)

What do you mean 'evenly'? By having the thermostat work right the whole block might have a lower standard deviation of temperature (temp points taken from all points within the block) than if it ran colder or warmer than it's supposed to, but I can't think of any other way to make sense of what you said.

SpeedOfLife

iTrader: (16)

So, is dealer cost higher or lower than 'Joe Schmoe' cost?
Dealer cost from a normal parts store is cheaper than that same part from a mechanic's shop, because the mechanic buys the part from the store (at what I understand as dealer cost) then charges you up the butt for it.