kouki_fc3s

i just put in a koyo radiator in my 7. it's a S5 N/A, and it still runs at the same temp. i but in a 40/60 mix, with half a bottle if watter wetter. i was wondering if anybody has taken out their thermostat so its always open. are there any negative side effects to this besides the engine taking longer to warm up? any response is much appreciated. thanks.

ilike2eatricers

Is it running too hot or something? What temp did you want it be running at?

patman

iTrader: (3)

no, no side effect other than warming. but i ask the same question as ilike2eatricers. i doubt if the thermostat is gonna change much of anything.

kouki_fc3s

so i can just remove the thermostat w/ no poblems?

ilike2eatricers

I think you need the seal that goes around the tstat. RETed I believe has cored out tstats before. Do a search on it.

sunshine

iTrader: (3)

Ah the majic of the Search button:

https://www.rx7club.com/showthread.p...rmostat+remove

I'm personally with NZ on this issue.
But the facts are in that thread, and its for you to decide.
-a

kouki_fc3s

thanks for the help guys

therotaryrocket

50/50 mix is the best for everything. i think

geargrabber

you need the thermostat!! when the thermostat is closed, it circulates coolant around the engine -- keeps the engine temps even around the entire engine.

When the thermostat is open it flows coolant through the radiator.

dont remove it, it is vital.



edit: wouldnt it be neat if there was an electric thermostat that flowed like a **** ??

maybe there is...

but i think a setup of electric fans, electric waterpump, and electric thermostat would keep temps purrrrrfect.

NZConvertible

Unless it was overheating before then that's exactly what should happen. The purpose of upgrading the radiator is to increase the cooling system's capacity (i.e. how fast it can remove heat), not to make the car run cooler than normal. The thermostat should keep the engine at the correct temp regardless of improvements.

Yes there are. Read on...

What a load of BS. If it didn't "change much of anything" there wouldn't be one fitted to just about every car engine ever made. The thermostat is there to regulate the engine's temp. Without proper coolant flow control the engine's temp will rise any fall with engine load. It will be too cold at low load and too hot at high load. You can also cause hot spots in the engine.

patman

iTrader: (3)

i hate to tell you, NZ, but thats not quite how it works. maybe in an ideal world, it would, but this definately isnt.

the thermostat does regulate coolant flow, but not in any exact, precise way like you are assuming. it only reacts to major temperature changes. a fw degrees of difference between WOT and idle doesnt make enough difference to change anything.

what i meant about 'change much of anything' was that taking it out wont make his car run cooler. when its hot, the thermostat is all the way open, so taking it out wont make much difference in that situation.

there is a good reason every car has a thermostat...running an engine cold is not good for it. you want it to warm to operating temp as quickly as possible to minimize the time when everything is cold and brittle and lubrication is poor. gas mileage is affected too. that is the reason for the thermostat, nothing more. there is no precisely metered control of engine temp. in fact, if you'll notice, temps DO rise and fall with load. just not that much, because once the engine is at operating temperature, it tends to stay pretty close to that temp. the only way to change that is a better cooling system all together.

as for hot spots, where do you get that idea? hot spots in the engine are caused by air bubbles in the coolant, or by impaired coolant flow. having coolant flowing all the time is not gonna do any such thing.

now, aside from the the theory and all that, i do agree with you. there is no reason to ever remove the thermostat, and doingso is a bad idea. but not for any of the reasons you mentioned, just for the shorter warm times. because the less time you run that cold engine, the better. (note cold for an engine is not the same as cold for you or me, its like...under 150*F is bad, so living in CA or HI doesnt help much)

that aside, he didnt ask about that, he specifically omitted warming time. the whole idea seemed kind of dumb t me, which is why i asked why he wanted to do this. which he never answered by the way.

Aaron Cake

iTrader: (1)

There's a huge difference in temperature between WOT and idle. For one thing, at idle, the engine is under no load. Under WOT, it is being asked to produce it's maximum power. More fuel/air, more fire, MORE HEAT is produced.

The thermostat is not an "on/off" device. It will open different amounts based on temperature. For example, as the engine begins to heat up, the thermostat begins to open. Coolant circulates through the rad, which then cools down. The thermostat then begins to close up again. It's almost like a "closed loop" control.

So you're agreeing? The thermostat tries to regulate the engine temp, while still offering a quick warmup. If you don't have a thermostat, you can get the engine to cool WAY down at idle, back to the point where the ECU will again enter the cold start mode. You're burning way too much fuel, causing carbon buildup, stressing the engine, getting poorer lubrication, etc. Constantly heat cycling the engien is not a good idea.

Of course they rise and fall with load. And of course it tries to stay at a constant temperature, since that's the job of the thermostat.

If you just shove a larger rad on the car, the engine will stay at the temperature the thermostat is designed to maintain. If you change the thermostat, you will change the operating temperature of the car ASSUMING that the rad is large enough to reject that amount of heat.

Coolant that flows too fast will not stay in contact with the engine long enough to transfer as much heat as it could. This, of course, will NOT show up on temp readings because you are seeing the temperature of the cooant, and not the engine.

NZConvertible

Well Aaron's basically said everything I was going to say, but I'll add this. Look at the thermostat's specs in the FSM. It starts to open at ~180degF but is not fully open until over 200degF, and that just happens to be the generally recommended "normal" range. Guess what's happening between those temps. The thermostat is regulating the coolant's flow in an effort to keep the temp within a fairly small range where the engine runs best.

SureShot

The stat has a second - often overlooked function.

It has a second spring loaded disc that covers a bypass port in the pump housing.

Without the stat, the pump will bypass about 1/3 of the coolant flow back to the block without going through the radiator at all.

So - do you want your radiator to act like it's 1/3 smaller?

Generally, with a stock radiator, you need to keep the stat.

With an oversize radiator, you can optionally pull the stat & plug the bypass port.

rawdog905

I have been running without a stat for 6 years 1985 gsl with 205,386 miles, my car kept over heating with a stat, so I pulled it. I dive this car from Mississippi to Georgia often.

patman

iTrader: (3)

i forgot about this thread, but despite all the theoretical blabber of the guys up there, the stat doesnt do much of anything once the car is warm. ive got a good counterargument to every one of theirs, but whats really the point? i could go on arguing back and forth forever...oh well...we agree on everything excet the 'variability' of the stat. no big deal. plus i got a calc 3 honors final in a couple hours. ****** forum always distracts me. lol.

pat

Aaron Cake

iTrader: (1)

Please explain to me how the thermostat "doesn't do much of anything" once the car is warm. I'm dying to hear this...

hondahater

iTrader: (2)

lol, why are people always arguing on this forum smile on your brother, come on everybody get together, try to love everybody right now this tstat argument has been around for years with all sorts of engines. I doubt anything will be said in this thread that will make any ground braking differances for or against the tstat removal. Me I think if the car was designed with it and your car is still overheating once you change it than there is something else wrong with your cooling system.

Aaron Cake

iTrader: (1)

There's nothing to argue. If you understand how the cooling system works, that is.

jon88se

That's because either the thermostat was stuck closed or you were using the wrong thermostat. Parts store thermostats are hit or miss...sometimes they work alright, sometimes not. I just put in a parts store 180 degree t-stat and it's worked just fine. The car warms up quickly, heat is strong and ges mileage has improved. I was running no thermostat over the summer since the rebuild was fresh and I thought I'd try to take the possibility of overheating out of the equation during a summer break-in. Now that the weather is cold and break-in is just about over (2.5K miles since July), I thought the T-stat would be a good idea.

NZConvertible

Your ignorance and unwillingness to learn is amazing. There's nothing theoretical about it, it's the way cooling systems are designed to work and the way they've been working for many decades.

Put up or shut up. I'll repeat Aaron's question. Please explain to me how the thermostat "doesn't do much of anything" once the car is warm. Explain to us what's happening during the 20deg between fully closed and fully open.

mwpayne

I have a thermostat question, I replaced mine last summer just as part of maintenance. It is a 88 with an s4 turbo motor. Anyway, the thermostat to me seems too small for the housing, lots of room side to side, The rubber gasket (more of an 'O' ring to me) that snaps on the side of the stat didn't help. Car now takes forever to warm up, I think the thing has slipped out of place. Any chance it's the wrong stat? Got it from the mazda dealer.

NZConvertible

Sounds like they gave you the wrong one. It should abe a fairly snug fit.

Icemark

The other thing you are forgetting is that even all the way open the thermostat acts as a restrictor to help slow the flow of coolant through the engine increasing the efficency of the coolant to remove the heat.

Even in the 26B and 20B and 20G race engines they use a restrictor plate to help slow the flow. Something that is a serious issue with Rotary Engines (water pump operation too fast at high RPMs).

So you can argue and whine that this is all therorectical blabber (as you call it) but anyone with even any sort of long term rotary experience (such as many of the people replying with in depth answers in this thread), and with both long term real world and/or racing experince prove otherwise.

patman

iTrader: (3)

yes, i am aware that they know much more about rotaries than me. and i suppose the word theoretical was bad diction on my part. but i still have to disagree with the 20* variable opening thing. however, in the interest of not arguing this forever, tomorrow i will take a spare stat, toss it in a pot of water, put it on the stove with a thermometer in it, and take pics as it opens. then we shall see just how it acts. sound fair?

pat