The engine OVERcools SC4.
 

Okay, strange problem, searched, and searched for "Thermostat", but couldn’t find an answer.

Usually people have overheating issues, but I’m having quite the opposite. My 93 SC4 w/130K takes forever to heat up, and when I’m parked, it wont really go past 4 O'clock position, no matter what. and IF it does go after some hard driving, it will come back down when I park, or on the highway. The radiator has been replaced by the previous owner (just got the car last month), and now I’m suspecting a bad thermostat, that’s stuck open. Does this sound about right?

Any special instructions, info, or hints I need to know before replacing it? I've never replaced one, but it seems like a in/out job. Any help is appreciated.

I've read some stories about the NAPA ones, should i only buy an OEM with new O-rings?

Thanks.

I don't know if the thermostat is stuck open. I always believed that a stuck open thermostat will also result in overheating. The reason being, the coolant is rushing through the fins of the radiator too fast. The thermostat allows coolant to stay in the radiator longer in order to cool. Then, when needed, the thermostat open, allowing cooled down coolant to enter the engine. With an open thermostat, the coolant would continually get hotter. At least this is how I always believed it worked. :uh:

What is your estimate of operating temperature? My guage also hovers in between the 3 & 4 o'clock position. Which I believe is roughly 200-210 degrees F. (Unsure at the moment, and can't check since I'm at work)

My tep gauge also stays between 3-4 O'clock more tours 3 but it don't take too long to get to that. Hell 10 min at idle or have the car runing at normal runing temp. Replace the thermostat an see
what it do. But you do need to get it from lexus so it will work properly. Napa parts are just like auto zone parts not worth a damm.

Hmm... I always thought that if it were kept open, it would keep the car cool, and not give the engine any time to cool off. Hence, if it was shut closed, the engine would overheat.

Not sure what the temp might be, but its near the 4-4:30 position... its really low, that’s why I’m somewhat concerned, with the low gas mileage got me thinking they could be related due to running efficiently. I believe I got 230 miles to my tank last time.

Thats how my LS is, and all the Lexus car I've drivin, except for my SC4.

Do I have to change the rings, or anything else when chaning the thermo? (I've never changed one before, any instructions can be helpful, thanks).

Yea otherwise you will have a leak. The O ring is a must you will not be able to reuse it.

Nope, that's exactly backwards. The thermostat stays closed to keep the coolant from circulating, thus heating up quicker. Once the coolant reaches the thermostats rated temprature, the thermostat opens to allow the coolant to circulate through the radiator, thus cooling it.

So, having the engine not reach full operating temprature usually means a thermostat that's stuck wide open.

it might not have a themostat in there.. my beater doesnt have one, unless i hit the highway the temp gauge barely reads

I read this.... just passing info along to others...

"Contrary to popular opinion, operating the vehicle without the thermostat doesn't make the engine run cooler. It will actually run hotter because there isn't a thermostat to slow the coolant flow. This means the coolant doesn't stay in the radiator long enough to dissipate its heat."

cheers

absolutely correct, .... off topic how have you been bud?

anyway, dont be cheap buy the dealer stat & a new 'o' ring seal. if toyota's easier get 1 for a
supra n/a or turbo. the cheapy thermostats really dont last as long or become troublesome.
if its stuck open, the car will run richer (use more gas) & have poor heat. (a problem up here
in the north)

:egads: I don't know where you read this, but it's just plain wrong... Obviously written by somebody who just doesn't understand engines. :uh:

To update you guys, I changed the TS and it fixed it, I got a OEM one from Ebay for $23 shipped new. Installation took 5mins. Thanks everyone :thumbup: