Car is STILL overheating, Need help! Options

[ILoveMySilly97]

yea i got mine at AutoZone and it does look like the oem one. I know it works because there's flow.

Working does not mean working correctly. If your thermostat is miscalibrated and opening too late -- at say 90C instead of the proper 82C -- then I could easily see the issues you're having. Proper testing requires bringing the temperature of the pot of water up slowly, so you can tell at exactly what temperature the thermostat opens. I had the opposite issue, my thermostat was opening early, but only by a few degrees below 82C. Rapidly heating the water made it look like the thermostat was working correctly because the reading wasn't precise enough.

The other possibilities which occur to me are the radiator cap being too high a pressure value, thus allowing the coolant to reach a higher temperature than it should, and the temperature sensor on the radiator fan being not turning the fan on at the appropriate temperature.

However, have you checked your ignition timing? You mentioned it was having issues with smooth running, and incorrect ignition timing is one of the possible causes listed in the BGB.

I never really thought about those small minor things. Yea I think my ignition timing is a bit off. I don't know how to time it so I'm going to ask my cousin to time it for me. See if it'll stop the minor misfire I have.

It can also be a clogged radiator. Failed water pump. Clog in the system. A trap air pocket. Weakened radiator fan. Sensor malfunctioning. Bad temp gauge in your dash. Inproper engine ground. Corrosion of that water ways in that water jackets of that block. Crack in engine block. Blown head gasket. Ect ect

Now you have to rule out each one of those problems one by one until you find the problem.

One of that first test you can do is to remove that thermostat and wire your cooling fans directly to the battery and see if it still over heat. If the car does not over heat you know your radiator is fine, your fan is okay, there are no air pockets and your water jackets are fine. Basically this free test rule out half the potential problems.

Do that test and report back.

How do you wire the cooling fans to the battery?

[Hanyo]

You unplug the fan and you run a wire to each one of the terminal with Some Terminals. You can buy the wires and terminals at any hardware or parts store.

[zfjohnson07]

cant he just pull his temp sensor and see if they turn on, if they dont then he knows they are bad?

also the for the air pockets, cant he just take the radiator cap off and let it run, while it sits there?


usually if your ac doesnt work even if everything is correct, it would be the water pump

This post has been edited by zfjohnson07: May 26, 2012 - 8:36 PM

[ILoveMySilly97]

cant he just pull his temp sensor and see if they turn on, if they dont then he knows they are bad?

also the for the air pockets, cant he just take the radiator cap off and let it run, while it sits there?


usually if your ac doesnt work even if everything is correct, it would be the water pump

Actually my AC blows COLD and it's already bled and I have a new sensor.

You unplug the fan and you run a wire to each one of the terminal with Some Terminals. You can buy the wires and terminals at any hardware or parts store.

Okay. I suck and scared of things when it comes to wires. I don't know why. Lol. Just always been like that. I'll have my in law do this test for me.

[zfjohnson07]

ill show you an easy way tomorrow

[ILoveMySilly97]

Just got back from testing my car and it seems to like to heat up to about 60% right until the fan kicks in. It'll drop to 45% then immediately and slowly climb back up to 60% and then stays there until the fan turns off. It'll slowly crawl back down to 45%. And it repeats itself. I'm thinking I might just have a faulty Coolant Temp Sensor, the one that goes to the ECU and not to the Dash. Any ideas?

This post has been edited by ILoveMySilly97: May 27, 2012 - 2:18 AM

[ILoveMySilly97]

The two in green are definitely coolant temp sensors, I believe one is for the ECU and one for the gauge cluster. The one in yellow is the oil pressure sensor, if I'm not mistaken. It's been a while since I've had a look at a 5S and a whole lot longer since I've seen a 7A.

Which one is the one that goes to the gauge cluster? And which one is the one that goes to the ecu?

[kevinpetch]

2 wires sensor for ECU / single wire one for gauge.

[xrayjm]

Just got back from testing my car and it seems to like to heat up to about 60% right until the fan kicks in. It'll drop to 45% then immediately and slowly climb back up to 60% and then stays there until the fan turns off. It'll slowly crawl back down to 45%. And it repeats itself. I'm thinking I might just have a faulty Coolant Temp Sensor, the one that goes to the ECU and not to the Dash. Any ideas?

To see if I have this right.... 60% the fans kick on, drops to 45% fans still running, climbs back to 60%, fans still running, fans then shut off, and then it drops to 45%?

if it climbs to 60% before the fans kick on then after the fans kick on it slowly drops back down to 45%((as in your first part of the description) and then repeats this process, I would suspect the ECT/water temp switch on the bottom of the radiatior as being bad.

I know on my 94 GT 2.2 the fans kick in before the gauge moves off of normal operating temp (about 45% on the gauge). My gauge doesn't move much off operating temp. I just was testing other items on my car, pulled up an 6-8% grade for about 10 miles, 3rd gear, about 5200 rpm(approx 65mph), A/C on, outside temp of 100 degress and the temp gauge didn't budge. I was also idling for about 30 min, in 108 temp, no A/C. Fans cycled on and off, temp gauge stood steady the whole time.

Here is a link for cooling fan troubleshooting for my '94. click here

I'm not sure about the second part of your description, fans shutting off at 60%, and then the temp magically cooling down. Would make more sense if your situation was fans kick on at 60%, cools to 45% and fans shut off, then repeats the cycle from there.

As a side note they must of made those '97 much quieter than my '94, cause there is NO way I can hear my fans kick on and off rolling down the road!

[Special_Edy]

Well my 94 GT doesnt fluctuate once it reaches operating temperature. It stays exactly in the middle of the gauge no matter what type of driving I do. Youre going to need to test each of the three sensors with a multimeter and a pot of boiling water to the shop manual specification.

[Galcobar]

With the further description, I'd also chime in on the fan switch being bad. A proper working fan switch keeps the temperature in the radiator -- and subsequently the rest of the engine -- from fluctuating. The ECT (Engine Coolant Temperature) sensor, which is the two-wire connector you circled, tells the ECU how to manipulate the air, fuel and timing. The ECU doesn't actually moderate the temperatures in the engine. That duty is left up to the thermostat which determines whether coolant needs to flow, and the radiator fan switch which determines if additional cooling is required.

Simply disconnecting the water temperature switch, which comes off the fan and is mounted on the bottom of the radiator, should cause your fans to run -- it's a safety measure, since the thermostat can keep the engine warm even if the radiator is below 83C. The water temperature switch should cause the fans to start running at 93C. To inspect the switch you'll have to remove it, which once you disconnect it is simply a matter of unscrewing it -- though you will leak coolant as a result so I'd do it when the engine is cold, and find something to temporarily plug the hole.

The water temperature switch can be inspected in the same manner as the other coolant temperature sensors, with a multi-meter and a pot of water on the stove. A key to properly testing these sensors is that they cannot be sitting on the bottom of the pot, since the pot's bottom will be a different temperature that the water. There should be continuity between the connector's terminals below 83C, and no continuity above 93C. If otherwise, replace it.

[bsamps4]

You should perform a leakdown test. Possibly could have a blown head gasket.

[trdproven]

^ I did not read the whole thread but it seems like everyone has mentioned the most common problems, if all else, then check the head gasket. Is your oil milky? or is your radiator coolant not looking like it? IDK, i just read pieces of the thread.

[199celica]

im surprised no one has asked yet but when was the last time you replaced your pressure cap i recommend 30k some people say 3 years if the cap isn't holding pressure thats why you are overheating even if it is fluctuating it could be caused by that i had the same problem i took the cap off of my integra and put it onto my celi and it solved my problem so give it a try another thing when was the last time you replaced your water pump you may have corrosion in the pump if you are using the toyota factory red coolant it has a solidfying agent in it to help detect leaks. just a thought good luck man.

[xrav22]

im surprised no one has asked yet but when was the last time you replaced your pressure cap i recommend 30k some people say 3 years if the cap isn't holding pressure thats why you are overheating even if it is fluctuating it could be caused by that i had the same problem i took the cap off of my integra and put it onto my celi and it solved my problem so give it a try another thing when was the last time you replaced your water pump you may have corrosion in the pump if you are using the toyota factory red coolant it has a solidfying agent in it to help detect leaks. just a thought good luck man.

X2 Time for a water pump. You need to know that is good before you spend a lot of time on fans ect. Even if it isn't toast yet it could br underperfoming.

[Special_Edy]

The water pump either leaks and makes a bunch of screeching noise or it operates 100% normally. If it isnt leaking out of the weep hole then dont replace it. Its two solid hunks of metal with a bearing at the center.

[zfjohnson07]

i didnt think of that, that could be it, its always the smallest thing, it does make a lot of sense, tho, if your temp is going down and up so easily and the fans are kicking on, i would have changed the cap when you changed your thermostat, and your anti-freeze

This post has been edited by zfjohnson07: May 28, 2012 - 8:58 PM

[ILoveMySilly97]

I don't think most of you guys are reading the thread before posting but I already had replaced my Radiator cap and the previous owner recently changed the water pump and he even left me with the receipt. I never thought or heard of the fan switch. I'll think I'll have to give that a try tomorrow.

[ILoveMySilly97]

Just got back from testing my car and it seems to like to heat up to about 60% right until the fan kicks in. It'll drop to 45% then immediately and slowly climb back up to 60% and then stays there until the fan turns off. It'll slowly crawl back down to 45%. And it repeats itself. I'm thinking I might just have a faulty Coolant Temp Sensor, the one that goes to the ECU and not to the Dash. Any ideas?

To see if I have this right.... 60% the fans kick on, drops to 45% fans still running, climbs back to 60%, fans still running, fans then shut off, and then it drops to 45%?

if it climbs to 60% before the fans kick on then after the fans kick on it slowly drops back down to 45%((as in your first part of the description) and then repeats this process, I would suspect the ECT/water temp switch on the bottom of the radiatior as being bad.

I know on my 94 GT 2.2 the fans kick in before the gauge moves off of normal operating temp (about 45% on the gauge). My gauge doesn't move much off operating temp. I just was testing other items on my car, pulled up an 6-8% grade for about 10 miles, 3rd gear, about 5200 rpm(approx 65mph), A/C on, outside temp of 100 degress and the temp gauge didn't budge. I was also idling for about 30 min, in 108 temp, no A/C. Fans cycled on and off, temp gauge stood steady the whole time.

Here is a link for cooling fan troubleshooting for my '94. click here

I'm not sure about the second part of your description, fans shutting off at 60%, and then the temp magically cooling down. Would make more sense if your situation was fans kick on at 60%, cools to 45% and fans shut off, then repeats the cycle from there.

As a side note they must of made those '97 much quieter than my '94, cause there is NO way I can hear my fans kick on and off rolling down the road!

Yea. It's like how you said it. And I meant when I heard the fan kick on when I came to a red light. My car only has a short ram so it's not a loud car. And lemme rephrase it. The fan turns off once it hits about 50%. I never really thought about it but my temp gauge actually goes up to the operating temperature pretty quick. For a fact much quicker than before I encountered the over heating problem. It takes roughly 3 min to get to operating temperature when before it takes about 6 mins? I don't know if that had to do with anything but I just found that not really normal?

[delusionz]

couldnt tell if its been asked or answered yet but is it blowing out water from the radiator into the overflow bottle?


by the way, instead of rewiring the radiator fans to run them full time you simply unplug the thermo-switch in the bottom, just leaving it hangin there the ecu will run the fans will full time.