Engine Overheating Options

[Araykhel]

I have an ST204 that just crossed over 107k miles and I'm having some overheating issues after the car has had about twenty minutes of drive on it. When my car is driving at normal speeds my indicated temperature usually sits at half, great and normal . But once I let off the gas and decelerate the temperature climbs in no time. I find that idling is the worst and my temperature sits just below the red line when I do so.

I've used the great and nifty search feature to educate myself on all the issues to check/ possible fixes however I still have some questions. The first thing I want to check/ replace is my thermostat however I tried searching for a how-to assuming it wouldn't be a simple swap and found none. Do I need to drain fluids ( ) to do so?

[samir0189]

the thermostat would be a good place to start. It would be advisable to change the coolant once you are there. If you don't drain the coolant before you start, a lot of it will come out when changing the thermostat. It's pretty easy to change the thermostat.

Find the lower radiator hose, and follow it to where it connects to the engine. Remove the hose from that end. Then, there are 2 10mm(i think) bolts that need to be removed and will lead right to the thermostat. Make note of the direction the thermostat sits. Change the gasket while in there as well!!

When putting the thermostat back, find the "jiggle valve" or "v notch" on the thermostat. Most come with a v-notch unless you get OEM. Hold the thermostat up to the light, and you will see the v notch. It MUST be aligned with the protrusion on the little metal neck!!!! Then put it all back together, refill with coolant, and you're done!! Make sure it is not overheating anymore.

[kagemidnight]

I really hope for your sake it's not the case but...I bought and put in an engine last year and started having the same problem soon after. The first thing I was told to do after asking about it was let it sit idle for a while and check to make sure the radiator fans are kicking in when the temp starts to rise ( I guess you could check this also). What it ended up being was a small crack in the block( we thought it was a blown headgasket at first, until I dumped a few hundred into fixing it only to have the same problem). Basically what my mechanic told me was, when I was driving it's shooting coolant into the engine and keeping it around normal, when you idle, it stops and the temp starts to rise because it's not getting any coolant. It did this for a few days before I noticed any smoke. Once you see smoke it's definite. I had to replace it right after I tried letting it idle to check the fans because doing that allowed it to get hotter and hotter and expanded the crack. When I drove it next the temp immediately shot up and smoke billowed out. good luck man.

[PolliS_5S-FE]

Probly be alot easier to just drain the coolant into a bucket or suitable size tray first. Its not hard to do and would save alot of mess just incase lol

[Araykhel]

the thermostat would be a good place to start. It would be advisable to change the coolant once you are there. If you don't drain the coolant before you start, a lot of it will come out when changing the thermostat. It's pretty easy to change the thermostat.

Find the lower radiator hose, and follow it to where it connects to the engine. Remove the hose from that end. Then, there are 2 10mm(i think) bolts that need to be removed and will lead right to the thermostat. Make note of the direction the thermostat sits. Change the gasket while in there as well!!

When putting the thermostat back, find the "jiggle valve" or "v notch" on the thermostat. Most come with a v-notch unless you get OEM. Hold the thermostat up to the light, and you will see the v notch. It MUST be aligned with the protrusion on the little metal neck!!!! Then put it all back together, refill with coolant, and you're done!! Make sure it is not overheating anymore.

Awesome, love 6GC and these kind of responses. Tackling the issue today after a nice meal and a cool head I drove her a few miles to warm up and took a look under the hood. Read this message literally after I found what I thought was the thermostat but when I first checked on the opposite side of the engine I found a valve that clearly needs to be replaced. Was hoping you could help me identify it.




Back on track, there was literally a minimal amount of coolant left. Soooo a quick fill-up later while running the engine things started to look a lot more amazing. The fan actually engaged after the new coolant was added and the engine temperature stayed at the cool middle.

I really hope for your sake it's not the case but...I bought and put in an engine last year and started having the same problem soon after. The first thing I was told to do after asking about it was let it sit idle for a while and check to make sure the radiator fans are kicking in when the temp starts to rise ( I guess you could check this also). What it ended up being was a small crack in the block( we thought it was a blown headgasket at first, until I dumped a few hundred into fixing it only to have the same problem). Basically what my mechanic told me was, when I was driving it's shooting coolant into the engine and keeping it around normal, when you idle, it stops and the temp starts to rise because it's not getting any coolant. It did this for a few days before I noticed any smoke. Once you see smoke it's definite. I had to replace it right after I tried letting it idle to check the fans because doing that allowed it to get hotter and hotter and expanded the crack. When I drove it next the temp immediately shot up and smoke billowed out. good luck man.

This is exactly what I am facing now, this car has been mine for 6K miles out of her 107K, so I can assume that the previous owner was an idiot or that I have an internal leak. Lets hope...

[samir0189]

Oh. that is the bimetallic vacuum switching valve.... and that's about the extent of my knowledge on that one. I am not sure what is does... I don't think it is going to solve your overheating problem though.

Mine was broken in the same way. However, I never noticed a difference in vehicle performance when it was broken, nor after replacing it.

I must add, your radiator is looking preeeettttyy old. Check it for cracks, leaks, etc. A common place is under the fill neck, it likes to crack there. And if you are missing coolant, it'd be nice to figure out where its going anyway.

[Araykhel]

Oh. that is the bimetallic vacuum switching valve.... and that's about the extent of my knowledge on that one. I am not sure what is does... I don't think it is going to solve your overheating problem though.

Mine was broken in the same way. However, I never noticed a difference in vehicle performance when it was broken, nor after replacing it.

I must add, your radiator is looking preeeettttyy old. Check it for cracks, leaks, etc. A common place is under the fill neck, it likes to crack there. And if you are missing coolant, it'd be nice to figure out where its going anyway.

Yeah I don't plan on letting this go. Thanks for your help! Will do a nice checkup on the car now.

[Bitter]

IIRC the bimetallic valve is for the evaporative emissions system.

[Araykhel]

Didn't mean to bring this back from the dead for any reason other than to finally put this to a close. The ST-204 just crossed over to 109K and I replaced the thermostat somewhere around 108500K. The overheating problems stopped altogether however one evening I had a sneaking suspicion after a night of aggressive driving ( had to escape from a traffic officer with my friends, terrible I know, but very fun) that there was going to be a coolant leak. Sure enough I didn't have to walk very far from my home before I could smell the coolant there was a sizable puddle right beneath my water-pump. My thoughts are that the thermostat faults may have led to overheating which damaged my water-pump. Thanks for all the help figuring it out, definitely more fluent with the ways of cooling systems now than I was before I asked for the help way back then.

Currently in the process of getting her fixed. I can get the pump from Toyota for $99.16+tax, timing belt for $60 or so, not sure what else I should replace while I am at it. Finding the place to have her worked on is another project since med-students don't make much money nowadays.

[Bitter]

tensioner, idler pulley, tensioner pulley. Water pump probably wasn't related to the overheating, it has to get nuclear hot to damage those seals.

[Araykhel]

I figured that my not replacing the thermostat in time led to the leak. The overheating being the thermo, the leak being ruined water-pumP.

[Bitter]

btw, when the radiator gets brown like that its usually not long after that it cracks.

[delusionz]

can u tell where its come from? mines always come out of the overflow in mass amounts.

when u did ur thermostat did u use a new gasket? u have to order it separately

[zfjohnson07]

im having a problem with mine to, last couple days it wasnt too bad until yesterday, saw the radiator dump all the fluid next ot the battery. canged the fan temp sensor, changed the thermostat earlier, and my fans wont turn on. i've pulled out the plug to get them to run continously and i think it was still overheating. oil is fine, no smoke. i noticed that if i take the cover off the relay and touch it with a cresent wrench they kick on, so im assuming that they arent grounding out. any help

Edit::: took out the crappy termostat i had from autozone and put the oem from toyota. filled the radiator all the way up. got the temp to stay consistant and in the middle... ughh but didnt get the fans on, my opiniion its hott but it might not be any input.

This post has been edited by zfjohnson07: Mar 3, 2011 - 1:51 PM