so today, I drive my car home from work. get out of the car and notice a strong coolant smell. I let it cool down for a while, then went out to check it. The radiator was still full with coolant, but the overflow tank was kinda low. so I poured some coolant in (pre-mixed 50/50). anyway, so I go to drive the car again and after a short trip, only a couple miles, I'm hearing this weird whining sound. I glance down and see that the water temp gauge is reading HOT! like, it was all the way into the red! I pull into the closest parking spot and shut off the car. I let it sit for about half an hour and decide to drive it back home. I start the car up, and the temp gauge jumps to 1/2 way. normal. and as I start driving, it starts climbing. it gets to about 3/4 of the way to hot and then very suddenly just drops back down to half. then it stays there the rest of the way home. I pull into my garage, and get to work. I tried my best to track down a leak and decided it appeared to be that the hose that feeds coolant to the throttle body was leaking. so I replaced it. so after a couple hours of work (decided to do some other stuff too since I had everything taken off anyway) I go to drive it again and same thing. the temp gauge reads normal, then it will climb in temperature, then drop back down to normal, then climb again, then normal. anybody have any ideas? thermostat? water pump? malfunctioning sensor and/or gauge?

The thermostat could be sticking. That would cause a sudden increase in temperature. I would test to see if it is opening or not. I would let the car sit and idle until it warms up, and see if it begins to overheat. That way you may be able to pinpoint where the problem is at.

definatly change the thermostat, it's bad at this point. Be careful how much you drive with it overheating like that, you could kill your headgasket.

also, before it overheats, do you drive it hard or just normal (lower RPMs) driving ?

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ok, will change the thermostat asap.

and, the first time, when I drove it home from work I probably drove it a little hard, like revving to 4500 a couple times maybe. after I smelt the coolant I took it easy and shifted at 3000-3300. and after it overheated I took it as easy as I could on it and shifted it at 2700-3000. also, I was told turning on the heater was good for cooling down the engine because you use the heat from the engine to heat the air coming in. I don't know if that's true or not, but after it overheated I turned the heater on full blast. I don't know why, but it would only blow lukewarm air in when the temp climbed above normal, then after it dropped back down to a normal temperature the air coming in would be hot.

It sounds more like you have an air pocket somewhere in the coolant.
It certainly won't hurt to replace the therm just in case though.

After you replace the therm, put the front of your car up on jackstands SECURELY so it won't fall [this includes pulling the ebrake] and let it run with the rad cap off. Keep topping off the coolant if it drops. Keep your heat on full the whole time.


Also, just FYI for you guys, overheating doesn't actually damage the HG, what happens is it CAN warp the head. Which then doesn't allow the HG to seal properly. So you get a BHG. But the overheating itself doesn't damage the HG.

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I agree... It seems that you found and fixed the leak, but the thermo is toast by now, so try changing out the thermo and see if the car runs normally after.

I would change that thermostat and see where that gets you. Mine was acting weird and the car wouldn't pass 140 degrees even under hard driving. Changed the thermo and now she sits around 180.

Could it be that its sticking so therefore the engine heats up, the coolant is not allowed to travel through the radiator etc, and no Hot coolant is sent to the heater core? I guess this could happen if the heater core was part of the loop that went to the radiator.

anywho try the thermo and see where it gets you.

ps: running the heat will cool the engine. (how much, i don't know) but its basic physics where you are transfering the heat from the coolant to the air in the cabin

keep us updated

This post has been edited by jcbass7: Feb 14, 2007 - 2:00 PM

I went out and bought a thermostat and o-ring gasket. (the guy at the parts store said there were two gaskets, but they only had one...) I doubt I'll have time today to get it in. Valentine's day, you know. maybe late tonight or after work tomorrow. I hate having to drive my car while it's like this, but it's my daily driver and I don't have another car to drive. I'm trying to take it easy. when I went out to get the thermostat, the car started heating up again. so I though, if the thermostat is sticking, maybe I can get it unstuck with a quick jolt of power. so, I was in 2nd at about 2K rpms, I floored it until about 4K rpms, then let off and a couple seconds later everything cooled off... on my way back home, I tried it again but it didn't work... after I got out of the busy part of town and was able to start moving about 35 mph it slowly cooled off though... I will keep you guys updated after I change the thermostat.

keep the heater on full blast when you see it over heat. it will definetly help.
but try not to drive the car. you could really damage something.

thermostat is an easy thing to try, just to rule it out. but when was the last time you had your water pump changed? how many miles are on the car?

you should also check your coolant and your oil. check to see if there is anything in there that looks like coffee with milk.

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Welcome to my world^ ^ ^

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car has 154K miles. and I really have no idea when/if the water pump was changed. I bought the car at 144K and have done a ton of maintenance work to it since then, but no water pump. according to carfax, it had a major service done by a mechanic every 30K. so, if a waterpump was due at 120K, then I would guess it was done... but I can't be sure. I really hope it's not the water pump, I really can't afford to fix that. anyway, I'm off to change the thermostat right now, so I'll give an update after that's changed and a test drive.

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If it is the water pump.... you might as well get the timing belt changed as well..... since the belt will be accesible at the time... and since it has high miles... the belt can go whenever.....

I hope its not though man..... that will suck.... and since its a newer japanese car... the job will be more difficult and expensive..... i remember when my old dart had a bad water pump.... it only cost 25 for the part and about 45mins of my time to swap it. I wouldnt even attempt to do that to my celi......

If u need any help with anything... let me know.....

Sorry, I'm not trying to insult or anything, but the only time I've seen mine do that was when the coolant was low. Are you sure you got everything topped off right after you fixed the leaking hose? It still sounds to me like there is air in there, which would explain the lukewarm heat while it was overheating (air transfers heat way worse than liquid) and the rapidly changing engine temps. If you were filling the reservoir and not the radiator itself, that would be the cause.

alrighty. so I get out there, drain the coolant (after spilling a bunch all over myself and the floor) pull the hose off the thermostat housing, pull one nut off the housing, and cannot for the life of me get the other nut off! in my hayne's manual it says in some fine print "on 5sfe engines the retaining nuts may be difficult to access" wow, now that's an understatement! I tried every tool imagineable to get it off, nothing worked, until finally I found an extremely small wrench that fits in there after I removed the oil filter. of course, after trying all the other tools the corners of the nut are now mostly rounded off and I cannot get a grip on it at all. so basically I'm stuck.

btw, when I pulled the radiator cap off I noticed it was NOT full with coolant. I checked it yesterday and I'm pretty sure that it was full.

another problem. all across the bottom of my radiator is traces of leaks. I can't say for sure, but my brand new-ish koyo radiator may have a poor weld across the bottom.

I'm tired of having something break on this car every few days. aren't toyota's supposed to be reliable?

If your Koyo radiator is what's leaking, you can't blame that on Toyota.

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Did you notice the traces of coolant on the radiator after you spilled coolant? it might just be dripping down the sides and collecting on te bottom. I think 94GT might be right though... make sure its topped off.... fill it up and wait for the level to go down then do the same thing over again.

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no, I noticed it before I drained the coolant. all white and crusty so you know it leaked and then baked on.

and no, I can't blame toyota for my koyo radiator leaking, but I can blame toyota for my toyota radiator leaking which is why I bought the koyo radiator to begin with. on top of all the other things that have gone wrong with the car. I dunno. maybe just because the car is 13 years old with 154,000 miles on it...

still, anybody know how to get a stripped nut off?

This post has been edited by 6strngs: Feb 15, 2007 - 2:40 PM

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There are a couple things u can do..... If you rounded it with a 12 point socket.. try using a 6 point that fits well.
You can try to dremmel or gring a philips notch into the bolt...

Craftsman makes a pretty good 10pc damaged/stripped bolt/nut remover set and theyre only like 30 bucks at sears.

Autozone might have damaged nut removing tools for rent also.. I know they rent all kinds of stuff out.

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Its a nut.. so it won't work

but those things from sears are the ballsss

This post has been edited by jcbass7: Feb 15, 2007 - 3:13 PM

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yea... duh....haha
actually then..... he can just dremmel the nut right off with a cutting disc.... Ive done it before....

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13 years for a radiator that has plastic reservoirs is quite good. You're not going to find a domestic that has a radiator that lasts that long... You just have to remember that even with a car as superior as a Toyota, there are some parts (like timing belts and water pumps) that have a limited lifespan.

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+1

you did purchase a car with 140k+ miles on it..... depending on how well cared for it was before you got it... its about due for some of the wearable parts to start getting swapped out....

^
exactly

We had a guy come in with a Camry he bought new. Had 2x,xxx miles on it.
The engine had seized on him. He expected a warranty claim.

Until we found out he had NEVER changed his oil since the day he bought his car.

"It's a Toyota, I shouldn't have to change the oil"......

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i dont know where to start with this an air pocket isnt going to do **** seeing as it always has air going threw it, the second is the second you start the car without a rad cap on it will spray out seeing as it needs presure to run the coolent, and yes overheating the engine will blow a head gasket because the gasket of course is made out of a rubber substance and the header is aluminum so heat from the engine will weaken the gasket and the preasure from the enclosed engine will blow the head gasket.

lighten up guy and do some research, do you work for toyota ?

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just 2 quick articles I found when I googled "air bubbles in coolant".

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You obviously don't.....

You're not supposed to have ANY air in the coolant system. If "it always has air going threw it" then you have a problem.
An air pocket can cause a temp sensor to read incorrectly, and cause the heater core to not work right. As well as cavitation in the water pump, hot spots, ect, ect, ect.
Bottom line, you DON'T want them in your coolant.

The only pressure in your coolant system is from it heating up. When it gets hot, it expands. The rad cap controls how much pressure stays in the system.
So if you start it/run it cold, there will be NO pressure. Rad cap on or not.
And when it's cold the thermostat is closed, so the flow from the pump doesn't effect the radiator. Once it reaches temp it will slowly rise above the level of the rad, assuming it's full. When this happens you can put the cap on and let it pressurize. But it won't build ANY pressure until the cap is put on. It will just overflow.

A Head Gasket is NEVER rubber. It would melt.
A "header" is an exhaust manifold, so throw that term out the window when talking about a head gasket.
Yes the head is aluminum. Has nothing to do with overheating, other than it warps easier than cast iron. File that away for a minute.
Heat doesn't damage head gaskets. Normal coolant temp is 180 - 220*F [roughly] How hot do you thing your coolant is when you overheat? 280*F? 300*F? 500*F?
CONSTANT temps in your combustion chamber are WELL over 1500*F. It can spike to over four THOUSAND *F during combustion.
Do you honestly think even 500*F coolant temps [which you shouldn't ever see] are going to damage the gasket?
Now detonation/preignition CAN damage a HG. But not from the heat. From the pressure.
Back to the overheating/BHG.
When the coolant in the head/block can't get to the rad to cool itself off, your engine overheats. When this happens much of that extreme heat in the head cannot escape anymore. So the head gets hotter and hotter. When you heat something, it can change shape. Aluminum is much more susceptible to this than cast iron. Which is why you don't hear about old school cast iron head engines blowing HG from overheating very often...

When the aluminum warps, it no longer has a flat sealing surface with the block, it's now warped, or rippled.
Which means the HG no longer has flat pressure all over it. Without the pressure it can no longer hold in the pressures from the oil, coolant, and combustion. so it leaks.
Blown HG.


I wasn't trying to be a dick, just to help you out.
I've worked on cars for 8 years. I currently work for a Toyota dealer as a tech.
That doesn't mean I know everything, nor am I always right.
But what I posted is basic stuff. Which I have down pat.
Please do some research before you jump on my case next time.

Batman!!!!!!!

I'm working on an answer. I have most of it, just checking on one more thing.

Back to thread.

The reason I recommended you raise the front of the car up BTW, is to create more pressure for any air bubbles in the system to come to the top. This makes the "burping" more effective.

it will not hurt the engine to have air in it
example:
if i where to run water threw a closed system (with clear tubes) their would thousands of air bubles going by and if i wher to stop the flow the bubles would colect to make large bubles (or air pockets) and if i where to try to remove the bubles and then pump the water it would create more air via H2O consist of oxygen and where to stop it again it would creat bubles so no matter what you do it creats bubles (air pockets) and i didnt include the factor of extreme heat from the engine and evaporation

engineers think of these things and think hmm we need a substance between the header and the block that inkase an engine overheats it will break befor the header has extensive damage im not saying the the header does not warp it does but the gasket blows for that reason

Dude.
It's HEAD.

NO headER......

A header is an exhaust manifold, NOT an engine head.......

First off, water and coolant are 2 different things.
Second, there is a big difference between some small bubbles [Not that many, BTW. One of the products in antifreeze prevents them] in the system and large air pocket[s].

Do a little research on the subject.
I hardly think it would be mentioned in textbooks and all over online if it didn't matter.

The HG isn't there to blow before anything else. It's there to seal the gap between the head and block.
It does happen to be the weakest link, but once again, if the engine overheats, it's the head warping that causes the HG to leak.

soo uhh yea........

Hows the car comin along Nathan??

hehe. sorry it's my fault this whole argument started. anyway! I finally got the thermostat housing off about 5 minutes ago when I finally resorted to a dremel to get the darn thing off. I pulled out the thermostat, compare it to the new one I have and the new one I have is totally the wrong size and it's about 9 PM and all the parts stores are closed now. so basically, since I have no school tomorrow I'm gonna run down to the parts store and either get a refund or find out if they just pulled the wrong one off the shelf and they do have a correct sized one. if not, I'm gonna make some phone calls to all the toyota dealers within reasonable driving distance and see if any of them have one. I want to get my car running by saturday for the nor cal meet!