Overheating on Highway

[C110GTR]

My '93 3VZFE Auto Camry is overheating on highway but the weird thing is not always.

I've been using it on local roads, sometimes on the highway for like 15-20mins 100kph and its been fine.

now if its more than that on the highway it doesnt like it, slowly creeps up till I stop before it hits the red section.

Here's the story...

I was on my way to the beach and it started overheating (110kph) so stopped for a while then drove it on 100kph for like 10mins and it slowly getting hot, once it was on 60 - 70kph the needle went just above the gauge then it would go hot again on the traffic light. It would go down if I put it on neutral and idle it a lil higher.

But after 15 mins driving like this the temp wouldnt go down anymore and had to let it cool down again.

after 5 hours the drive on the way home 100 kph and 25mins on 60kph (90 kms drive from the beach to my house) it was sitting just below half and toward the end it was going hotter and when I got home it was 3/4 on the gauge.

now the history of the car...
it had blown head gasket last year, replaced the gasket, shaved and clean the head, new tensioner, pulley, water pump, belts so basically a timing kit job. But it had issues with the thermostat I had a topic here somewhere having to try 5 different ones inc OEM and my mechanic ended up leaving a gutted up thermostat.

Its been running like this for the last few months.
Checked the oil, water, power steering fluid level before we left.

Any ideas???

[hill8570]

What sort of coolant are you running?

How old are the radiator caps? Are they both OEM? Are they both connected to the reservoir? Does the coolant level in the reservoir change between hot and cold?

How old is the radiator? Do the fins on the radiator (or the A/C condensor in front of the radiator) look clean? Has the radiator been tested for flow?

Is your fan running fast when you're idling after one of these highway runs?

With a gutted thermostat, I'd expect the engine to run w-a-a-y cooler than 1/2 gauge most of the time.

[BamZipPow]

I'm gonna say either yer radiator is blocked up pretty well and/or the fan/fan switch is bad.

[Mike Gerber]

^ I have to agreee with BamZipPow on the radiator being partially clogged. You didn't say how many miles are on the car/radiator, but as a radiator get's old it can become partially clogged. It then has a difficult time dissipating the extra heat caused by high speed driving. It may do fine in local driving, but when on a highway at increased speeds a problem like this can surface. I suggest trying to back flush the radiator. If that doesn't work, you can take the radiator out of the car and have it flow tested at a radiator shop.

Mike

[C110GTR]

when I was having the overheating issue with the thermostat, my mechanic told me that the radiator was partially blocked so he got it professionally cleaned. Before I had the headgasket replaced I replaced both caps but they are not OEM caps. But then again I got it pressure tested by a radiator joint and they said its in good condition holding up the pressure.

I didnt check the fans if they were running faster when hot, but I can hear it as its louder when I was driving when hot.

The hoses are connected right on the reservoir, the coolant is a generic green coolant, the reservoir level when it was hot was FULL like up to the cap of the reservoir bottle.

Most of the time the car is running below half on the gauge.

[hill8570]

Originally Posted by C110GTR

when I was having the overheating issue with the thermostat, my mechanic told me that the radiator was partially blocked so he got it professionally cleaned. Before I had the headgasket replaced I replaced both caps but they are not OEM caps. But then again I got it pressure tested by a radiator joint and they said its in good condition holding up the pressure.

I didnt check the fans if they were running faster when hot, but I can hear it as its louder when I was driving when hot.

The hoses are connected right on the reservoir, the coolant is a generic green coolant, the reservoir level when it was hot was FULL like up to the cap of the reservoir bottle.

Most of the time the car is running below half on the gauge.

If it's full to the top of the reservoir when hot, what is it when cold?

So both caps were tested for the correct pressure release? Sorry to harp on this, but systems with two radiator caps are somewhat rare, and it only takes one releasing at too low of a pressure to really screw things up. I've also developed a serious distrust of aftermarket radiator caps over the years...

[C110GTR]

sorry havent posted back on holiday right now....
I've noticed that its loosing coolant as I've put maybe 3 litres the next day I drove the car after it was overheating. There is no visible leaks in the engine bay to loose that much. No white smoke, no mixture of oil and water.
The heater works fine, you could hear a gurgling noise when you 1st put the heater on.

I could try getting OEM radiator caps and see if that solves the issue.

[the_professional]

I'd hate to say it but you may have another head gasket issue, unless those radiator caps are utter crap.

Like you said, your hearing the gurgle, the sound of the bubbles in the coolant system run through the heating core.

Air is entering the system somewhere, and sadly my bet is on the gasket.

[The Camry Man]

sqeeeze the radiator hose to make sure pressure is down before removing radiator cap.

or wait till cool..

Then

1. Remove radiator cap SLOWLY
2. Tape up a funnell so it fits in the radiator cap tightly
3. Fill the radiator to 1/4 up the funnell
4. start car look in funnel
5. See any air bubbles comming up through funnell? if yes it most likely is coming from the head gasket. Let car warm up 20 min to norma temp..
6. Now while looking at the funnell, reach over to the throttle and raise the RPMS.. if even more bubbes come out... You found your problem

Here i s the senerio: The GEN3 4 cylinders are notorious for getting small head gasket leaks (even after one has been replaced) and when this happens the leak is NOT always gonna send white smoke from the exhaust.

More than likely on these models the leak goes from the cylinder to the water jacket on the block and pushes HOT air into the cooling system.

On smaller leaks this can not pose a problem on short workday trips but as soon as you go out for a longer drive the hot air coming from the leak EVENTUALLY is more than the cooling fans and raditor can handle. This makes the temp SLOWLY rise till it it overheats.

At this point you can sometimes see the air burping all the way to the OVEREFLOW Tank and out onto the ground.

Some people have even taken the thermostat out so it takes longer to overheat ( typical trick when they are trying to sell this problem to an unsuspecting buyer). Thn after you buy thecar and don't notice anything till you go for a long trip some weekend.

I ALWAYS do this test when I go to buy a car. Believe it or not just in the last 6 cars I looked at 3 had this problem... I bought the other 3

IHAVE FOUND THAT SOME MECHANICS WILL GO THROUGH ALL THE TROUBLE OF YANKING THE HEAD OFF AND PUTTING A NEW GASKET ON AND NOT CHECK THE HEAD OR BLOCK SURFACE>

[73sport]

2 things come to mind.

Before we assume the worst (head gasket), that gutted thermostat can be equally bad. If the coolant through the systems is to quick (as in no restriction) no heat is absorbed by the coolant and no heat is dissipated by the radiator.
I've also seen the missing stat aerate the coolant and make bubbles. Especially with aftermarket water pumps as they sometimes change the impeller design from the OEM and it can be overkill.

Is the engine really hot? Just because the gauge says so, doesn't mean it is. Boil overs, pinging, oil burning off the head and block, too hot to touch PLUS when the heat is turned on in the cabin its scorching are all signs it is hot and the gauge is right. Is it right?

Hot tap water about 120 most people can handle sticking their hand in it or touching pots pans. 160 is hot, but you can touch it for 2 to 4 seconds. 210 or near boiling, your hand retreats fast! So when you pull over and touch the radiator hose (top) is it as hard as rock and how long can you touch it?


You never said if the AC was on during this overheating spells or if the heat was on. Hint, turning the cabin heat on and the AC OFF can keep you from walking/waiting for it to cool as it adds more cooling capacity to the system.

Find out if the fans kick on and clean the AC condensor as mentioned and report back.

Good luck,

[93celicaconv]

You can also run the car over to a Toyota dealer, or a mechanic, to get the coolant tested for exhaust gas contaimination. It is a very simple test, with the strip of paper, I think. Maybe even auto parts stores carry this now. At least with this test, you can rule out or in a head gasket leak causing exhaust gas entry into your cooling system.

[C110GTR]

The engine is really hot, and you can even tell the engine is running differently when its near the red section of the gauge.

the aircon was off when it overheats, last time it overheated was just driving on local road doing 60- 70kph for 20mins
I had it tested before we gutted the thermostat to confirm that its not the head gasket.

since we installed the gutted thermostat it runs like shit when its cold like it lacks power/hesitates but after that its fine.

[C110GTR]

I thought the fan kicks in as I can hear it when I was driving it but when I stopped to let the engine cool down and the engine was just on idle the fan doesnt turn faster than it should, like i can stop the fan with my hands. But it shouldnt be the reason why it would overheat on highway?
Plus Im leaking power steering fluid, but its topped up.
Anyone care to give me more ideas or advice? Im thinking of just selling the damn thing now...

[C110GTR]

i have bridged e1 and op1 and the fan turns faster, now what do i need to check or replace to get it working as it should.

[93celicaconv]

I don't know if you have a different cooling setup for a non North American car, but in North America, this car would only have 1 radiator cap, and that would be on the water outlet housing on the engine. The radiator would not have a radiator cap. I haven't heard of an automotive application requiring two coolant pressure caps, and I don't think yours in an exception.

That said, you may not have the correct radiator in your car right now - perhaps the original was replaced at one time and the replacement is not correct for the application. It should, however, radiate off the heat absrobed from the engine. And it should do this without need for fans when you are driving on the highway.

Are the fins on our A/C condenser coil (located just outside the radiator) clean without any debris obstructing air flow? How about the current radiator? Sometimes debris can get in between these two coils and block air flow.

When did the problems with overheating begin? Immediately following your headgasket replacement?

When the engine is at or above normal operating temperature, are both large hoses going to the radiator equally hot?

By-the-way, your radiator cooling fan(s) are hydraulically driven, right? I'm assuming this to be correct. The fan speed is determined by the engine coolant temperature information received by your cooling fan ECU by the engine coolant sensor. If you coolant is very hot, that sensor should be sending information to your cooling fan ECU to increase speed to maximum (around 1,100 RPM). It is very possible your engine coolant sensor is defective, especially if your radiator fan turns slowly when your coolant temperature gauge is reading at a relatively high temperature. That would be an easy sensor to replace.