2000 Toyota Camry overheating issues

November 5, 2010 9:07 AM

2000 Toyota Camry is having engine overheating issues - what is causing them?

Mechanics can't reproduce the issue, they say the car is fine, I'm not so sure. 2000 Toyota Camry 4 cylinder 135,000 miles. Timing belt replaced at 85,000 miles.

There are 2 things about this car that concern me.

1. When I start the car in the morning, there is a rattling sound that comes from the engine area. It goes away after about 3-5 minutes of the engine running. The timing belt is fine. So what is causing this sound? Is it possibly the reason for the overheating described below?

2. Engine temperature needle slowly starts rising when idling after driving at highway speeds for 2-3 hours. The needle comes down a little if I turn the heater on. Problem is fixed when driving at highway speeds. Turning car off and on doesn't fix the issue.

This also happens when climbing a steep hill for more than a minute at lower speeds. I think the electric fans on the radiator are not turning on when they're supposed to. But I never had a radiator flush and some people say that may be the issue. Other fluids, like coolant, are full.


The car is great for driving around town. I have lately been renting cars for lengthier drives. I would rather try to figure out the issue before finding myself in an emergency situation.

posted by abdulf to travel & transportation (21 answers total)

Same thing happened to me, different car. The temp rising while idiling, but fine at highway speeds is the key here. There is a fan that will cool your engine when you're not driving fast enough for it to be cooled by moving air.

Mine was fried, an cost about $300 to replace.

FWIW, I'm a 24 year old woman who knows stereotypically and shamefully little about cars, and this was exactly what I suspected the problem was. Your mechanic sounds worthless.
posted by fontophilic at 9:12 AM on November 5, 2010

Oh, and if it were a radiator problem, I suspect the temp would be even hotter at highway speeds, not the reverse.
posted by fontophilic at 9:13 AM on November 5, 2010

Possibilities that come to mind:

- Fan problem: Electric fan not working as you mentioned, or if it is an older mechanical radiator fan, then the thermal clutch is not engaging correctly.

- Old coolant that doesn't conduct heat as well as it used to. When was the coolant last replaced?

- Low coolant level (when you say the coolant is full, do you mean in the plastic overflow bottle external to the radiator, or in the radiator itself?)

- One or more of the radiator channels that the coolant flows through is kinked or blocked, due to a road debris hit.

- Radiator fins jammed full of dead bugs/leaves etc. preventing adequate cooling airflow at low speeds/standstill.

- Radiator fins corroded away

- Corrosion/sludge inside the radiator itself that decreases heat transfer.
posted by de void at 9:17 AM on November 5, 2010

Fontophilic has it. "Overheats standing still, fine on the road" means you need a new radiator fan and a new mechanic.
posted by mhoye at 9:17 AM on November 5, 2010

Here are the things that came to mind...

1. Stuck thermostat?
2. Non-functioning (or subpar functioning) fan?
3. Plugged radiator?
4. Head gasket failure?

Overheating is a fairly common problem and any competent mechanic should be able to check out all these things as well as more technical problems.
posted by _DB_ at 9:18 AM on November 5, 2010

Just a reminder, abdulf said the car is fine when slow/standing still and has problems when at higher speeds.
posted by _DB_ at 9:21 AM on November 5, 2010

This exact thing has been happening to me in a 20 year old minivan (about 115,000 miles) for the past year. And I, too, have been renting cars for (infrequent) distance drives -- it's bizarre to be afraid of your own vehicle!

Could be a thermostat problem, or a fan problem... several knowledgeable folks have given me the same estimate of $300 to fix it that Fontophilic mentioned. But my 20 y.o. van is not worth that much... so I just put the heater on (which vents the excess heat somewhat) in traffic jams... rather amusing to do in the summer on the way to the beach, to say the least.

As I also developed an ominously long crack in the windshield, and the parking brake snapped, I've decided to take the plunge and retire this old rustbucket, and get a new Prius. The savings on both repairs and fuel (not to mention rentals!), and the peace of mind, will be worth the initial expense.
posted by RRgal at 9:31 AM on November 5, 2010

Just a reminder, abdulf said the car is fine when slow/standing still and has problems when at higher speeds.

Ummm, no, abdulf actually said the exact opposite... car is fine at highway speeds, overheats at slow speeds/idling.
posted by RRgal at 9:36 AM on November 5, 2010

You need to do some experimental observation. First and foremost, establish whether the cooling fan is coming on or not at those times when the temperature needle is climbing. Try driving on an empty stretch of highway, then pull over somewhere, open the hood, and carefully check both the temperature gauge and the cooling fan.

If the fan comes on but the temperature climbs, this points more toward a radiator problem. After the car has been shut off for several hours, open the radiator and make sure it's topped out, and make sure that there's not debris or rust in the fluid. Whether it tends toward clear or green should tell you whether there's 100% coolant, 100% water, or a mix in there; that has some bearing on the cooling performance.

If the fan does not come on, then either debris is jamming the fan, the relay that turns it on is shot, the fan motor is shot, or the wiring to the fan is.

That said, I don't know whether a 2000 Camry has a cooling fan that only comes on when the engine temperature is hot, goes temporarily into "hyperspeed" mode, or has a secondary fan, so I'm not really sure exactly what you should be looking for, but if you see a lot of serious fan action when the car is stopped, then you know that the issue is probably more with the radiator than the fan.
posted by crapmatic at 10:01 AM on November 5, 2010

I think the electric fans on the radiator are not turning on when they're supposed to.

Very likely, yes. You can even do a basic check yourself - after driving on the highway, stop, leave the engine running, pop the hood and have a look. Don't stick your fingers in there. If the fans aren't running, then you need to figure out why, which is a little more involved.
posted by ssg at 10:05 AM on November 5, 2010

Timing belt replaced at 85,000 miles.
Did they also replace the water pump when they did the timing belt? The rattling noise you describe is somewhat classic of a water pump destroying itself. Though, that would tend to be a constant rattling. Still, a failing water pump would most certainly cause overheating.
posted by Thorzdad at 10:26 AM on November 5, 2010

'93 Camry Driver here. My car was doing something similar last summer, though at highway speeds it was getting hotter still (though it wavered). I took it in. At first they thought maybe my radiator was just leaking fluid, so they recapped it - but it turned out my whole radiator was melting and my fans were shot. I had to have both replaced. I think it cost me something like $700.
posted by Lutoslawski at 10:30 AM on November 5, 2010

Yes a radiator flush could help - it sounds like your cooling system is running at a lower efficiency than it should be to cope with the heat your car produces. It's not much less efficient than it should be, which is why edge cases (fully warm components in fully warm engine bay after a long drive is too much heat for the radiator to remove unless it has maximum air flow) result in the slow gain of heat in the system.

Also giving these symptoms would be the electric fan not functioning (instead of not enough water flowing, it's just not enough air). This is relatively easy to check as you can just run the car for a long period (driving it and then leave it idling) and see if the fan comes on when the temperature rises a bit above halfway. You'll either hear it or you can open the bonnet and look at it to see if it is turning. If it doesn't until the car gets hot (like into the red on the gauge) then the fan is no good. If it does come on, then the radiator has some sort of blockage in it that is meaning water flow through it is restricted in some way.

In the unlikely event that it is neither the fan nor the radiator, it is possible that a waterway in your engine is clogged which could be difficult or expensive to remove, so cross your fingers on that one.

Oh, and if it were a radiator problem, I suspect the temp would be even hotter at highway speeds, not the reverse.

No. This is incorrect.
posted by Brockles at 10:31 AM on November 5, 2010

Did they also replace the water pump when they did the timing belt? The rattling noise you describe is somewhat classic of a water pump destroying itself. Though, that would tend to be a constant rattling. Still, a failing water pump would most certainly cause overheating.

This is true, also. Slow water flow give the same net result of insufficient water/air balance through the radiator to cool effectively. Best hope it is the first two options though, I think. Eliminate those first (especially if the water pump was done at timing belt time)
posted by Brockles at 10:33 AM on November 5, 2010

Nth the above but one other thing that comes to mind that a mechanic wouldn't be able to replicate- a faulty relay for the cooling fan. (Your car may have two relays)... this would cause it to overheat sporadically... FWIW I am a mechanic.
posted by peewinkle at 10:45 AM on November 5, 2010

So, engine hot (driving for a while) car barely moving, it overheats?
Problem solved by speeding up again?
Airflow problem. (Fan not turning on, partially plugged radiator on the air side, ). If it was a water problem, you would overheat at highway speeds, because the coolant wouldn't be circulating through the system. No idea about the rattling noise.
posted by defcom1 at 5:20 PM on November 5, 2010

If it was a water problem, you would overheat at highway speeds, because the coolant wouldn't be circulating through the system

Not necessarily. A water flow problem doesn't necessarily mean a zero flow problem. Insufficient flow of either medium through the radiator could cause the symptoms in the post.
posted by Brockles at 6:05 PM on November 5, 2010

This is most likely a problem with the fans or a component of the fan circuit.
A stuck usually thermostat exhibits symptoms of rising to normal operating temperature and then overheating no matter whether or not the fans operate and at any speed. A failing water pump often exhibits symptoms like overheating at idle but elevating the engine RMP results in marginally better coolant flow and the temp drops a little bit. It's true that a water pump can make a nasty rattle when it's failing, but it'll rattle pretty consistently. Most underhood rattles that clear up after a couple minutes are usually related to a belt tensioner malfunction.

Here's a good quick test. Start the car, open the hood and then turn the AC on MAX mode. Do the fans operate? If the fans come on, then there's probably a faulty engine coolant temperature switch. I can't remember off hand if this car has a thermostatic switch that operates the fan relay or if it has a sensor which communicates to the ECM which in turns grounds the fan relay.

Additionally, if they replaced the water pump when they did the T-Belt, then you've got pretty new coolant in the system. Even if they didn't, coolant condition, in my experience, comes it pretty low on the list of frequent causes of overheating (with the exception of GMs). If the coolant is so bad that it's not working, you'll usually be able to open the radiator cap and see rusty mud where the coolant should be.
posted by Jon-o at 5:31 AM on November 6, 2010

Took it to another mechanic.

1. New water pump
2. New timing belt
3. New thermostat
4. Radiator flush, new antifreeze/coolant
5. New radiator cap


Cooling fans work. After doing all of this, the car now seems to have the temperature gauge just above where it should be - seems to suggest its running 25% hotter than it should be.

Mechanic says, however, that a temperature check shows the car is running properly. The gauge may need replacement and that will cost ~$300 for the part...
posted by abdulf at 11:22 AM on December 16, 2010

I would look into replacing the temperature sensor itself. The temperature sensor probably costs about $12 and takes about 10 minutes to replace.
posted by ssg at 1:38 PM on December 16, 2010

I asked the mechanic about the temperature sensor - said he changed that too. Still tells me that the gauge is wrong.
posted by abdulf at 7:05 AM on December 28, 2010