97 Camry 4-Cylinder Overheating

Previously the 2 electric cooling fans were not turning on even when the engine was hot. Currently, I have the 2 fans on all the time (by unplugging two connectors near radiator). Now, overheating only occurs on hot days when climing hills and is proportional to speed. It is OK even on hills, if I slow down to 55 mph and have the heater on full blast. It seems to me that the hot water is not circulating through the radiator. What is the most likely cause for this? Thx.

Reply to
jay
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It's almost 10 years old, radiators tend to get plugged up after a while. They are not hard to change, and rebuilt ones are not very expensive.

jay wrote:

Reply to
Mark

Forgot to say, the radiator is always full and oveflow resevoir is always at a level between low and high lines. It doesn't seem to consuming or venting any coolant.

Reply to
jay

Before getting to the radiator, I'd check the thermostat, and possibly one of the radiator hoses is (if it's the original) is collapsing, sucking the hose flat and not allowing the circulation of coolant. and how old is your coolant?

Reply to
mack

Thanks. Is there a valve of some sort which controls flow of coolant through radiator? If so how could I check it prior to replacing radiator?

Reply to
jay

Yes, there's a valve where the (upper, I think) radiator hose enters the engine. To test it, you put it in some water and heat it up _gradually_ (i.e. don't dump it into already-hot water) and note how the length changes. See the manual at

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for the exact procedure.

Reply to
Nobody Important

I would flush the system and replace the thermostat, use a Toy, ive had several defective aftermarket ones, one where the gasket never sealed. You can see if your radiator has scale built up, lower the water level a bit. Maybe your hoses are bad also.

Reply to
m Ransley

If I understand you, you're saying the engine needs both fans on all the time to ward-off overheating, and the use of the small amount of extra cooling by using the heater, also improves things. Because your car is not losing coolant, it points to inadequate radiator performance and/or the thermostat is opening too late.

If the coolant is either ordinary water or has never been changed, its also a chance the radiator may have rust and gunk blocking some of its cooling tubes,...but as I mentioned, as well, the t/stat needs replacing anyway, as they aren't too expensive. Use a genuine Toyota thermostat.

For good maintenance, you should replace any old hoses, otherwise, any work you do can be negated by a blown hose further down the road (so to speak).

Jason

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Reply to
Jason James

Are you using 50% antifreeze, 100% antifreeze and it can overheat.

Reply to
m Ransley

I believe you are on the right track. Today, Goodyear replaced the thermostat, temperature sensor (with OEM part), temperature switch, upper and lower hoses, flushed/refilled the coolant. Although the fans are now turning on, the car still exhibits the same problem. At the end of the day, the technician said I may yet need to replace the radiator, pump or possibly the head gasket (in that order). He did say that the coolant looked quite brown in color. Is there a standard way for a technician to determine if the radiator is corroded or obstructed?

Reply to
jay

Lower the water level in the radiator , use a turkey baister if you want, you will see corosion buildup and how much of the coils are obstructed if they actualy are. Mine are maybe 20% obstructed and im fine, maybe its your pump if that is possible, Call a Toy dealer-mechanic for ideas.

Reply to
m Ransley

The brown coolant, if it was just replaced, indicates the prescence of rust and gunk in the cooling system, which includes the engine water-jacket. Now normally, even under these conditions, provided the radiator is *flowing* over 80%, the car will be OK for non-towing work or severe hot weather service. So either the rad is knackered or there is a more subtle fault occuring which can include a leaking water-pump seal, altho this almost always shows up as coolant on the floor after some idling time of the engine whilst hot, or hopefully less likely a slow head or head-gasket leak. This last one depending exactly where the leak is ocuring, causes substantial coolant loss or if less severe and not involving leakage into the cylinders, wetness down the side of the engine and drops of coolant onto the floor.

As I said tho, *if you aren't losing coolant* meaning you *dont* have to top up the rad-expansion bottle all the time, its more likely to be an inefficient cooling system which just allows the engine to run hotter. In rare cases, the water-pump can contribute to this as well due pumping reduction,..but its fairly rare.

Get some-one who knows what they are doing, to declare the radiator as either faulty or OK. These modern radiators have crimped on tanks which makes re-crimping difficult as the little aluminim fingers lose their tension. So if they cant say that the head and or gasket is at fault by doing pressure tests, and a similar declaration about the water-pump, I'd replace the radiator.

Jason

Reply to
Jason James

It turns out, the main cause of the overheating was a bad radiator. Approximately 3/4th of all the passages had significant "gunk" buildup. With the new radiator ($240), the car now climbs hills with AC on max without the temp needle budging from center :) Thx to all.

Reply to
jay

============================ Jay, If you're still reading this, . . . make sure you're using Toyota red coolant and distilled water. Change it every couple of years and you will never have any "gunk" buildup.

Reply to
Daniel

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