Overheating

Make sure your condenser fan is not locked up and that it comes on when the car is idling and hot.

Do NOT allow your car to overheat or even approach it. Drive with the A/C off if necessary until the problem is found. For most people, a little sweat is less expensive than a new engine.

The fan appears to be working fine.

This often indicates a blocked air path through the AC condensor and radiator, or conceivably a fan problem.

Here in Texas, we sometimes get 'love bug' infestations so bad that they will plug the condensor/radiator path. Have also seen grass clippings, etc, accumulate there.

Nothing there... looks clean to me

Have your radiator back-flushed. It is probably restricted. When the car starts to overheat, try running the heater at full blast. If that brings down the temp, then your radiator is almost certainly clogged up.

There are three places in the engine compartment where heat can be removed - the condensor, the radiator, and the heater core. The condensor only needs heat removed from it when the A/C is running, but if the heat is not removed, it will decrease the A/C efficiency and increase the heat load on the radiator that it is mounted right next to.

There are four ways that heat can be removed from the engine compartment: the cabin blower (from the heater core), the radiator fan (from the radiator), the condensor fan (from the condensor) and air from driving (from the condensor and radiator).

When you are no longer driving (idle), you are relying on the fans to remove excess heat. If all of the fans are running and sufficient heat is not being removed, you have a coolant flow problem. That flow problem could be due to lack of pressure in the cooling system (due to a leak) or due to a clog, which prevents the radiator from removing as much heat in parallel from the coolant as it is designed to.

Keep in mind that if your radiator is clogged full of rust from allowing the coolant to age and become corrosive, your water pump's days are likely numbered too.

This sounds great, thanks. The coolant in the resevoir looks clean and happy..

Have your radiator roded. I don't think flushing will help much. Also the blades of the water pump maybe corroded or worn out that when idling they hardly move the coolant. Also check the radiator fan clutch if your car has it.

Roded?

'Rodded out'. They manually clean the tubes, removing foulant,scale, etc.

Radiators can be fouled with a lot of things, but one of the worst is silica, which comes from the decomposition of older antifreeze corrosion inhibitor additives. You cannot remove this sort of deposit (if this is what you have) by flushing or using over the counter chemicals, etc. It has to be cleaned at a radiator shop.

Since you have checked the external system, fans, surfaces, and have found nothing, it is time to go a little deeper. What engine are your running?

Generically I would take a comprehensive look at the system more or less as outlined below.

- Take a good look at the system. Look at the radiator, hoses, water pump, freeze plugs, etc and note any leakage, looseness, or other signs of wear.

- If you have a viscoelastic fan clutch, be sure it is holding.

- Make sure the belt driving your waterpump is in good shape and is at the correct tension. ( Belts sometimes get burnished and slip. Tensioners can lose their force)

- Make sure that you do not have an air bubble trapped in your cooling system. Some cars can be hard to get this bubble out.

- You may have to have your radiator professionally cleaned. If you remove the hoses and flush water through it, you should be able to get some idea of how freeflowing it is.

- If you haven't changed hoses in a long time (perhaps more than 40.50,000 miles), it is a good time to do it. AND if you can get to the thermostat easily, change it too. It just costs a couple of bucks for most cars. (While you have the thermostat out, put the garden hose in the hole and flush the block until you are pretty sure everything is clean)

- Manually check your water pump for shaft play. If it has noticeable play, or has been leaking at the weep hole or shaft seal, you may want to replace it. You can't tell without dropping it if your impellor is corroded, loose, etc)

By now, you should have detected the most likely cause of the problem, unless you have some internal engine problem, such as cracks, leaking gaskets, etc.

The key is to work calmly and with a purpose, and eliminate the simple things first.

Getting the system flushed tomorrow night. The fan appears to be working just fine, I've checked as many of the hoses and connections I could find, they all look fine... there are no apparent leaks anywhere.

Thanks for all the advice, I'm sure I'll be back if this doesn't solve the issue.

Next week's project, assuming this goes well, is to change the shocks and struts..

Let us know how this finally works out. It always helps to get feedback.

To further explain, rodding out is actually forcing rods down the tubes of the radiator to push out any deposits that has formed in the tubes.

-Bruce

Sorry for my typo,

Thanks Bruce, yes rodding

Well, I brought it to the shop today. They looked in the cylinder and said something to the effect of "I've never seen Dex-cool that clean. It would be a crime to charge you for flushing this out. It's probably either the thermostat or a genuine plug in the radiator."

So I guess a new thermostat is the next step.