I recently replaced the radiator in my 99 Maxima (Did it myself with a OEM from Pep Boys). It worked fine for a few days and I even made a 2 hour drive to Cleveland. Coming back from Cleveland I was about 5 miles away from home and it started overheating. After reading a few posts on here I decided it was the thermostat. I replaced the thermostat yesterday and it overheated again today. I opened the overflow reservoir and let it run on idle to make sure there weren't any air pockets. Fluid levels are all good. I didn't replace the cap or any of the hoses, I don't know if that could be an issue.

I'm thinking its either the water pump or maybe I just purchased a bad radiator. Any thoughts?

 

If it helps, here is a link to the radiator I purchased...

http://www.pepboys.com/product/detai...25/?quantity=1

 

Is the coolant level low or is it full? The overflow tank does absolutely nothing regarding the bleeding of air pockets from the engine.

First check the coolant level in the engine. You do this when the engine is completely cool/cold. Remove the radiator cap and look inside. The radiator should be completely filled to the bottom of the radiator cap.

To bleed any air pockets out of the radiator, preferably have the car on an incline. When the engine is completely cool, remove the radiator cap and then start the car. Let it run until it reaches operating temperature and the thermostat opens. If there is air in the engine, it will come bubbling out the radiator filler neck. Monitor the coolant level in the radiator so that the top tank does not become empty. Let the engine run for several minutes to ensure that all air is purged.

Note that water expands when hot. This means that if the radiator tank is completely filled when you start with the engine cold, the coolant will overflow when it gets hot. This is the real purpose for the plastic overflow tank. But when bleeding the air from the engine this means that coolant will come out and splash on the ground. Maybe you want to half empty the radiator tank before starting the car.

 

Are the fans coming on? If they are and you are not losing any coolant I would think the water pump may have gone out. Not really sure how the radiator can go bad unless it is leaking. Are the fins on the radiator damaged or anything?

 

Just tried this, Dennis. No luck. But thanks for the thought.

 

I'm not sure if the fans are working or not. There is no damage to them. How can I tell if they are working properly? At what point do they turn on?

 

they should come one when the thermostat opens when the car is stopped the radiator temp should rise and when it hits a point about 3/4 up the temp gauge the fans should kick on, if they dont it sounds like that is your problem.

 

Test the fans by opening your hood and turning the A/C on just to see if they both spin. If they do, then you need to take the A/C off and wait for car to reach operating temp to see if it will turn on and turn itself back off.

 

Well, it looks like it's the radiator fan. At idle the temp never went above the mid-point, when I turned on the A/C I got nice cool air but the fans did not turn on. Is there a way to test it to see if its just the relay or motor? Or do I need to buy a whole new assembly?

Thanks for the help everyone.

 

I would start with relays as they're cheaper.

 

apply 12 volts to fan and see if it works... thats easiest way to determine if fans are operational...only 2 wires to fan 1 gets ground and 1 gets 12volts

 

Check the fuses for the radiator fans. They are under the hood by the battery. "RAD FAN 1" is for the low speed and "RAD FAN 2" is for the high speed.

You could have bad fan motors. Take a hold of the fan blade and wiggle it front to back. There should be NO detectable wiggle in the fan blade. If it wiggles, replace it. The bearings are destroyed and have also destroyed the brushes.

FYI, without the a/c on, the fans should come on when the engine coolant reaches 203 degrees Fahrenheit. The thermostat should open at 180 degrees.

 

UPDATE:

Thanks again everyone for the help. Everything with the new radiator has been working fine now except for one thing. I've been having to replace the radiator fan fuses "RAD FAN 1" and "RAD FAN 2" every once in awhile. Sometimes they will last a few months sometimes a few weeks. What i've been doing is buying 4 or so fuses and storing them in my glove box and then when I overheat I pull over and put the new ones in and I'm good to go for another little while. Its starting to get old and sometimes happens when I'm in a hurry or can't pull over.

Anyone know why it's doing this?

 

Since you have replaced the radiator, it is possible that the wiring harness somehow got damaged and shorts out to the chassis. You need to inspect the wire harness very carefully for a cut especially where it goes over a thin piece of metal.

But I think a more likely happening is that you have a fan motor that is going bad. RAD FAN 1 provides power to both motors for the low speed. RAD FAN 2 provides power to both motors for the high speed.

Check the fan motors for 2 things.
1) Spin the fan blade. It should turn fairly easy using 2 - 3 ounces of pressure.
2) Wiggle the fan blades. There should be no wiggle at all.

A last resort would be to unplug one fan motor at a time and drive the car. With cooler weather, running on one fan shouldn't be a problem if the fan is good.

 

Thanks for explaining this to me Dennis! I didn't know that is how it worked. I was wondering why they were both blowing out. I'll test the fan motors.