theherdmaster

My 2000 Maxima SE with 173k miles on it overheats while I'm driving. It can only handle short trips, and I've searched the forums - I think it's the thermostat going bad. Fingers crossed it's not my head gaskets.

So I bought a thermostat, and I'll install it tomorrow. My one question: how ill-advised is it for me to try and swap out the old thermostat without draining the old coolant? I'm really, super broke right now. If it's not too stupid, I'll consider re-using my coolant. It's not too old, and it still looks pretty clear.

Dumb move? Should I wait until I can get myself two gallons of coolant?

foodmanry

iTrader: (15)

How do you know it's the thermostat? It could very well be a clogged radiator or even a bad cap in your radiator.

It could also be one of your fans not turning on.

Have you checked all of this to rule them out?

Very doubtful it is a head gasket as those are pretty much bullet proof on the maxima.

theherdmaster

I don't know it's the thermostat. I just did a few searches on the forums, and most threads lead to the thermostat being replaced. I am kindof jumping to conclusions, though. The thermostat issues reported by others on the forums were similar to the issues I have been having.

That being said, I haven't checked to see if both fans are turning on. I can do so and report back. I believe my radiator cap is Nissan OEM, but I can double check on that. I do know that I'm not leaking any coolant, and the coolant level at the overflow tank is just below max. And if this clues into anything, the temperature seems to stabilize whenever the car is moving for a long period of time, and whenever the engine idles for a long period of time it starts to overheat. Interestingly enough.

But good to hear the head gaskets are bulletproof. That's one of the biggest reasons I bought this car - everyone has raved about how long the engines last. I bought this Nissan after having owned a Subaru. . and this feels way too familiar (to the time when the head gaskets went on the Subaru).

foodmanry

iTrader: (15)

Tells me either a fan is out or your radiator is clogged which are both common issues in these cars.

theherdmaster

I just drove it around to figure a few things out. When it's warming up, neither fan is on unless I turn the A/C on. Once I got up to warm temperature, the temperature stayed there while the car was idling. Both fans still off. I drove it around and stopped, running temperature still warm (good temp) and both fans are on. I drove it some more until it began to overheat, and I looked under the hood, both fans were on while the temperature was slowly climbing. So it looks like both fans are working, but they aren't doing enough to keep the temperature down. Seems like my radiator may need to be flushed? How can I tell that it's poor flow in the radiator, and not a thermostat issue?

Side note, I had the air in the cabin on hot, and even when the engine was warm the air blowing in the cabin was cold. No hot air blowing in the cabin.

Another side note, I think I need to clean the MAF sensor, because sometimes upon starting up the engine struggles for air a little. I just replaced the air filter recently. Could this have to do with the overheating at all either? Not enough air circulation?

DennisMik

iTrader: (2)

Many times when the heater does not blow hot air, it is because the radiator level is low.

When the engine is cold, remove the radiator cap. The top tank of the radiator should be 100% full, no space for air.

theherdmaster

I just checked to make sure the engine was cold, and then took off the radiator cap. It is indeed not full, and there was a hiss of air when I took the cap off. Seems I need to add some coolant. Which is odd, because the overflow tank coolant level is where it should be and the coolant is in good condition.

Should I burp the radiator and fill it with coolant? You know, the whole deal where I raise the front end up, take the radiator cap off with the engine running, and add coolant until full thing.

Best recommendation for what I do next?

DennisMik

iTrader: (2)

The overflow tank doesn't always empty out. I don't really know why.

Whether you need to burp the cooling system depends on how low the coolant level is. It doesn't have to be that low for the heater to stop blowing heat, but it would have to be lower than that for the engine to start overheating.

Overall, I would recommend doing the burp thing. But you don't take the radiator cap off while the engine is running. You take the radiator cap off while the engine is cold and then start the engine.

Don't fill the radiator all the way at first, just enough to cover the tops of the cooling tubes and then start the engine. If you have the radiator filled all the way, when the engine heats up and the thermostat opens, any air that is trapped in the engine will make the coolant blow out of the radiator filler neck when it escapes. Once the thermostat has opened, you can then fill the radiator all the way and put the cap on. Make sure that the overflow tank has enough coolant in it.

Drive the car for a day and then remove the radiator cap the next day when the engine is cold and check the coolant level. Top off if necessary.

theherdmaster

Simple enough. I'll do this and see if it does the trick. If I don't have to replace the thermostat, that would be great.

foodmanry

iTrader: (15)

No relation to your overheating. You should look to clean both the MAF and the throttle body. On 2k's cleaning both will not affect the car. Make sure you use intake cleaner. I've never used MAF cleaner to clean my MAF...I think that is just a gimmick to get you to buy another chemical.

I've had good success with Berrman's B-12 Chemtool carb/injector cleaner. You can get it in a can with spray or without spray. I would go with the spray. Anything leftover you can spray in your gas tank if you want to clean the injectors. If you get without spray you can clean your parts, but more manual intensive, the side benefit is any leftover can be easily poured into your gas tank.