Hello!

I have a 2007 Maxima that I really like, except that it has had an overheating problem for a while. It runs fine most of the time except when it is 80+ degrees out. If it gets that hot out, it runs fine on the highway. But if I turn the AC on, or drive in stop and go traffic, it heats up pretty quickly. It cools off if I turn the AC off or get on the highway, but it can take a while. I always stop and turn it off if it comes near the red line.

I have been doing some research into this on maxima.org. Most of the advice says:

1. check the coolant level -- I did this.
2. check the fans -- they turn.
3. check the thermostat
4. check the radiator
5. check the water pump

I have some questions though. I'm not a mechanic (though I'm not afraid to do stuff).

1. How do I check the fans? Just let the engine warm up and visually check? My understanding is that the fans in this model operate at 3 speeds, so how would I check that the high settings work? How would I even tell what speed they're running at?

2. My understanding is that I can check the thermostat by touching the radiator intake hose when the engine is warm. I think it's okay -- the radiator gets hot. Is there anything else I should look for?

3. How can I tell if a radiator is clogged?

4. What order would you do these tests in?

Ideally I'd like to know what's wrong before I go to a mechanic. (Or maybe I'll fix it myself if its the radiator or fans or fan control). I'm definitely willing to poke around, but I don't have any jack stands and I'd like to make some progress soon.

Thank you!

 

First off, that old, get the radiator flushed. You'll find out quick if it's buildup. Should be done I think every 50,000, especially after the car gets older...but check the manual for actual interval. Some cars may be as low as 30,000. Either way, get that done ASAP. Firestone can do it for under $100. They can also tell you if the thermostat is broke or if the pump isn't working well.

 

BTW, I'd guess the thermostat first in a lot of these cases, if the buildup is minor. But with bad buildup, you could have a bad pump, bad thermo, and bad waterflow...so yeah, coolant flush is a must.

 

Awesome. Thanks for your advice. Definitely a cost effective plan to find out, plus it's regular maintenance anyway. I'll do it this weekend.

 

Are the fans on when you turn on the AC?

 

OK, so I just got a coolant flush. I asked them if they could let me know about any problems and they were cagey about it. But he did say that if it was a bad water pump it would probably be leaking badly, and it wasn't.

So my guess is I'll have to go to a real mechanic. :sadface:

One thing I found out is that the front-side splash guard is missing from my car. Could that be the cause? I wonder if it being missing is causing air to go through the radiator too slowly or something.

The fans were blowing really hard when I got home and the car was close to the red line temperature. (Yes, I tried the AC after the flush. It worked for about 5 minutes)

 

Yeah, plastic shroud under the car is there to force air to flow through radiator. Could be contributing to your problem.


What do you mean cagey, and why didn't you take it someplace that could do the work? Firestone can do thermostat and water pump replacement. If they seemed like they were iffy, and could only do a fluid swap/flush, it would have been a good idea to walk out and find another place.

 

I mistakenly went to my Valvoline since I knew they offered the flush service.

I got a new shroud and clips, which will arrive tomorrow. I'll install it and give it a try next.

If that doesn't work, I'll go to a full-service mechanic like Firestone and see what's next.

Thanks for all your help.

 

Something to think about, since the bottom is already out, you can get adequate drainage. If I recall the front bumper grill is easy to remove too, I replaced mine with an aftermarket as I recall didn't need to take the bumper off. I'd suggest you get the grill off and run some hose pressure water (not pressure washer though) through the AC condenser with enough force to also clear out the radiator behind it. Since you're working on the car already, just to make sure you don't have a bunch of road dirt/bugs or other buildup in the cooling fins of the condenser and radiator...may be overkill, but it only takes a few extra minutes to perform...