Overheating on a 2002 2.5L Altima

[idean]

Hi,

I have a 2002 Nissan Altima with a 2.5 L engine. The other day while stuck in traffic the needle on the temperature gauge crept to High in a matter of 1 minute. The needle would fluctuate between High and 3/4 from the midpoint to the high point.

This persisted while I was in traffic until I was driving at a steady speed of 30 mph. Afterwards the needle immediately backed down to the midpoint in a matter of seconds. Before I take the car into the mechanic shop I wanted your opinion on what the possible problems could be to this problem.

Alittle background on the car and problems that I've been having with this vehicle, hopefully some of this info will help with the overheating problem. I'm going to be as detailed as possible.

The car is currently at 93000 miles, at 92000 (about a month ago), the pre-catalytic converter was replaced due to the dreaded high oil consumption that I'm sure one or many of you have read about at some point that occurs in the 2002 year models. The converter finally decided to kick the bucket and since being replaced, then the oil consumption has not returned.

The radiator was replaced at 75000. I do not get heat when the car is not moving. Only when the car is moving at a steady pace (above 30 mph) does the heater work. I thought it was the radiator and had that replaced, but alas that did not fix the problem and the heating problem persists to this day. The termostats of the car were also replaced after the radiator work was done since having the radiator changed did not fix the problem.

When the overheating problem occured yesterday, I heard the fans of the car turn on to help cool down the vehicle. I turned on the AC to see if this would affect the temperature, but it did not. Also, the AC was definitely luke warm when it was turned on during this time period.

Other forums listed the problem of overheating as a possible sign that the head gasket could be going. I checked the spark plugs for any corrosion or fluid residu (I read that this could help diagnose possible problems with coolant getting to the engines cylinders and/or the head gasket needing a replacement). The spark plugs looked fine.

At this point I was thinking that this problem could be caused by a clogged radiator, maybe a radiator flush will help solve this problem if pressure is building up inside of the unit. I did notice one detail after I popped the hood after getting home, the radiator reservoir tank was above the max line. After waiting for the car to cool down, I opened the radiator cap and a bit (not more than a 2 fluid ounces) of radiator fluid spewed out due to pressure buildup. Maybe I had added too much radiator fluid in the car, since I had filled it up to the Max line in the reservoir tank about 2 weeks ago. Afterwards, I siphoned out a bit of coolant out of the reservoir tank so that the level of coolant was exactly betwen the min and max lines. But I am not sure how this could effect the car overheating.

If you need any more info, post, and I will reply as soon as I possibly can. I'll keep you guys posted if I figure anything else out on my end.

Thanks!

[tech22]

It sounds as if air is trapped in the coolant system.(real common on this model).

[idean]

Hmmm, earliest I'll be able to bleed out to system is Thursday morning. I'll post once I get this done.

[superkid667]

Some Points ....

1. In Regards to no heat while idling, this is a very common problem with Altimas, even my 2005 Altima had the exact problem last winter and it's a easy fix.

2. Overfilling the coolant reservoir tank cannot be causing the overheating because during the pressure buildup and expansion, excess coolant will escape through the pressure cap and discharge on to the road.

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From what i gathered of your lengthy post, I believe 5 things can be the cause.

1. Air is trapped in the coolant system

2. Bad radiator cap

The radiator caps seals your cooling system, keeps the system pressurized when needed, allows excess pressure and coolant expansion and allows coolant to return. A worn radiator cap can be preventing proper coolant flow

3. Water pump corroded
Usually the result of using cheap after market coolants, never changing your coolant or mixing coolants that are incompatible.

4. Bad Thermostat

Thermostats can stick shut or open, get lazy, or fail to open at the correct temperature

5. Failed head gasket

To confirm this, a mechanic can apply a pressure test (NOT a "compression test"), where air is blown into each cylinder in turn until the technician sees bubbles in the radiator. If no bubbles are seen, the problem is elsewhere, such as an external leak.

[crankshaft]

I have an 2004 Altima with the 2.5L; I want to change my coolant. What's the best way to bleed the engine? Is there a bleeder screw?

[d0ugmac1]

Lowtech Zerobudget way:

Do the paper clip trick around the radiator cap pressure valve, then find yourself a steep parking lot ramp (30'+) after hours somewhere, and then rev it up a number of times over a 5 minute period with your heater on full blast. Drive slowly home, let cool and remove paperclip.

PS that would be with the front of the car pointing UP :)

[idean]

To change the coolant, you need to get under the car and find the radiator screw, get a bucket and be ready to immediately place it under the radiator screw when you loosen it up. After performing that, open the radiator cap and pour a 50/50 mix of antifreeze and water. Bleeding the radiator will become necessary afterwards.

After bleeding the system and ensuring I had a 50/50 mix with water, my car hasn't over heated yet, but the true test will come when I'm stuck in rush hour traffic tomorrow.