2001 QX4 - Overheating

[gordon.su]

Hey NICO,

I beleive I have a common problem with many other pathfinders and QX4's I was wondering if you could share some insight on how you solved this problem(read below)!

I have a 2001 Infiniti QX4 with close to 220,000km.

Since the summer before I noticed my QX4 gets really hot in warmer temperatures (18-25 degrees celcius) after the engine runs for 20 minutes or more.

The thermostat will ocasionally go close to the very top. This happens especially when I am stuck in traffic bumper to bumper. The thermostat goes up even faster when I turn on the AC in the car.

However if I am driving and higher speeds 60km/h+ it seems as the air going into the radiator will cool down the car, but again if I stop for awhile in traffic the thermostat will climb again.

Some instant remedies I used this far was by turning the heat in the car to the highest settings, which can get very uncomfortable, it is strange even when i turn off the heat the heat still appears to be coming out of the vents.

I've been able to get away with it the 2 summers as I was ocasionally driving in the summer but now that I am working which requires a farther commuting distance and everyday I am stuck in traffic for more than 1 hour, I am affraid on a hot summer day I might not make it back home in traffic in warmer wheather with summer approaching.

some other interesting notes:
- coolant was leaking last summer, but after adding in some solution into the radiator it magically stopped
- my radiator cap appears to be worn out - I looked in the FAQ i am ordering a new one but am not convinced that will be the full soltion to my problem
- could it be my radiator needs to be replaced? - is there a way to find out whether or not it will solve my problem?
- coolant was topped off

[Towncivilian]

The radiator sounds like it's clogged since the engine stays cooler at higher speeds, where the cooling system isn't dependent on the cooling fan to dissipate heat. Has the coolant ever been changed?

[gordon.su]

I do not recall, I have just been toping it off, what would be the corrective course of action?

just a simple radiator/coolant flush?

[Towncivilian]

You can do a drain and fill of the coolant to see if the radiator is clogged. Flush distilled water through the radiator while the drain plug is off until it drains more or less clear, then refill with 50/50 coolant to distilled water. I would use Nissan OEM coolant only.

[gordon.su]

oh thanks for the thorough steps, my question is whats the main difference between OEM coolant and a universal one my mechanic may carry?

[Chuck Tribolet]

The biggest concern with coolant is compatibility with the prior coolant. You don't see it much
here, but over on CorvetteForum.com, lots of stories about problems using the first versions
of DexCool -- Jello in the radiator. Newer versions may be better. But I carefully sought out
genuine Nissan when I recently flushed the rad on my '01 PF.

And do use distilled water, not tap water, to fill. I don't see a problem with using tap water
to flush, just drain well. But fill with distilled (or deionized, but maybe not quite as good)
water. I got into this in college, my roommate was dating a chem professor's daughter, and the
prof. turned us on to a tap on the outside of the chem building that delivered seriously
deionized water (WAAAY better than what you can buy.)


Chuck

[gordon.su]

@Chuck, thanks that's great information.

How's your Corvette?

Don't most coolants already come premixed with distilled water?

[gordon.su]

Hey everyone,

So I went to the shop yesterday and did the coolant flush:
- Allowed all of the air to bleed out of the radiator

But after running the car for a while coming to a stop the car's temp. gauge was almost at the hot range - to cool the car I need to either turn on the heat or continue driving over 60 km/h to force more air into the radiator

what would you suggest that could be the problem?
- thermostat?
- clutch fan
- radiator?

I spoke with a friend and he said my symptoms really points out to being a bad thermostat.

Thanks!



When I am driving and air is being forced into

[gordon.su]

also to note:

- i replaced the rad cap
- after rad flush
- car still gets hot, thermostat almost to the top
- after turning off the heat , shutting off the fan system completely
- i still feel heat from the bottom fan vent close to my legs

could this be redirected to my possible idea of a faulty thermostat?