2001 Pathfinder Still Overheats

[Allen.Pathfinder]

My 2001 Nissan Pathfinder keeps overheating (running hot and then up to the "H" symbol on the Temp gauge) when I run drive it while running the A/C.

Here is what I've done within the last 30 days: I replaced the radiator with a brand new one, all the hoses are now new, the thermostat is brand new, and I replaced the radiator cap so it is brand new. I then had a test done to make sure the original water-pump was working (it passed), pressure tested the coolant system for leaks (it passed), tested to see if the Coolant Temp gauge was broken and not working properly (it passed), tested to make sure my head gasket was not bad (it passed), tested the breath system to make sure/remove air pockets, and just and hour ago it ran hot again! I am very frustrated, and confused. What on earth is the cause?! Has anyone gone through this...and can point me in the direction of the cause so I can fix it??

[note: i have 160k miles on it and have had the vehicle since about 42k miles]

[Towncivilian]

Is the radiator fan operating at idle? Have you cleaned the A/C condenser to ensure it's not being restricted by bugs or leaves?

Welcome to NICO.

[Allen.Pathfinder]

Thanx for responding, Towncivilian. I can both see and hear the fan spinning at idle.

Now, clean the A/C condenser? Never thought of that one...let me try that, and see if it helps at all. I was at the point today were I was just going to replace the water-pump because I figured that maybe its just not pumping with enough flow (it is the original part). That was all I could think to do next...but I will try cleaning the A/C condenser.

[Chuck Tribolet]

What were you doing when it overheated? Stopped at a light? Cruising down the freeway? or ??

Chuck

[xswamperx]

Its your water pump. Replace that and your therm. And since your there, if you haven't replaced your Timing belt for awhile i.e. 60-100k, might as well since your gonna be ripping it apart there.

[Towncivilian]

Its your water pump. Replace that and your therm. And since your there, if you haven't replaced your Timing belt for awhile i.e. 60-100k, might as well since your gonna be ripping it apart there.

VQ35DE engine uses a timing chain.

[Allen.Pathfinder]

Well, the a/c condenser cleaned (check)...just had brand new water pump installed yesterday (check). Drove approx 25 miles home and ran the a/c just to see if it would overheat, watching the temp gauge the entire time. Right before we arrived home, and I was stopped at a light, temp rose to overheating AGAIN! I stopped for gas, and after filling up ran the vehicle without using the a/c - temp gauge stayed at the normal level - but as soon as I turned the a/c on a few blocks down the road - temp gauge shot the heck up. Now I'm starting to "overheat". What on earth is going on that makes the a/c overheat my Pathfinder???

This is the most frustrated a vehicle issue has ever gotten me. Any more ideas???

[Towncivilian]

What brands of parts did you use for everything? Did you drain the old radiator? If so, what was the fluid's condition?

[4xq]

Replace the fan clutch & you should be good to go.

There is an old mechanics rule of thumb: Overheats on the highway, then repair the radiator. Overheats in heavy traffic/when idling/at stoplights, then fix the fan clutch. Sounds like you are overheating at slow speeds / stoplights.

You can research how a fan clutch works, but it must be working properly for the engine fan to spin fast enough to cool the engine at low speeds. At highway speeds, the air being forced thru the radiator will essentially cool the engine without the fans help, or very little help.

After you replace the fan clutch expect to hear the fan "roaring" when you first start the truck on a cold morning. This will happen for a couple of minutes until the oil in the fan clutch warms up.

It doesn't need to be an infiniti part, any decent replacement brand is just fine!

[Allen.Pathfinder]

Replace the fan clutch & you should be good to go.

There is an old mechanics rule of thumb: Overheats on the highway, then repair the radiator. Overheats in heavy traffic/when idling/at stoplights, then fix the fan clutch. Sounds like you are overheating at slow speeds / stoplights.

You can research how a fan clutch works, but it must be working properly for the engine fan to spin fast enough to cool the engine at low speeds. At highway speeds, the air being forced thru the radiator will essentially cool the engine without the fans help, or very little help.

After you replace the fan clutch expect to hear the fan "roaring" when you first start the truck on a cold morning. This will happen for a couple of minutes until the oil in the fan clutch warms up.

It doesn't need to be an infiniti part, any decent replacement brand is just fine!

Thanks 4xq...my mechanic friend said the exact same thing to me yesterday, and this morning when we talked about this. It sounds like it's the last thing that I can do, that I haven't already done. Oh well...back to the shop again...to pour more money into this {sigh}

I'm really starting to believe that I had multiple cooling system issues that were either right at the brink of failure, or failed at the same time, or when out in secession after my original radiator died back in June and started this entire roller coaster ride. I love my Pathfinder, and it has been a very good and reliable vehicle - up to this point. This overheating/cooling system mess has been unlike anything I've ever encountered with ANY vehicle I've ever owned.

Also, did anyone else also find that getting the air out of the cooling system after replacing the radiator or other parts was a pain in the butt as well?

I'll report back after I have it check over again...and possibly have a new fan clutch put in.

[Chuck Tribolet]

Getting the air out is easy. There's a rubber cap on a metal line at the top center of the firewall. Pull it off. Add
coolant. Done. Be careful taking the Jesus clip off so you don't loose it. There may also be one at the front of the engine
on the passenger's side. The FSM shows it but my 2001.0 stick shift sure doesn't have it.

Chuck

[oke1konbe]

I have the same truck ran into this issue after using 10w40 oil from castrol full synthetic try royal purple 10w30

[Towncivilian]

A higher or lower operational oil viscosity grade will not appreciably increase or decrease average oil or engine temperature since the engine's temperature is controlled via the cooling system.

Allen.Pathfinder, have you had the fan clutch replaced?

[Chuck Tribolet]

And I've been running 10W40 Castrol for a long time.

Chuck

[xxectoxx]

Have you had any success ? I am in the same boat. It only would over heat when on the highway, but now it's overheating when I'm at a light. This is very frustrating.

[stilleto]

Morning Allen,
Im new to the site. Hoping to find some INTEl!!! Been having problem with the headlamps. Any intel would help:)) I don't have module on passenger side firewall. Plan B??
Its amazing when you go to the library and pick-up all repair manuals in Asian Vehicles. I found a great deal of information. Book looked like the encyclopedia!!))

NOTE: 2001 Pathfinder 3.5 liter (thermostat)

This motor has "2 (TWO) THERMOSTATS"

1. One in front

2. Second Thermostat in located towards the firewall. With mirror, try looking from the passenger side.

Note: My experienced in replacing the 2nd thermostat, I had to remove the intake manifold. There is a tightening sequence in the manifold bolts. Ft. lbs/ in. lbs
Not sure what might be more easier. Dropping the engine or removing the intake. I had to replace the engine cradle, and had just finished the install, then ran it and started overheating. So I went back into the Hanes repair manual. From What I member, the 2nd thermostat was not showing the repair manual.
Your going to need the thick Asian Repair manual.
I hope this helps.

Regards
Andy

[stilleto]

Morning Allen,
Im new to the site. Hoping to find some INTEl!!! Been having problem with the headlamps. Any intel would help:)) I don't have module on passenger side firewall. Plan B??
Its amazing when you go to the library and pick-up all repair manuals in Asian Vehicles. I found a great deal of information. Book looked like the encyclopedia!!))

NOTE: 2001 Pathfinder 3.5 liter (thermostat)

This motor has "2 (TWO) THERMOSTATS"

1. One in front

2. Second Thermostat in located towards the firewall. With mirror, try looking from the passenger side.

Note: My experienced in replacing the 2nd thermostat, I had to remove the intake manifold. There is a tightening sequence in the manifold bolts. Ft. lbs vs. in. lbs
Not sure what might be more easier. Dropping the engine or removing the intake. I had to replace the engine cradle, and had just finished the install, then ran it and started overheating. So I went back into the Hayes repair manual. From What I member, the 2nd thermostat was not showing in the Hayes repair manual.
Your going to need the thick Asian Repair manual. It list the 2nd thermostat towards the fireball. Center Left.
You may have to purchase top motor gasket. Some I was able to salvage, but not all of them. I used all new, saving old for a rainy day!
I hope this helps.

Regards
Andy

[stilleto]

Morning Allen,
Im new to the site. Hoping to find some INTEl!!! Been having problem with the headlamps. Any intel would help:)) I don't have module on passenger side firewall. Plan B??
Its amazing when you go to the library and pick-up all repair manuals in Asian Vehicles. I found a great deal of information. Book looked like the encyclopedia!!))

NOTE: 2001 Pathfinder 3.5 liter (thermostat)

This motor has "2 (TWO) THERMOSTATS"

1. One in front

2. Second Thermostat in located towards the firewall. With mirror, try looking from the passenger side.

Note: My experienced in replacing the 2nd thermostat, I had to remove the intake manifold. There is a tightening sequence in the manifold bolts. Ft. lbs vs. in. lbs
Not sure what might be more easier. Dropping the engine or removing the intake. I had to replace the engine cradle, and had just finished the install, then ran it and started overheating. So I went back into the Hayes repair manual. From What I member, the 2nd thermostat was not showing in the Hayes repair manual.
Your going to need the thick Asian Repair manual. It list the 2nd thermostat towards the firewall. Center Left.
You may have to purchase top motor gasket. Some I was able to salvage, but not all of them. I used all new, saving old for a rainy day!
I hope this helps.

Regards
Andy

[Fortescue]

Hey guys, i bought my 01 Pathfinder about 3 months ago, i drove it back and forth to work for about a month no problems at all. Then all of a sudden i have to take about a 40 mile trip. On my way back it starts overheating. For the last 2 months ive been throwing parts at it to no avail. I replaced thermostat, water pump, radiator, upper radiator hose, coolant many times. I havn't done nearly as much as some people but it is still frustrating. I took it to a nissan dealership to have it diagnosed. They said it was the radiator (before i had replaced it). I dont have 800 dollars to drop into labor for them. So i got a new one myself and put it in. Didn't solve it. So i recently took it back to have my pathy flushed. Didnt work again. So now i have no idea what next to do. The dealership says thermostat but the one i put in is brand new. Surely it cant be that? Since they f*** me twice already i think i may as well sell the damn thing.

[nalz]

Sounds like all that's left is the radiator cap, the radiator fan clutch (this would apply to vehicles that overheat at low speeds in warm-to-hot ambient temps, operating in cold ambient temps, and/or constant highway cruise conditions would keep enough airflow moving through the radiator to prevent overheating), and maybe things like water-to-antifreeze ratios, air trapped in the cooling system from an improper bleeding procedure, and last and the least appealing: a head gasket failure.