One is almost getting the impression the overheating is not as a result of defective cooling components. Plugs, ignition, worn cylinder gaskets? Are these other possibilities? As I said, you may check the plugs. If burnt-out, it's obvious to the eye. It seems your SES light is not on (you've not mentioned it). Scan the vehicle nonetheless for whatever it's worth.

Innovation4real:
Thnks sir 4 taking your time.
1. Yes d radiator was removed b4 flushing. Surprisingly, d water coming out of it was as clean as any other thing thing: nt in any way dirty.
Only d condenser was nt removed bt back-flushed (both front & back) 2 avoid loss of a/c gas.

2. D heating is wt both with/without a/c.

3. @adanny01 suggested d water pump test b4 & we experimented it. D water had a whirl wind-like move wt d rad cap open.

Do we still look at d possibility of replacing dis even when no obvious sign of defect?

4. On d hunch, d plugs are d ones dat came wt d ride. We didn't replace dis it at maiden servicing. Now, hw do we know burst-out plugs? Do we just go ahead & replace it whether it's a suspect or nt?

5. D milage is 180,000 plus.

More observations:
1. When d temp. is already rising, d ride vibrates when d gear is in N position.
2. I usually turn d eng. off when d ride is heated up 2 enable it cool off b4 re-starting. D truth here is dat d eng. does nt start at once again & I may even need 2 depress accelerator a little while kicking 4 d eng. 2 come up. On a normal note, d eng. starts at once.

Pls help o!

You shouldnt have removed the radiator, i was positive it wasnt dirty since in had original anti freeze installed.

Since the thermostat is out what you need to do is check for leaks and replace your radiator pressure cap. Though i really doubt its the cap cos it doesnt lead to overheating but loss of pressure and coolant.

Ask your mechanic to remove you serpentine belt and check the water pump bearing. Also look for leakage on the water pump or around its gasket. Check all hoses for leakage when the car is hot. Check for leakage around the head gasket.

Innovation4real,

You dont troubleshoot a vehicle with viscous fan coupling, exactly the same way you troubleshoot an overheat issue with vehicle with electric fan.

If truly your Pathfinder has Viscous fan, then you ought to have ruled out the fan first, as not the culprit.

That the fan starts spinning as soon as the engine starts doesnt mean the fan is still good.

To know if viscous fan still work or not, try this:

1. Start the car when engine is cold, e.g. first start in the morning.

2. Let the engine idle for more than 30 mins.

3. As temperature gauge gets close to the middle, pay attention to the engine.

4. You will hear a click and the engine sound will drop a little or you feel the car vibrate a little. Thats when the fan has clucthed and start its work. After seconds or a min, you may hear another clique or noise from engine will drop. Thats when the viscous fan clutch has release and fan is free again, even though it will still spin, but not with enough pressure to suck heat out of the radiator.

A failed viscous fan will not do the above.

Depending on your Viscous fan trigger, you need to be sure the problem is not the trigger. Some Viscous fan are triggered electrically and not mechanically. Such ones will have a brush that does the trigger work. The brush will eventuall wear out and will need to be replaced. Another viscous fan trigger type is the fluid type. The fluid usually is on the part where the plastic blades are bolted. That part that faces the radiator directly. The fluid will sense when the radiator temperature is about to get too high and will magnet the clucth and spin the blades. If there is leakage and the fluid dries up, the fan is dead. If dirt cover the surface of the fan, the fluid wont be able to sense the heat from the radiator and wont do its work when it should, hence, overheating sets in. If I were you, I would clean that fan coupling thoroughly with water, incase dirt is the culprit. I know all these because some Peugeots had both electric and mechanical viscous fan trigger in the past. My ZN3J had the mechanical trigger (Viscous) when i first got her. It failed and i converted it to electric fan.

As for your thermostat, its a waste of energy, time and money to remove the thermostat to test if the thermostat ws the culprit. It can easily be tested without removing from the cooling system. But thats for Peugeot systems though. But you could try and see if that helps. Even to test water pump, you may or may not need to remove the water pump to test that. Find the peugeot method in the link below:

http://www.peugeotowners.com/forum/viewtopic.php?f=12&t=8

Since you have removed the thermostat, dont put it back without testing it in a pot of water.

Are you sure no one introduced air into the cooling system? Has it been bled properly as it should be done? Find out from Nissparts how your Pathfinder cooling system can be bled or you google it. I only know of Peugeot Method.

Good luck!


Ikenna

Ikenna351: Innovation4real,
You dont troubleshoot a vehicle with viscous fan coupling, exactly the same way you troubleshoot an overheat issue with vehicle with electric fan.
If truly your Pathfinder has Viscous fan, then you ought to have ruled out the fan first, as not the culprit.
That the fan starts spinning as soon as the engine starts doesnt mean the fan is still good.
To know if viscous fan still work or not, try this:
1. Start the car when engine is cold, e.g. first start in the morning.
2. Let the engine idle for more than 30 mins.
3. As temperature gauge gets close to the middle, pay attention to the engine.
4. You will hear a click and the engine sound will drop a little or you feel the car vibrate a little. Thats when the fan has clucthed and start its work. After seconds or a min, you may hear another clique or noise from engine will drop. Thats when the viscous fan clutch has release and fan is free again, even though it will still spin, but not with enough pressure to suck heat out of the radiator.
A failed viscous fan will not do the above.
Depending on your Viscous fan trigger, you need to be sure the problem is not the trigger. Some Viscous fan are triggered electrically and not mechanically. Such ones will have a brush that does the trigger work. The brush will eventuall wear out and will need to be replaced. Another viscous fan trigger type is the fluid type. The fluid usually is on the part where the plastic blades are bolted. That part that faces the radiator directly. The fluid will sense when the radiator temperature is about to get too high and will magnet the clucth and spin the blades. If there is leakage and the fluid dries up, the fan is dead. If dirt cover the surface of the fan, the fluid wont be able to sense the heat from the radiator and wont do its work when it should, hence, overheating sets in. If I were you, I would clean that fan coupling thoroughly with water, incase dirt is the culprit. I know all these because some Peugeots had both electric and mechanical viscous fan trigger in the past. My ZN3J had the mechanical trigger (Viscous) when i first got her. It failed and i converted it to electric fan.
As for your thermostat, its a waste of energy, time and money to remove the thermostat to test if the thermostat ws the culprit. It can easily be tested without removing from the cooling system. But thats for Peugeot systems though. But you could try and see if that helps. Even to test water pump, you may or may not need to remove the water pump to test that. Find the peugeot method in the link below:
http://www.peugeotowners.com/forum/viewtopic.php?f=12&t=8
Since you have removed the thermostat, dont put it back without testing it in a pot of water.
Are you sure no one introduced air into the cooling system? Has it been bled properly as it should be done? Find out from Nissparts how your Pathfinder cooling system can be bled or you google it. I only know of Peugeot Method.
Good luck!
Ikenna

You've said it all.
@Innovation4real try go through the above test procedure and let's see the result.

Also never rule out possibility of internally clogged radiator as it might also be the cause.

Innovation4real:
Thnks sir 4 taking your time.
1. Yes d radiator was removed b4 flushing. Surprisingly, d water coming out of it was as clean as any other thing thing: nt in any way dirty.
Only d condenser was nt removed bt back-flushed (both front & back) 2 avoid loss of a/c gas.

2. D heating is wt both with/without a/c.

3. @adanny01 suggested d water pump test b4 & we experimented it. D water had a whirl wind-like move wt d rad cap open.

Do we still look at d possibility of replacing dis even when no obvious sign of defect?

4. On d hunch, d plugs are d ones dat came wt d ride. We didn't replace dis it at maiden servicing. Now, hw do we know burst-out plugs? Do we just go ahead & replace it whether it's a suspect or nt?

5. D milage is 180,000 plus.

More observations:
1. When d temp. is already rising, d ride vibrates when d gear is in N position.
2. I usually turn d eng. off when d ride is heated up 2 enable it cool off b4 re-starting. D truth here is dat d eng. does nt start at once again & I may even need 2 depress accelerator a little while kicking 4 d eng. 2 come up. On a normal note, d eng. starts at once.

Pls help o!

This looks like a head gasket issue.

GAZZUZZ:


This looks like a head gasket issue.

+1. I already broached that idea. Who knows why the car was sold in the first place?

Op, check if oil mix with the coolant..
Check if the fan is blowing in the right direction and NOT backwards.
Your engine fans shouldn't come up at engine start. That shows the wiring has been tampered with.
Lastly, what does your rev do at startup? 500, 750, 1000-2000?

Revert back for experts in the house to help you appropriately..

Ikenna351:
.... Good luck!

Got so disturbed, dis was d last post I read & had 2 sit back indoor 2 re-read to be able 2 give responsible answers 2 my Oga @ d top. Thnks sir.

@all. I'm obliged 2 express my gratitude 2 u all 4 taking your precious time 2 look deeply into my challenge & proffered options/solutions. I was actually away for some time now, even leaving d ride alone.

Having read all your posts all over again & again, a few days back I just decided 2 allow of d mechanics 2 proof one of d options he vouched for: working on d cooling fan. Lo & behold, within 2 hours we were able 2 confirm dat d fan was actually d 'culprit'. D heat has actually subsided & d temperature guage is now always half-way inspite of traffic even wt A/C running. Labour costs only N1,500.

though still placed under observation, d only heat being noticed at d moment is of d engine inside d bonnet: though nt as b4. Dis still really gets me scared anyway.

I hereby express my profound appreciations 2 u all for all I known & learnt now thru your contributions. I will still keep u posted on d developments. Still observing.

Wishing u a great season's celebration IJN.

Also, pls feel free 2 advice more helpful tips.