Help, overheating problem in 2010 Nissan Pathfinder

[ronin026]

I don’t have the tools to pressure test coolant system or compression test the engine unfortunately. As far as radiator cap, I understand this vehicle to have a pressured coolant reservoir. The cap on the radiator itself isn’t spring loaded for pressure, it’s just a flat cap. The spring loaded pressure cap is on the coolant reservoir.

[ronin026]

So I took my pathfinder down the street to a buddy of mine that knows more about cars than I. He said it looks like I put one of the hoses on backwards after doing the thermostat, so its partially kinked and restricting flow. Also that the fan clutch appears bad as the fan is free spinning with no resistance when the engine is off. He also recommended I replace the radiator cap, which I believe someone else mentioned here too. So I'll be ordering some parts and doing this all tomorrow.

Really hopeful its not the block.

Also I idled the vehicle again for about 30 minutes and it stayed cool today. If that helps at all.

[mdmellott]

That's great to hear those fairly minor corrections to make were found. One note I need to make regarding a previous post you made is that when you initially filled your radiator, after replacing the thermostat, you let the engine idle with your A/C running when you should have had your heater running instead. Your 2010 has a front and rear heater core and a heater pump. When you drained the radiator to replace the thermostat, air may have been likely to enter the heater cores and lines. To eliminate the air trapped in the cabin heater system, the heater circulation must be turned on with the heater temperature set to high so that air can be pumped out and vented while you filled the cooling system. As for the fan clutch, it should be free spinning with the engine off. Just be sure that the fan is engaged when the engine gets hot.

[ronin026]

Ok I will definitely run the system with heat on and make sure it’s topped off afterwards.

Help me understand the fan clutch. I was told there should be some resistance when engine is off and spinning the fan blade. Your saying it should freely spin with no resistance? It does Indeed spin when the car is running.

[mdmellott]

There should be very little resistance when you freely spin the fan by hand. If you give the fan a good push and it freely spins more than one or one and half full turns, the clutch may be slipping too much and probably should be replaced. Because of the little resistance that is normal, the fan will spin when the engine is running and the clutch is slipping normally. What you should be able to observe and hear when the engine is hot enough is that the fan clutch will stop slipping and the fan will then spin at the same full speed the fan belt is driving the water pump at. You should be able to hear this happening when it occurs and feel the increased air flow blowing toward the engine. Just don't put your hand down there to check it out. If you do not hear the fan fully engage after the engine has gotten hot, the fan clutch needs to be replaced.

[AZhitman]

I don’t have the tools to pressure test coolant system or compression test the engine unfortunately.

They can be rented at most large auto parts stores.

Cheaper than a head gasket repair. Remember, we don't do shortcuts here. Let's fix it right.

[ronin026]

AZhitman

I understand. I have to get it fixed so there will be no shortcuts. I replaced the fan clutch today and adjusted a hose that was partially kinked from doing thermostat install. The original fan clutch was spinning at least a full rotation if not more, the new fan clutch does not spin nearly as much. With a solid hand spin on the new fan clutch it i'm getting 1/4 turn or so. So that does appear that it was slipping more than it should have. Also burped the system quite thoroughly with the heaters on in back and front full blast. However It is still overheating, and in fact it is over heating while idling I just needed to bring RPMs up to 3000-4000 rpm for it to do so. So thermostat is new, fan clutch is new, AC condenser is new. I took a infrared temperature gun and read the lower and upper radiator hoses to see what was going on and got drastically different readings. Granted the readings were through the hose so the exterior of the hose is probably reading cooler than the actual liquid inside of it. Nonetheless, lower Radiator hose was coming in at 90-95 degrees and upper radiator hose was reading at 150-165 degrees. This is with the car idling for 30-45 minutes and at a solid idle temp. That seems to me as if fluid is not flowing properly through the motor? Or is this normal for the coolant to be that much cooler prior to going into the block?

I'm really at a loggerhead here. I don't know what to do next. My neighbor is saying replace the water pump, but I just watched a video on the water pump for this vehicle and it includes disassembling the whole front end as well as removing the timing chain tensioner and removing the water pump from within the block. Furthermore the video I watched he went through all that effort and the water pump was just fine.

https://www.youtube.com/watch?v=Qe2KV9IAOuo&t=665s

If you think I should rent some tools to check pressure on the block and coolant system then I will. Another person earlier in this thread recommended replacing the entire radiator as well, yet another person(my neighbor) has recommended I replace the water pump. I'm wondering if its the vehicle temp sensor, but don't really know. I'm not sure which direction I should go. I'm coming up on 300$ into this, and as with anyone don't want to spend money on parts and/or tools that wont fix the problem.

[mdmellott]

A little over a week ago, a wise man once said, "I'd replace the thermostat, but I'd also pull the radiator, clean the fins, clean the condenser (back to front, to clear the fins), flush the block and radiator, and also flush the reservoir." You mentioned the condenser was new so that's probably fine. If you can see clearly that the fins on the radiator and the condenser are not blocked up with dirt, bugs, and debris then they likely have good air flow for cooling. You can do a quick check on the coolant temperature sensor by checking the resistance between the two terminals on the sensor which is located on an outlet pipe at the back of the engine. When the engine is completely cooled down, unplug the connector from the sensor and measure the resistance of the sensor terminals. At 20C(68F) the resistance should be 2100 to 2900 ohms. On page EC-132 of the factory service manual you will see a graph that you can use, and other temperatures and corresponding resistance values, if your sensor is not right at about 70F. https://www.nicoclub.com/service-manual ... 010/EC.pdf
Be sure the connector and terminals were not wet as that could have made the sensor signal a false positive indication of high temperature. However, your symptoms seem more mechanical than electrical. Page CO-29 of the FSM will show you where the engine coolant temperature sensor is located. https://www.nicoclub.com/service-manual ... 010/CO.pdf Page CO-9 gives two of the most probable causes, in my opinion, of your poor heat transfer condition. A stuck closed thermostat or clogged radiator cooling tubes. I know you just installed a knew thermostat. Assuming that part was not dysfunctional right out of the box, that leaves a clogged up radiator to be considered as the source of the problem. On page EC-319 of the FSM you will see a list of 12 main causes of overheating. #6 points to a thermostat issue again when both the upper and lower radiator hoses are not hot after the engine has run for awhile and the coolant temperature should be hot enough to have opened the thermostat. There will be some temperature difference, with the upper hose being hotter, but there is no spec indicating what that difference should be. However, I would think they should be closer than the 65F average you measured. So either the coolant isn't flowing as it should through the lower hose because the thermostat is stuck closed or the radiator cooling tubes are clogged. I wouldn't touch the water pump because it seemed to be working before you started on this journey. Are there any fault codes being detected and read with a scan tool?

[ronin026]

So I have it fixed! Apparently I failed to burp the system properly. I was topping off the coolant reservoir and leaving the radiator capped, which I had assumed would work since coolant goes through the reservoir as it's a "pressured" reservoir. Anyways long story short that didn't work. I opened the radiator today and attempted to "top it off" but was surprised that it took over 1/4 gallon of coolant. I left both caps off and let it run for an hour, topping it off everytime it went down below the neck. I got A LOT more air out this time. After it got warm enough to open the thermostat I closed the radiator lid and coolant reservoir lid. A short while later it started overflowing out the coolant reservoir since I had everything completely topped off, but it didn't overheat. Drove the vehicle today for about an hour in several different kinds of conditions and it cooled well.

Sorry for the trouble and my incompetence refilling the system. But I have it fixed now.

[mdmellott]

It's good to hear that the overheating issue is no more. I think everybody else on this thread, myself included, assumed that when you refilled the radiator you actually refilled the radiator completely while allowing all the air in the system to escape through the open radiator. Hopefully, no harm was done.

[ronin026]

Yeah I did refill the radiator completely, but didn't top it off at the radiator afterwards, I topped it off at the reservoir. Live and learn. Thank you for the help none the less.

[AZhitman]

Spectacular!

I've never run into this, but I'll certainly keep an eye out for it in the future - Good catch, Ronin!