The Nissan Path

My 2010 Pathfinder 4.0L literally roars everywhere I go. On startup it roars to life with the fan being extremely loud, and then during regular driving the fan roars along with the speed of the engine. Initially I liked this, but I am sure it is sucking a good amount of fuel economy away.

Any idea on how to quiet it down and possibly re-gain some fuel economy?

Fuel economy on this truck is absolutely horrendous. I am getting 220 miles on a full tank, mainly city driving. That is terrible.

Sounds like it's time for a new fan clutch.
Had to replace mine a few years ago. Go with a genuine Nissan replacement. I tried aftermarket first and wound up having to replace that with a Nissan.

Hate to promote what some consider snake oil, but I did SeaFoam my engine and then poured some Berrymans B-12 into the tank and got a nice bump in gas mileage. Previously I was getting around 240ish if I remember correctly. Now I'm around the 270-280 mark. I usually fill up around 18 gallons so that divided by 270 comes out to about 15 mpg. Not the best, but it's good for a heavy truck.

I'm about the change plugs this weekend so hoping that helps me a bit too. Though about changing the upsteam O2 sensors as well, but they're a little too pricey to change, "just because".

Careful with Berrymans on older vehicles, its pretty harsh solvent based.

Seafoam is much safer to put in the tank.
Techron is good. and BG44k is probably the best (Source: I am a chemist)

Sounds like I will need to do a seafoam on the truck, but definitely need to change the fan clutch. Seems like is locked and causing the mechanical fan to spin 100% of the time, which will kill fuel economy.

Typical bad fan clutch issue. As already mentioned, stick with genuine Nissan. There have been a lot of reported problems with the aftermarket replacements.

So how can do you tell if too loud and fun clutch needs replaced?

BullDozer wrote:So how can do you tell if too loud and fun clutch needs replaced?

In Queens NYC there are a ton of these R51 pathfinders for some reason. Many of them are quiet at idle and at low RPM's around town. Mine on the other hand sounds like a garbage truck. It is always roaring at low RPM's and the rad fan seems to be blowing at full blast...when I open the engine bay and stand over the fan or go under the fan its pushing a ton of air at idle.

BullDozer wrote:So how can do you tell if too loud and fun clutch needs replaced?

If you have a working clutch, on cold start the fan should essentially be free spinning a few seconds after startup. The fan should not be moving any air.

elementZ wrote:

BullDozer wrote:So how can do you tell if too loud and fun clutch needs replaced?

If you have a working clutch, on cold start the fan should essentially be free spinning a few seconds after startup. The fan should not be moving any air.

Are you saying the fan should not be spinning all the time?

BullDozer wrote:

elementZ wrote:

BullDozer wrote:So how can do you tell if too loud and fun clutch needs replaced?

If you have a working clutch, on cold start the fan should essentially be free spinning a few seconds after startup. The fan should not be moving any air.

Are you saying the fan should not be spinning all the time?

bump. I'm curious too.

It'll spin...but freewheeling and at a slower speed than it would if the clutch were engaged and causing the fan to pull the air through the radiator core. The only time I hear my mechanical fan is for a second when I first start up and also when I come to a stop after driving a while and sit at idle, as when I go through a drive-thru line at a fast food joint or at the bank. It happens more so in hot weather.

Great info as always smj. Wish you my neighbor! While tearing things down today to do t stat, belt, tensioner,hoses tranny lines ( amongst other things) etc when I pulled the fan off of the clutch, what I thought was normal grime was actually hard packed sand in every nook in fan. Space between the stat housing and timing cover was also packed solid with oily sand. Just bought Pathfinder last month and finally got to work on her, so didn't see this before now. Never seen anything like it. Looks like she was dropped from a C47 nose first into into a beach. I'll bet that it will be quieter now that it's clean, and maybe mileage will be a smidge better. It sounds obvious but double check for heavy grime in and around fan. This could cause noise and in my case put extra wear on clutch and bearings, maybe the extra weight could interfere with clutch operation (there really was that much crap in there!)

I replaced the fan clutch this past weekend with an OEM unit, and the truck is extremely quiet now.

However my heat isn't working. I removed the radiator top hose to wiggle out the upper rad shroud, and in the process spilled some rad fluid. Is it possible I either introduced air in the system, or I am low on rad fluid which is adversely impacting the heating?

Top off the coolant and purge the air out of the system. Make sure you didn't mix up the coolant reservoir and radiator caps; the reservoir cap will have a spring on it and the radiator cap will not.