Degraded performance and fuel economy

[Xourque]

Hello Everyone!

 

I hope that you guys can give me some advice. I have a 2003 Nissan Pathfinder 2003 LE with 52,000 miles on it. Here are some more specs on it:

 

- Original ignition components (haven't had to change anything, due to the maintenence schedule - it isn't time yet)

- K&N Drop in filter (8,000 miles old, cleaned once, properly oiled)

- Mobile1 fully synthetic 5w30, changed every 8,000 miles

- All gear box and transfer case fluids changed at Nissan dealership about 5 months ago*

- Front wheel bearings repacked about 4 months ago when I had the front brake rotors re-surfaced

- Yokahama HT-S tires (nice highway tires)

 

The problem is this - I have been noticing a gradual decline in engine performance and fuel economy. I have been noticing it in hot and cold weather, and the gas hasn't changed locally here. It also doesn't matter what gas station or grade (I only use mid-grade or higher).

 

One thing that I notice the most, is that while coasting down hill, the car will slow down instead of speeding up like it used to. I am thinking it could be the front wheel bearings? Maybe the brakes? Propeller shaft (driveline)?

 

What do you think? What should I do? Are there any maintenance-related things I should do to it, even though its not due?

[94extreme]

check your brakes as they could be locking up on you.. otherwise it's hard to tell as the symptoms aren't that pronounced.

[Xourque]

check your brakes as they could be locking up on you.. otherwise it's hard to tell as the symptoms aren't that pronounced.

 

Yeah, exactly. I try to be as perceptive to ANYTHING but it's really hard to tell if there is anything wrong. The only things I notice are:

 

- I hear a "wobbling" sound, kinda like a woo-woo-woo-woo-woo-woo sometimes when coasting. I am thinking it's the wheel bearings? CV axles?

- It sometimes seems as though the alternator is streining under the load of the headlights (OEM) and heater fan.

 

Anyone else?

[adamzan]

Wheel bearings, our truck is doing it too.

 

thats what im betting on

[zonianbrat]

I'm guessing the woo-woo sound is tire balancing. Was there a reason why you had your brakes resurfaced when you truck now only has 52,000 miles on it? Were they grooved or warped? Did you replace the brakes too? Did you see how your bearings looked?

[Xourque]

I'm guessing the woo-woo sound is tire balancing. Was there a reason why you had your brakes resurfaced when you truck now only has 52,000 miles on it? Were they grooved or warped? Did you replace the brakes too? Did you see how your bearings looked?

 

The tires are about 8,000 miles old and I rotated them yesterday and it didn't seem to change anything.

 

I had the rotors resurfaced because there was brake pedal jutter (it would vibrate when braking). My mechanic said that they were warped and had to be resurfaced, but not replaced since apparently they had a lot of life left in them. I had my mechanic do it and didn't see the bearings when it was there. They repacked them while they had it and it seemed to be ok afterwards. Actually now, the same jutter in the brake pedal is back - BUT NOT AS BAD.

 

I am going to make an appointment with them to diaglose the woo-woo-woo noise. Since I am friends with them, they will diagnose it for free! I will let all of you know what they say. Hopefully I can get in sometime next week!

 

THANKS TO ALL!!