My 03' xlt explorer 4wd automatic has had the accessory belt tensioner, idler pulley and belt replaced about a year ago due to tensioner noise. All replaced with motorcraft parts. With the new stock length belt it still made noise. I took the belt off and started the motor and the noise was gone so I figured it had to be somewhere along the accessory belt path. I inspected everything and found no issues. My fix was to use a shorter belt. Which eliminated the noise and seemed like a good fix. Well the noise is back and I'm wondering what I'm missing? I mean these parts have less than 5000 miles on them and they are showing this problem again. I hear this issue especially when the vehicle is put into reverse. As the rpms drop slightly I hear this rattle. The tach on the dash shows a drop of maybe 50 rpms. If I slip the trans into neutral the rpms go up and the rattle goes away. That tensioner should last a lot longer than that. Belt stretch? Again with only 5k miles that doesn't add up. Is there an underlying issue here? Timing chain guides?
I've read several posts about the timing chain guides breaking and wearing out and thought by this model year Ford had upgraded this area so the issue had been resolved. This being an interference motor I don't want a chain guide breaking and thrashing the motor. This SUV has 170k on it and overall runs very well. It's driven on the street and not very hard at all.
Thanks
Jcris
Should I just replace the tensioner and belt again? Just the belt? Or?
Thanks

 

it seems odd that the NOISE only happens when in gear at idle.. Makes me wonder if the motor is idling 50 RPM too low and it is vibrating and making the noise....... as you speed up a little, the noise goes away , so I don't see how it is the tensioner or belt.... unless you have noises at other times ?

 

Hey Steve,
I see you have an 02' Explorer. As far as I know idle rpm is controlled by the computer and is not adjustable. I'll have to check on that to be sure. The only reason this bothers me is maybe this is timing chain related. Has your explorer shown any similar issues? BTW, my sister has a 2013 F150 eco-boost and it's V6 seems to be a solid rendition of a modern motor. Very reliable.
Thanks for weighing in,
Jcris