Serpentine belt position

Discussion in 'KJ General Discussion' started by JBDive, Sep 18, 2018.

  1. JBDive

    JBDive Full Access Member

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    Me again. I had the engine replaced in my 02 less than two months ago and I have started getting an oddball rattle from the engine area. It is very hard to make it rattle as it does it mainly when in drive at a slow roll. I was able to get on an incline and with some help with the Jeep in drive isolate the rattle to the Serpentine belt area around the AC compressor. I am pretty certain the rattle is coming from the lower pulley and in the images attached you can see the belt is not centered on that roller and actually hangs off the backside by at least a 1/4 of the belt.

    So first off can anyone confirm on their own Liberty the belt should be centered as seen in the wear marks? I am certain it should be but confirmation will make my case with the mechanic stronger. Second off can anyone confirm why the belt would be that far out of alignment, is it that the roller/pulley is not fully installed or would another pulley on the belt course be pulling it that far out of alignment.

    Thanks
     

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  2. ltd02

    ltd02 Comfortably numb KJ Supporting Member

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    Looks wrong to me and I'm running the 02 tensioner on my 05. I've had an 02 also and never had the belt hang off like that. If you remove the belt are the pulleys all tight? Is that one loose? They have a bolt on them so wondering if it is loose. How old is the tensioner (they do wear out)?
     
  3. Tog

    Tog Full Access Member

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    I had a rattle like that for months only seemed to hear it when the AC was on thought it was the AC clutch till it suddenly got bad turned out to be the tensioner pulley the bearing clapped out and melted the plastic pulley

    Sent from my SM-G960F using Tapatalk
     
  4. JBDive

    JBDive Full Access Member

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    WAs 9pm when I was able to look in there with the sound actually going on so I have not pulled anything off and I'm not going to most likely. Going back to shop for them to check their own work.

    Belt is just a year old, all pulleys, tensioners, etc are original except for water pump and mechanical fan. Anything related to cooling was replaced with the engine. AC compressor was replaced two years ago and sound happens with or without the clutch kicking in.
     
  5. Damotee

    Damotee Full Access Member

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    My bet is the belt tensioner pulley.
     
  6. JBDive

    JBDive Full Access Member

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    So the mechanic already got back with me and said it is surely the tensioner assembly and to just replace it. That's fine however all the aftermarket parts I am finding are plastic vs. the OEM metal. I am really not interested in putting on a plastic pulley so anyone got a source for a real part? Will be calling dealer here in an hour to see what they have and the cost ($$$) even though they give me a discount usually.
     
  7. Joenavy85

    Joenavy85 Full Access Member

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    You were lucky enough to get a rattle? I got a faint squeel for about 2 days before my tensioner died, and by faint i mean you had to have everything off but the engine in order to hear it. The AC fan being on would mask it. I was driving to pick up my niece when it gave up, drove the last mile to her house with a christmas tree on the instrument cluster, heat blasting the whole time, and of course no power steering. Oddly enough there is apparently some amount of natural circulation in the system, as the heat never died off from lack of hot coolant flow to the heater core. Shut it off when I got there and popped the hood for about 15 minutes to let it cool off. Reached in and started spinning pulley's, sure enough, tensioner was seized. Drove it to my father in laws and parked it, drove his truck the rest of the weekend (which included driving around for 3 hours trying to find a shop that had the proper replacement pulley) took 10 minutes to change and put on a new belt and I was back in bsiness.
     
  8. Joenavy85

    Joenavy85 Full Access Member

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    Every place I looked had metal pulley's, except Advanced. My OEM pulley was plastic so that's what I replaced it with.
     
  9. ltd02

    ltd02 Comfortably numb KJ Supporting Member

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    I got my tensioner from Rock Auto. It's a Gates. Actually got it for my 02 before I moved to the 05. I put it on the 05 with the slightly longer belt. The plastic tensioner on my 05 was the 76/76 so should be fine but you will need the shorter belt unless they have a 76/90 plastic version.
     
  10. JBDive

    JBDive Full Access Member

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    Where are you finding metal?

    Also seeing two sizes, 76mm and 90mm. I have no clue which I have with it sitting in a parking garage while at work. Not the easiest thing to just reach in a measure either at just 14mm difference. I assume the difference would require a different built which is what the dealership is saying.
     
  11. JBDive

    JBDive Full Access Member

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    I just posted that apparently there are two sizes. So only one of the two pulleys is larger, 90mm. Without getting all dirty at work trying to measure such a small difference, how sure are we that the 02's used a 90mm?

    I really hate to go from metal to plastic but I'll be darn if I can find anyone with metal and certainly nobody that can get me the part within 24 hours.
     
    Last edited: Sep 19, 2018
  12. JBDive

    JBDive Full Access Member

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    Well went ahead and ran up to the dealership and grabbed one from them. I get a discount there so it was actually cheaper than Autozone and since they are all plastic the Mopar one is probably better than aftermarket. They were able to filter on my VIN to confirm it has the 76/90 pulleys but they did show the belts changed over the past years. No difference in sizing but they did something to make them less prone to slipping. As I changed my belt 1.5 years ago there's no sense in updating again plus I keep a spare under the back seat.

    No time tonight to change it out most likely, will see. Would hate to have the new part in the car and have the old one let the belt go. As it only takes 20 mins or so I might be able to get it done.
     
  13. ltd02

    ltd02 Comfortably numb KJ Supporting Member

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    I'd just use whatever you can get. Don't think the plastic vs metal matters. Make sure you get the correct belt for the pulley system. Just go to the Rock Auto catalog. The 76/76 tensioner takes the 86.3" belt and the 76/90 takes the 87.4" belt. The factory tensioner on all 3.7L 02s was the 76/90. Not sure when they switched but makes no difference as long as you got the right belt. I have my original 76/76 and the shorter belt in the back of mine as a spare.
     
  14. Tog

    Tog Full Access Member

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    I went with the metal pulley the bearing is replaceable and it wont melt

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  15. Tog

    Tog Full Access Member

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    here in Oz the pulley (metal) is also used on Ford Falcons
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  16. Joenavy85

    Joenavy85 Full Access Member

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    Fair enough, I just don't like replacing parts with ones that aren't an exact replacement. It only needs to last until spring when I swap the engine out.
     
  17. JBDive

    JBDive Full Access Member

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    I clearly had 90/90 on my arm. I pulled the 90 off the old part and put it on the Mopar 76/90 so it would be 90/90. I don't understand why the parts catalog shows 76/90 for the 02 and the dealer even confirmed my VIN was showing 76/90. As the belt was replaced last year or so based on the exact same size as the one that came off I can only assume the belt and the 90/90 were matched as they had never been serviced before, all stock.
     
  18. ltd02

    ltd02 Comfortably numb KJ Supporting Member

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    Very interesting!
    Are you sure it was stock? Is there a part number on it? If it isn't OE then someone either must have put the wrong part on or at least changed the one 76mm pulley with the wrong one. What belt was or is on it now with the 90/90? Must be pretty tight if it was the factory 87.4.

    My 02 was an early one (Nov 01 I think) and it had the OE 76mm plastic grooved /90mm metal flat. What's your build date? Driver side door sticker has that info.

    FWIW and IMHO, I still would have gone with the intended size even if plastic. I think you are underestimating the power of that plastic. I think the spring in the tensioner will fatigue before the bearings in those pulleys wear out anyway.
     
  19. Joenavy85

    Joenavy85 Full Access Member

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    Still have the original tensioner on mine, just the new smooth pulley. somewhere i have a picture of the pulley i pulled out.
     
  20. ltd02

    ltd02 Comfortably numb KJ Supporting Member

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    Never had a tensioner or one of its pulleys go bad. I really prefer the OE tensioner since it has the markings on it to check the belt stretch. The one on my 02 (I bought the one I put on my 05 for my 02 years ago as a spare) was the factory original and still working after 179k and 14 years when I got rid of it. I only replaced the one on the 05 since I thought it was getting noisy and I had the spare. Might swap back to the OE one since the belt drive noise was my PS pump which is fixed now. :gr_grin: