2000 Century, Belt Loose, New Tensioner/Belt

[trag]

The 2000 Century has a 3.1L V6.

I'm in Texas; the car is in Kansas with my Son.

I thought we had a simple case of bad belt or tensioner. The engine runs but the belt is loose and doesn't spin the accessories.

My Son, Eli, replaced the belt, but result was the same and he reports it seems exact same length as old belt. Also, the "old" belt was less than 5 years old.

Today he replaced the tensioner and same result. We ordered the "Genuine Parts" tensioner from Amazon, because the local store didn't have one in stock.

https://www.amazon.com/GM-Genuine-Parts-12563084-Tensioner/dp/B0049Z34ZK

The belt is routed properly, but I will attach photos to get another eye on this.

Eli says he's tried firmly to move each pulley to make sure they're not sliding. Also, all pulleys turn freely except crankshaft, which makes sense.

What else could be causing a loose belt? Defective new tensioner? Should I have gotten the cheap $25 one, or the Dorman? I've been pretty happy with Dorman stuff in the past.

The first photo shows the belt routing diagram. Still there after all these years.

Thank you for any helpful or humorous comments.

 

[chem_man]

For whatever reason, the pictures are not expanding when they are clicked on so it is hard to see the belt routing.

Unfortunately, purchasing OEM parts of any brand is a gamble on Amazon due to the rampant counterfeiting of name brand auto parts that is occurring on both Amazon and ebay. I would say the odds of your son receiving "an honest to God" real GM OEM belt tensioner is about 50:50. If you had ordered spark plugs, it would be almost 90% that they are counterfeit. Even if they are ordered from the "GM Store" or the "ACDelco Store" on Amazon. You would have been much better off purchasing a tensioner from rockauto.com or a local parts store.

Replacing a belt tensioner on a 3.1L V-6 engine in the Century is not a difficult task, and neither is routing the belt. I have replaced the belt and belt tensioner on our 1999 Century a couple of times over the years using Gates belts and tensioners (I purchased a Gates belt and tensioner kit part number 90K38353 and saved a few bucks). The belt was nice and tight after installation.

The only thing I can think of besides a defective belt tensioner is that either one of the pulleys is missing or one was missed when installing the new belt.

Good Luck!

 

[DrivenDaily]

I also can recommend Rock Auto.

 

[02LTD2.0]

I agree with DrivenDaily regarding RockAuto although I myself have had good luck ordering from Amazon. I tend to use RockAuto as a reference but order from either RA or Amazon depending upon which source will have the lowest overall cost including shipping. I guess that I've been lucky to not have received any counterfeits from Amazon.

Regarding the OP's dilemma perhaps the easiest way out of their current situation would be to double check the routing and if it proves correct then go ahead and get a smaller diameter belt. Look into the part details on Rock Auto and you should find the specs. A good counter man at a local parts store should be able to cross reference the belt to a smaller size. Hold on to your parts receipt and if it doesn't fit properly take it back and try the next smaller size until you get the correct tension.

 

[trag]

Thank you for the suggestions. Had already ordered the Dorman tensioner and will give that a try. Might try the Gates if no other ideas present. Or just go to a smaller belt.

I'm also going to "discord" with Eli to try and see if maybe the rear bolt for the alternator has come loose. That might have allowed the alternator to pivot up and forward, reducing tension/belt length? Grasping at straws.

Eli has said since the start of this that he thought he heard a clang. Could have been a nut or bolt working it's way out of the alternator and getting thrown by the belt before dropping out.

Just to be complete -- there's really nothing but the belt length (and routing) and tensioner that can affect belt tension? That's how it looks to me, and yet...

Will report back in any case.

The photos expand okay for me. I'm using Win 10 with Firefox. I can throw them up on my web space if you really want to download them. Ah, just noticed, I can't use the scroll wheel. Clicking after opening zooms in, but it's not adjustable.

It's been several years... @chem_man or other, do you know how the rear of the alternator is bolted? Is it a horizontal or vertical bolt? I think the alternator is still original equipment. The only time I removed it was to get the intake manifolds off, or was that to reseal the rear valve cover? Again, six years ago or more.

I ordered on Amazon rather than Rockauto or 1AAuto because we were hoping for Eli to drive the car home to Texas this weekend. Speed of delivery was key. He bought a new car, so after serving him through HS and all of undergraduate, the Century will go back to sitting next to the Lucerne in my driveway -- if we can get it back to Texas...

 

[chem_man]

Thank you for the suggestions. Had already ordered the Dorman tensioner and will give that a try. Might try the Gates if no other ideas present. Or just go to a smaller belt.

I'm also going to "discord" with Eli to try and see if maybe the rear bolt for the alternator has come loose. That might have allowed the alternator to pivot up and forward, reducing tension/belt length? Grasping at straws.

Eli has said since the start of this that he thought he heard a clang. Could have been a nut or bolt working it's way out of the alternator and getting thrown by the belt before dropping out.

Just to be complete -- there's really nothing but the belt length (and routing) and tensioner that can affect belt tension? That's how it looks to me, and yet...

Will report back in any case.

The photos expand okay for me. I'm using Win 10 with Firefox. I can throw them up on my web space if you really want to download them. Ah, just noticed, I can't use the scroll wheel. Clicking after opening zooms in, but it's not adjustable.

It's been several years... @chem_man or other, do you know how the rear of the alternator is bolted? Is it a horizontal or vertical bolt? I think the alternator is still original equipment. The only time I removed it was to get the intake manifolds off, or was that to reseal the rear valve cover? Again, six years ago or more.

I ordered on Amazon rather than Rockauto or 1AAuto because we were hoping for Eli to drive the car home to Texas this weekend. Speed of delivery was key. He bought a new car, so after serving him through HS and all of undergraduate, the Century will go back to sitting next to the Lucerne in my driveway -- if we can get it back to Texas...

There are 2 mounting bolts on the firewall side of the alternator that need to come out in addition to the one on the front side of the alternator in order to remove the alternator from the engine. There is also a clip that the front alternator mounting bolt screws into, but I do not remember if that needs to be removed.

 

[chem_man]

I'm unable to insert a diagram of the alternator's mounting. You can see it by going to:

McDowell County Public Library - Chilton Auto Repair

mcdowellpubliclibrary.org

and going to the repair instructions for generator replacement in the 2000 Buick Century.

 

[02LTD2.0]

The 2000 Century has a 3.1L V6.

I'm in Texas; the car is in Kansas with my Son.

I thought we had a simple case of bad belt or tensioner. The engine runs but the belt is loose and doesn't spin the accessories.

My Son, Eli, replaced the belt, but result was the same and he reports it seems exact same length as old belt. Also, the "old" belt was less than 5 years old.

Today he replaced the tensioner and same result. We ordered the "Genuine Parts" tensioner from Amazon, because the local store didn't have one in stock.

https://www.amazon.com/GM-Genuine-Parts-12563084-Tensioner/dp/B0049Z34ZK

The belt is routed properly, but I will attach photos to get another eye on this.

Eli says he's tried firmly to move each pulley to make sure they're not sliding. Also, all pulleys turn freely except crankshaft, which makes sense.

What else could be causing a loose belt? Defective new tensioner? Should I have gotten the cheap $25 one, or the Dorman? I've been pretty happy with Dorman stuff in the past.

The first photo shows the belt routing diagram. Still there after all these years.

Thank you for any helpful or humorous comments.

Unfortunately you are not there on site to help your son. This is pretty basic stuff and shouldn't be complicated for someone with mechanical aptitude which with some people just simply don't have. Either you need to take a road trip to help on site or your son has to swallow his pride and enlist the help of someone who is capable of going over what has been done and figure out a solution. Until either of those two things happen all of this guessing over the forum is just a waste of time. Keep it simple and get a second ON-Site opinion from a seasoned mechanic. Tough love baby, tough love.

 

[02LTD2.0]

By the way the pics can be enlarged but are totally worthless as an example of if the belt is routed properly.

 

[02LTD2.0]

If the belt was only 5 years old then why did your son attempt to replace it? What was the original issue?

 

[trag]

I don't know if anyone is still watching, but the mystery is finally resolved. My Son had time to take it to a fairly good shop in Lawrence, KS this week.

The Harmonic Dampener had apparently fallen apart and I guess on the Century it is the outer layer of the crank pulley. So now the pulley was smaller. The last Harmonic Dampener I remember working on is on a '78 Cutlas, and IIRC, it kind of bolted to the front of the pulley, but that's a really old memory.

Anyway, that's the issue. So, if other folks have mysteriously too short belts on cars old enough for rubber to have rotted, might check the status and position of the harmonic dampener.

 

[trag]

If the belt was only 5 years old then why did your son attempt to replace it? What was the original issue?

Son heard a clunk or clank and suddenly had very difficult steering. Was close to home, parked it, checked under hood and none of the accessories were turning because the belt was suddenly too loose.

We tried replacing the belt on the theory that maybe it stretched. It seemed farfetched, because it doesn't explain the clunk sound, but it was a cheap test. Replacing the tensioner made sense because the spring breaking could have made a sound, but that did no good either.

I guess we'll ahve spares now.

 

[chem_man]

Thanks for letting us know about the harmonic balancer! That's a part one seldom thinks about.