Rattling when AC kicks on

[khoney]

Hey everyone,

I'm getting a loud rattling sound (can be clearly heard through the right front wheel whenever the AC kicks on. Inside the engine bay, it sounds like it's coming from near the firewall down low, where the serpentine belt is. I've read about the belt tensioner going on this car, but I got the impression that the noise from that is constant. This noise only happens when the AC/fan kicks on.

Any idea about where to look?

 

[spdjnke]

most likely you are hearing the A/C clutch which cycles the unit on and off to give you the cooling.

 

[khoney]

It appears to be the drive belt auto-tensioner. I can see the bolt holding that sucker on moving all over the place when the AC kicks on. Funny thing, it was fine when I first started the car and even after letting it idle with the AC running for about 10 minutes. It didn't start making the noise until I took it for a drive and then parked again. Must be temperature-related.

 

[spdjnke]

I would say if that's the case, try and get that bugger off and put some loctite and put it back and see what happens.

 

[dmention7]

I don't think it's an issue of the tensioner bolt not being torqued down... most likely the tensioner is on its way out. Usually there's a spring (internally or externally) that holds tension on the belt, and the tensioner has a bit of resistance to moving with/against the spring. If it loses that resistance, it'll flop all over the place like you are describing. If the bearings in the tensioner start to go, that would be more of a constant noise, versus the tensioner losing its ability to maintain a smooth constant tension.

 

[khoney]

I took the tensioner pulley off, and the bearings in it are shot. The idler pulley bearings are shot as well, but I'm having trouble getting the bolt off. The torque spec is only 22ft-lb, but I can't get it off even with a cheater bar. I guess I'll let the engine cool for a few hours and try again. The tensioner spring seems to be OK, it moves smoothly when I pull it down. Maybe the bolt moving was an optical illusion - it was probably the pulley moving around, which made it the bolt look like it was moving.

 

[khoney]

All right, I'm about to take a sledgehammer to this POS! How the F*** did you guys get that serpentine belt back on? I've been working at it for two hours, and just about busted to damn tensioner pulley trying to pry the belt back on with a screwdriver. I got the pulley pushed up as far as I can get it (I'm not Hercules, so I had to use a pry bar even for that). Should the belt just slip back on? Should the belt just slip on over the tensioner pulley? MINE DOES NOT!!! WHAT'S THE SECRET???!!! I'm at wit's end - please help!

 

[creedns]

uh oh, ur gonna blow

 

[khoney]

Hull pressure depth will be reached in 10 feet... hydraulics restored!

Damn - finally got it! Just hope there weren't any neighbor kids playing outside I'da probably made my son and his Marine buddies blush.


I took off the bottom splash shield and managed to get the belt over the bottom front pulley. I'm not even gonna turn her over tonight - we'll see what the morning commute brings...

 

[dmention7]

Hmm, I suppose since there's a tensioner, there aren't any adjustments on the alternator/PS pump/AC compressor are there?

Often the easiest way to get belts on is to get the belt around everything working counterclockwise from the crank. Then when you get to the last pulley before reaching the crank again, have a buddy turn the crank clockwise with a ratchet while you guide the belt onto the last pulley. Or at least some permutation of that, depending on the setup of the pulleys.

 

[88323GT]

Nope. The tensioner is the only adjustment on the motor, and its either on or off. A 14mm Wrench would hold it back, and then to make things easy, use a zip tie and wrap part of the belt around the PS pully and run the zip tie through one of the openeings to hold the belt in place, and fish the rest of the belt on. When you come to the Tensioner, release the tensioner pressure using the 14mm till it is all the way released, slide the belt in, and release the 14mm.

 

[khoney]

Thanks for the advice, albeit post-completion

My biggest problem was probably not having a long enough 14mm - I actually pulled so hard on that thing I must have tweaked some nerves in my hand - three of my fingers went numb. My fingertips are still numb today. The good news is, it fixed the rattling problem.