How do you replace the serpentine belt for a 1999 Grand Am?

Answer 1

It depends on if it has a mount in front of it or it doesn't.

yes in front

In order to change the serpentine belt on a 99 grand am, you have to loosen the motor mount that is directly in the way. Once you have loosened the motor mount, you have to raise the engine (with the use of a floor jack) with enough of a gap to remove the old belt and slip the new belt on. Once the new belt is roughly in place (it doesn't have to actually be on the pullies yet)you can lower the engine back into place and secure the motor mount. Now you have to fight the tensioner, which is located on the lower rear of the engine (towards the firewall). Either get a wrench on the tensioner and slip the belt over, which may not work because you may not be able to get the wrench in there, or try getting to it from the bottom of the car. It's a real blast to change one. Wait to you change the headlights!!

New HeadlineAnd enjoy the day as you try to replace the timing gear cover gasket. That's a RIOT...

--trp3141592

Detailed answer

If you have the 3.1 L V-6, it's a job and a half.

Ok, here goes. First, buy, rent, or pay the deposit on the parts store's loaner long-handled serpentine belt tool. It has skinny sockets that you will need to replace the tensioner. Bite the bullet and get the tool. Also--bite another bullet and buy the tensioner when you buy the belt. Get the best quality belt and tensioner you can get: this is NO time or place to go cheap.

If your serpentine belt BROKE, you likely have a greater problem than a worn belt. Before going to the parts store, check to see if the water pump or AC compressor is frozen up. Buy parts accordingly. The forces involved in breaking the belt will also tear the pulley on the tensioner to pieces. Just go ahead and replace the tensioner pre-emptively. That's why you bought it when you bought the belt, so do it now.

Now, grit your teeth and accept the fact that you have to remove all the moter mount stuff. You'll have to support the engine (with a jack on a 2x4 to spread the weight) from underneath. You'll remove the 3 nuts (don't lose the blind bolt under the 3rd nut) on the top of the black stamped steel bracket, the two bolts in the passenger side fender well that hold the bottom of the 2nd stamped steel bracket, the two bolts holding the heavy duty silver bracket, and the three bolts holding the heavy black cast bracket to the underside of the heavy silver bracket.

You will find that getting the 3/8" drive of a ratchet into the slight space offered by GM at the tensioner may be impossible. However, there is a 19mm flat-sided boss on the tensioner facing the front of the car. You can get a 19mm open end wrench, or a Crescent wrench, onto that boss and lift forcefully to turn the tensioner. Turn counterclockwise, as viewed from the passenger side, to loosen the belt. I would still opt to get the serpentine installation tool set from the parts store. (I also went ahead and made a 3/8" tool with more offset than the store-bought one. If you have welding capability, it's worth it to have the home-made tool.)

Since you have removed all the motor mount stuff removed already, this is the time to remove and replace the tensioner. Just do it. A good new one (a Dayco brand tensioner) is about 50 bucks at a parts store. By now you'd pay three times that not to have to do this job again. So just do it. Considering the work you are going through to do all this on your day off, replacing the tensioner as a preventative measure is well worth it. You need skinny hands to get the bolt started, but it can be done without too much grief. Put some Never-Seize on the bolt threads before installation. Note that you have to engage the pin on the tensioner into the hole in the engine timing gear cover before tightening down the bolt. Use the NEW BOLT that will come with the tensioner: it's different than GM's.

You already have removed the black stamped steel brackets that were attached to the fender, right? And you have also removed the heavy silver one that has the three big bolts (15 mm heads, two toward the back and one toward the front) and one empty hole at the front of the silver piece. You have replaced the tensioner because you do not want to go through this again next Spring. To install the new belt, you must LOOSEN the three bolts on the heavy and thick black cast and forged bracket that is attached to the engine. They are low and toward the front. This heavy forged thick bracket was attached to the thick silver piece with the three heavy bolts, and it is the black piece that prevents you from simply installing the belt around the Power Steering pump pulley. (BTW, removng the power steering pump won't help you--you have to get the belt around the black bracket.) By LOOSENING the three bolts in the heavy black bracket, you can just barely cause a gap at the rearmost heavy bolt location between the stamped steel engine mount boss and the heavy black bracket that will just barely allow you to slip in the belt. You may need to do a little gentle levering, but don't break anything. Note that I said LOOSEN--if you remove the three bolts you'll have coolant all over the place. Even so, you may have to remove the upper one completely to get enough of a gap at the rear for the belt to go through.

Once the belt is "through the loop" of the heavy black bracket, be sure you also get it around (over) the power steering pully, under the water pump pulley, and headed down toward the AC pulley. Tighten the three bolts that you just loosened, and thread the belt on to the pulleys. It goes (ribbed side) back around the alternator, down and around the crank pulley (ribbed side), up and around the tensioner (smooth side), down and around the AC pulley (ribbed side), up and around the water pump pulley (smooth side), over the power steering pump pulley (ribbed side) and rearward to the alternator (ribbed side.) Whew! You'll quickly find that it won't voluntarilty go over the alternator pulley unless you relieve the tensioner. Use the tool you rented or bought or made to relieve the tensioner (see above), slip the belt over the alternator pulley (ribbed side), and then ease up on your death grip on the tensioner tool to allow the belt to tighten itself.

CHECK ALL THE PULLEYS to be SURE the ribbed surface is centered on each ribbed pulley!! Misalignment will break the belt in a hurry, and then you can do this delightful task all over again.

Ok, that was all easy. You started at 10:00 thismorning and now it's 8:30 tonight. Now it's time to reassemble this beast. Whether today or tomorrow is up to you.

If you decided not to replace the tensioner yesterday, this is a good time to reconsider the wisdom of that decision. Thankfully, Auto Zone and Advance are open on Sundays...

You will find that dealing with the motor mount pieces is a challenge, especially in re-assembly. The one and only nice thing GM did for you is to have provided that 4th hole (the empty one) in the silver bracket--it allows you to pry and wiggle the motor mount pieces into alignment. Be prepared to adjust the engine up, down, front, and back a lot. With patience and some jockeying around, it all bolts together in reverse of disassembly.

Check for tools and anything you may have forgotten to tighten. The only left over part should be the original GM tensioner attachment bolt and the old tensioner, both of which you replaced with the new tensioner. Check coolant level. and Voila !! You're done.

Until it breaks again.

--Tom

New HeadlineI little harder than #1 above but not as difficult as #2 made it sound either.

I just completed this today (Feb 22, 2009), it took about two hours at a slow pace with my son helping. It's my daughters 99 grand am. Also I'm not a mechanic, I'm slow, I just did it to help my daughter. Her serpentine belt is not broken, it's old and worn with lots of cracks and it needed replacement before it broke. All I was doing was a simple belt replacement. I hoped. As it turned out it was.

In order to change the serpentine belt in a garage we first supported the engine using a small wood block and a floor jack. The board was 1x because a 2x4 was too thick for my jack. After the engine is supported it was back to the belt.

To make this job easier we needed some room to wrench. So we removed the Coolant fill/over flow tank by removing the single bolt holding down. With the tank loose we simply lifted it or swung it out of the way as needed through out the project. We then removed two bolts holding another bracket in the way. Not sure what that component was, it's about 4x4x4 black electrical looking widget on a black metal bracket attached to the wheel well by two hex head screws. Now with every thing open we could see better and had much better access.

Next we removed two bolts and two nuts and removed the engine mount plate. Then it was time to release the tensioner. I don't know what Tom above was doing but my 3/8" drive rachet fit right into that perfect 3/8" square hole that GM put there. This does suck because it's located on the lower rear of the engine (towards the firewall). My 3/8" rachet is short of course so I used about a 14 mm deepwell socket with an 8" long 3/8" extension to extend the length of the handle. This gave me the leverage needed opperate the tensioner. The ratchet once it moved forward as the tension released would not come out of the hole from reduced clearance with the wheel well. So it just sat there and we wiggled the new belt around it. I will say this, I had two 3/8" rachets but only one of them would fit, the other was too fat. So it's possible you would have to get another tool. By the way you need a good set of metric sockets.

Now jack the engine up enough of a gap to remove the old belt and slip the new belt on. With the new belt roughly wound around the lower pulley's we started bolting back up the engine mount bracket. We simply pushed on the engine and leaned on the front end of the car to lower/raise the suspension just using our weight and pushing it around a bit. It bolted back up and went back on fairly smooth to this point. Use caution with those bolts and that alluminum block, one of our was stubborn.

With the motor mount now secured again. We released the jack and it settled back. From there we finished routing the upper half of the belt to the point where it was ready for the tensioner again. Once the belt was back on I checked that the belt looked snug and straight on all pulley's, it was. Then we remounted the black bracket thing and the coolant tank and, picked up the tools and started the engine. Ran great, end of job! Job well done.

Doug