You are so lucky to have this older, tough engine. The newer Neon and Stratus use an "interference engine" meaning a timing belt problem will cause serious damage from open valves hitting the coasting pistons as you coast to a stop. Actually, the engine computer should shut the engine down before it gets that bad, but in your case, it's a normal "freewheeling" engine and no damage was caused by the broken timing belt.
The plastic side cover must be removed if it isn't already. You'll also need to remove the harmonic balancer / pulley from the bottom of the engine. That will require a special puller. Do not use a jaw-type puller to grab around the outside of the unit. It has an outer metal ring held onto the metal center hub, with rubber sandwiched in between. Pulling on the outer ring will tear it off. The only fix for that is replacement.
Halfway up the engine is a tensioner pulley. Loosen the center bolt and the pulley will relax the belt. It turns on a cam, or offset mounting peg. You'll notice there is a large hex nut cast into that assembly. When that hex nut turns, the pulley moves away from the belt. When you install the new belt, it must be tensioned properly for long life. It's real complicated if you have the right tool, (not). The special tool is a wrench that fits on that cast-in hex nut and has a weight on the end. You simply install that wrench and let gravity do the work. As it turns that hex nut, the pulley will turn on the cam and get pulled tighter against the belt. It took me entire minutes to type all that. It takes a couple of seconds to plop the tool on and let it do its thing. While that tool is holding tension on the belt, tighten the center bolt. Now you can remove the tool and the pulley will maintain belt tension. That tool is available at any auto parts store and from the guys who drive the tool trucks around and visit the local repair shops every week. Snap on, Mac, Matco, and Cornwell are the best know ones. Just tell them what you're trying to do and they'll know exactly which tool you need. Some parts stores rent or borrow these kinds of tools too, especially if you buy the parts from them.
It should go without saying that the top and bottom sprockets must be in the correct relationship before installing the new belt. A service manual is the best place to find a picture of the timing marks. As I mentioned in the beginning, if the belt is installed incorrectly on THIS engine, nothing will be damaged; it just won't run. There is also an intermediate shaft that runs the distributor. It's toward the front of the engine and must also be timed correctly. If it's off by a tooth or two, you can just turn the distributor to make up for it on most engines, but that shaft on the 2.5L is also a "balance shaft" that dampens out normal 4 cylinder engine vibration. For that reason, it too must be timed perfectly or you'll have an annoying vibration. The clue here is sprockets with teeth have them to insure they stay in proper relationship to each other. Smooth pulleys that ride on the back of the belt don't have any special timing relationship to worry about. They just gotta turn.
Saturday, December 12th, 2009 AT 3:43 AM