| RE:Timing Chain ? |
Subject: RE:Timing Chain ? by 94z07 on 2008/1/29 15:50:04 The timing chain keeps the crankshaft indexed to the camshaft so that the valves open and close in time with the pistons' travel. Timing sets consist of a crankshaft gear, a camshaft gear that's twice as big, and a chain that connects them. Timing sets do wear out and they do fail and when they do they can cause enough damage that a rebuild is needed. The chains are strong but the rollers develop flat spots. The gears' teeth become scalloped and can break. Also, GM made several engines with timing gears that were steel coated with some plastic that was supposed to reduce the noise from the timing set. That plastic stuff can break off and collect in the bottom of the timing cover. On interference engines, engines where the pistons' travel and the valves' travel overlap, a broken timing set can cause contact between the top of the piston and the bottom of the valve. That contact can break things and send metal shards that cause additional damage. I had an Olds that failed when the camshaft gear broke off of the camshaft. I had a Jeep that didn't quite fail but ran rough until I replaced the timing set's plastic coated gears and tensioner. |
