I got this from Tundra forum
01-08-2011, 12:48 AM
Say if I were to work on my 2000 V8 Tundra and the timing belt is OFF and the cam marks are mixed up and the crankshaft mark is unknown and not lined up. Could I possibly just align the crankshaft at '0' top dead center (compression or exhaust stroke unknown) and just adjust the cam timing marks so that they now align with the marks, would everything workout okay? Or would I still have to know if the crank was on a compression or exhaust stroke?
Will rotating the crank around a few times or the cams a few times without the belt on damage each other?
01-11-2011, 11:44 AM
The white mark on the crank dampener indicates "top dead center" for the number 1 cylinder only. The camshafts position, relative to crankshaft position, determines whether or not the pistons are on their intake, compression, power, or exhaust strokes.Since each piston reaches it's own TDC once per crankshaft revolution, 1 piston out of 8 is at TDC for every 45 degrees of crankshaft rotation. If you need to realign the camshafts to the crank..... be aware that the toyota V8 is an interference engine. Valve damage will occur if you rotate the crank without using caution. The following is the safest way to realign the timing belt without risking major damage to the engine.
1. remove the spark plugs, this step will allow you to turn the engine by hand and let you feel for any piston to valve contact.
2. Gently turn the crank to 22.5 degrees BTDC ( before top dead center ) or ATDC (after top dead center). This position will assure that none of the 8 pistons is at TDC, which reduces the chances of piston to valve contact.
3.Realign the camshaft pullies to the respective timing marks.
4. Rotate the crankshaft back to TDC.
5. Install the timing belt on the engine.
6. Rotate the engine by hand a few times and double check the belt alignment.
7. Reinstall the spark plugs.
Provided that you put everything else back together correctly during the reinstall phase, your engine should run fine.