97 Chevy s10 replacing timing chain Where is the marks?

The 97 Chevy S10 (assuming the 4.3L V6 engine, as that's the most common engine in that year) doesn't have timing chain marks in the traditional sense like some engines do. Instead, the timing is set using the crankshaft position sensor and the camshaft position sensor signals. These sensors tell the computer the position of the crankshaft and camshaft, and the computer controls ignition and fuel injection accordingly.

Therefore, you cannot rely on visual marks on the chain and sprockets to time the engine. Attempting to do so will likely result in damage.

To replace the timing chain correctly, you MUST:

1. Consult a Repair Manual: A factory service manual or a reputable aftermarket repair manual specific to your year and engine is absolutely essential. These manuals will have detailed procedures, diagrams, and specifications for the timing chain replacement. Relying on online information alone is risky.

2. Use Specialized Tools: You'll likely need special tools, such as a crankshaft holding tool and possibly camshaft alignment tools, to correctly position the components during the replacement. The manual will specify these.

3. Follow the Procedure Precisely: The procedure for replacing the timing chain is intricate and involves several steps. Deviation from the instructions can lead to engine damage.

4. Consider Professional Help: If you are not comfortable with advanced engine repair, consider taking your vehicle to a qualified mechanic. Incorrectly timing the engine can result in catastrophic damage, requiring a much more expensive repair.

In short, there are no simple marks to align. The precise timing is determined by the crankshaft and camshaft sensor positions, and a proper procedure needs to be followed meticulously.