What size of bolt goes in the idler pulley on a Chev Astro Van?

There's no single answer to what size bolt goes in the idler pulley on a Chevy Astro van. The size depends on the year of the van and which idler pulley you're referring to (as there may be more than one). The bolt size can vary from a small 10mm to a larger 14mm or even a slightly different metric size.

To determine the correct bolt size, you must either:

* Consult your vehicle's repair manual: This is the most reliable method. The manual will specify the correct bolt size for each pulley.

* Remove the bolt and take it to a hardware store: This allows for a direct comparison.

* Check a reputable online parts store: Using your Astro's year, make, and model (and possibly the engine size) on a site like AutoZone, Advance Auto Parts, or RockAuto will let you view diagrams and potentially find the correct bolt size within the idler pulley assembly listing.

Attempting to guess the bolt size could lead to using the wrong size, potentially damaging the pulley or threads. Always use the correct size and torque specification.