Rebuilding an air compressor pump takes a lot of time, a lot of tools, and a lot of parts. To properly break down an air compressor pump and diagnose the problem may take anywhere from 1 to 2 hours of time. A myriad of issues may come to your attention like: the bearings are busted; or the crankshaft front housing seal is leaking; or the piston rods have dug into the crankshaft and won't move freely.

The cost to rebuild a pump varies from one machine to another. It typically takes anywhere from 1 to 2 hours to completely break down the machine and determine what the issues are. To do it right, you should remove and replace your bearings; replace all the seals; replace all the gaskets; replace all the rings on both the high and low pressure pistons; replace the valves along with the valve gaskets; hone the cylinders and change out the oil. This process with removing and pressing in the bearings and cleaning up the machine; reattaching all the lines and testing the machine on a test stand can and will take anywhere from 5-8 hours depending on the size and complexity of your pump. The average cost to completely rebuild a 5-10 HP pump is anywhere from $500 - $1,500 dollars and will take between 2-5 business days to rebuild. If done correctly, it should last you for decades to come.