Q: Threw a rod in my 09 H3 3.7 can just the bad rod be replaced from the bottom side and what should it cost to have that done denver

The connecting rods can only be replaced by removing the piston from the engine. Pistons can only be removed from the top, ad that means the cylinder head has to removed from the engine. To access the rods on this engine and replace even one requires 18 hours of labor. The connecting rod itself is not that costly and of course you will need new connecting rod bearings. A problem in estimating this is once the engine is opened, it might be clear that there is additional damage and it is unknown if all other parts will be re-usable. Certainly, the estimate would start at $1,500 and go up from there to perhaps several thousand dollars if other engine components are damaged and, worse, if the cylinders need to be honed or bored or the crankshaft bearing journal was damaged. To have your circumstance estimated and learn of your repair options (repair, replace engine, etc.), please request a service appointment and the responding certified mechanic will get this taken care of for you. If you have any further questions at all, do not hesitate to re-contact YourMechanic as we are always here to help you.