About Us

US Engine Production has been a trusted provider of new and remanufactured high quality engines at competitive prices for over 35 years. USEP produces over 5500 diesel and gas engines each year in our 180,000 sq. ft. production facility in Vassar, MI. We offer a flexible core return policy that allows up to 30 days to return your core, and we pay the return freight. Many units require no up-front fee and have an average lead time of 3 – 5 business days.

We also offer transmissions, parts and accessories such as fuel injectors, fuel pumps, water pumps and turbochargers. We believe that lasting business relationships are based on mutual trust and respect, and that customer service is of the utmost importance. Our workplace core values demand that our employees conduct themselves with integrity, accountability, diligence and discipline. Given the opportunity, you will find us to be a trustworthy partner.

Our Manufacturing Process

Engine Blocks

US Engine Production only uses blocks that pass our strict quality inspection process. Every cylinder is bored to within .004 of the finished size. Next, we use a diamond hone to ensure bore geometry is held within 200 millionths of an inch. Every block is then subjected to a surface finish test to measure the roughness and plateau finish of the cylinder wall. (With todays lightweight motor oils and low-tension oil rings, this is critical for achieving the proper ring seal.) Blocks are checked and align honed through the main bearing bores to align and size to the proper factory specifications. This is critical to maintain uniform oil clearances and good oil pressure. After all machine work is done to the block, it is cleaned until it is completely grit free. We scrub each cylinder with soap and water and clean all oil galleys with a high-pressure wash.

Engine Heads

Valve seats are cut on the latest state of the art equipment, forming all three angles at once. This ensures the correct seat width and connectivity for good valve seal and heat transfer. Once the head is machined, it is ready to be assembled to factory tolerance by using high temperature valve stem seals, valve springs, and hardened valve locks. Each valve/spring combination is individually tested to provide the correct spring pressure and vacuum tested to ensure a tight valve seal.


Crankshafts are re-ground to factory tolerance. The crankshaft is then micro-polished to exceed the original finish, ensuring proper bearing lubrication. A final wash is done to ensure that every crank is clean.
  • Bake cleaned and then shot blasted
  • Checked for bend
  • Ground to size
  • Oil holes chamfered
  • Journals polished


  • Each and every rod installed in our engines goes through a rigorous restoration process.
  • Rods Are Chemically cleaned
  • 100% re-manufactured - bores are machined to original tolerances for size and surface finish
  • Checked for bend and twist - any rod that doesn’t meet our exacting tolerance is discarded
  • All bushings are 100% replaced


  • Cam lobes are re-ground to the same specifications as the original cam
  • Cams are Parkerized
  • All camshafts are replaced with new or remanufactured camshafts

Engine Assembly

US Engine Production assembles each engine in a clean and controlled environment under the supervision of our highly trained Quality Control department. Constant supervision, testing, and cross-department auditing ensures every Engine gets the same attention to careful assembly and results in consistent superior quality.

Testing and Final Inspection

Following assembly of the engine it is put through a vigorous load-bearing run on the DYNO TEST Machine for over one hour to test its excellence, after which it heads over to our lead technician for a final inspection and approval for release to the customer

In addition, to guarantee the satisfaction of our clients we provide a one year Unlimited Mileage unlimited mileage-parts onlywarranty on all of our engines

Prop 65 Warning
The State of California requires that this warning to be posted for California residents purchasing products.
WARNING: Products may contain one or more chemicals known to the State of California to cause cancer and/or birth defects or other reproductive harm. For more information, visit www.P65Warnings.ca.gov.