engine component supplier
Performance. Precision. Peace of Mind.
Founded in 2000 in Willits, California, Smooth Engines began as a small, family-owned automotive workshop with a simple yet ambitious goal: to become a reliable source of precision-tested automotive components for everyday drivers, mechanics, and businesses alike.
From day one, we’ve been guided by integrity, technical expertise, and a belief that trust is earned—not claimed. Today, after over two decades of hands-on experience, Smooth Engines stands as one of the country’s most dependable names in pre-tested powertrain solutions and engine component distribution.
Why We’re Different
- Experience that Matters – With over 23 years of industry presence, our insights go far beyond inventory management. We’ve helped thousands of customers find the right-fit replacement systems, understand part compatibility, and minimize repair downtime.
We understand what matters most: dependability, fast fulfillment, and a support team that’s invested in your outcome—not just your order.
- State-of-the-Art Testing Infrastructure – Smooth Engines uses both manual and computerized diagnostic systems. Every part is tested using compression verification, fluid inspection, and visual defect elimination before packaging. All packaging is custom-secured, and shipping includes full tracking for peace of mind.
- Dedicated Customer Support – Unlike drop-shippers or call-center companies, our team knows the parts. Whether you’re a seasoned mechanic or replacing a drivetrain for the first time, you’ll talk to someone who understands the language of performance. We don’t just sell—we consult, assist, and stand behind what we deliver.
- True Warranty Protection – Each of our major components ships with a 6-month, unlimited mileage protection plan, ensuring that customers never feel abandoned after the sale. This isn’t boilerplate. It’s backed by real support and a fair resolution process.
Our stats over the years
We take pride in the scale we've achieved—but more importantly, in the satisfaction behind every transaction.
+1091672
satisfied clients served
+2230864
certified engine and gearbox units delivered
+24
years of experience
+450
clients served monthly
Each figure reflects a genuine relationship, a successful repair, or a solved mechanical challenge.
Our Evolution: From Service Garage to National Distribution Center
What started in a modest space at 21021 Locust St, Willits, CA 95490 has grown into a streamlined parts operation serving customers across the U.S. In our earliest days, we managed everything manually—handwritten service orders, ledger-based accounting, and hours of diagnostics done without digital tools.
The turning point came with founder John’s deep mechanical knowledge and relentless work ethic. Through word-of-mouth and proven reliability, demand quickly expanded beyond local borders. Over the years, our facility grew into a multi-bay operation with five large service bays, advanced diagnostic infrastructure, and an entire logistics arm dedicated to dispatching certified power units nationwide.
What We Deliver
At Smooth Engines, we go far beyond simply stocking parts—we provide carefully sourced, precision-tested powertrain systems that restore reliability, performance, and peace of mind to your vehicle. Our product catalog is curated with a singular focus: functionality, compatibility, and longevity.
We specialize in four major categories of automotive and marine components:
Pre-Owned Engine Blocks Verified for Quality and Mileage
Our replacement engine blocks undergo a multi-point inspection process to verify:
- Actual mileage (via VIN trace or vehicle history)
- Compression levels across all cylinders
- Structural integrity (crack, warp, and gasket leak detection)
- Cleanliness and residue buildup
- Mount compatibility for your vehicle make/model
Rather than offering unverified salvage parts, we focus on units with clear usage history and strong core health. Every engine block is cleaned, pressure-tested, and tagged with compatibility data. Whether you’re working on a Japanese import, a domestic pickup, or a late-model SUV, we aim to deliver a like-for-like drop-in solution that minimizes downtime and prevents fitment headaches.
Our stock includes a diverse array of engine types, from compact four-cylinders to V6 and V8 configurations, ensuring flexibility for both daily driver repairs and fleet-level replacements.
Inspected Transmission Systems Ready for Installation
Transmission issues are often misdiagnosed or underestimated. That’s why we take a meticulous approach when preparing our pre-owned gearbox systems.
Each transmission unit is:
- Disassembled and visually inspected for wear patterns
- Checked for clean fluid condition (no metal shavings, burnt residue, or sludge)
- Tested for shifting smoothness and gear engagement
- Matched for torque converter compatibility (where applicable)
- Bench-tested under simulated load conditions
We also take care to verify sensor module health, wiring harness compatibility, and control unit readiness, especially in modern electronic transmission systems. Every gearbox system is shipped fully drained, re-sealed, and packaged for safety, allowing for straightforward installation by your mechanic or shop.
Whether it's an automatic, CVT, dual-clutch, or manual transmission, we ensure the unit is mechanically reliable and plug-and-play ready.
OEM-Compatible Parts Sourced for Long-Term Use
Not every vehicle needs a full engine or gearbox replacement. Often, smaller OEM-compatible components are what stand between a warning light and a breakdown.
That’s why Smooth Engines also supplies a rotating inventory of:
- Intake manifolds and throttle bodies
- Engine wiring harnesses and control modules
- Crankshaft and camshaft assemblies
- Valve covers, oil pans, timing covers
- Engine mounts, brackets, and more
We prioritize original manufacturer components (OEM), not aftermarket replicas, to ensure perfect fit and performance integrity. These are parts sourced from low-mileage vehicles, verified for quality, and packaged with clear labeling and compatibility notes.
Our clients include body shops and rebuilders seeking trusted replacements without the inflated cost of new dealership parts.
Marine Propulsion Systems, Including Select Outboard Units
Beyond automotive parts, Smooth Engines also stocks marine-grade engine systems, including Yamaha outboards and select other makes.
These outboard motors are inspected for:
- Compression balance and piston integrity
- Corrosion or saltwater damage (especially for coastal-use units)
- Prop shaft wear, water pump functionality, and gear housing condition
- Electrical systems (starter, stator, CDI module health)
- Cosmetic condition and mounting integrity
We serve individual boat owners, marine service centers, and import/export operations, offering trusted units for fishing vessels, watercraft rentals, and recreational boats.
All marine components go through a stricter corrosion check process and are shipped with detailed performance test results to give you full confidence in what you’re receiving.
Quality is Non-Negotiable
At Smooth Engines, our in-house technician team is the first and last line of quality control. Every unit that passes through our doors is:
- Inspected for obvious flaws and wear
- Tested under standardized protocols
- Matched for vehicle-specific compatibility
- Packaged using heavy-duty materials to prevent in-transit damage
- Documented with clear labels and SKU-linked tracking
Our goal is to eliminate any guesswork for the installer—whether you're a master mechanic or a DIY restorer. We treat every component as if we were putting it in our own vehicle, because your trust is our most valuable currency.
What We Deliver
Smooth Engines provides tailored solutions for a wide audience:
- Auto repair facilities needing ready-to-install power units
- Fleet operators managing multiple vehicles with precision timelines
- Restoration shops rebuilding older models or classics
- Parts resellers and exporters sourcing high-quality stock
- Everyday vehicle owners looking to extend the life of their car or truck
We understand the challenges each group faces, and we align our services to match them—from technical guidance to shipping logistics.
Our Operating Values
At Smooth Engines, we operate by a strict Code of Ethics that governs every recommendation we make:
- Clarity – We explain what each component does, how it fits your vehicle, and why it was selected.
- Transparency – We provide upfront pricing, warranty terms, and lead times—no surprises.
- Options – We never force a one-size-fits-all solution. We present choices and let you decide.
- Efficiency – All estimates, quotes, and deliveries are streamlined for your time.
- Respect – We treat each vehicle like it’s our own, and every client with dignity and fairness.
Our business was built on personal integrity. That’s why we’ve never compromised—even as we’ve grown.
Our Mission
Our mission is to equip customers with reliable, pre-inspected automotive components that restore performance, extend vehicle life, and save money over full engine replacements or new car purchases. We aim to:
- Reduce mechanical uncertainty for vehicle owners
- Improve inventory access for repair businesses
- Ensure quality parts circulation in the U.S. automotive ecosystem
- Promote reusability and reduce waste in vehicle lifecycle management
Our clients trust us to deliver what matters: a proven part, a fair deal, and lasting performance.
Our Team
Behind every shipped part is a team of professionals—technicians, engineers, logistics coordinators, and support staff—working in sync to ensure every transaction is handled with care.
We believe people make the difference in this business. That’s why Smooth Engines invests in continuous training, technical certifications, and in-house quality assurance programs to keep the bar high.
Looking Ahead
As the automotive industry continues to evolve—toward electrification, digitization, and sustainability—we remain committed to staying at the forefront. While our current focus remains on internal combustion systems and marine components, our long-term roadmap includes:
- Expanding into hybrid-compatible drivetrain systems
- Developing an inventory API for seamless garage integration
- Offering eco-certified parts with traceable sourcing and performance history
We’re not just reacting to change—we’re preparing for it.
Built to Serve, Powered by Trust
Smooth Engines wasn’t built to scale fast—it was built to last long. Our commitment to reliability, customer care, and tested component integrity remains as strong today as it was when we opened our doors over 20 years ago.
So when your vehicle needs a second life, we’re here to deliver the part—and the confidence—you need to keep moving forward.
LOOKING FOR THE BEST USED ENGINES & TRANSMISSIONS FOR YOUR VEHICLE?
+1(840) 201-2318
