Engine Rebuilding & Machining in Riverside, CA
When an engine is worn out, overheated, or burning oil, you don't always need to replace it — you need it rebuilt right. At Diego's Machine Shop, engine rebuilding and precision machining is our specialty. With over 20 years of hands-on experience, we machine every component back to factory tolerances so your engine runs strong and lasts. We work with both repair shops and car owners. Every job starts with a free estimate.
What Is an Engine Rebuild?
An engine rebuild means disassembling your engine, cleaning and inspecting every part, machining the worn components back to spec, and reassembling it with new gaskets, seals, bearings, and rings. Done correctly, a rebuild restores compression, power, and reliability — often at a fraction of the cost of a brand-new engine. The difference is in the machine work, and that's exactly what we do in-house.
Our Engine Machining Services
Precision machining is the heart of a quality rebuild. Most repair shops have to send this work out — we do it under one roof, to spec.
Cylinder Boring & Honing
When cylinders are worn, scored, or out of round, we bore them to a precise oversize and hone them to the correct crosshatch finish, so new piston rings seat and seal properly.
Crankshaft Grinding
We grind worn or scored crankshaft journals back to a true, smooth surface at the correct size, restoring proper bearing clearance and eliminating knocking and vibration.
Line Boring
We re-machine the main bearing bores back into perfect alignment so the crankshaft spins true — critical after overheating or warping.
Valve Jobs
We recondition valves and valve seats so they seal tightly, restoring compression and proper combustion. See also our cylinder head resurfacing.
Pressure & Crack Testing
Before we machine anything, we pressure-test and inspect blocks and heads for cracks and leaks — so we never rebuild on a part that's already failed.
A full rebuild also relies on a clean foundation and the right parts. We thoroughly clean every component in our hot tank, resurface cylinder heads with our surface machine, and handle piston fitting and replacement matched to your machined cylinders.
Engines We Rebuild
We rebuild and machine a wide range of engines. Daily driver, work truck, or project build — bring it in for a free estimate.
Signs Your Engine May Need a Rebuild
Not sure if it's time? These are common signs your engine needs attention — bring it in and we'll diagnose it with a free, honest estimate first.
Our Rebuild Process
Seven steps, done in order, every time.
Free estimate & inspection
We assess the engine and explain your options.
Teardown
Full disassembly and component evaluation.
Cleaning
Every part is cleaned in our hot tank.
Testing
Pressure and crack testing of blocks and heads.
Precision machining
Boring, honing, grinding, line boring, and valve work to spec.
Reassembly
Rebuilt with new gaskets, seals, bearings, and rings.
Final quality check
Verified before it goes back to you.
Engine Machining for Repair Shops
Don't have the equipment to machine engines in-house? We're a reliable wholesale machining partner for repair shops across Riverside and the Inland Empire. Send us your blocks, heads, and cranks — we deliver accurate, on-spec work with fair pricing so you can offer engine rebuilds without sending jobs across town.
Call to talk shop pricingCylinder boring, crankshaft grinding, line boring, valve jobs and more.
Pricing built for shops that send us regular work.
Offer engine rebuilds without sending work across town.
Why Choose Diego's Machine Shop
Frequently Asked Questions
How much does an engine rebuild cost?+
It depends on the engine, its condition, and the parts needed. That's why we inspect every engine and give you a free, detailed estimate before any work begins — no surprises.
How long does an engine rebuild take?+
Timing depends on the engine and the machine work required. We'll give you a realistic timeframe with your estimate, and we take the time needed to do the job right.
Should I rebuild or replace my engine?+
For many engines, a quality rebuild restores performance and reliability for less than a full replacement. We'll inspect yours and give you an honest recommendation based on its condition.
Do you rebuild diesel and motorcycle engines?+
Yes. We rebuild and machine cars, light trucks, diesel engines, and motorcycles.
Do you do machine work for other repair shops?+
Yes. We're a wholesale machining partner for shops that need cylinder boring, crankshaft grinding, line boring, valve jobs, and more.
Do you offer free estimates?+
Yes — every job starts with a free estimate.
Get a Free Estimate Today
Ready to get your engine back in shape? Call us, send a message, or stop by the shop in Riverside. Every job starts with a free, honest estimate.
Sat 8:00 AM – 2:00 PM · Sun Closed