J4 Automotive
“Patient, caring, understanding, good sense of humor, and willing to go beyond what is needed to help make sure any vehicle I take to the shop is well taken care of, and I feel safe and comfortable driving the vehicle.”
Best Engine Repair & Rebuild in Helena, MT
19 technicians listed · 10 in Helena · 2 open weekends · 16 rated 4.5+
Data verified October 16, 2026
Dj's Automotive
“I was traveling from out of town needing a repair, Their professionalism and courtesy to accommodate my situation in fast timely matter was outstanding.”
Grizzly Diesel Services
“These guys, despite being super busy worked in my new-to-me truck and gave it a thorough look over and took the time to run through what they found and what to expect.”
Prestige Automotive
“The got me right in to rebuild my transmission when everyone else said it would be a month or more I will saw more after the job is done so 5 star for now”
Auto Worx Plus
“It is always daunting to try to find mechanics who you can trust and these guys have shown that you can trust them and that is what is most important to me.”
Blue Collar Diesel & Equipment Repair
“I'm glad these guys decided to set up shop in the Helena area because after my experience with some of the all flash no wrench tune shop we desperately need them.”
Listed for drivers in and around Helena, MT, these 19 shops repair, rebuild and replace engines. What each one says about machine work, warranty terms and the engines it supplies comes from its own website; ratings and quotes come from public reviews.
Area overview: Helena, MT
10 of the 19 technicians we list are based in Helena; the other 9 serve Helena from towns including Belgrade (69 mi), East Helena (5 mi) and Clancy (1 mi). The technicians on this page are rated from 4.2 to 5.0 across 709 reviews; 2 have 50 or more reviews and 16 are rated 4.5 or higher. 2 are open on weekends. 4 list staff certifications (ASE) and 3 have a BBB rating of A or A+. 5 have ten or more years of experience, the longest 30 years. 2 offer emergency or roadside call-outs; 1 offers financing; 1 gives free estimates; 2 are family- or locally-owned and 1 lists coupons or special offers. We have a website on file for 14 of the technicians on this page; 9 publish a contact page; 8 list a public email and 1 takes bookings online. We count these figures across the technicians on this page; distances are straight-line, and hours and prices change, so confirm the details with the technician before you visit.
Why do some listings show another city?
10 of the 19 shops are in Helena itself and the rest come from other towns within 70 mi. An engine job means leaving the car for days, so the drive happens once at each end rather than every morning.
Green Handle Garage
“Best diesel shop in Helena, I had work done at other shops in Helena and Green Handle Garage is by far the best, quick service, and the owner Kale is very knowledgeable”
Advanced Engines
“He not only worked us in (we were broken down in an RV), but also gave us some good tips, ordered the gasket from Seattle, and did a great job resurfacing the heads.”
4th Dimension Suspension
“And very honest!”
Queen City Off Road
“It was pretty evident at the first consult and then when I dropped the truck off before and picked it up after the install by the questions they asked about preferences for the setup and what not that they are really enthusiastic about doing thorough...”
Threshold Diesel and Fabrication
“Very knowledgeable even give me poi ters on what I need to do if I am doing something my self.”
Transfleet Services LLC
ESL Road Service
“Down time was greatly minimized.”
Cady Company
“He slowly (and simply) explained what was happening with my car and even though I could see that he didn't have time to fix it, he just stopped what he was doing to put my car up and quickly fixed it!”
Yetti Diesel
“Some of the nicest most personable people I've worked with absolutely willing to help with whatever they can took very good care of my truck and Driver on a roadside call”
Apex Diesel
“I didn't catch his name, but the mechanic identified the issue (missing bolt), went out himself and got the part, and had it repaired - all within an hour and some change.”
Daigh's Diesel
“I was passing through Bozeman with my 2006 T1N Sprinter and needed someone to look at it and provide an evaluation before driving it home to California.”
J&M Repair
“Great shop with knowledgeable staff”
Battle Ridge Diesel
“Got me my oil change, filter change, full inspection and a new battery for the same price another local shop was going to charge me just for oil and filter.”
Why these companies made our list
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