Best run garage I’ve been to. Was stuck with low fuel pressure light and had to leave the pickup for repair. Left package in back seat but they delivered them to my door. Great customer service and caring for their client. Everyone is knowledgeable and quick to get me back on the road. Wish there was a shop like them in every city along my travels.Happy Trails everyone !!!!Jerry

They have some best service around and Ray can tell you anything that you want to know about diesel injection. Did a great job cleaning and testing my injectors.

This shop is top notch! When my service truck went to another shop to have the fuel system replaced. I was a fiasco. Constantly taking it back for additional problems related to the work performed. Once I was fed up with the other shop, I took my service rig to Rocky Mountain Diesel. These guys took care of me! They did so at a fair price, and fixed the problems from the previous repair.Fair prices!Honest assessment!Quality workmanship!

I had the worst experience with “MONDO,” if you don’t do as he says you will be labeled problematic. He told me to pick up my truck and take it, questions are not welcome here. He even offered to escort me out! If you don’t like being respected as a customer ROCKY MOUNTAIN DIESEL is the place for you! In addition I received a call after removing the truck and Mando harassed me. Customers beware!I will also advise you that DEFAMATION isn’t something to be taken likely, which you just did. Mr. Rodriguez you are making false accusations and are stating I said things which aren’t true and I never said. I would advise you to revisit your post, which contains nothing but lies.DEFAMATION AND INTIMIDATION!

Its very rare for me to give a 5 star review.I have been looking for a good Deisel repair shop in the northern Colorado area. I will say now that I have found it, Rocky Mountain has done everything they can to fix my truck issues.I took my truck to weld county garage, and they couldnt fix the electrical issues. They would tell me that it was fixed, they changed filters, sensors and a lot more things. Well long story short they never fix the problem.Rocky Mountain Deisel fixed the problem within the month.You may think a month is a long time, but they went through all of the electrical and found the bad wire.Any way I will take my truck to Rocky Mountain, from now on.Personal note, shops are overwhelmed every where right now so be kind and patient. Dont rush your mechanics so they can do their jobs right and fix your issues. Thank you all at Rocky Mountain Deisel.

Mando is awesome. The whole crew there is amazing. I would recommend them to anyone who is having diesel issues!!

2014 ram 2500 6.7 , they got my new turbo actuator installed and calibrated also fixed some leaks , from drop off to pick up they diagnosed and fixed in a short period of time and the truck is now running great. Also was fair on price, I will definitely take it back for future work.

I just went in here for a last minute VIN inspection. Eric was super friendly and helpful. I really appreciate the great service! Thank you.

It was raining and my passenger side back window fell off the track so I came here to have them fix it! They were busy I could tell by the people waiting in the lobby so asked if there was anyway they could squeeze me in cause it was raining and my kids were in the car with me. They took my car to the back ASAP let me know what the problem was and secured the window for FREE. This place is very clean and professional, we will be taking all of our mechanical problems to the. Great experience!!!

This place is all about the money, theyll shove you out the door knowing theres stuff still not fixed.Im just the driver, so I dont represent what my company may say but if I have anything to do with it Ill never take a power unit there again.

Mondo and the guys did a great job diagnosing a fuel pressure problem on my C5500 Kodiak chassis Toy Hauler. I was thinking I would need new injectors and was prepared for a huge expense. These guys quickly figured out the real problem was simply a fitting & filter! Though they could have replaced the injectors and hit me with the large repair bill I was ready for, they instead proved their level of honesty and expertise! Kudos fellas! Ill be utilizing these guys exclusively from here on for ALL of my trucks!

They are a ok place to take your truck to. I had called initially to see how far out they were and mando told Me that they were a couple days out. After telling him all the diagnosis that I’ve done and what had lead me to believe my 2005 F350 6.0 low pressure oil pump was bad. Mando had said bring it by that they would get right on it so $75 I had it towed over In the next 2 hours. When he received the truck told me he would call the next day with a game plan. I must mention this is my work truck I relied on this truck to make a living. Well next day no call. 3rd day I called to see how things were going and if it was that low pressure oil pump and mando proceeded to tell me that how diesels are complex and that it was probably my high pressure oil pump. Long story short on the 5th day mando tells me it’s my low pressure oil pump an that it would take about a week to fix. Well the good thing was I had already ordered my low pressure oil pump and front cover. I had my truck towed back home and replaced my low pressure oil pump and front cover myself no experience ever working on a diesels at-least for the most part and I was back up and running by Sunday night $600 part from dealership vs a starting price of $3,000 an down for a week. I gotta business to run but other than that I do bett that Rocky Mountain diesel is a great place and that they do kickass at getting it done. But unfortunately for me time is of the essence

First thing is first mando, there wasnt a time where you called me to tell me what you were doing to the truck. I had to call you first , but you were out running errands so you had to call me back. On Wednesday I called you in the morning and you told me that the truck was going to be ready by lunch time, after having it for 4 days. Secondly, you told me that you were going to take the fuel tank out of the truck to take the old diesel out, and when I got home and checked it hadnt been moved, after calling you said that you had token the diesel with a pump, after saying it was going to be unmounted. The problem is not the price or the performance parts its about not doing the labor its that youre showing me that it takes 4 days to take out and put back a gas tank. I shouldnt have to learn anything youre the professional and should know what youre doing.

These guys are AWESOME. Took great care of my truck and its running better than it has in a long time. Finding a good mechanic I could trust has been impossible until I took my truck to these guys. Very much appreciated, Thanks guys.

Fixed my truck in a timely manner, no issues

I have been bringing my truck here for the last few repairs and maintenance issues. I like trying to help small businesses whenever possible. I took my truck in for an oil change, tire rotation and fuel filter. 2010 Silverado Duramax. I was charged 481.00. I called Truck City and was quoted 210.00. I wont be going back.

For some reason I thought they charge $75.00 dollars rate for all diesel emissions test.I just take my ram 5500 I got charge $90.00 dollars they said because the type of the truck VERY GOOD PEOPLE BUT EXPENSIVE PLEASE I THINK

Took my F-250 in when my starter died. They got right on it for me. With a huge snow storm coming and me working in a different city I sure did appreciate it. I Will be taking it here the next time i need work done.

This is long overdue. I’ve been coming here for over a year now. I bought an old Dodge truck and they have done lots of upgrades for me. They’ve also worked on a second truck of ours. They rarely make mistakes and when they do, they own the problem professionally. (EVERY mechanic will make mistakes because they are human). They go above and beyond. They know their stuff and they stand behind their work. Thanks RMD, Scott.

Mando is what makes this place great! Top notch customer service from him.

Friendly Staff and no appointments needed for emissions testing. Ill go back every year.

This place........this place is absolutely the BEST place to go!! The whole team is just simply amazing! Best Experience a person could have! A HUGE SHOUTOUT to MONDO!!! He is the most understanding, helpful person we have ever dealt with! He worked with us on everything and called to discuss problems BEFORE fixing them so we werent shocked at the end. We will never go to a different shop and we will make sure everyone knows to take their business to Rocky Mountain Diesel and Auto!! Mondo, we cant thank you enough for everything! Your the Best!

The team there is so awesome to work with. Mando and Spencer are tops! Thanks for always helping us out with our vehicles!

They were super helpful and quick! We needed an emissions test on our sprinter. Thanks guys!

GREAT customer service!! Definitely would recommend.

Its unfortunate when you find out that you need a new engine. They did me right. Even though I didnt get it fixed they gave me the diagnostics customer service.

The only place I’ll take my Silverado to for repairs. Those Guys do a good job and back their work 💯

Worst experience I’ve ever had with a diesel shop! These guys think they are the only ones in the game and will tell you that everyone else does junk work. Completely rude. Completely arrogant. And this has been multiple experiences with them over years, under old management and new management. Their prices are also extremely high! They price like they are a dealership.

These guys are awesome. Ive had little to big reasons to go here and never regretting it!

If you go here be careful with your money they just take it and dont even touch the truck theyll let it sit for a while. They’ll call you and say it’s ready , but they havent touched it , this is the second time its happened to me be careful out there guys.

This is the shop you want to take your truck to. We have a 2017 Truck. My husbands welding rig, the ejection pump was Faulty ( Chey has a big problem they dont want the public to know about). There where metal shaving in the fuel system. !!!Rocky Mountain Diesel wants nothing but the best for there customer. They back there work. A very honest company. Not like The Truck City in Greeley. The couldnt fix our truck. But Rocky Mountain Diesel did.

Good people & good service. 👌🏾 Thank you Mando & your crew.

Great place great people I will be coming back

I was looking for a #25 chain for my electric scooter. They didnt have it but were able to send me in the right direction to locate it. Great customer service!

Very good explanation clear and gently

Needed some work on my truck and these guys were great. Honesty and good customer service.

Great emissions shop...in and out!

Great and friendly staff. Mando was very helpful with keeping me updated. Just wish that for what they charged me my pickup wouldve been fixed 100%.

The shop is clean and the staff is a good mix of friendly, knowledgeable and honest, which I appreciate. My work truck had left me stranded and these guys really bailed me out. The head gasket had lifted and I wasnt able to pay for the repairs immediately. They let me pay for parts and after repairing my truck stored it for almost 2 weeks free until I got the money together to pay for it. This is the only shop I know of that would work with me like this. They have my business from here on out.

Good guys and good work

Love this place these guys are always right there to help with all your problems great place to take your vehicle . Thanks guys for all that you do

Always great service and knowledge

I brought my husbands truck in for emissions and learned they were also a full service repair shop. They were friendly and we ended up bringing his work truck back for a head gasket repair and were treated well. The repair was made correctly and we havent had any issues with the truck since. Were happy with the service and repairs, we will return and definitely recommend this shop if you need you diesel worked on.

Rocky Mountain was super awesome! They work with you to make sure you get the things that you need done to your vehicle! I recommend them to anybody looking for service!

Great Business! Very professional. Mando was Friendly and helpful, he answered my questions and got us in and out quickly.

These guys are awesome! I came in for an emissions test, in-out 30 mins tops! Great place, great people

Quality work👍

Great bunch of guys. Got me in quick when i needed it.

Exceptional service! I didn’t have an appointment scheduled for my emissions and they got me right in. They were very efficient as well, they were done in under 15 mins. The customer service is similar to what you get in a small town where you know everyone; they were very welcoming, and friendly. I highly recommend and will be returning for any of our diesel needs!

Nice place friendly staff these guys know what theyre doing

I brought in a dump truck for emissions. When it was done I noticed that the radio and cb were not working. Knowing that it was probably something simple like a loose wire or a fuse I turned around and went back. They told me that they didnt have time to check something like a fuse. When I bring in a vehicle for something like a emissions I expect to get it back in the same condition it arrived. I will not be bringing any vehicles to this shop again.

I was in need of emissions, so I stopped in. While waiting the front staff took the time to talk instead of sending me to a chair to wait. Because the staff was so nice, when our truck was acting up, I returned. They where able to get me in the next day for diagnostic work, I was given a run down of what must be done and what could wait. Even with the extensive work, I had the truck back in 2 days. Just this week, my engine light came on, since I was on my way to the parts store, I had the store scan it. I then called RMDS with the codes, they let me know symptoms that may occur and what to watch for until our busy schedule can accommodate another repair. I have had only good experiences and will continue to do service with them.

Had great service today getting an emissions test on our new diesel truck. They gave us some excellent tips on maintaining it. Thank you!

Great service. They found what was wrong when another shop couldnt. I recommend them if you need your diesel worked on.

These guys provide excellent old school top notch service. if i could give six stars i would. come here for all your diesel needs, this shop is WHATS UP.

Clean and comfortable waiting area. My emissions test was done so quickly, that I didn’t even have time to finish a short magazine article! I’ll be back.

Needed an emissions test so I called these gentlemen (we live close by and I needed it done rather quickly). They said, bring it on down, first come, first served. We were in and out within 40 minutes and their service was top notch. Ill be using them for any future work on my Duramax!

Love this place... they get you in and out fast, and professional. They have completed my last two emissions testings and Ill be back for the next.

Great experience! The man at the front desk was so helpful!

We had our truck towed there about a month ago because of a fuel issue causing it not to start. It had been doing this randomly wont start then will start issue for a tad bit but was just getting worse. They called us 2 weeks later when they finally looked at it and told us it was a battery issue without looking at anything else. To our surprise (sarcasm) it is not starting and with all the same problems. Its disheartening that this shop will not only just sell us a part to fix this issue ourselves but openly mocked my spouse when he picked it up stating If you dont leave we are going to have to charge you hourly, and that we are still down one vehicle . We now are just throwing parts at it to see what the issue is because of the poor excuse for service at this shop. Also, when we initially contacted them they said they would look at it that day not 2 weeks later. I would not go here!!!

I had to get a VIN verification for my truck. The staff was very kind and professional. I was in-and-out in 20 minutes.

Went in for a E-test, in and out in 10 minutes

Very friendly and trustworthy

They got me in and out quickly when I needed and emissions test for my truck. Great service!

Helpful and informative save me a lot of money thank you guys again! M

Mando is the best! He is extremely informative and very helpful. I highly recommend Rocky Mountain diesel services and I highly recommend that you speak with Mando.

Worth the trip to Greeley to see these folks! David and Eric were great, fast and appreciative of my business. Definitely recommended!

Great place to get diesel emissions. Fast and friendly

LOVE them! Got my truck in for inspection and fixed all in one day! Guys were great to work with!

Emission test done quickly and did not need an appointment. Awesome service.

Awesome service. The problem was fixed. Dave and Eric are awesome to work with. Will be going back when our truck needs work. Thanks guys.

My son Eddie broke down in Greeley with transmission problems. Eric and his staff went out of their way to ensure my son was taken care of and back on the road!! Outstanding service and professionalism!! Thank you Eric!!

Once again I have gone in to get my emissions done and these guys have gone ABOVE AND BEYOND. I really enjoy going in there and speaking with Eric (the owner ) who actually did my test for me and David. Yall are very fast and friendly. Im glad that I have found a automotive shop where I can have all my concerns and needs meet . I wish all shops could be like yall . I definitely give 5 *****. Thank yall again for your hard work

Do not take your vehicle here. They are thieves and liars. They tried to charge my 50 year old father 5500 dollars for something that was not broken. We took it to somewhere else for a second opinion and not only were they wrong they would have grossly overcharged him. Found a fix for the problem for 1500 and thats including some upgrades on the fuel system. SHAME ON YOU!

Took my 7.3 powerstroke in because of hard starting issues. They did almost $2000 worth of work to it and never fixed the problem. It really upset me because I used them last year when I thought my clutch went out, scheduled it to have a new south bend clutch put in. Then I get a call from the mechanic and its just my master cylinder. Saved me over a $1000. I really thought I had found a shop that was going to treat me right. Guess I was wrong. Took it to Mr. Diesel in Cheyenne and he had it diagnosed and fixed in less then half a day. Truck starts great now

Guy at the front counter was completely rude and unprofessional. After a 30 second conversation I had already realized I should take my truck elsewhere

Good customer service and best place to get your emissions done for your diesel truck

My husband took our diesel in yesterday and was in and out within fifteen minutes. The staff was very knowledgeable and prices were very reasonable.

Just being honest not trying to bash no body or company because they seemed to be very Kool people. I was looking for a shop that would help me and want me back as a loyal customer which Im definitely looking for a good shop to help me upgrade my Duramax (02 LB7) for longivity and reliabilit because I want to make it a welding rig truck but I was quite disappointed because I payed $668 which is alot of money tell me not for one part which didnt come complete and was also used before.. I gave it 3 Starz because they seemed nice and knowledgeable but to gain loyal customers you have to be honest and help them to feel safe and comfortable in their vehicle who will always come back ... I havent yet worked with them with something this major like talk to them yet so depending on how it goes on Monday when I speak to them I will update my rating and review. So they called me back and fixed my problem so I take it all back and can honestly say they are very helpful and will answer any questions you might have with your vehicle.. good service and knowledgeable people. Overall Im happy wouldve been better if they offered to put it in for me or help me while they show me at a discounted price ... Have a great day everyone who read this

Good place to get diesel emissions.Thes people know diesels.

Always great service, these guys know what they are doing.

Great service! And fast emissions testing.

Honest and trustworthy. Quick turnaround. Ill be going back.

Fast. Emissions test in and out and they did my VIN inspection too!

Professional and courteous for a simple emissions test

Place was quick and painless and the staff was super friendly!

Ray was very informative and knowledgeable of my volvo D12 injectors! Extremely friendly and helpful. This is now my where Ill be going for any problems in the future. I would and WILL recommend this shop. The guys at the front counter were helpful as well dont shop around just check these guys out and im sure you will be pleased as I am!!!! Thank you guys!!!!You helped me get rolling for a very reasonable price. I know for heavy duty stuff this is the place just like for light duty needs. Im very happy with everthing!!!!!

David Valencia and Eric Smith are always able to help get my used Kenworths emissions tested and ready to deliver to my customers everytime I ask, sometimes on short notice.

Went in for emission test on my truck. In and out in an hour with no appointment.

Great place to do business!

I paid 121 dollars for a diagnosis that said my EGR valve was stuck open causing white smoke from my Duramax, was told the balance rates on injectors was fine. I pulled the EGR valve out cleaned it checked the operation, checked the vacuum pump put it back together still white smoke, next step removed the EGR entirely figured cooler may be leaking still white smoke. Bought a CTS2 and found 3 injectors out of the balance tolerance one is at a -7.0. Did some research and found out also have a head gasket problem top radiator hose hard as a rock even when off for 30 minutes. Disappointing that I pay a professional shop and have figure out the problems on my own.

Great, In and out in a day, had all parts in shop and was well priced. Great communication as well.

Complete fail on diagnosing a 2006 5.9 Cummins fuel problem!! Took a week and $1000 from me for no benefit. Another shop diagnosed the real problem (lift pump) and repaired in 2 days. RMDS Owner was unwilling to defray any of that cost.

Dishonest, poor workmanship, and do not stand behind their Warranty. Stay away from this place.

Dropped $25k in to motor swap on a powerstroke 6.4 not even 20K miles on it and blown head gasket oh and the talked me into the ARP head studs upgrade lmfao BulletProof they told me!!! smfh ... After the reply still the head gasket..and it never ends missing the the vacuum pump to on my a.c. ... foreal these guys..😋🤣🤣

Best place in Greeley area to go for big truck emissions

Very nice staff, very friendly.

This company treats our company with respect thats why we continue to do business with them.

Great customer service, and fast on productivity

Excellent customer service!