Mike and his boys got my 1990 international running back up when it had lost power. Not a lot of shops work on older trucks but he decided to take it in. Mike and his mechanic Pete figured it out. Solid guys. I’d 100% recommend this shop. They know what they’re talking about and good communication. 10/10.

Mike was the 3rd diesel mechanic I’d brought my truck to since we bought it two years ago. He’s the only one to let us know it was previously used as an ambulance and what was needed to get it running for years to come. Additionally he broke down exactly what we need done in order to fix the alternator setup, as well as the A/C which wasn’t working. Super thankful for Chris at Polish for recommending Mike and the team at LI Diesel Guys. I give these guys five stars and beyond and really appreciate their communication and checking in after going through the truck and making sure we were on the same page with the repairs and most importantly getting the truck back on the road in two days.

Best diesel repair shop in Long Island. Enter that into Google and LI Diesel Guys is the top result-for a good reason! Mike and his team recently fixed a long running barometric pressure problem with my old 7.3L F450 that 2 other shops before could not figure out. They won't rush you out until they are 100% sure that your truck is in tip top shape and runs perfect. Price is fair and repair work is superior!

Best diesel shop!! 10/10 recommend
Has worked on 2 of my trucks and a handful of my buddies. If you are looking for a diesel mechanic look no further, Mike and his team know how to get you fixed up and back on the road without breaking the bank!!

Once again Mike and his Technicians have done a great job. They have given me back my 2006 F250 with 436,000 miles 6.0 turbo diesel running like new. I brought it in on Tuesday for the driver side injectors dummy plug stand pipe glow plugs and harness oil service and fuel filter service oil change and I picked it up today Friday, three days. Last year they did my passenger side. Honestly I won't let any other mechanic to go into my engine but Mike and team. Where else can you get that done in three days and for reasonable price? Im so glad I found the Diesel Guys.

I own a 2015 F-350 Dually 6.7 Powerstroke. 18 Months ago the dreaded CP4 pump had a catastrophic failure. Estimates at two Ford dealers were $16k and $13K to repair. I was given the name of a contact who worked at a dealership and did the work on the side at the dealership after work. Price was $9K. I did not know about Mike and L.I. Diesel Guys at that time. The old saying you get what you pay for was never more true. Truck was never really right. Taken back several times for weeks at a time. Low pressure fuel lines blowing off and getting the run around when I contacted the contact who was really a go between to the diesel guy at the dealership. After the second time this year while towing my 16k fifth wheel and getting stuck on the expressway while leaving for yet another camping trip and losing money I had it.

It was at that point I learned of Mike and L.I. Diesel Guys.
I towed my truck to their shop and met Mike who went over the truck and all the problems he saw. Mike took the time to diagnose my truck and explained everything to me that needed to be done to make it right. He had documentation, photos and video of the shoddy work done before. Missing bolts. Injectors not torqued. I can go on and on but you get the point. The wife said get a new truck which most guys would probably jump at but I love my truck like most guys do. Mike said I will get your truck right again.

I put my faith in Mike and L.I. Diesel Guys and their talented crew. I was not let down. Mike had Shawn get to work on my truck. Mike was never to busy to answer my questions via text or call and kept me informed every step of the way. On an unannounced stop at the shop Mike took me out to Shawn in the shop and showed me the progress on the installation of the DCR Pump (highly recommend) and the other work being performed to get my truck right again. Shawn is a wizard and very meticulous.

My truck was delivered on time as promised and better than I can ever remember. I have had my truck a month now and waited until I had a chance to really put her to the test before considering writing a review which I never do. I can now say after two successful camping trips upstate pulling my Fifth Wheel, this is the first time I have towed with confidence. The truck ran flawless. Fuel mileage has greatly improved. The engine is as responsive and powerful as if it were brand new!

Thank you Mike, Shawn and the expert mechanics at L.I. Diesel Guys for your honesty, integrity and for making my truck right again as promised. I will be a customer for life.

Oh and by the way, "when" that dreaded CP4 pump in your truck goes unexpectedly and should you find yourself at the western most Ford Dealer in Suffolk County with a diesel mechanic name "JOSE " run like hell to L.I. Diesel Guys!

Mike had great customer service and did great work on my f350 dually.

Fast, efficient, knowledgeable, and helped get me the best price for all the work that needed to be done.

This is the best my truck has ever rode. Will definitely come back when in the area for any maintenance needs.

Mike and his guys took great care in fixing my truck. Finding terrible work from the last shop in there they didn’t hesitate to go do it right. Very knowledgeable about 6.0s and powestrokes, I won’t bring my truck anywhere else now.

Mike from LI Diesel guys was able to diagnose an issue that 3 other mechanic and myself have not been able to figure out for 3 months in the matter of a few minutes. They have a large Diesel facility with all the bells and whistles with a good sized experienced knowledgeable and friendly staff. I wish I knew about these guys years ago they have an exceptional customer service experience, respond to any calls and questions quickly and thoroughly and the work area is very clean and organized. I’ve been so impressed with them I live an hour and 20 away and I will use them for every repair in the future.

Called and spoke to Mike the owner for advice on what truck to buy and can't thank him enough for all the insight and education for what to look out for! He took the time to make sure I understood exactly what the warning signs were. Great guy! 🇺🇸🦅👍😎

Mike and his team gave me piece of mind by swapping out my CP4 pump with the DCR pump on my 2014 6.7 powerstroke. They are customer oriented company turning out great service in a timely manner. And left me with a clean vehicle. I will be back to use his services again.

I was a little hesitant, but Mike diagnosed my truck and went through the repairs with me. He recommended the most important rather than the most expensive. I will use him again.

Very knowledgeable, professional.

I called Mike about my 2008 ford f250. He took care of everything I needed done and more! Great work with my truck, I will be returning for all my mechanical repairs from now on! Highly Recommend!

Mike and his team are awesome diesel mechanics. They do a monthly PM service on my trucks and repairs as needed. They also installed a Titan XXL fuel tank in my 2023 F450 and reprogrammed the computer to recognize the larger tank.