Mahon’s Diesel Performance & Repair

04/28/2026

This customer brought her 2015 F-250 with the 6.7L Power Stroke in for an upper engine noise. The issue was narrowed down to cylinder 7. After suspecting a failed injector, we removed it and scoped the cylinder, where we found heavy scoring on the cylinder walls.

We pulled the engine for a rebuild, and during disassembly, discovered that it had previously been rebuilt. The piston in cylinder 7 had been installed backwards, which caused it to break off the cooling nozzle—starving the cylinder walls of oil.

The engine was sent out and bored .010 over. New Dualoy pistons were installed along with ARP rod bolts, main studs, and head studs.

The truck is now back and ready for many miles to come!

02/05/2026

This L5P Denali stopped in for a much-needed transmission upgrade. We installed a 950+ HP Screamin Diesel Performance Street Series transmission paired with a Goerend Extreme Clutch “DK” stall converter. While it was here, we also added a Mishimoto radiator, Pacific Performance Engineering transmission cooler, and a set of Fleece Performance transmission cooler lines. To top it off, we went with UDT SOTF engine and transmission tuning.

This is one of the best-running and smoothest-shifting trucks to leave the shop yet! Huge thanks to Koen Marlow for trusting us with his diesel performance needs.

If you’re considering a transmission upgrade or any other performance part install, reach out today for an estimate!

01/08/2026

We are proud to support Philo Athletics!

01/01/2026

Happy new year!
We are excited to see what 2026 brings us!

12/25/2025

🎄Merry Christmas from Mahon’s Diesel Performance & Repair!🎄
We want to thank all of our customers for an amazing year. Your trust and support mean everything to us. We hope you and your families have a safe, happy, and blessed Christmas!

11/28/2025

11/27/2025

Happy Thanksgiving from Mahon’s Diesel Performance & Repair! We are very thankful for all of our loyal customers who have given us the opportunity to take care of you. Have a great and safe day!

11/23/2025

My favorite thing to do in the shop is build engines. This customer brought in his ’03 4500 Kodiak with a misfire, heavy smoke, and a lot of blow-by. An injector had failed, which ended up melting a piston. The customer decided to go with a full rebuild!

We installed a set of Pacific Performance Engineering cast-iron cylinder heads, clamped down with ARP head studs, along with MAHLE .020 pistons and a Callies Stage One alternate firing order camshaft. This combination will be great for reliable towing power!

If you need an engine rebuilt, we do everything from stock refreshes to full-on race builds. Reach out today!

11/07/2025

We consider this an essential upgrade for all 2020+ L5P trucks. If you’d like to include it with your next service, contact us to schedule it!

10/21/2025

This customer was in town from Texas on a work trip when his 2019 L5P started pushing oil into the cooling system and out of the reservoir. We quickly diagnosed a failed stock oil cooler as the culprit. The entire system was flushed multiple times to ensure all oil residue was removed. We then installed a oil cooler upgrade, a set of silicone coolant hoses, and a new reservoir. The customer is now back on the road and headed south! Give us a call or shoot us a message for any if you’re diesel performance or repair needs!