Shop Tour: Maximum Diesels In Southern California


Southern California is by no means a Mecca of diesel, but that isn’t it to say that it’s nonexistent. On the contrary, the diesel crowd out here is as rowdy and fun-loving as you’d find elsewhere in the USA. Sure, CARB likes to beat us over the head pretty hard with all kinds of restrictions, but diesel trucks have found a way to survive out here, and the shops that maintain and upgrade these heavy-duty vehicles do pretty well for themselves, too.

IMG_9139One such shop is Maximum Diesels out of San Jacinto. Speaking with founder and owner Russ Kennell, we got to see the premises and treat ourselves to this particular slice of the SoCal diesel scene pie. Russ has been in the industry long enough to know how to deal with any problem, and sure isn’t shy about getting his hands dirty to get a job done.

Together with his team of seven employees, Russ is attracting customers thanks to proven, solid service and extensive knowledge. We stopped by recently to talk to Russ and learn what makes Maximum Diesels tick.



Back in the 2000s, Russ was living in Poway, California. He was a graduate of GM’s Automotive Service Education Program (ASEP) and a self-taught practitioner of the Mopar and Ford arts. “I was more into off-road and trucks, not very big on cars,” Russ commented. “I drove a 12-valve that was souped-up from the dealer, and at the time I had no idea that they were capable of so much muscle. From that point on, I was interested.”

Prior to opening Maximum Diesels, Russ Kennell was working on Cummins at a Dodge Ram dealership.

Prior to opening Maximum Diesels, Russ Kennell was working on Cummins at a Dodge Ram dealership in Poway, California.

Prior to that time, a Dodge Ram dealer also in Poway was in need of technicians who could handle the Cummins, which other mechanics hated because they were messy. Russ got the job and learned he had a real knack for diesels, and decided to go into business for himself, starting in 2009. What follows is our interview with Russ.

Diesel Army: What do you find is the commonality between diesel people? What is the thing that draws people into diesel?

Russ Kennell: It seems that they’re all into something outdoors. The desert, the river, camping, fishing, hunting, those guys are always drawn to diesels because there’s something fun and active about them. I think that’s the biggest common denominator, is that they use it for a purpose. The truck is not just a commuter.

We always get the vehicle back to the customer in better shape than it was from the factory; something to be proud of, something to depend on. –Russ Kennell, Maximum Diesels

DA: How did you start Maximum Diesels?

I was working for another shop and they were going out of business. It forced the loss of my home. I had the option to go work for another shop or start my own business, and at that point there was nothing else to lose. So it was myself and a 2,000 square-foot shop. It didn’t have any lifts, I did everything on the ground. I slowly built up the company from that, and here we are today.

What helped you establish yourself early on?

There were clients from the shop before. They knew me by reputation and working with me, and they liked my honesty. Then I had the Dodge Ram truck, the green one in the back of the shop here. Racing it at drag events got me some notoriety and before I knew it, I had customers coming up from as far as San Diego to get their trucks worked on.


Now you’re here in 2016. How many employees work here, and how big is the shop?

Between the two locations, it’s 11,000 square feet and we have seven employees.

What is the typical customer coming to Maximum Diesels for?

It varies. It depends on make and model of the truck. The majority come in for service, maintenance, and repair, but we always get the vehicle back to the customer in better shape than it was from the factory; something to be proud of, something to depend on. Contractors have to have their trucks in and out as soon as possible. If a truck has been here a few days, we get it washed and cleaned up so it’s looking nice. There’s a lot of horror stories from going to other shops …

She's a bit barky at first, but eventually the shop pit bull becomes a friendly creature.

Like what?

Oh, they’ll sell the customer a defective part, especially on Power Strokes. Head gasket failures, or saying they’ve replaced a part when they haven’t. We have a truck outside that supposedly received new valve springs with the new motor, and it didn’t. So now it needs another new motor.


What is your connection with racing and high-performance diesels?

I got into it through the green Cummins. I’ve always like the Cummins, they’re the easiest to work on, especially with the 12-valves. The thrill of it, the torque, the on-demand burnouts at 40 miles per hour, it’s a pretty good time. I was on a budget when I started working on the green Cummins, so it was one way to get my name out there. I learned the ins and outs and saw the stuff that other guys were running, and from there, it was an addiction.

Kennell's 1995 Dodge Ram was out back, resting until its next repair.

Have you ever had a mishap on the track?

IMG_9081Oh, yeah. It was a new motor on the green truck and I’d just made my third pass on it, and the turbo let go, and when it let go, it actually exploded. I coasted into the pits and the stack was shooting flames out like a torch, and that went on for about 30 or 40 seconds. It finally put itself out, and we found out it was the oil from the turbo. Fortunately, the fire didn’t go anywhere else and burn the truck down. I fixed it and carried on.

I’ve broken the planetary gear set on the 47RH transmission that was in it. That makes a really long bang. I broke three intermediate shafts, two at an NHRDA race in Bakersfield. We launched at 24 pounds of boost, and when the shaft let go the first time, the whole truck came six inches off of the ground in the rear. The dash fell on me and all the gauges flew out, it was that hard of a hit. It must have been too much power for the shaft, because it was still stock after so many good runs before.

IMG_9026Has there ever been a situation where you’ve been overwhelmed? Like a truck had too much for you to handle?

Yeah, several times. We had a 6.4-liter Power Stroke that we put a 30,000-mile motor in, and it melted a piston within 15 miles. It was a complete motor with turbos and everything, and it was just one injector that froze up and the piston had no choice but to run dry and eventually melt. That was a challenge figuring it out. Then we rebuilt it and the crankcase started filling up with fuel. So with that we found the injection control pressure switch was leaking and got that repaired. That took about two weeks to take care of everything.

IMG_9117The most challenging is when you’re trying to diagnose something with the truck and it’s not giving you any information. The scanner won’t communicate, so you’re kind of on your own. You can call tech assistance all you want, but it really doesn’t help.

On the whole, what I found difficult was the whole business side of this operation. I didn’t know how to do invoicing, insurance, zoning, etc. It still is overwhelming sometimes.


What is the most rewarding part about owning your own business?

I would have to say, having a client happy with our work and then referring us to their friends and family. Coming up and saying, “Thank you, I appreciate it,” that’s what it’s all about.

IMG_9157What do you have to do behind the scenes to keep everything running?

Ordering parts is one thing. It’s not like it used to be. They pick a minimum wage person and put him behind the counter, and if it’s a technical part, it gets tricky to get what you want. So I deal with that. A lot of customers only know me, and our service guy, Ron, has only been around for nine months. So we get customers that are picky, and yet they’re some of our best clients. Some of them just roll up, drop the truck off, and say, “Send me the invoice when you’re done.” They don’t ask for estimates or anything. So Ron is following the rules like he’s supposed to, but he has to deal with these customers from time to time and it can get stressful.

But for all that, I’m grateful that I have rock-solid employees. They’re practically self-sufficient, so all I have to do is make sure they’re happy and paid right and have the adequate tools. No micromanaging, it’s awesome.

IMG_9133How would you rank the diesels that you have to work on, in terms of difficulty?

That depends on the year, really. I like the Duramax. We’re seeing them with really high mileage now, so I think they’re an excellent motor. They were ahead of their time when they were built – the aluminum heads, the common-rail injection. Every manufacturer has their flaws, though. Ford’s 6.4-liters were a quick production line and they had a lot of issues. As far as the early GM models, they had injector issues and fuel filters are a must on those, and customers were not properly educated on these issues. Head gasket issues and little wiring things, too. I think every vehicle has their flaws, though.


That’s All, Folks

Maximum Diesels is making a good living these days, and come a long way from the jack stands and small garage that Russ started all those years ago. For 2016, he plans to bring together everything under one roof. “I’d like to build our own building and customize it the way we want,” he said. “And then at some point, I’d like to start a second location. I have the manpower for it, and I have a leader in mind, so that just leaves timing.”

From the outdoorsman to the contractor to the everyday guy, a diesel can do so much, and then some. That’s why it’s good to have shops like Maximum Diesels around to pick these trucks up when they break down, or to soup them up for even more demand on the blacktop.

“I want to get back to racing and just expand and keep going,” concluded Russ. Judging by the state of things, we’d say these goals are definitely within reach. Find out more about Maximum Diesels online, and stay tuned to Diesel Army as we cover future shops, builds, tech installs, and more.


About the author

David Chick

David Chick comes to us ready for adventure. With passions that span clean and fast Corvettes all the way to down and dirty off-road vehicles (just ask him about his dream Jurassic Park Explorer), David's eclectic tastes lend well to his multiple automotive writing passions.
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