c/diesel-mechanics

I finally cleaned my shop air lines after 8 years of putting it off

The difference in tool performance is night and day. My impact wrenches used to sound weak and lag, especially on cold mornings. Last month, I spent a Saturday blowing out all the lines and installing a new filter-regulator at the main drop. Now, everything hits with full power on the first pull. I should have done this years ago. Has anyone else seen a big jump in air tool life after a good system clean-out?

Just hit 500 hours on a rebuild and it's still running quiet

Finished a full rebuild on a 6.7 Powerstroke for a local contractor about eight months ago. I logged every hour on my phone after the first test drive. Checked it today and the truck just passed 500 hours of run time with zero new issues. No injector knock, no weird smoke, oil pressure is solid. For a motor that was basically scrap when it came in, that's a solid win. What's the most hours you've seen on a rebuild before the first real problem showed up?

TIL a shop in Phoenix got hit with a $15k fine for using the wrong DEF fluid

I was reading a trade magazine at the parts counter and saw a story about a shop that filled a whole fleet's tanks with off-road diesel by mistake. The EPA came down hard because the trucks were registered for highway use. How often do you guys double-check the pump labels before you start a fill?

I hit 500 hours on a single set of injectors in a 6.7 Powerstroke and everyone said I was crazy.

The common shop talk is you swap them at 300 hours to be safe, especially on the high-pressure units. I kept a strict fuel filter change schedule every 50 hours and used a specific additive, running it in a fleet of delivery trucks. They just kept testing fine. It made me question if we're replacing parts too early just because it's the easy answer. Has anyone else pushed a component way past its supposed life with good results?

Finally got that old Detroit 8V92 to fire up after a week of chasing air

It was in a '78 Kenworth that came in from a farm near Salina. I must have bled the lines a dozen times, checking every fitting with soapy water. The trick was a tiny crack in the primary fuel line fitting you could only see with a mirror. Put a new copper washer on, cranked it twice, and it roared to life like nothing was wrong. Anyone else find air leaks in the weirdest spots on those two-strokes?

Hot take: I used to think a torque wrench was a waste of time for most jobs

For years, I'd just go by feel on things like valve covers, oil pans, and even some suspension bolts. I figured if it was tight and didn't leak, it was good. The tip off came last spring when I was fixing a persistent oil leak on a Duramax. I'd replaced the gasket twice, but it kept weeping. An old timer I know, who used to work for a fleet in Boise, watched me for five minutes and said, 'You're crushing that gasket. Get a wrench and look up the spec.' I did. The spec was 18 foot-pounds, which felt like nothing to my arm. I'd been cranking them down to what felt like 40 or 50. Using the wrench felt slow, but that leak never came back. It made me realize I'd probably been causing more problems than I solved with my 'good and tight' method. How many of you actually use a torque wrench for what you'd call 'simple' gasket jobs?

Can we talk about using a heat gun on a seized injector?

Everyone at the shop said to soak it in penetrant for days, but I was in a bind on a 6.7 Powerstroke last Thursday. I carefully heated the injector body with my Milwaukee heat gun for about 90 seconds, tapped it with a brass punch, and it came right out without a fight. Has anyone else had luck with controlled heat instead of just waiting?

Just lost a whole day to a cheap knockoff torque wrench

I was putting a head back on a 6.7 Powerstroke last week and used a new torque wrench I got online for $40. It clicked fine during the first pass, but when I went for the final torque, the head bolt snapped clean off. Had to pull everything apart again, drill it out, and wait two days for a new bolt kit. That $40 'deal' cost me about $600 in lost time and parts. Has anyone found a good budget brand that actually holds calibration, or is it just worth paying for Snap-on every time?

Rant: I fought against electronic service manuals for way too long.

For years I insisted on my paper manuals, even for a 2018 Freightliner Cascadia. I'd spend 20 minutes flipping pages to find a torque spec. Last winter, a buddy showed me the dealer portal where you can search the whole thing in 10 seconds. I bought a cheap tablet for the shop, loaded the software, and now I won't go back. Who else made the switch and what's your setup?

I swore by the old school way to seat injector cups until a guy in the shop showed me something better

For years I'd freeze the new cup and heat the head with a torch, then tap it in with a brass drift. It worked, but I'd still get the occasional leak on a 6.0 Powerstroke and have to redo the whole job. This old timer, Frank, who works the night shift, saw me fighting one and said 'try this, kid.' He took a piece of 3/4 inch copper pipe, cut it to the exact length of the cup, and used it as a driver with a regular slide hammer. The copper is soft enough not to damage the cup but transfers the impact perfectly. I tried it on my next job, a 2005 F-250 that came in last Tuesday, and it seated flush on the first solid hit. No walking, no cocking, just a clean seat. I've done three sets since and haven't had a single comeback. Anyone else use a trick like this for stubborn press fits?

Had to pick between a 3/4 inch impact and a 5 foot cheater bar on a frozen kingpin nut in a Minnesota winter.

I went with the cheater bar, which worked until the nut finally broke free and I fell face-first into a snowbank, so what's your go-to method for seized hardware when the air tools just laugh at you?

Spent 8 hours chasing a phantom knock on a 6.7 Powerstroke

Customer complaint was a loud knock at idle. Checked the usual stuff first, injectors, lifters, even pulled the oil pan. Nothing. Finally found it was a broken motor mount bracket letting the engine rock just enough to tap the firewall. Took me all day to figure that out. Anyone run into something like this before?

Changed my tune on that old 'just add more additive' fix for a rough idle on a 6.7 Powerstroke after it made my injector balance rates go haywire.

My boss in Tulsa said to try a double dose of cleaner before pulling the injectors, but after 3 days the truck started missing so bad I had to replace two of them anyway, costing me a full Saturday and $400 in parts I could have avoided.

Question about a runaway skid steer in a tight spot

Had a 2018 Bobcat S650 decide it was done with me last Tuesday at the old Johnson farm. I was swapping a hydraulic line when the throttle linkage jammed wide open, and it took off across the field with me hanging off the side. Managed to kill it by yanking the fuel shutoff cable after it plowed through about 30 feet of a corn row. Anyone ever had a machine just decide to go for a joyride on its own?

I thought those fancy synthetic oils for my 6.7 Powerstroke were just a waste of money until I saw the oil analysis after 10,000 miles.

DAE miss the smell of a shop before all the new emissions stuff?

Last week, a new apprentice in our Denver shop asked what that 'weird sweet smell' was, and I realized he's never known the raw diesel and oil stink of a 7.3 Powerstroke bay from 3 years ago, before all the DEF and DPFs really took over.

TIL a 'no start' on a 6.7 Powerstroke can be a $5 sensor buried behind the turbo

Had a truck come in with a crank but no start, and the computer pointed to the high pressure fuel pump. Spent a full day pulling the pump and testing it, only to find it was fine. The real issue was a tiny exhaust back pressure sensor that had failed, which was tucked way up behind the turbocharger. Getting to it meant pulling the turbo and a bunch of other stuff, turning a simple diagnosis into a two day job. Anyone else run into a sensor causing that much trouble on these engines?

That time a customer's 'engine knock' was just a socket wrench rolling around in the frame rail

Spent 45 minutes with a stethoscope before we lifted it and the 3/8 drive fell out, dude just laughed and said 'well that's cheaper than a rebuild'. Anyone ever find something truly ridiculous during a diag?

Just found out how much a single drop of DEF can contaminate a whole tank

I was reading an old technical bulletin from Detroit Diesel the other day. It said that just one gallon of diesel exhaust fluid in a 100-gallon diesel fuel tank can ruin the entire batch. That's a 1% contamination level causing major injector and pump damage. I always knew to keep them separate, but seeing that exact number really drove it home. Makes you double-check your transfer hoses, right? Has anyone actually dealt with a full system flush from a DEF mix-up?

Wasted $150 on a 'universal' DPF pressure sensor that didn't fit my 2015 Ram 3500

The connector looked right online, but the pinout was different, so I had to eat the cost and order the OEM part after losing a whole afternoon on it.

Hot take: The new DEF pumps at the truck stop off I-80 are a step back

They're slower than the old ones and the nozzle design makes a mess every time. Anyone else had to clean up a gallon of spilled fluid because of these things?

Just hit 5 years without a single comeback on my own personal rig... and I was sure I'd never make it past 2.

I've always been the guy who fixes it just enough to get by, you know? A quick patch, ignore a small leak, tell myself I'll get to it later. My old 7.3 Powerstroke was a testament to that. Then, about 5 years and 3 months ago, the high-pressure oil pump went. Stranded me for a full day. I decided right then to do every single repair by the book, no shortcuts, even the annoying stuff like torque specs and replacing all the seals every time. I kept a log. Hit the 5-year mark last Tuesday... not one tow, not one 'oh crap' moment on the road. It's not flashy, but that number... it convinced me that doing it right the first time, every time, actually saves you more headaches than it costs. Anyone else have a personal milestone that made you change your approach?

Rant: Saw a 'diesel mechanic' at the county fair in Springfield using a kitchen knife on a fuel line

I was at the fair in Springfield last weekend and walked by a food truck that had broken down. The guy working on it said he was a diesel mechanic and was trying to fix a cracked fuel line on the truck's generator. I mean, idk, maybe it's just me, but using a serrated kitchen knife and a roll of duct tape to try and make a splice was a new one. Has anyone else seen a repair that made you just stop and stare?

A farmer told me my torque wrench technique was making his tractor cry

I was working on an old John Deere 4020 in Salina last spring, doing a head gasket job. The farmer, a guy named Earl who'd been running the thing since the 70s, watched me snug down the head bolts. He said, 'Son, you're cranking on that thing like you're mad at it. You gotta feel the click, not just hear it.' I realized I was rushing and not letting the wrench settle. Now I always pause for a full second after the click, especially on those big bolts. It feels slower, but I haven't had a single come-back for a leak since. Anyone else get called out on their torque habits?

Rant: I finally saw what a difference cleaning the EGR cooler can make on a 6.7 Powerstroke

Had this 2015 F-250 in the shop for a week with a rough idle and low power. The owner said it had been getting worse for about six months. We pulled the EGR cooler and it was just caked solid with soot, maybe a quarter inch thick. After a full clean and a new valve, it ran like a new truck. Anyone else find that's the first place to look on these when they start acting up?