c/diesel-mechanics

I finally noticed why those injector cups keep leaking on 6.7 Powerstrokes

I have been swapping injectors on these trucks for 3 years now and kept getting a comeback leak at the cup seal after about 6 months. Turns out I was using the wrong O-ring lube that was swelling the rubber instead of protecting it. Has anyone else had this issue or found a fix that lasts longer?

That one time a old mechanic told me to stop using so much torque on oil drain plugs

I was working on a 2015 Freightliner in Phoenix last summer and I always cranked those drain plugs down tight. This old guy walks over after I stripped the third one that month and says 'you're not building a bridge, you're just keeping oil in.' He showed me how to hand tighten then give it just a quarter turn with a ratchet. Changed my whole approach and now I haven't stripped a plug in over 6 months. Has anyone else had a senior mechanic drop some simple wisdom that saved them from dumb mistakes?

Realized I had been torquing cylinder head bolts all wrong for 8 years

So I was helping a buddy do a rebuild on an old 5.9 Cummins last month and he was nagging me about not following the sequence. I told him I always just do a crisscross pattern by feel and it's been fine. He pulled up the factory manual on his phone and showed me the exact order with torque specs and angle turns. I had been guessing on every single engine I've done. Has anyone else found out they were skipping a crucial step for years and never knew it?

TIL letting a reman injector sit on the bench too long can cause air locking

Pulled a set of injectors on a 6.7 Powerstroke last Tuesday. Had one reman unit sitting on the bench for maybe 45 minutes while I chased down a stuck glow plug. Popped it in and it fired rough, stumbled bad for a few seconds before it cleared. Guy I work with said the plunger can drain down if they sit upright not submerged. Never had that happen before. Anyone else run into this with reman injectors sitting around?

Overheard a kid call a Detroit 60 series 'old school' yesterday

I was at the parts counter getting a fuel filter for a 2006 International, and this young mechanic pointed at a 60 series core on the shelf and called it old school. Felt like a gut punch because I learned on those engines back in the late 90s when they were the new thing. The guy next to me laughed and said he remembered rebuilding Deeres with a hand pump. Got me thinking how much this trade has changed in 25 years but some stuff still holds up. Anyone else catch themselves feeling ancient when the younger guys start talking?

Question about going with a reman injector over a brand new one

I had to choose between a $250 reman injector and a $450 new one for a 6.7 Cummins last week, went with the reman to save cash. It fired up fine but now I'm wondering how many miles you guys usually get out of remans before they start acting up?

Rant: Blew a turbo on a 6.7 Powerstroke outside of Phoenix last week and now I'm second-guessing my go-to oil change interval

I had a 2015 F-450 I've been maintaining for a local ranch since 60k miles. Ran perfect until 185k when the turbo seized up on the I-10 near Casa Grande. I've always done full synthetic changes every 7,500 miles like clockwork, but my buddy swears he runs his farm trucks to 10k with no issue and says 7.5k is just wasting money. Anyone here ever had a turbo failure that early on a 6.7 and think it was oil-related?

Threw $400 at a cheap injector tester that gave wrong readings every time

Spent 3 days chasing a misfire that turned out to be a bad tester instead of bad injectors, has anyone else dealt with a tool that cost more in lost time than it was worth?

Hit 500,000 miles on my 6.7 Powerstroke last Tuesday

Was rolling into Lubbock for a parts run and the odometer ticked over. Half a million miles on basically the original engine. Just injectors at 380k and a water pump at 420k. My first diesel I barely got 180k out of before things got expensive. Got me wondering how many of you guys are running high mile trucks and what your secret is. Do you do oil analysis or just run Rotella and pray?

Remember when we actually used to re-line brake shoes by hand?

I was cleaning out the shop yesterday and found my old rivet gun from my first job in 2008. Back then my boss would have me spend half a Saturday relining shoes for an old Pete. Now I just order them pre-lined from the parts house and swap them in 20 minutes. Do any of you still bother with rivets or is everyone just buying premade these days?

A master tech told me my torque wrench was wasting time and I stopped being lazy

I used to set my torque wrench to one number and use it for everything from head bolts to injectors. This old guy with 30 years in pulled me aside and said I was beating the threads on half the jobs. He showed me how to use a beam-style wrench for smaller stuff and keep the clicker for bigger hardware. Now I switch between three torque values per job and I haven't had a single callback in 6 months. Has anyone else had to unlearn bad torque habits from YouTube videos?

Pro tip: That $80 injector puller set saved my bacon on a 6.0 Ford

Bought a cheap injector puller set off Amazon for $80 and it worked like a charm on a 2005 F-250 that had a stuck injector. Tried to use a slide hammer I borrowed from a buddy and just about wrecked the bore, so now I swear by that kit. Any of you guys used a specific brand that held up better?

Serious question, why do people keep torquing head bolts dry?

I had a guy in my shop last month snap a 14mm bolt on a 6.7 Cummins because he wouldn't put any oil on the threads. He said the manual didn't say to and that's how he's always done it. How do you convince someone that a dry torque reading is completely wrong for these engines?

Switched from used oil analysis to filter cutting last year and never looked back

I used to just send oil samples off to Blackstone every change and hope for the best. But after a 2018 Cummins ISX ate a camshaft on me, I started cutting every oil filter open with a bandsaw to look for debris. Now I can spot bearing flakes or ring material right there in the shop. Has anyone else found metal in their filters that the oil report missed entirely?

Had to pick between a junkyard motor and a reman for my 5.9 Cummins

Threw a rod in my '02 Ram last month and had to make the call. Junkyard motor was $1,200 with 180k miles on it, no warranty. Reman from the local shop was $3,800 with a 2 year parts guarantee. I went with the reman because I didn't want to gamble on someone else's problems. Got it dropped in last week and it runs smooth, no leaks, oil pressure is solid at idle. Has anyone else seen those junkyard motors hold up long term or is that just asking for trouble?

I used a zip tie to fix a coolant leak on a 6.7 Powerstroke last week, and it actually held for three days.

Spent $400 on a Milwaukee M18 cordless grease gun and it's the best shop purchase I've made in years.

I used to waste so much time dragging the air hose around for a five-second lube job, but now I just grab this thing off the charger and zip around the bay in half the time. What's one tool that changed your daily routine?

Rant: My Milwaukee 2767 impact gun just gave up the ghost on a Friday afternoon

Was trying to pull a stubborn crank pulley bolt on a 6.7 Powerstroke and the anvil straight up sheared. Anyone know a better impact for heavy truck work?

Rant: A veteran mechanic told me my injector cleaning method was too aggressive

I was working on a Duramax with a rough idle and kept pulling injectors to clean them with my usual ultrasonic bath. After the third time, this old timer named Carl from the next bay said, 'Kid, you're cooking the solenoids. That bath is too hot and too long.' He showed me his method: a 15 minute soak in a specific solvent at room temp, followed by a gentle air blast, not a full pressure wash. He said the heat from my old process was degrading the internal seals over time, causing the repeat issues. I tried it his way on the next set, and the truck ran smooth for over a month now. Has anyone else found that less is more with modern high-pressure common rail injectors?

Stopped at a truck stop in Amarillo and saw the wildest 'repair' on a Peterbilt

I was grabbing coffee at the big Petro off I-40 last week and saw a guy trying to fix a coolant leak on his rig. He had the hood up and was using what looked like an entire roll of duct tape and a cut-up soda can as a patch. I watched for a minute, and he was layering it on like he was frosting a cake! He told me, 'It's holding for now, just gotta make it 200 more miles.' Has anyone else seen a roadside fix that made you just shake your head?

Spent 4 hours yesterday tracing a parasitic draw on a 6.7 Powerstroke only to find it was a bad aftermarket trailer brake controller module the owner forgot to mention.

What's the weirdest hidden gremlin you've had to chase down on a modern diesel?

Just realized my $700 scan tool was a total waste of money

I bought a fancy Autel scanner last year thinking it would save me time on diagnostics, but it barely works on the older Detroit engines we see a lot. My buddy just uses a basic OBD2 reader and a service manual, and he gets the job done faster. Has anyone else had a scanner that just didn't live up to the hype?

Pro tip: A stuck injector line on a 6.0 Powerstroke taught me to always check the little things first

I was under the hood of a truck in our shop bay, fighting with a line for an hour. My boss walked over, tapped the hold-down clamp with a wrench, and it popped right off (the bolt was just a quarter-turn too tight). Now I start with the simple stuff before I grab the big tools. Anyone else have a 'duh' moment that saved you a ton of time?

Switched to a 1/2 inch drive impact for lug nuts after years with a 3/8

I always used a 3/8 drive impact for everything, even on big truck lug nuts. Figured it was fine if I just leaned on it. Last week on a Freightliner, I spent maybe 15 minutes fighting one stubborn nut, just heating everything up. My lead guy, Frank, tossed me his 1/2 inch Milwaukee and said 'Why are you making it hard?' It zipped them all off in seconds. I guess I was just stuck in my old way. Anyone else have a tool they held onto way too long?

Question about a weird injector knock on a 6.7 Powerstroke

Had this truck with a knock that sounded like a rod but only at idle. After checking everything, I tried backing off each injector line nut one at a time with the engine running. The noise stopped when I cracked the line on cylinder 3, so I swapped that injector with a spare. Fixed it in twenty minutes, saved the guy a teardown. Anyone else used that old school trick lately?