c/diesel-mechanics

Showerthought: I just learned how much torque a big rig's starter motor puts out

I was watching some old truck restoration show on YouTube last night, and the host said a typical 12-volt starter for a big diesel can crank out over 30 pound-feet of torque. That's more than some small car engines make, just to get the thing turning over. It blew my mind a little, thinking about the sheer force needed just to start the engine before it even fires. Has anyone else come across a random fact about our gear that made you pause and go 'huh'?

A guy at the truck stop in Boise called me out on my fuel filter routine

I was always just swapping them every 10k miles like clockwork, no questions asked. This old-timer saw me grabbing a box of them and said, 'Kid, you're tossing good money if you don't check the water separator first.' He was right. Now I drain the bowl and check for water every 5k, and I've stretched my filter changes to 15k without a single issue. How many of you actually check the separator before you just swap the whole thing?

Watched a guy at the shop try to clean injectors with carb cleaner

He was working on a 6.7 Powerstroke and just sprayed the whole thing down. Carb cleaner eats the seals on modern diesel injectors, it's not the same as an old gas engine. I had to stop him before he put it back together and wrecked a $400 part. How do shops not teach this basic stuff anymore?

A trick for those stubborn 6.7 Powerstroke turbo bolts that saved my weekend

I was doing a turbo swap on a 2015 F-250 last Saturday and hit the usual wall... the two lower bolts on the up-pipe flange were totally seized. I’ve broken them before and it’s a nightmare. This time, instead of just cranking on them with a long breaker bar, I tried something different. I got the engine up to full operating temp, shut it off, and then immediately sprayed the bolts with a penetrating oil made for high heat. I let it sit for about 10 minutes while the metal was still hot and expanding. The heat pulls the oil right into the threads. I got them out with steady pressure and no snapping. It was the difference between finishing the job that day and ordering a whole new up-pipe assembly. Has anyone else found a good method for these specific bolts when they’re cold?

Vent: An old farmer in Nebraska told me I was overthinking a fuel line leak

I was out on a farm call near Grand Island last fall for a balky John Deere 8R. Found a weep at a fuel line fitting that had me ready to pull the whole manifold to replace a gasket. The owner, a guy who must have been 80, watched me for a minute, then just said, 'Boy, you got a tube of Permatex 2 in that truck?' I said yeah, and he told me to clean the threads, put a thin bead on, and torque it back down. Said he'd been doing that on that same tractor for twenty years. I was skeptical, but it worked. No leak. It wasn't the 'right' fix by the book, but it got him back in the field that afternoon. Ever have a customer hand you a fix that goes against everything you were taught, but it just works?

Showerthought: I was cleaning out my old toolbox from my first rig in '08 and found a set of feeler gauges that were basically new. Realized I haven't touched them in maybe 7 years because everything's got a sensor now.

My instructor at the trade school said 'a clean shop is a safe shop,' but the best mechanic I know works out of a bay that looks like a bomb went off. What's the real deal?

Overheard a guy at the truck stop in Flagstaff bragging he never changes his fuel filters

He was telling his buddy his 6.7 Powerstroke has gone 60,000 miles on the original filters and 'runs fine'. I just shook my head and kept walking. That's a $10,000 injection system waiting to grenade. Has anyone actually seen one fail from that, or do they just get lucky until they don't?

I thought those cheap Bluetooth code readers were junk until my buddy's truck threw a code on a job site

He pulled out a $40 OBD2 scanner from Amazon and paired it with his phone. We pulled the P0087 code for low fuel rail pressure right there in the field, which saved us from towing it back to the shop blind. I was sure you needed a $2,000 scan tool to get anything useful, but that little thing pointed us straight at the lift pump. Has anyone else had a good run with one of those budget scanners on a modern diesel?

Just fixed a 6.7 Powerstroke that was down on power for months

The truck came in from a farm in Salinas, it had been running rough since spring planting. We chased our tails for a while, but the real fix was the MAP sensor tube. It was full of soot and oil blow-by, basically choking the computer with bad data. Cleaned that little tube out, cleared the codes, and it ran like a top. Anyone else seen a simple clog cause that much of a headache on the newer engines?

Finally swapped my old 3/8-inch drive impact for a 1/2-inch Milwaukee Fuel after struggling with a seized 2008 Duramax hub nut for an hour.

The extra torque made the job take about 30 seconds, but now I'm wondering if I should have just gone straight for a 3/4-inch drive for future heavy truck work.

Used to just eyeball valve lash on our fleet's 6.7 Cummins, but after a rough idle on unit #7 last month, I started using a go/no-go feeler gauge set.

The old way was fast but inconsistent, and we had one injector rocker arm get way too loose over 15,000 miles. Now I check every 10k with the gauges and torque to spec, which takes an extra 20 minutes per engine. Do you think the extra time is worth it for preventative maintenance on high-mileage rigs?

I think the 6.7 Powerstroke oil pan design is actually a decent setup

Just did a full reseal on a 2017 F-250 last week, the one where you have to drop the front axle. Everyone groans about it, but it took me and my apprentice 4.5 hours start to finish with a lift. The gasket kit was $120 and we had zero leaks after. It's a straightforward job if you're organized and have the right socket extensions. What's a diesel job you think gets more hate than it deserves?

TIL a trick for getting a seized turbo housing off a 5.9 Cummins

Heated it with a torch for about 30 seconds while tapping the flange with a brass hammer, and it popped right off after I'd been fighting it for an hour. Anyone have a different method for those stubborn ones?

Had a weird injector issue on a 6.7 Powerstroke last Thursday

It was on a 2015 F-250 that came in with a rough idle and white smoke. The scan tool said cylinder 3 was misfiring, but all the electrical checks were fine. I pulled the injector and found the nozzle tip was actually cracked, something I've only seen a couple times before. Has anyone else run into a cracked injector tip causing a misfire code without a clear electrical fault?

Had to pick between a new torque wrench or a used one from a retiring mechanic's sale.

Went with the used Snap-on, and after checking it against a master gauge, it's still dead on after 15 years. Anyone have a good source for rebuild kits for the older click-type models?

PSA: My torque wrench was lying to me for months

I was putting a head back on a 6.7 Powerstroke last Tuesday and the bolts just didn't feel right. Turns out my digital Snap-on wrench, the one I paid over $600 for, was reading 20 foot-pounds low. I checked it against a master gauge at the tool truck and my heart sank. I had to pull the head back off and start over. Has anyone else had a digital torque wrench go bad like that without any warning?

Pro tip: I was using the wrong size socket on fuel line fittings for way too long

Honestly, I was working on a Duramax injector line last Tuesday and kept rounding off the same fitting. I must have tried three times, getting more mad each time. My old man stopped by the shop, watched me for a minute, and just said, 'That's a 12-point, son. You're using a 6-point.' I felt like a total fool. I'd been grabbing the 6-point because I thought it had a better grip, but it was just chewing up the corners. Switched to the right socket and it came off smooth as butter. I guess I just got stuck in a habit from working on older stuff. Has anyone else had a simple tool choice mess up a whole job like that?

My old boss swore by a 5-gallon bucket for parts, but a magnetic tray changed my life

I spent a whole day on a Detroit 60 Series rebuild fishing bolts out of a bucket, dropped a 10mm socket in the oil drain pan. Grabbed a $15 magnetic tray from Harbor Freight and haven't lost a single piece since. What's your go-to for keeping small parts from vanishing?

I was over-tightening injector lines for years without knowing it

I was working on a Duramax in my shop on Tuesday, putting the fuel system back together. My old boss always said 'tight is tight' and I'd crank those lines down hard. This time I used my new torque wrench set to 44 ft-lbs like the book says, and it felt way lighter than my usual muscle. The tip off was seeing a tiny crack in a line nut on an old core I had laying around. How many have I stressed like that? Anyone else have a 'book spec' moment that went against what you were taught?

Spent a whole day chasing a coolant leak on a 6.7 Powerstroke that wasn't there

Customer complaint was a slow drip under his F-250. Pressure test showed nothing, dye test showed nothing. Finally found the 'leak' was just AC condensate dripping onto a crusty oil spot from a past valve cover gasket job, making it look fresh. Took me 8 hours to figure that out. Anyone else ever waste a ton of time on a problem that turned out to be something stupid like that?

Finally cleared 1000 hours on my personal scan tool without a single software crash

That's a full year of daily diagnostics on everything from farm tractors to city buses. Has anyone else had a tool just quietly become completely reliable like that?

Saw a guy at the shop yesterday using a 3/4 inch impact to seat a wheel bearing.

He was really cranking on it, and I had to tell him that's a great way to crush the cage and ruin the whole assembly before it even gets on the truck. I learned the hard way on a Pete 379 last year that you should only use hand tools for that final seating torque. How do you guys handle bearing installs to avoid that kind of damage?

Pro tip: A frozen job site in Fargo taught me to always pack a second block heater

Got sent out to a construction yard in Fargo last January. It was minus 20, easy. The main generator for the site lights was a big Detroit 8V92. My usual block heater cord was plugged in, but the outlet on the pole was dead. Found out the crew had overloaded the circuit the night before. I was stuck. My boss had to drive 45 minutes to bring a portable propane heater so we could even get the oil warm enough to turn over. Lost half a day of work and the whole crew was standing around. Now I keep a spare 1500-watt magnetic block heater in my service truck, along with a 50-foot heavy-duty extension cord. It cost about $120, but it has saved my butt twice since then. What's your go-to backup for a dead cold start when the usual setup fails?

Saw a truck stop in Bakersfield with the worst fuel filter setup I've ever seen...

I was grabbing coffee at a spot off the 5 last week and watched a guy trying to change a primary filter on a late-model Duramax. He had the housing completely off the block, just dangling by the lines, and was trying to wrench it from underneath with a pair of channel locks. No drain bowl, fuel was dripping right onto the hot exhaust. I had to walk over and tell him to at least crack the water drain first... how do people get this far without knowing the basics? Ever come across a repair that just made you shake your head?