c/diesel-mechanics

Tried to save $200 on injectors from eBay and now I'm out 3 days of work

Picked up a set of reman injectors for a 6.0L Powerstroke off eBay for $350. Looked good in the pics, seller had decent feedback. Got them installed Tuesday, truck ran rough immediately. Pulled them and sent them to a local shop to get tested - every single one was out of spec on pop pressure. Couldn't even get a refund cause the seller ghosted. Between the injectors, the gaskets I wasted, and three days of lost shop time I'm probably out close to a grand. Has anyone else had luck with eBay injectors or is it just me?

Had a conversation with an old fleet mechanic who made me realize my torque wrench habit is costing me time

He said 'you're chasing numbers that don't matter on a 30-year-old Cummins, just feel the bolt' and now I'm wondering if I've been overthinking every goddamn head gasket job, anyone else ditch the clicker and go by feel?

Pro tip: Let your injectors soak before pulling them

I fought a set of injectors on an '06 Cummins for almost 4 hours last week. Broke a puller and about lost my cool. An old guy at the shop next door told me to fill the bores with penetrating oil and let them sit overnight. Came back this morning and three came out by hand. Has anyone else had that work that well or did I just get lucky?

Old timer told me I was overtorquing cylinder heads and he was right

I had this old guy watch me torque down a 6.7 Powerstroke head last month and he told me I was going too far. I always went to 175 ft-lbs because that's what I read online but he showed me the actual spec is 160 wet with ARP lube. Tried his method on the next one and haven't had a single weep since. Kinda embarrassing to get schooled by someone twice my age but hey it saved me a comeback job. Anyone else get humbled by a veteran mechanic?

Got a bad batch of diesel at a truck stop in Ohio last fall

I filled up at a Pilot in Toledo around 3am on a Friday. By the time I got 80 miles down the road, my injectors started acting up and I lost power bad. Shop later found water and algae in the fuel, which clogged my fuel filter and cost me $600 in repairs and a tow. Now I always carry spare filters and check for water at the pump before I even fill. Has anyone else dealt with contaminated diesel at bigger chain stations?

Just found out some marine diesel engines use keel cooling instead of radiators

I was watching a YouTube video from a guy in Maine who rebuilds old lobster boat engines, and he was talking about keel cooling. Basically they run raw sea water through pipes welded to the bottom of the hull instead of using a radiator and fan. Never even crossed my mind that you could cool an engine like that without a traditional cooling system. He said it eliminates water pump cavitation issues and keeps operating temps more stable in cold water. Has anyone here ever worked on a keel cooled engine?

TIL the hard way: manual compression release vs decompression cable on an old Cummins

So I was messing with this 1992 Cummins 5.9 in a Dodge W250 last weekend, trying to get it started after sitting for 2 years. The truck had a manual compression release on the valve cover, but I'd also heard about people using a decompression cable to make it easier on the starter. I figured the cable would be smoother and less hassle, so I spent a good 2 hours installing one from a parts kit I got off eBay for $40. Hooked it all up, turned the key, and the starter just grinded and barely turned the motor over. Then I tried the old manual release - pulled that lever by hand, cranked it, and it fired right up on the second try. The cable just didn't give me the same leverage or feel. Now I'm thinking I should've just replaced the starter solenoid instead of messing with the cable. Anyone else ever try one of those cable setups and have it flop on a 12-valve?

Just realized how much a good fan clutch changes engine temps

I did a water pump and fan clutch on a 2014 Freightliner Cascadia last month. Before the swap, that thing was running 210-215 degrees even on a cool day. After I put in a thermal fan clutch from Horton, it dropped to 185 and stayed there through a full load haul. The old clutch was slipping bad and didn't pull air through the radiator. Has anyone else seen a 30 degree drop just from a fan clutch replacement?

Crankshaft pulley walked off a Cummins ISX on I-35 last Thursday

Had a 2018 Peterbilt come in with a weird vibration, thought it was a fan clutch. Got it up on the lift and the crankshaft pulley bolt had backed out almost half an inch, chewed up the keyway. What's the trick to keeping those bolts torqued on these engines without pulling the whole front cover?

Hit 10,000 hours of turning wrenches last month and it hit me different than I expected

I was just cleaning up my toolbox after a long day at the shop near Tacoma and I started adding up all the time I've spent working on diesels. Between my regular gig at the fleet yard and side jobs on weekends, I figure I crossed 10,000 hours of actual hands-on work. That's like five years of full time labor if you think about it, and for some reason that number made me realize how much I've seen go sideways. I never thought I'd be the guy counting hours like a pilot, but it got me wondering - does anyone else keep track of their total time in the shop or am I just getting weird about it?

Old timer told me my injector swap method was trash

I used to always just yank injectors out with a slide hammer on 6.7 Powerstrokes. Had a retired mechanic watch me at a shop in Denver and he said I was damaging the bores. Showed me to soak them in penetrating oil for 20 minutes and use a puller with a steady hand. Anyone else switch up their removal technique after someone called them out?

Had a moment last Tuesday troubleshooting a Cat C15 and found a cracked cylinder liner I missed the first time

I was chasing a coolant loss for hours and finally pulled the head again on a hunch. Has anyone else had a liner crack that only showed up under a certain pressure?

Chased a no-start for 3 hours yesterday, turned out to be a bad ground on the frame rail

Got a call about a 2015 Freightliner that wouldn't crank. Pulled the batteries, checked the starter, even swapped the ECM relay. After 3 hours of pulling my hair out, I noticed the main ground cable was corroded where it bolts to the frame near the front axle. Cleaned the contact spot with a wire brush and it fired right up. Anyone else waste a whole afternoon on a simple ground issue that looked fine from a glance?

Overheard a guy at the parts counter say he never changes his fuel filters

I was standing in line at the Cummins shop in Nashville last Tuesday, and this older fella in front of me tells the counter guy he's gone 80,000 miles without swapping his fuel filters. Said he just lets them ride until the truck starts acting up. I almost choked on my coffee. I've been in this trade for about 12 years now, and I've seen what happens when you push those things too far. Injectors get starved, water gets through, and suddenly you're looking at a $3,000 repair bill instead of a $60 filter change. The counter guy just nodded and sold him a set anyway, which I thought was smart. Made me wonder, is this a common thing with owner-operators trying to stretch every dollar, or just a stubborn old-timer thing? Has anyone else run into customers who outright refuse to do filter changes on a schedule?

TIL a bad ground on a 2005 Freightliner can mimic a failing ECM

Chased a no-start for 3 hours on a washout site near Amarillo. Truck would crank but not fire. Threw parts at it - fuel filter, CPS sensor. Turned out a ground strap behind the driver side battery tray was rotted clean off. One new cable and it fired right up. Has anyone else wasted a day on something that simple?

Blew a turbo on I-40 last month - stick with factory rebuild or go aftermarket?

My '96 Pete threw a turbo at mile marker 210 on the way to Flagstaff. Shop foreman says factory rebuilds are safer for the EGR system, but my buddy swears by a BorgWarner aftermarket kit he got for $1200 less. Who's had better luck with one over the other long term?

That time I thought synthetic oil was a gimmick until a customer's 450,000-mile Cummins convinced me otherwise

I always ran conventional in my own rigs but a guy came in with a 2004 Ram with 450k on it, never rebuilt, and swore by Rotella T6, so I switched my F-350 over 50,000 miles ago and the oil analysis keeps coming back clean, who else here was dead set against synthetics and got proven wrong by real world results?

Saw a fleet of garbage trucks at a rest stop last Tuesday and it clicked for me

I was grabbing coffee at a Love's off I-40 in Oklahoma and noticed five different garbage trucks all parked together. They were all different brands - a Mack, a Freightliner, a Peterbilt, and two Internationals. The drivers were just hanging out and I asked one of them about it. He said they all run the exact same Cummins ISL9 engine under the hood, just different cabs and badges. Has anyone else noticed how much badge engineering happens in the medium duty world?

After 8 years of doing wet stacking on generators, I finally saw what clean exhaust looks like

I run a shop near Tulsa that services backup gensets for a few hospitals. Last month I took a load bank test on a 500 kW Cummins that had been running at 30% load for years. The exhaust pipe had tar dripping out. After a proper 4 hour full load run the soot just vanished and the pipe turned gray. Has anyone else had luck fixing wet stacking on older units or do you usually swap the injectors first?

Cracked head on a 6.7 Cummins taught me something about coolant

I had a 2014 Ram 3500 come in last month with a cracked head. Guy had been running just water instead of coolant because he thought it was cheaper. I looked up the actual specs and found out that water alone drops the boiling point by about 30 degrees in a hot engine. That extra heat cycling is what cracked the head. Has anyone else seen damage from people skipping proper coolant mix?

Rant: Just caught myself torquing head bolts dry for 7 years before I realized the oil thing

I walked away from a job in Kansas City because of a 12V oil pump

I was on a 2005 Peterbilt in the yard and the shop foreman told me to drop the oil pan just to check a sensor he guessed at. I pulled the pan and found a broken pickup tube, but he still wanted me to R&R the whole pump as a "just in case" on my dime. Is it just me or do some foremans treat warranty time like it's coming out of their own paycheck?

Old timer told me to stop using vice grips on hydraulic fittings

Guy I work with saw me clamping a line with vice grips. He said I was gonna oval the fitting and cause a leak later. Switched to proper line wrenches and padded clamps. Been 6 months now and no more weeping connections on my repairs. Anybody else fight the urge to grab vice grips first?

Learned a hard lesson about Hydrocarbons in coolant from an old Cummins guy

I ran into a retired mechanic at a parts counter in Austin last month who told me his shop replaced 3 ISX heads that were cracked from cavitation in a single week. He showed me how to check the coolant additive levels with a simple test strip, and I realized I’d been ignoring them for two years on my own truck. Has anyone else had a head go bad from not keeping the SCA levels right?

Tried two different injector pullers on a 6.7 Cummins today

I had a stuck injector on a 2019 Ram 4500 this morning. First I used the cheap slide hammer kit from Harbor Freight and it just bent the adapter after 20 minutes of pounding. Swapped over to the OTC 7481 puller and that thing popped the injector loose in under 2 minutes without any fight. Has anyone else found a specific brand that actually works better for the newer high-pressure injectors?