c/diesel-mechanics

16

brooke_jones•3d ago

Finally replaced the injectors on my 7.3 after putting it off for 2 years

Was blowing white smoke bad on cold starts for the last 6 months, drove me crazy. Took a whole Saturday last week in my buddy's shop in Tulsa to swap all 8 injectors out, and now it fires up like a dream. Anyone else drag their feet on jobs like this just because they're dreading the labor?

15

phoenix_grant•3d ago

Had a conversation with a retired fleet mechanic that got me thinking about tolerances

I was swapping out a fuel pump on a 2005 Freightliner last week, and this old guy who used to work for a trucking company in Dallas walked up. He watched me torque the bolts down and said I was overdoing it, that I should trust the gasket more. He explained how he'd seen guys crack housings from cranking too hard, and it hit me that I've been treating every bolt like it's a head stud. Has anyone else had to unlearn bad habits from being too careful?

18

iris_schmidt•4d ago

Switched from adjusting valves with feeler gauges to doing it by sound 6 months ago

I used to spend 45 minutes on every valve adjustment with a set of feeler gauges on my Cummins ISX. Then a shop foreman in Des Moines told me to listen for the lash instead. He had me set the first one at .015 and then tap it until I heard the right click. Now I do a full 6-cylinder adjustment in 20 minutes flat and I haven't had a single comeback. Has anyone else tried going by ear on overhead adjustments?

7

blair_chen81•5d ago

Warning: Check your fan clutch before you get stranded on I-40

I was rolling down I-40 outside of Nashville last Thursday when my temp gauge started climbing fast. Pulled over and found the fan clutch was completely seized up, bearings shot and everything. Had to call a buddy with a wrecker to tow me 30 miles to a shop in Jackson. Cost me $450 for the part and labor plus the tow bill. Anyone ever had a fan clutch fail that suddenly on a Cummins ISX?

21

danielm80•5d ago

That old timer at the shop told me to use ATF in my injector pump and it actually worked

He swore by a quart of Dexron III in the fuel tank every 3,000 miles to keep the plungers lubed on my 7.3 Powerstroke, and after 6 months of doing it the injector stutter is completely gone has anyone else heard of this trick?

24

simon_carr•9d ago

Stopped at a shop in Bakersfield and saw an engine hoist rigged with bungee cords

The whole shop had that greasy smell of diesel and sweat. I stood there for a solid five minutes watching him work under that load like it was nothing. He said he learned the trick from his grandpa who ran a fleet of old Fords. I get that sometimes you use what you got, but bungee cords on a engine hoist feels like tempting fate. The part I needed was a injector seal that cost me 12 bucks, but the lesson I got that day was free.

28

simonk98•9d ago

Threw $600 at a used injector cleaner machine and it paid for itself in a month

Picked up a beat-up ultrasonic cleaner off Craigslist from a shop in Akron that was closing down. Ran a set of crusty HEUI injectors through it and got them working like new instead of spending $4k on replacements. Anybody else grab secondhand shop gear that actually worked out?

4

max_cooper21•9d ago

Watched a guy spend 90 minutes trying to start a Cummins with a bad lift pump

I was at a truck stop outside Flagstaff last Tuesday and instead of checking the fuel pressure first, he swapped the starter, alternator, and batteries before finally asking me for help, so has anyone else seen people skip the basic tests and burn a whole day on parts that were fine?

29

jenny_lane12•12d ago

Took a before and after shot of a 6.7 Powerstroke oil cooler swap

I did a coolant filter and oil cooler job on a 2015 Ford F-250 last Tuesday in Austin. Before the swap it was running 230 degrees on the EOT vs 195 on the coolant on a hot day. After the new cooler and a flush the temps dropped to within 10 degrees of each other. Anybody else seen that big a difference on these trucks or was mine just especially clogged?

18

wood.uma•14d ago

Finally ditched my old timing light for something newer

Used to do timing by ear on my older trucks, just guessing and going by the sound. Last month I got a digital inductive timing light from the NAPA in Tulsa for around $80, and it's way more accurate. Took me maybe 15 minutes to set the injection pump on a 5.9 Cummins right the first time instead of messing around for an hour. Anyone else hold onto old tools too long before upgrading?

21

zara_sanchez•14d ago

Spent 6 hours chasing a ghost in a Cummins ISX at my shop in Phoenix

Last week I had a 2014 Peterbilt come in with this weird intermittent power loss. It would run fine for like 20 miles then just fall flat on its face. I checked fuel pressure, changed filters, even pulled the turbo actuator to test it. After six hours of poking around I finally found a tiny chunk of rubber clogging the fuel return line back near the tank. It was a piece of old hose that must have broken off years ago. Has anyone else had a small trash piece like that drive them crazy?

18

felixm29•15d ago

I think modern OBD2 scanners have made us lazy troubleshooters

Been at this since the early 90s and I can tell the difference from 2010 onward - guys plug in a $500 scanner, get a code, and throw parts at it without ever looking at the engine with their own eyes. I watched a kid spend 3 hours swapping sensors on a Cummins ISX in Nashville last week when it was just a chafed wire hidden under the harness. Has anyone else noticed the younger guys skip the basics like checking oil pressure or doing a cylinder cutout test first?

1

stella22•15d ago

Stopped at a truck stop in Ohio last week and saw a mechanic rebuilding a Detroit 60 series with zip ties and duct tape holding the valve cover gasket in place

Has anyone else run into these shadetree field repairs on fleet trucks or is it just me seeing this stuff more often?

3

ward.anna•18d ago

Spent 4 hours chasing a ghost in a Freightliner engine bay near Amarillo

Found a blown fuse hiding under a corroded wire loom that looked fine from the top. Took three test drives and a call to my dad before I spotted it. Anybody else ever waste a whole day on something stupid like a fuse?

9

robinp89•19d ago

Chased a fuel pressure drop for two days on a 3126 Cat.

It ended up being a tiny piece of trash in the check valve at the transfer pump. Bled the system like ten times before I pulled the pump and actually looked at it. Anyone else ever had something that simple turn into a whole weekend project?

31

carter.mila•20d ago

Stopped by a truck stop in eastern Wyoming and watched a guy rebuild an injector pump with a butter knife

I was grabbing coffee at a Love's outside of Cheyenne last Tuesday when I noticed a driver working on his old Freightliner in the parking lot. He had the injector pump spread out on a newspaper on the ground, using a butter knife to pry off the delivery valve holder. I walked over to ask if he needed a hand and he just laughed, said he'd been doing it this way since 1998. Turns out he was a retired fleet mechanic who still refused to buy the proper tool for the job. He had the whole thing back together in under 20 minutes and the engine fired right up. Has anyone else seen a roadside repair that made you cringe but also kind of admire the resourcefulness?

16

young.michael•21d ago

I think guys are sleeping on acetone for fuel system cleaning

Everyone I know swears by that Diesel-Kleen stuff but I've had better luck with plain acetone at $12 a gallon for clearing injector deposits. Has anyone else actually tried it on a high-mile Cummins or am I just getting lucky?

13

lucast81•24d ago

Update: I chose to rebuild the injection pump on a 6.0 Powerstroke instead of swapping it

The customer's truck had a classic low power complaint and the pump was showing 500 psi on the stand test. I was looking at a $2200 reman unit with a core charge or about $400 in parts and seals to rebuild it myself. I went with the rebuild, spent a full Saturday on the bench, and got the pressure back up to 3100 psi. It's been running solid for three months now. For those of you who've been in this spot, when do you decide a rebuild is worth the time versus just installing a new unit?

21

charles720•24d ago

Had to pick between a full rebuild or a used engine for a 6.0 Powerstroke

Customer's F-350 with a 2005 6.0L came in with a blown head gasket and suspected cracked heads. The quote for a full rebuild with studs and new heads was pushing $8,500. I found a low-mileage used motor from a salvage yard for $4,200. We went with the used engine to save money, but after three weeks it started showing the same low power and white smoke. Now we're back to square one with a bigger bill. Has anyone else had a used 6.0 turn out to be a total gamble like this?

9

fionafoster•24d ago

Listening to a farmer talk about his old tractor made me rethink rebuilds

I was grabbing coffee this morning and this older guy at the next table was telling his friend about his 1985 John Deere 4440. He said, 'I've rebuilt that injection pump three times myself. The book says replace it, but I know its quirks.' It stuck with me all day. We get so focused on the manual and the 'right' way, swapping parts for new ones. But sometimes, the real fix is knowing a machine's specific history and personality. That pump might have a worn cam ring that needs a shim from an old kit, not a whole new unit. It made me realize I've been too quick to write off some older units as not worth the time. Maybe I should listen more to the guys who've lived with a rig for 30 years. Has anyone else had a machine where the 'wrong' fix was the only thing that worked long term?

10

quinn606•24d ago

Was reading an old service manual and the torque spec for a 6.0 Powerstroke head bolt was way lower than I expected

I was flipping through a 2005 Ford binder in the shop and saw the final torque for the M11 bolts listed at 120 ft-lbs, not the 140 I've always done. Found it on page 04-10 under 'cylinder head removal and installation'. Did they revise that spec later on, or was I just taught wrong from the start?

5

maxl93•26d ago

I used to think cleaning injectors with a bench setup was a waste of time

For a long time, I'd just swap in a reman injector if I had a rough idle or low power code on a 6.7 Powerstroke. It was fast, and the customer got a fix. But about a year ago, I got a truck from a local farm that had three bad injectors. The quote for three new ones was over $900 just for parts. I decided to pull them and run them through our old Snap-on bench cleaner and tester. Two of them cleaned up perfectly within spec after three cycles. The farmer saved over $600. Now, unless an injector is physically damaged, I test every single one. It adds maybe an hour to the job, but it's the right call. Has anyone else moved from just replacing parts to actually trying to fix them first?

13

henryt18•27d ago

Switched from a standard 3/8 impact to a Milwaukee mid-torque for lug nuts

I was always using my old 3/8 impact on truck lug nuts and it would just click away forever. Grabbed a Milwaukee 2962-20 mid-torque last month and it zips them off in seconds, even on a frozen F-550 from our last big snow. The extra power and the right socket size just makes the whole job faster. Anyone have a go-to tool for stubborn wheel work?

18

kai_chen2•28d ago

Changed my mind on using the same oil for every diesel engine

I kept seeing guys at the shop just grab the 15W-40 jug for everything, from old farm tractors to new pickups. Figured it was fine. Then we had a 2021 Duramax come in with a sticky turbo actuator. The owner said he'd been using that same oil. Checked the manual, it specifically calls for a low-ash CK-4. The wrong stuff can clog up the newer emission systems. Anyone else run into this with the latest models?

3

angelam80•29d ago

Rant: Saw a brand new dump truck at the county fair with the fuel cap left off

I was at the Orange County Fair yesterday and a brand new Freightliner dump truck in the equipment display had its diesel cap just sitting on the fender, not screwed on. The whole tank was open to dust and moisture for who knows how long. How does something that basic get missed on a rig that costs over $150k? Do you guys see this kind of careless prep from dealers often?