c/diesel-mechanics

12

olivermason•21h ago

My coolant flush machine broke down and I thought I was toast

Picked up a used coolant flush machine at auction last month for $200. Saved me tons of time on the first few jobs but the pump gave out halfway through a big fleet job last week. Had to finish flushing a dozen trucks by hand with a bucket and a hose. Cost me an extra 6 hours of labor. Has anyone else had luck fixing those pumps or should I just pony up for a new one?

3

charlies37•2d ago

Lost a whole morning on a coolant leak that was sitting right in front of me

Last Tuesday I was working on a 2015 Freightliner Cascadia at the shop here in Tucson. Spent about 3 hours chasing what I thought was a bad water pump, pulling hoses, checking the EGR cooler. Turned out it was just a loose clamp on the lower radiator hose that I tightened the day before but forgot to double check. Has anyone else had a simple fix eat up half their shift before you finally looked at the obvious spot?

4

flores.emma•2d ago

Old mechanic at a pilot in Ohio told me something that stuck

I was changing a fuel pump on a 2001 freightliner outside Columbus and this retired guy comes over, watches for a minute, then says "you're fighting the rust instead of working with the patience." He showed me how to tap the bolts a certain way with a brass punch and they came loose in half the time... has anyone else had an old timer drop a simple trick like that on you?

14

evan_davis•3d ago

Old timer at a truck stop taught me a fuel filter trick I still use

Back in 2019 I was changing a fuel filter on a Freightliner at a Flying J in Ohio and this crusty old mechanic walks over, says "you're bleeding it wrong kid." He showed me to crack the bleeder screw on the housing and crank the starter for 3 seconds instead of pumping the primer a million times. Has anyone else gotten a random tip from a stranger that actually works better than the book way?

10

kellygrant•3d ago

A customer told me my injector tick was just 'normal noise' for a year

I had a 2015 Cummins come in last month with a loud tick at idle. Customer said his buddy told him it was normal until he blew a hole in a piston. I pulled the valve cover and found a cracked injector hold down clamp. Swapped all six injectors with reman Bosch units and the tick disappeared instantly. Now I tell every owner with a 6.7 to bring it in if they hear anything different on cold starts. Anyone else run into injector issues that sounded like a valve tick?

14

young.michael•4d ago

Switched to synthetic gear oil and saw a 15 degree temp drop in 6 months

Been running the same 18 speed Eaton Fuller in my Pete for about 4 years now. Always used conventional 80w90 and had to baby it on long grades during summer. Switched to a full synthetic 75w90 last winter and after 6 months of hauling I'm seeing transmission temps drop 15 to 20 degrees on the same runs from Portland to Spokane. The shifting feels smoother too especially when cold. Anyone else notice a real difference going synthetic in their transmissions?

21

logan_wood•4d ago

Spent 5 hours chasing a ghost injector issue on an 05 Cummins

Had this 5.9 in the shop last Tuesday, rough idle but no codes. Pulled my hair out for hours checking fuel pressure, swapping sensors, even pulled the valve cover to look at the rockers. Turned out to be a chafed wire on the injector harness under the intake horn, took maybe 20 minutes to fix once I spotted it. Anyone else ever wasted a whole day on something dumb like wiring instead of a real mechanical problem?

1

abby_cooper•5d ago

Spent 6 months using the wrong oil filter because the parts guy swore it fit

Was working on a 2005 Freightliner Cascadia at the shop in Phoenix and kept having oil pressure issues after every change. Finally had an old timer come over and point out the filter was about half an inch too short, letting crap bypass the media. Turns out the parts store gave me a filter for a different Cummins model and I just trusted their computer system. Has anyone else had a parts counter guy lead them totally wrong like that?

21

troyknight•7d ago

Hit 500,000 miles on my old Cummins this morning and it actually caught me off guard

I was rolling into a yard in Bakersfield to unload and glanced down at the odometer. Half a million miles on a 12-valve that still starts every time without fail. Never thought I'd see that number on a truck I bought for $3,500 with 180k on it back in 2008. The funny thing is I never did anything special to it, just regular fluid changes and replaced the injectors once around 300k. Anyone else have a truck that just refuses to die way past what you expected?

6

keith274•8d ago

Went with a used ProMax pump over rebuild kit and kinda regretting it

Had a old CAT pump on my service truck that finally gave out after 3000 hours so I had to decide between a $1400 rebuild kit or a $900 used ProMax off Facebook. I figured saving $500 was worth the risk but now the used one is leaking past the packing after only 12 hours of use. Anyone else try buying used pumps and end up kicking yourself for not just rebuilding the original?

9

nelson.wren•10d ago

That old timer who told me to always torque head bolts by feel was dead wrong

After I snapped two ARP studs on a 6.0 Powerstroke following his advice and had to pull the heads again, I learned the hard way that $75 for a proper torque wrench would have saved me a full weekend of work, has anyone else gotten bad advice from the old guard that cost them time and money?

15

adam_baker•11d ago

Saw a kid rebuilding a 12-valve with a torque wrench from Harbor Freight

He was cranking down head bolts like they were lug nuts. Told me the click was just a suggestion. Anyone else notice new guys don't respect torque specs on these old Cummins?

9

bailey.jennifer•11d ago

Overheard a shop foreman say something that made my blood run cold

I was grabbing parts at the counter yesterday and heard the foreman from the shop next door tell his apprentice "just run that rod up to 80 ft-lbs, it'll hold for now." That was for a head bolt on a 2018 Cummins ISX. I didn't say anything but I walked away thinking about how many engines get ruined by shortcuts like that. Has anyone else caught someone doing dangerous torque specs and not known what to say?

20

wade_kelly77•13d ago

Was sure injector cleaning was a scam till I did one on my 7.3

Had a 2000 F-250 that was running rough and smoking like crazy. Buddy kept telling me to pull the injectors and clean em but I thought he was full of it. Finally caved after the truck died on me at a light in Charlotte last Thursday. Pulled em, soaked em in cleaner for 2 hours, put em back and now it runs smooth as silk. Anyone else have a job they put off forever that turned out to be dead simple?

32

kellygrant•14d ago

Spent 4 hours chasing a no-start on a 5.9 Cummins, turns out it was the fuel heater relay

I mean, I was ready to pull my hair out. The truck would crank but wouldn't fire, and I checked everything - pump pressure, injector pulse, even pulled the valve covers to look at the rockers. My buddy kept saying 'check the stupid little stuff' but I was convinced it was something major. After 4 hours, I finally looked at the wiring diagram and saw the ECM kills the lift pump if the fuel heater relay grounds out. One $18 relay later and it fired right up. Has anyone else had a tiny electrical gremlin eat up a whole afternoon?

33

gracethomas•14d ago

Shoutout to the old timer who told me to stop being lazy with bearing preload

Had a guy at a truck stop in Billings chew me out for just torquing wheel bearings to spec without checking end play. He said I was gonna cook the bearings in 20k miles. So I started using a dial indicator every time, even on trailer hubs. Has anyone else had a customer fight you on paying for that extra 15 minutes of work?

16

spencer_gonzalez1•17d ago

Best week I ever had was 2017 pulling a blown 6.7 out of a beat up F-450

Buddy's truck dropped a valve on I-35 Tuesday morning, had it torn down by Thursday night. Friday we pulled the whole thing in under 6 hours with just a cherry picker and a come-along. Has anyone else had a job where everything just clicked like that?

18

theas28•17d ago

Heard a shop foreman say 'you either fix it once or fix it five times' and got me thinking about torque specs

Some guys at my shop swear by just gut-feeling the final torque on injector hold-downs while others follow the book down to the pound. Which side do you lean on when you're under the gun on a job?

30

abby_morgan18•19d ago

Found out my shop's 'certified' mechanic never passed the Cummins test

I was digging through old training records last week and found out one of our senior guys never actually passed his Level 2 Cummins certification. He just kept retaking the prep course and claimed he got it. Now I'm stuck wondering if I should snitch to management or let it slide since he does decent work. What would you do in my shoes?

25

charles_baker28•19d ago

Drove 3 hours to a shop that claimed they were 'certified' on Cummins engines

Last month I towed my truck to a place outside St. Louis because their website bragged about being Cummins certified specialists. Turns out their cert was a 2 day online course and the mechanic couldn't even tell me the torque specs on a head bolt without looking at his phone. Has anyone else run into shops that slap a certification sticker on just to charge more?

15

richard_young80•20d ago

Was dead set against synthetic oil in my 7.3 Powerstroke until I pulled the heads at 280k

Old timers always told me these motors need conventional or they'll leak, but after I pulled my valve covers the sludge was way less than my buddy's truck that ran Rotella 15w40 its whole life. Anyone else get converted by seeing the inside of a high mile motor?

3

olivia670•21d ago

Debate: is it better to rebuild an injector or just swap in a reman?

I had a 6.0 Powerstroke that was acting up last spring, so I pulled the injectors. Rebuilding them myself with new seals and nozzles cost me around $120 for the whole set, but a reman set was like $800. The rebuilt ones ran fine for 3 months, then started stuttering again. Now I'm wondering if I just wasted my time. For you guys who do this full time, do you rebuild or go with remans? What's your rule of thumb on that?

28

young.thomas•22d ago

Just crossed over 500 engine rebuilds and still don't trust factory torque specs

I been doing diesel engine work for about 12 years now and last month I finally hit my 500th rebuild on an old CAT 3406. Every single time I've seen a factory torque spec fail on head bolts or main bearings, so I always add 5 ft-lbs and go over them twice. Has anyone else had factory torque numbers let them down more often than not?

21

elliot_roberts•23d ago

Those cheap aftermarket injectors from eBay cost me $1,200 in labor and towing after they failed in 3 months

I rolled the dice on a set of reman injectors for my Cummins for $400 instead of $1,200 for OEM, and by the time I paid for a tow from Cheyenne and extra shop time to swap them again, I ended up spending more than if I'd just bought the good ones from the start - anyone else been burned by budget rebuilds?

7

rodriguez.mia•26d ago

Should have trusted my gut on that injector cup leak

Had a 6.0 Powerstroke with a slow miss that took me 3 full days to track down. Ended up being a cracked injector cup that only showed up after I pulled the rail and pressure tested it individually. Anyone else fight ghost leaks that waste a whole weekend?