c/diesel-mechanics

Drove past a shop outside Boise that had a sign saying 'we fix anything with a diesel'

Pulled over to ask about an old generator I've been fighting with. Guy behind the counter spent ten minutes telling me about a 1972 Cat dozer they just rebuilt from the ground up. Said they found a mouse nest in the oil pan that had been there since the 80s. Made me feel better about the mess I deal with daily. Anybody else ever find something weird inside an engine that shouldn't be there?

Unpopular opinion: I think pre-filling your fuel filters is overrated

I've been doing dry installs on my CAT C15 for the last 6 months and haven't had a single air lock issue. Anyone else skip the messy pre-fill step?

10 years of fuel filters and I just learned I was priming them wrong

I always filled the filter housing to the brim before installing it on my 6.7 Cummins thinking I was doing it right. Last week a buddy watched me and pointed out I was bypassing the water separator by not bleeding the air from the secondary filter. Any of you guys ever mess up a simple step for years without realizing it?

Finally caved and bought one of those fancy coolant refractometers for $45

Old school trick I still use for tough injector cups

Been doing this 15 years now and I still see guys fighting with injector cups on older Cummins engines. My old mentor showed me this back in 2010 on a job in Denver where a cup was stuck bad. We got a cheap induction heater from Harbor Freight and heated the cup tube for about 45 seconds. Came right out with just a slide hammer and no drama. Anybody else got a weird one-off trick that still works way better than the fancy tools?

That old mechanic's trick about diesel fuel additives nearly cost me an engine rebuild

My buddy at the parts counter swore by adding two stroke oil to every tank of diesel to 'lubricate the injectors', so I ran it in my 2015 Cummins for about 8 months straight. Last week when I pulled the injectors for a leak test, three of them were completely coked up with carbon deposits from that oil burning wrong. Has anyone else seen long term damage from running that two stroke oil trick on a common rail system?

Heard a fleet manager say something about air dryers that stuck with me

Guy I know who runs 30 trucks said he replaces desiccant cartridges twice as often as the manual says and he hasn't had a wet brake can in 4 years. Anyone else running a shorter change interval and seeing results?

That Tuesday that turned into a nightmare with a blown injector cup

Last month I had a 6.0 Powerstroke come in that fought me for three straight days. The customer said it just needed a simple injector job, but when I pulled the cups, one was corroded and started leaking coolant into the oil. I spent 8 hours on a Tuesday alone trying to get that cup out without destroying the head, using a slide hammer and then heat, and it finally popped at 4 PM. The whole job ended up taking 27 hours total, which is way over what I quoted. Have you ever had a simple job turn into a multi day battle and how do you handle re quoting the customer?

Rookie mistake with a fuel injector job almost cost me a 6.7 Powerstroke

I was swapping injectors on a 2017 F-350 at my shop in Phoenix last Tuesday. Got one of the hold-down bolts torqued wrong and cracked the injector body as soon as the truck fired up. Fuel started spewing everywhere and I had to shut it down fast, then spend $300 on a new injector and a tow bill. Anyone else had a fuel system job go sideways over something this small?

Hot take: I don't think compression release brakes are worth the hassle on smaller rigs

I was reading through a forum debate last night and someone dropped a stat that surprised me: modern diesel engines with VGT turbos actually build enough back pressure that compression release brakes only add like 10% more stopping power on loads under 20k lbs. Found it in a thread on TruckersReport. For the cost of installation and maintenance, I'd rather just use the service brakes harder and save the $1,500. Am I missing something?

Finally got a 24-valve Cummins to fire after a full rebuild, took 6 hours of cranking and troubleshooting

Had a 2001 Dodge 3500 that sat for 2 years before I touched it. Turned out a ground wire on the ECM was corroded almost through, swapped it and she lit right up. Anyone else run into weird electrical gremlins on these 24-valve trucks?

Talked to a old school mechanic who changed my mind about oil change intervals

Was helping a buddy swap a transmission in his '98 F-350 last weekend and his neighbor came over, dude's been turning wrenches since the 70s. He looks at my oil jugs and says I'm wasting money changing every 3k miles on my newer truck, said the oil analysis I did at 5k showed it was still good. He explained how modern oils and engines don't need that short interval unless you're running heavy loads or idle all day. Now I'm questioning everything - anyone here actually do oil analysis or just stick with the old rule?

TIL a cracked injector line can make a 6.0 Powerstroke run like it's got a miss

I spent a whole Saturday chasing a miss on a 2006 F-350. Checked the ICP sensor, tested the FICM voltage, even pulled valve covers to look at rockers. Turned out it was a hairline crack on the #5 injector high pressure line that only showed up when the engine got hot and expanded. I only found it because I let the truck idle in the dark and saw a tiny flash of fuel mist catching the headlights. Has anyone else found phantom issues by just letting the engine sit at night?

Why do I keep seeing guys say to always torque injectors to 100 ft-lbs on a 6.0L?

I've had three people this month tell me that's the spec, but the Ford manual says 25 ft-lbs plus a 75 degree turn, so are you all just guessing or did I miss a TSB that changed it?

I finally changed how I torque heads after a shop owner ripped me apart

Guy told me I was using the torque wrench wrong on Cummins ISX heads, said I need to go slow and steady not just crank till it clicks. Been doing it his way for 6 months now, anyone else had to unlearn bad habits from old shops?

Why does nobody talk about how much fuel a bad alternator can waste?

I was working on an older Freightliner last week, a 2001 model with a Cummins N14, and kept chasing a low fuel economy issue. The owner was complaining about 4.2 mpg on a good day, which felt way off for that engine. After checking injectors and pumps, I finally put a load tester on the alternator and it was only putting out 12.2 volts. The ECM was running in a power-save mode trying to keep voltage up, dumping extra fuel to compensate. I replaced the alternator with a 160 amp unit, and within a week he messaged me saying it jumped to 5.8 mpg. That's a 40% difference from one bad charging component, and I'd never seen that stat in any manual or forum before. Has anyone else run into weird fuel economy killers like this?

I used to think injector balancing was all hype...

Been running a 5.9 Cummins for 8 years and always just threw injectors in and called it good. Until last month when a shop charged me $200 for a balance test and the truck started like a dream. Still think it's overpriced for a daily driver, but for a work truck it makes a real difference. Any of you guys balance injectors on older motors or just send it?

Had a supervisor tell me my injector timing was off by 2 degrees, changed everything

I was doing a routine rebuild on a Cummins ISX at my shop in Tulsa and the boss came over, watched me set the timing, and said I was chasing the wrong mark on the gear train. Turned out I'd been using the camshaft timing mark instead of the injector drive gear mark for like 6 months on these engines. Anyone else have a simple fix like that that made a huge difference in how engines run?

Finally finished a full engine rebuild on my own time, feels good

Three years ago I could barely change an oil filter without help. Last month I tore down a 5.9 Cummins from a 2001 Dodge in my buddy's garage in Austin. Last week I got it started and it ran smooth on the first try. Took me about 40 hours of evenings and weekends to get it all sorted. Anyone else remember their first big project that made you feel like you actually knew what you were doing?

Picked a Bosch injector over a Denso on that old International and it ran rough for 2 weeks straight

I swapped in a Bosch reman injector on a 2000 International 4700 with the 7.3 and the number 3 cylinder misfired something fierce till I finally pulled it and went with the Denso like everyone said to, has anyone else had mismatched injectors cause chaos like that on an old HEUI system?

Unpopular opinion: DOT inspections are way too easy to pass these days

I was talking to a guy at the parts counter last week who said he just runs his trucks through a quick check before inspection and calls it good. He said that's what everyone does. I've been doing this for 22 years and I think we've gotten lazy. I saw a rig on I-80 last month with a cracked brake chamber that clearly would have passed a DOT inspection if the inspector was in a hurry. Is anyone else seeing this trend or am I just old fashioned?

Fight me but I chose a mechanical fuel pump over electric

Everyone at the shop said I was crazy for putting a mechanical pump on my 7.3 when I did the rebuild last year. They all swear by electric with a regulator kit. But I spent $200 on a Bosch mechanical setup and it's been 8 months without a single hiccup. The truck fires up before the glow plugs even cycle. Has anyone else stuck with old school and had it work out better than the modern swap?

Heard a fleet manager say something about oil sampling that stopped me cold

He was talking about how they caught a failing injector cup 800 hours early just by sending oil samples every 250 hours. I had been skipping those on my own truck because they felt like a waste of $25. Has anyone else had a sample catch something before it turned into a real problem?

Warning: that cheap injector puller from harbor freight snapped on a 6.0 powerstroke job in albuquerque

Spent $40 on it on a friday and it broke on the first injector saturday morning. Cost me 3 hours waiting for a loaner from the parts store next town over. Anyone else had one of those break mid-job?

Can we talk about those counterfeit fuel filters floating around?

Last month I grabbed a cheap filter for my Cummins off a third-party site and it collapsed inside the housing after just 200 miles, has anyone else seen these junk parts ruin a pump?