c/diesel-mechanics

Appreciation post for the guy who helped me with a seized injector on I-10

Last Tuesday I was rolling down I-10 outside of Tucson in my 2007 freightliner when the whole thing started shaking like a paint mixer. Pulled over and found the number 3 injector was stuck so bad I couldnt even get a socket on it. A older diesel mechanic in a beat up F-350 pulled up behind me and asked if I needed a hand. He had a specialty puller in his truck that I had never even seen before. We got that injector out in about 20 minutes with a combination of heat and that tool. The whole thing was over by noon and I was back on the road. Has anyone else run into a stuck injector that bad in a Detroit series 60?

Finally got a torque wrench I can trust after years of guessing

Used a cheap click-type for 6 years until I snapped a head bolt on a Cummins ISX in Phoenix last spring. Picked up a split-beam from Precision Instruments and the difference in feel is night and day - no more wondering if I'm leaving torque on the table. Anyone else made the switch and seen fewer comebacks?

Tried the 'smoke test' on a Cummins ISX that had me stumped for 2 hours

I was chasing a no-start on a 2015 ISX at the shop last Thursday, compression was fine but it just wouldn't fire. Out of ideas I grabbed a cheap cigar from the gas station and blew smoke into the intake while cranking, saw it puffing out around the intake manifold gasket. Anyone else use weird cheap tricks like this when diagnostics get nowhere?

Am I the only one who sees guys cranking down air filters too tight?

I swapped out a filter on a Freightliner last week and the gasket was crushed flat from being overtightened. It lets unfiltered air into the engine, why do people keep doing this?

PSA: That cheap injector cleaning machine from Amazon is a scam

Bought a $60 ultrasonic injector cleaner off Amazon, ran it on a set of six injectors, and two came out worse than they went in with clogged nozzles. Anyone else find a decent way to clean injectors without dropping $400 on a real machine?

Had a conversation with an old Cat mechanic who swore retorquing heads was a waste of time on modern engines

He told me he hasn't retorqued a head gasket in 15 years and has only had one failure, but every manual I've ever read says you have to do it, so which camp are you guys in and have you ever gotten burned skipping that step?

Had a customer try to tell me his 18-speed transmission was possessed last Tuesday

Just ran across a stat that blew my mind about diesel emissions

I was reading through some SAE papers last night and found out that a single semi truck idling for 10 hours burns through about 10 gallons of diesel. That's like $40 down the drain for nothing. And it dumps nearly 200 pounds of CO2 into the air. Makes me wonder why more fleets don't push for APUs or shore power hookups. Has anyone here actually switched to an APU and seen real savings?

Chat with an old trucker changed how I think about engine idling

Was talking to a guy named Jerry at the TA truck stop in Flagstaff last Thursday. He's been running rigs since the 80s and told me he never lets his engine idle more than 5 minutes unless it's below freezing. Said the cylinder wash from cold idling wastes more fuel than restarting a dozen times. I'd been telling customers to let em warm up for 10-15 minutes in the winter. He showed me his maintenance log and his last rebuild was at 850k miles with zero ring issues. Made me rethink the advice I've been giving. Anyone else change their idle habits after hearing something like that?

Fought a stuck injector on a 6.7 Powerstroke for 3 hours yesterday

I had this 2015 F-250 come in last Thursday with a miss on cylinder 4. Figured it was just a bad injector, easy swap right? Wrong. That injector was seized in the bore so tight I thought I was gonna pull the whole head off the block. Tried the usual trick with penetrating oil and heat, nothing moved. Ended up having to fab up a puller from a harmonic balancer bolt and some threaded rod, and even then it took cranking the breaker bar until my arms shook. Finally popped out with a bang, scared my helper half to death. Put the new one in with plenty of anti-seize, fired it up, and it ran smooth. But man, has anyone else run into injectors that are practically welded in from carbon? What do you do different to get them out?

Old timer at a shop in Phoenix told me to stop using liquid wrench on rusty bolts

Guy said to use ATF and acetone mix instead. Tried it on a seized exhaust manifold bolt and it cracked loose in ten minutes. Anyone else ditch the spray cans for this homebrew?

Back in '09 at a shop in Billings, a blown injector cup taught me the hard way

I was working on a 6.0 Powerstroke at a dealer in Billings and had a injector cup that just would not seal. After three tries and a lot of cussing, an old timer walked over and showed me how to check the cup bore with a mic and feeler gauge. That ten minute lesson saved me probably 20 hours of warranty comebacks over the next year. Any of you guys still using that old school method or is it all bore scopes now?

That $90 ratchet set from Harbor Freight finally gave out on me

Last month I was underneath a 2005 Cummins in my buddy's shop outside Omaha, going at a stubborn bolt, and the 3/8 drive just snapped clean in half. I've had that set for maybe 3 years and it held up fine for light stuff but that was the second time a bolt almost stripped on me. My buddy handed me his Matco that he paid like $300 for and it grabbed way better. Anyone else regret cheaping out on tools and wish they just saved for the good stuff from the start?

Old timer said my torque wrench calibration was off, now I check it every month

Been doing diesel work for about 7 years and always thought my torque wrench was fine. Last spring a retired mechanic watched me torque down head bolts on an old 5.9 Cummins and said 'son, that wrench is lying to you.' I grabbed his Snap-on tester and sure enough I was 12 ft-lbs over on a 100 ft-lb setting. Changed my whole approach, now I take my main torque wrench to a shop in Nashville every 6 months for a $40 recalibration. Anybody else trust their tools too long and get burned?

Just had a customer tell me they 'fixed' their own truck with zip ties

Had this guy roll into my shop in Philly yesterday with a 2015 Ram 3500 that sounded like a dying lawnmower. He tells me he saved money by doing the repair himself, but he's real proud showing me how he zip-tied the turbo actuator arm to the vgt ring. I'm standing there looking at engine codes reading overboost and underboost at the same time. He actually argued with me for 20 minutes that it was fine because the truck still moved. Took me 3 hours to un-jam everything and replace the actuator he cooked. Customer's still mad at me for charging him $400 instead of his $5 fix. Anyone else get people who think a temporary bodge job is the same as a real repair?

That 12-hour diagnostic on a junker Freightliner that should have taken 2

I spent last Thursday chasing a phantom electrical problem on a 2005 Freightliner Columbia that was intermittently killing the dash cluster. Customer said it would just cut out after driving an hour, then come back after sitting. I went through every ground, checked the ignition switch, even pulled the VECU connector twice. Nada. Finally after about 12 hours of swapping parts and staring at schematics, I noticed the CEN fuse holder had a hairline crack that only opened up when the engine bay got hot enough. That thing cost me a full day's labor because I trusted the fuse looked fine when cold. Anyone else lost a shift to something dumb like a hidden fuse crack that laughed at your multimeter?

Finally figured out why my compressor kept tripping the breaker

Took me three days to notice the unloader valve was stuck open. Replaced it for $12 at the local parts house and it's been running smooth since. Anybody else ever chase an easy fix for way too long?

Debate: Should you tear down a motor to find a ticking noise or run it until it blows? I spent 14 hours chasing an injector tick on a 7.3 Powerstroke

So I had this 2002 F-350 come in last week with a ticking noise that sounded like a lifter going bad. I spent a whole Saturday pulling valve covers, checking pushrods, even swapped a rocker arm. Fourteen hours later I'm about to give up when I notice the number 8 injector's o-ring was just barely leaking combustion past the copper washer. Two hours of actual work and it was fixed. But here's the thing, part of me thinks I wasted a day when I could have just ran it hot and let it tell me where the problem was. The other half says a thorough inspection is always better than guessing. I know some guys that just throw parts at stuff until it shuts up, but that gets expensive fast. What's your approach when you got a noise that could be three different things? You tear it all the way down or take a gamble on what you think it is first?

Warning: That 'lifetime' air filter might be costing you more than cheap paper ones

I heard a guy at the parts counter last week say he's run a K&N on his 6.7 Powerstroke for 80k miles without cleaning it. He swore it was fine. But I've seen dyno tests from a shop in Phoenix showing oiled filters let through more grit after 30k miles than a $12 Wix paper filter. So is the convenience of a 'wash and reuse' filter worth the potential cylinder wear, or are we all just overthinking this? What's your experience with aftermarket air filters on heavy tow rigs?

Switched from impact wrenches to torque wrenches after a bad call on a Cummins ISX last spring

I used to just crank down head bolts with my impact and call it good on highway trucks. Then last March I had a ISX come back with a blown head gasket after only 6 months because I overtightened three bolts on the left bank. Now I use a digital torque wrench from CDI and follow the spec sheet step by step, even on smaller jobs. Has anyone else had a come back happen because of torque guesswork?

Found out today that a loose injector cup can mimic a blown head gasket

I was chasing a miss on a 6.7 Powerstroke in the shop this morning, pulled the injector and noticed a tiny bit of carbon tracing around the cup. Turned out the cup was just loose, not cracked, and it was letting compression bleed by. I found a TSB from Ford that explains how the symptoms match head gasket failure exactly. Has anyone else wasted time chasing the wrong thing because of a loose cup?

Old Cat 3126 in a school bus threw a rod on I-40 outside Nashville last Tuesday

I was running a route for a local school district, just cruising along at 55 mph. No warning lights, no strange noises beforehand. Then a big bang and oil everywhere. Got it towed to a shop nearby and the mechanic said the number 4 rod went through the block. Turns out the previous owner had been running cheap oil and skipping changes. Cost me $3,200 for a used engine swap. Has anyone else run into hidden damage from poor maintenance on those 3126s?

Switched from synthetic to conventional oil in my 7.3 and here's what happened

I used to swear by full synthetic oil for everything. Ran Rotella T6 in my 1999 F-350 for like 4 years straight. Then my buddy Dave, who's been turning wrenches since before I was born, told me I was wasting money on an old high-mileage engine that leaks anyway. He said the 7.3 Powerstroke was designed for conventional 15w-40 and the thicker base helps keep the injectors quiet longer. So I swapped to Shell Rotella T4 conventional about 6 months ago. Truck actually runs smoother now and the oil leak I had on the rear main seal slowed way down. Has anyone else had better luck going back to conventional on these old IDI engines?

That time I tried cheap fuel injectors to save $200

Had a 6.7 Powerstroke with a dead injector. Looked at OEM prices and said no way. Bought a set of remanufactured ones for $600 instead of $800. Lasted about 4 months before one started knocking like crazy. Learned my lesson. Anyone else get burned by cheap injectors?

Hot take: I was wrong about using SAE sockets on metric bolts

I heard an old timer say it's only a matter of time before you round one off, and last week I finally did it on a 13mm bolt in a Cummins ISX, so I'm ordering a full set of deep metric sockets tonight - anyone else learn this the hard way?