c/diesel-mechanics

Finally got that stubborn 6.7 Powerstroke oil cooler to seal after three tries

Was doing a full service on a 2012 F-250 in my home shop yesterday. Put the new oil cooler in, torqued it down to spec, and it still leaked a steady drip from the rear housing. Took it apart, cleaned the block surface again with a razor and brake cleaner, same leak. On the third try, I used a tiny bit of anaerobic sealant on the cooler gasket, not just the housing, and let it sit for an hour before adding oil. Bone dry after the test run. Anyone else find these things need a little extra help to seal right?

Update: My old Detroit 60 series went from 4 mpg to 6.5 after swapping the injectors and tuning the pump.

That was after a full rebuild in my shop over two weeks, but now I'm seeing a slight haze at idle, so should I adjust the timing or check for a different issue?

Just lost a full day's pay chasing a bad sensor reading

Honestly, I was working on a 2019 Duramax with a rough idle and the scanner kept pointing to the MAP sensor. Tbh I swapped it out with a new one from the parts store, cost me $140. Ngl the truck ran the same and the code came right back. Turns out the real problem was a tiny crack in the intake boot letting in unmetered air, something I should have pressure tested first. I wasted about 5 hours and that sensor money for nothing. Has anyone else gotten burned by trusting the code reader too much before doing the basic checks?

Heard a new guy at the shop in Billings say 'it's just a fuel line' and the lead tech shut him down hard. Made me think about how we talk to apprentices.

Bought a cheap knockoff torque wrench and it cost me a cylinder head

I was doing a head gasket job on a 6.7 Powerstroke last month and needed a 1/2 inch drive torque wrench. Grabbed one from a discount tool truck for $60 instead of my usual brand. Torqued everything down in sequence, felt fine. Started it up and had a coolant leak from the back corner. Pulled it all apart again and found the stretch bolts weren't seated right because the wrench was off by almost 20 foot-pounds. Wasted a full Saturday and a $400 gasket set. Anyone have a reliable budget torque wrench they actually trust?

I just hit 10,000 hours on my main scan tool and the data it showed me was a shock

It's a Snap-on Zeus, and I bought it new when I opened my shop in Spokane six years ago. The total fault code count was only 1,847, which means a huge chunk of my time is just chasing weird electrical gremlins and doing PMs, not major diag. Makes me think we're all getting better at building these things, or the problems are just getting sneakier. What's the ratio of diag to repair time look like in your bay lately?

I used to think you could eyeball a torque spec on a head gasket job

For years I'd just crank bolts down by feel, especially on older 12-valve Cummins engines. Then I had a job come back after 4 months with a coolant leak from a warped head. The shop owner pulled the service manual and showed me the spec was 110 ft-lbs, not the 'good and tight' I was doing. How many guys are skipping the torque wrench because they think they know the feel? Ever seen a motor fail from something simple like that?

My shop's 12-valve Cummins just hit 850,000 miles on the original bottom end

We pulled the pan last week for a routine inspection on this old bread truck engine. The owner said it's never been opened up, just regular oil changes with 15W-40. The bearings still had visible cross-hatching and the crank journals looked great, no scoring at all. I've seen plenty of these go the distance, but this one was a shocker. What's the highest mileage you've seen on an untouched 5.9L?

Choosing between a full rebuild or a used long block for a 6.7 Powerstroke

The customer's budget was tight, so I went with a low-mileage used block from a salvage yard in Memphis. It's been running solid for 8 months now, but I still wonder if the rebuild would have lasted longer.

That time a simple coolant flush saved a $15,000 engine job

Last month, a fleet truck came in with a rough idle and white smoke. The owner was sure it was injectors, maybe even a cracked head. I pulled the coolant filter housing first, just to check, and found it completely clogged with casting sand from a bad factory block. A full flush and new filters fixed it in an afternoon. The guy was ready to spend thousands on a teardown. Has anyone else caught a major problem just by starting with the cheap stuff?

Just found out how much torque a modern semi truck engine can actually make

I was reading an old service bulletin from Detroit Diesel and saw that the DD16 can hit over 2,000 lb-ft. That's more than my entire service truck weighs. Who else has seen a spec that just made you stop and stare?

Just watched a guy at the shop try to seat a 12.7L piston ring with a hammer handle. That's how you get a $15,000 core charge.

Showerthought: I've been using the wrong torque sequence on cylinder heads for years and only figured it out when a head gasket blew on a 6.7 Powerstroke.

Used a cheap harbor freight bore scope on a 6.7 Powerstroke and the picture was way clearer than I expected

Hit 500 hours on a single injector puller tool and it made me rethink my whole kit

I was cleaning my box the other day and checked the service log for my Snap-on slide hammer puller, the one I got fresh out of trade school. The counter said 502 hours of actual use. That's just one tool, on one job type, over maybe eight years. I mean, I never kept track like that before. It hit me how much we rely on a few core pieces while the fancy stuff gathers dust. Has anyone else logged their main tools and been shocked by the numbers?

Just realized the old truck stop in Bakersfield still has a working diesel pump island from the 80s

I was fueling up my service rig there last week and noticed they never replaced the original Gilbarco pumps, just kept fixing them. The hoses are new, but the whole mechanical meter and display setup is still ticking along. Has anyone else seen a place still running that old gear, and is it even worth trying to keep it alive?

I finally had to pick between a full rebuild or a used engine swap for a 6.0 Powerstroke

The truck came in with a blown head gasket and some injector issues. The owner wanted it fixed for under $5,000. I could either do a full bulletproof rebuild, which would take about two weeks and cost him around $7k in parts and labor, or find a used engine with lower miles and swap it in a week for about $4,500. I went with the used swap to stay under budget and get him back on the road faster. It's been running fine for three months now, but I'm still nervous about the long-term reliability of the donor motor. What would you have done in that spot, stick with the known cost of a rebuild or gamble on a used unit?

Got schooled by a farmer on a frozen injector line in North Dakota

I was trying to get this old International running in minus 20 weather, and he just walked over with a heat gun and a rag soaked in hot water. He said 'Son, you're fighting the cold, not the part.' I've carried that little propane torch ever since. What's your go-to trick for a deep freeze start?

Spent 8 hours chasing a coolant leak that turned out to be a loose radiator cap on a 6.7 Powerstroke

Pressure tested the whole system twice, pulled the degas bottle, checked every hose clamp. My buddy finally walks over, jiggles the cap, and it clicks down another quarter turn. Leak stopped instantly. I felt like the biggest idiot in the shop. How do you guys avoid getting tunnel vision on a simple fix?

Just saw the difference between a cheap and a proper coolant flush on a 6.7 Powerstroke

Honestly, a shop near me was using a basic garden hose and a bucket for their flush service, charging $150. We did a full reverse flush with a dedicated machine and Motorcraft Gold, cost the customer $320. The old way left a ton of scale and old coolant in the block, the machine got it all out and the temp gauge runs a solid 15 degrees cooler now. Has anyone else seen shops cutting corners like this on something so basic?

TIL a lot of guys are still torquing head bolts dry on Duramax L5Ps and that's a big no-go.

The factory spec for the M14 bolts is 22 ft-lbs plus 130 degrees, but the procedure clearly states to lubricate the bolt threads and underside of the washer with clean engine oil, and I've seen three motors this month with uneven clamp because someone skipped that step.

Finally gave in and tried a Milwaukee M18 stubby impact on a stubborn oil filter housing

I mean, I always swore by my big 1/2 inch air gun for everything, even on those tight spots. But last month at the shop in Tempe, my buddy handed me his M18 after I was fighting a 6.7 Powerstroke for twenty minutes. Thing zipped it right off, no fuss. Anyone else switch from air to electric for specific jobs like that?

Just realized those aftermarket EGR delete kits are a total gamble after my buddy's 6.7 Powerstroke threw a code in the middle of a Wyoming haul.

He installed a 'reliable' brand from some online forum, but the welded flange cracked after 8 months and the sensor fault left him stranded, so now I'm convinced you either pay for the top-shelf kit or just leave the factory junk in and deal with the cleaning.

A stuck injector on a 6.7 Powerstroke in a Wyoming blizzard taught me a new trick

I was helping a friend get his plow truck running outside of Cheyenne when the third injector just would not seat. The cold made everything brittle and my usual puller was useless. I ended up warming the bore with a shop light for about 20 minutes and tapping the injector body with a brass punch at a slight angle, which finally got it to pop free without damage. Has anyone else found a good way to deal with frozen injectors in extreme cold?

Three years ago in a Wyoming winter, I swore I'd never use a cheap block heater cord again.

Last week, a guy brought in a 6.7 Cummins that wouldn't turn over. The cord had melted right at the plug... just like mine did back then. I spent a whole night in minus 20 weather because of a $15 part failing. Now I only install the heavy-duty ones with the braided jacket, no matter what the customer says. Anyone have a brand they trust for those brutal cold snaps?