6nz"d BXS Acert thumping noise

Check for broken valve spring. May possibly be valves trying to gall in guides. Just ran thru this with a tuned up emodel. Head was built at machine shop and guides were teamed too tight. Not trying to scare but some thing to think about.

 

My company truck with over 1 million miles on the 3406 E (almost 40,000 hours) is in the shop now getting new wiring harness installed and several sensors.

Truck sounded like it was running with a dead cylinder but runs on all 6.

Shop did injector cut out etc. Can’t find the problem. All 6 injectors pass.

Under load the truck would shake like the crank will break.

Cat ET couldn’t pull up any codes. Everything is good. Likely mechanical.

They said just change the injectors. All 6 done, top set done.

Truck also smoked pure black At times, also felt like it’s pulling harder than normal with a full load.

A few weeks later, I got the truck to pull hard coming up to the mechanic shop, got the flashing light and half power.

Told the mechanic to check quickly before the computer clears it like it was doing previously. The light goes out but the mechanic caught the code.

Found the problem, 5 volt reference, low voltage. Bad wiring harness.

 

W9L: Just got my truck back today.

so far the missing has disappeared.

hopefully it stays that way.

The mechanic showed the wiring harness to me, it was in terrible shape. Old.

This truck is completely straight piped.

No muffler anywhere other than the turbo.

It’s horrible to hear the engine sputtering, popping and missing when it’s loud.

 

This morning is the first time the truck fired up and ran smoothly.

Hauled a 200 Deere excavator 1 hour one way and so far, no missing.

Just smooth Cat power.

While the injectors were not at fault, the ones in the engine now does produce a bit more power.

They’re smokier than the previous ones but clean up nicer.

Overall, I’m happy.

The last truck I had, a 2001 Sterling with the M11 Cummins, went through a lot of injectors. 2 shops worked on it, replacing ones they thought were bad and I did some too.

One rebuilt injector lasted 900 miles. Another lasted 3,500 miles.

Then my boss gets a set of 6 used ones. They went trouble free for 31,000 miles.

Then 2 more failed.

They caused a lot of shaking and then gets stuck open keeping the engine up at 1,500 rpms making it a pain to shift gears since the top rpms are about 1,700.

I’ve learned since then that New injectors are the way to go, not just for big trucks but diesel pickups as well.

But my boss still doesn’t want to pay the price of new so gets them rebuilt.

 

Also, I have a company 2005 Freightliner Classic with the BXS ACERT.

I’m in the process of overhauling that engine.

While I have read and seen a lot of people convert to the single turbo, (my boss wants to too.) I have chosen to keep the 18 to 1 compression pistons, and the 2 turbos.

The computer is flashed with a 575 hp, 2,050 tq file which worked well.

The inframe is being done due to a cracked head from the previous driver running it without coolant (more than once). He had the 550 Cat file. Not the file I have now. Big difference between the 2 files.

 

Deleted IVA's, 18 to 1 packs and way way too much timing did the head in. Lucky that's all that happened and the pan wasn't laying on the ground.

You wanna retard the timing when dumping more fuel in. As the engine gets heat soaked, hotter intake temps + hotter fuel will actually ignite it sooner (meaning even more timing) so much that it's trying to force the crank to spin opposite way.

Read this article. The guy goes way in-depth

maxxTORQUE: Diesel Timing