DPF rear differential pressure sensor tube found broken at bung
My first post...
While changing oil on my 2009 LMM, I noticed the rear DPF differential pressure sensor tube was broken where it exits the fitting on the DPF. It was a clean break just above its threaded coupler. I have no way of knowing how long it was broken. It seems to me that the sensor would think the pressure differential was too high, but I did not notice any increased regeneration cycle frequency. However, my driving habits may have impaired my senses; I am usually looking on the right shoulder for hitch-hiking Swedish twin sisters.
The replacement part number is 25799002. I ordered one from the dealer yesterday. It arrived today. $90.76 plus tax. It consists of both the front and rear pressure tubes, couplers, routing clamps, bracket, and flexible hoses that go to the pressure sensor.
I removed the broken rear tube with a 17mm 12pt socket and long handled ratchet and some PB Blaster. A 6pt socket would have been better.
I took the rear tube off the new assembly and installed it along with the new flex hose. Tools used were a 17mm open end wrench for the coupler, two 13mm socket wrenches for the center bolts and nuts of the tube routing clamps, and pliers for the spring clamps on the hose. Now back on the road.
A few of things I noticed:
1. The flex hose has a very thin plastic lining that can easily be collapsed while pushing it on to the tube or sensor. One side of the lining can get bent inward and block the passage while the outside braided cover still looks normal.
2. The new coupler has black thread sealant preapplied to its threads. It took a couple of careful trials to prevent cross threading in to the bung on the DPF.
3. The manual actually tells you to look for loose or damaged pressure lines and sensors on the DPF every 25,000 miles. Hmmm...?
4. I could not found these Swedish twins on my test drive.
Drive on.
Constant Regenerations LML
My 3500 LML has been at dealer #2 for 2 weeks so far. Replaced EGR valve, still building soot and still having constant regenerations issues. Technicians have been working on it and testing other suggestions with technical assistance. Probably another week yet.
Hey, GM, how about another truck????? Maybe one that works correctly?!?!?!?!