Hello. I'm new to the forum and want to offer a note of thanks to all those who have contributed some fantastic information -much of which has already been very beneficial to me.

The following is my ownership experience so far. Warning, it's "long and involved", but I hope it may be beneficial to someone who stops to read it.

When the GM 2-mode pickups were introduced in the 2009 model year, I was intrigued by them, but the MSRP left me unconvinced that I wanted to buy one, with a fully-optioned 4WD Sierra having a sticker around $48k.

Moving forward to this year, I had decided that I wanted to replace the 2008 Buick Enclave I was driving with some sort of crew cab pickup. As it turns out, via cars.com, I located a 2009 GMC Sierra Hybrid 4X4 (3HB) at a dealer about 240 miles from where I live.

After making the trip to the dealer, I found the truck to be very tight and clean with 59,000 miles. I took a lengthy test drive and all systems appeared to function correctly. I went back to the lot and negotiated a deal to trade the Enclave and purchase the Sierra.

After all the paperwork was completed, I went out to start the drive home, turned the key and heard a rapidly repeating chime tone along with high levels of tapping coming from the ICE. This along with a "Engine oil pressure low - shutdown immediately" warning from the DIC.

After the truck sat for a couple of minutes, and the oil level had been verified via the dipstick(full) it started without oil pressure issues. A few minutes after that, the warning reappeared.

At this point, I had to make a decision as to whether I wanted to rescind the deal, or follow through with it. I told the general manager that I would like to follow through with the deal on the condition that they would take the truck to a GM dealer (the selling dealer was a former Chevrolet store that had lost their franchise but remained open as a used car dealership) for diagnostic and service and deliver the truck to me with the oil pressure issues resolved and an inspection of the engine for damage or other issues.

With this agreement in place, the selling dealer gave me a vehicle to drive while the issues were being diagnosed. The following business day, they took the Sierra to the nearest GMC dealership for service.

The GMC dealer opened a case with the GM Technical Assistance Center and began to diagnose the issue. It appears as though TAC was calling all the shots on this issue, often causing day-long delays in actual work, as the dealer waited on communication from TAC before taking "next steps".

Over the space of nearly three weeks, the following things were done:

1. Replace oil-pressure sensor filter.
2. Replace oil pickup tube and O-ring.
3. Replace oil pump.

After none of these items proved corrective, TAC advised the dealership to:

4. Replace the entire set of valve lifters.

While the lifters were in transit, I had a long conversation with the service person at the GMC dealer to ask what might be the next steps if lifter replacement failed to correct the issue. He indicated that the question of complete engine replacement had been raised and that he assumed this would be a logical next step, but it would require approval from GM.

Yep, you guessed it, the lifter replacement failed to correct the problem. The service writer informed me that they were requesting approval for an engine replacement.

Here's where it gets a little strange. The next day, the service writer calls me and declares that the truck is ready to roll. He explains that his service manager instructed the technician to contact a different department within TAC that specializes in hybrid vehicles.

According to the service writer, this "other" division of TAC led the technician through a series of tests involving the use of mechanical oil pressure gauges and various conditions of "heat soak", and that the engine was functioning correctly. He then went on to explain to me that a "no oil pressure" condition was normal in auto-stop and that his technician had been getting zero readings because he didn't realize that the engine had gone to the auto-stop state.

Since my own research into the vehicle had indicated that opening the hood on the vehicle would cause the engine to start, I felt doubtful regarding the "auto-stop" explanation. Still, they declared the vehicle "fixed" and returned it to the selling dealer and I took delivery the following day.

Upon delivery, the Truck performed perfectly. I made the ~240 mile drive home, making a couple of stops along the way, and had no issues.

About 4 hours later that evening, I get in the truck, start it, and ding, ding, ding, ding, ....low oil pressure.

At this point, I call the selling dealer who is now starting to try and back away from any responsibility. I tell the sales manager that I am going to manage the diagnostic and repair process and that I will hold him responsible for any "out of pocket" expense that I sustain as a result.

My next move is to go to the GM store that is nearest to my home. There, when I began telling my story (the diagnostic process so far) to the service writer, and when he realized it was going to be something more complicated than usual, he began to get this wide-eyed expression and started staring into the front counter of his service desk. At one point, I walked to the side of the desk in an effort to get some eye contact, but it was of no use. I forced myself to resist the temptation to strangle the writer and finished my story. At this point he says "My service manager is out of town and I'll have to talk to him before I take that in the shop".

Even though I knew said service manager from previous visits, I was in no mood to wait three days before I got the truck in the shop.

I then take the Sierra to a GM dealer in Nashville with whom I have dealt in the past. This dealership, Beaman Buick/GMC, gets rave reviews from me for their customer relations and courtesy. The service writer spent his time listening to me rather than assume I knew nothing, and when I asked for directions to the Enterprise counter, he responded by telling me to give him a couple of minutes. I go to the customer waiting area and he returns in about 5 minutes with a new Yukon XL, saying "Will this work?".

At Beaman, the technician re-opens the case with TAC and the diagnostic process begins again. This technician checks pressure on both the top and bottom of the engine, then pulls the pan to make inspection. After a couple of days, they call me and say the truck is ready.

When I go to pick up the truck, both the service writer and the technician talk to me, explaining that the pickup-tube O-ring was found to be pinched, and that they had replaced those parts. They did extensive test drives, both in downtown Nashville and out into the rural areas, started the truck over and over, and were encountering no more issues with oil pressure. The technician also told me that he inspected the engine and it was "incredibly clean" for 59,000 miles.

Just like before, I took the truck home with no issues. The next morning....ding,ding,ding,ding....low oil pressure.

Back to Beaman (once again, royal treatment from everyone there). After another day of diagnostic, the service writer calls to say "About an hour ago, we received approval to replace the engine in your truck".

So, a new 6.0 arrives and the installation and testing are done and NO MORE OIL PRESSURE PROBLEMS.

Now I find myself getting used to the nuances of hybrid ownership and the feeling of "is that noise normal". On one occasion I have heard loud noise that I believe to be the aux pump on the transmission. Still there are no apparent performance issues.

As for the good news, I have gotten mileage as high as 24.2, and nothing I have been able to do causes it to dip much below 21 under any conditions. This is verified by hand.

Those of you who managed to make it through this saga, thanks! I can't say enough good things about the staff at Beaman GMC in Nashville. If any of you want the name of the selling dealer or the first GM store that handled the diagnostic so that you can avoid them, drop me a note.

 

that good to know that despite everything else, a happy customer. I don't know what caused the low oil pressure. maybe a sensor that shuts the engine when it goes to autostop? a new engine is a better relief and no issues is better.

 

There have been sensor issues. However, real low oil pressure results in the clatter under the hood. Hopefully that GM customer service person posting here will ask you to send her the TAC case number that got it wrong.

 

I've speculated a great deal about the cause of the low pressure. What's interesting is that part of the time there was a warning, there was indeed low oil pressure causing lifter clatter and part of the time there was a warning and zero reading on the gauge, but no high levels of noise in the top end of the engine.

I'm convinced that part of the warnings were erroneous, but some of them were definitely correct.

 

Thanks for bringing the thread to my attention, Hillbilly_Hybrid!

Jimtoonz, I really appreciate that you took the time to share your experiences with the community. While I'm glad everything went well at Beaman, I'm very sorry to hear about your experiences leading up to that! If you don't mind private messaging me with your full name and the last eight of your VIN, I would be more than happy to document your feedback officially and research your case history.

Best,

Katie
GM Customer Service

 

Katie,

Thank you for the note. I sent you a private message with contact information.

Best,

James

 

Thank you, James! I wanted to let you know I received your PM and will reply to it shortly.

Best,

Katie
GM Customer Service