Recently picked up a 2010 Sierra with 155k miles. Already got a Range AFM delete module for it. I'm wondering if anybody has any insight or possible solutions on a few issues I'm having. The first thing is that it has a knock or tick when I start it up, which goes away when it warms up. It sounds very mechanical, and the exhaust manifold looks good so I believe it's a bad lifter. How concerned should I be about it?


When accelerating, the transmission kicks out of 2nd gear very abruptly, the RPM's jump up slightly, and there's a short delay before it goes into third. From what I've found online it's commonly known as the 2-3 shift flare and GM is aware of it. All other gears are fine.


I noticed after my last oil change that when I start the truck the oil pressure sits right around 40psi. It steadily goes down as it warms up and then will sit at 20psi give or take 1-2psi depending on RPM's. I noticed the last oil change I got the dealer put on a PF48 filter. Is that the best filter to run and could it affect the oil pressure? I've already replaced the oil pressure sensor and filter.


I got a third party warranty for the truck from the used car dealer I purchased it from, so hopefully I can have any future problems fixed under that, but I'm always skeptical about extended warranties. Has anybody here ever dealt with 'Alpha Warranty Services' or 'Alacar Unlimited' before?


Thanks in advance for any input!​​​​​​​

 

The PF-48 is A/C Delco oil filter. Nothing wrong with those at all. I tend to use Wix XP's or Purolator One's, but I dont think it will make much difference on your motor oil pressures. At 20 PSI hot, it likely that you have some crankshaft and camshaft bearing wear going on. 30-40 PSI would be more in the "normal" range with a high-mileage engine.

My GUESS is that the previous owners of your Chevrolet, didn't do diligent maintenance on it, and that is why it is in the state it is in. If it only makes lifter noise starting up, and it goes away fast, I would simply treat it well, and I'd also change every fluid in it. Axles, transmission, brake fluid, power-steering fluid (a simple suction device will suffice), all with synthetic fluids. It is is almost certain that they did none of these things, even greasing the front end fittings, and the drive-shaft zerk-fittings with high-quality grease.

I had to edit this, but I would also change out the fuel filter,(unless its inside your gas tank, as it is in newer model vehicles), check out all the hoses; the engine coolant; and buy a temperature gauge that simply fits into your interior vents, so you can see what your temperatures are. If the A/C does not put out 38-46 degrees Fahrenheit while traveling, and its warm or hot outside then you'll need to check the pressures in the A/C system.

I am not a true auto-tech, so I can't honestly diagnose your automatic transmission issues. I know nothing about engine or automatic transmission extended warranty's.