6.2L (L9H) Owners - Get all your questions answered here

[JCWaller1]

I have a 2007 Silverado Classic, Crew Cab 4x4. I recently had all the brake lines, master cylinder, and  abs modulator vvalve eplaced and the mechanic told me it was good to go. I left and about halfway home noticed that when I lifted from the gas it felt as though I was braking. The further I drove the more resistance I felt and before I got home it was very tight and smoking on the front driver side. I called the mechanic, told him about it and he said it must be the caliper. I replaced the caliper and hose connecting it to the brake line. I drove it for about ten miles with no issue but after sitting in a drive thru for a few minutes and pulling back onto the road it started doing the same thing. Any ideas what could be causing this?

[SierraHD17]

Well did an analysis on my 2013 6.2s oil and what a surprise... high iron content to the tune of 91 ppm which the lab is very concerned with.  No surprise as the thing has this ridiculous rattle that kind of comes and goes... it's almost a knock in the bottom end.  Truck has like 55000 miles on it.... Good thing I have a 6.2 core sitting in the shop I was going to build.. might need it soon.

[RyanbabZ71]

Well did an analysis on my 2013 6.2s oil and what a surprise... high iron content to the tune of 91 ppm which the lab is very concerned with.  No surprise as the thing has this ridiculous rattle that kind of comes and goes... it's almost a knock in the bottom end.  Truck has like 55000 miles on it.... Good thing I have a 6.2 core sitting in the shop I was going to build.. might need it soon.

Do you have a K&N air filter by chance?


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[SierraHD17]

5 hours ago, RyanbabZ71 said:

 

Do you have a K&N air filter by chance?


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No.  Truck is totally stock.

[RyanbabZ71]

No.  Truck is totally stock.

Ok just checking I had an oil analysis done with some issues for sheets and giggles I replaced the filter back to stock and the readings the next analysis went back in and stayed in.


Ryan B.

[SierraHD17]

K and N filters don't make the bottom end come apart... and would result in high silica on the analysis.  These 6.2s have plenty of wrist pin and piston fitment issues.. it's why I have a core one as they are easy to find as warranty replacements.  

[Lifted_6.2]

For any of you fellas looking to do a knock sensor job, for my 2012 Sierra 6.2l its not under the intake manifold! LUCKY right? The photo here is the knock sensor for the drivers side. The passenger side sensor is in a similar position. With some extensions and angles on a ratchet it should (SHOULD) be a simple job. (Please edit if my info is incorrect or off)

[Lifted_6.2]

By the way, im having a problem with stabilitrack, dash send a message “service stabilitrack system” any ideas??

[randy Vincent]

 

Just bought a 12 Sierra SLT w/ 6.2 L9H, how do i find out what trans i have, 4l60/80 or ? And it is E85 compatable any input running E85 good or bad? Performance/ fuel economy

[RyanbabZ71]

 
Just bought a 12 Sierra SLT w/ 6.2 L9H, how do i find out what trans i have, 4l60/80 or ? And it is E85 compatable any input running E85 good or bad? Performance/ fuel economy

It ran E85 quite a bit in my old 2010. Milage will drop but calculate the cost of 93 milage to the E85 milage. I found as long as E85 was 70 cents cheaper that was my break even point. Who cars about milage as long as the cost isn’t worse. Plus the E85 will bump up the performance I could tell a difference in my truck between the two


Ryan B.

[swathdiver]

10 hours ago, randy Vincent said:

 

Just bought a 12 Sierra SLT w/ 6.2 L9H, how do i find out what trans i have, 4l60/80 or ? And it is E85 compatable any input running E85 good or bad? Performance/ fuel economy

You have a 6L80, a 6-speed transmission.  It's a FlexFuel motor, so you can run any ethanol mix up to E85R.  If you run E15, mix in 4-5 gallons of E85 to get the octane rating up to 91 though, don't want to break rings or pistons from knocking.

 

Go to GMCs website and download an owner's manual and then read it.  Pick a hard copy up off of ebay to keep in your glovebox.

Edited March 3, 2020 by swathdiver

[Manav]

GMC Sierra 1500- 2500 (V8 GAS)

 

I have a dripping leak on front of the truck, under the hood on the front end in the centre. Never had the drip in winter, but now its warming up so I turn on the A/C.

 

The Liquid looks clear, but when touched feels a bit oily. Not sure if it is the condensation from A/C. Is it normal for the old truck to do this in summer time? and/or is it a serious or time sensitive issue to be fixed?

 

PS: There are no warning lights going off and all the gauges are normal. 

Edited April 13, 2020 by Manav
Typo

[ccoon10]

I have a 2013 with the 6.2. I love it. I bought it used a year ago with a 3 or 4 inch lift kit and 18 inch wheels. I only get about 11 mpg. Anything I can do to get a little better? I know the mods are a big part of it. Also, as far as I can tell it is stock as far as motor goes. I do love the power! 

[Colossus]

Nope.  No way to get any better fuel economy without removing the lift. 

[Chives3300]

Hey everyone. Looking for your guidance. Test drove a 2011 Sierra Denali about a week back and went to move forward with the purchase. They called me a few days later and said the engine started making noise when running through the shop. No noise was heard when I did the test drive. 

 

I know lifters are a major problem with AFM Motors, but since this is the L9H wondering is this too likely lifters & cam, or something else? 

 

118k miles 

 

Video of tick: