Hey everybody!
I drive a 2008 Chevy Impala LT with 132,XXX miles on it. Has a 3.5L motor, and a satanic 4 speed transmission. I'm a licensed mechanic, and I work as an engineering technician for an automotive supplier. I've done a bit on this car, and I'd like to share what I've done, and also my questions and curiosities. I figure this will let you know what I've experience with this car, and maybe can help with. Also, if you read the WTF section, maybe you could help me with my questions and curiosities.

What I've Done:
1. I have replaced the driver's side CV shaft. Why: Due to play and excessive wear.

2. I have replaced all blend door actuators.
Why: The internal plastic gears break teeth off. Then they start skipping and make this deafening, "POP POP POP," noise endlessly.


3. I have replaced inner and outer tie rods.
Why: Due to excessive wear and play.

4. I have replaced just about every bulb.
Why: Due to burnt out bulbs

5. I have replaced the headlight assemblies and replaced the halogen bulbs with Cougar Motors LED bulbs.
Why: The headlight assembles were getting hazy plaque on them, and the new lenses are all black internally and look badass. Also, since the regular headlights are the day time running lights, the halogen bulbs tend to burn out quick. Replacing them with LED bulbs will keep me from buying halogens at an alarmingly fast rate. So far, so good. (I've replaced almost all bulbs with LED's. 10/10, would recommend.)


6. I've replaced the tires and brakes several times.
Why: The brakes seem to warp easily on this car even though I don't drive like a NASCAR driver. Recently I've bought cross drilled and slotted rotors and performance pads in hopes that I get a longer life. Also, the tires just got replaced due to normal wear and tear.

7. Replaced the battery.
Why: I like the car starting, lmao.

8. I've replaced the upstream and downstream O2 sensors.
Why: That's a good question with an annoying answer. I'll answer in the beginning of the WTF section below.

9. Replaced the front Strut assemblies:
Why: You're supposed to replace them about every 75,000 miles. I did the front, but was too lazy to do the backs.

10. Replaced the right rear hub assembly.
Why: It was so loose it was about to fall off.

THE WTF SECTION. (Questions and curiosities)

1. The mysterious running rich check engine DTC:
So, one day I was relaxin' chillin' all cool when an annoying check engine light popped on. I thought AW SNAP. I better check this out. SO, turns out it's a O2 sensor code. Bank 1 sensor 1 detects a running rich condition. So I think, hey, it might not be it, but the sensors (like the rest of the car) is getting old. I best just replace them, then see what happens. So I do, and I clear the codes. Then, it comes back.... like herpes. Doesn't effect much, but the sight is ghastly. So, I check for vacuum leaks. None to be found. I hear it could be the intake gaskets. So, this is winter in Michigan when this happens, and it's like... negative balls degrees outside, so I decide screw it, I'll deal with it when it gets warm.
So, 7 months of Michigan winter go by, and... the check engine light went off on its own. I was happy, and also annoyed, because the check engine light causes the factory auto start to not work.
So, the one month of Michigan summer ends, and it gets cold... and the check engine light returns..... Why? Why must I be punished? Any answers?

2. The most concerning issue: the satanic transmission. The trans will be fine for hundreds, if not thousands of miles, then has these episodes where occasionally I'll go to start from a stop, and the RPM gauge goes up, the car doesn't move much, then there's a stutter or a slam, and then away we go. Feels so bad, it feels like I got rear ended. Or, it'll happen if I punch it at a lower speed. I think maybe because of it's intermittence, maybe its a sticky shift solenoid? Anyone every successfully diag and repair this issue? Does not throw any codes.

3. Oil leak: Has a small oil leak. If I go a while between oil changes, I may have to throw a half to a whole quart of oil in there. I think it's coming from the rear main seal. Hasn't gotten much worse at all really. Anyone else have the same issue? Is it worth fixing, or should I just throw caution to the wind, and top the oil off occasionally? I guess it's a personal thing, but am I being a bad owner?

4. Mysterious knocks from the rear... not innuendo:
So, occasionally I get three loud-ish knocks from the rear of the vehicle about 5 minutes after starting. Sometimes stopped. Sometimes driving. It's been happening since it had 40,000 miles, and now it has over 130,000. There's not much in the rear besides the fuel pump and tank... is it something to do with that, or is my car haunted? You tell me.


5. The hard to diagnose front end...ish popping noise:
So, sometimes when I hit a bump at a low speed with the wheel turned, I hear a pop/clunk. I've checked all front end components including the body mounts, and I've got nothing. However, many, many miles after experiencing this for the first time, I hear a sort of creaky groaning when I turn the steering wheel. I think the intermediate steering shaft may be warn out where it links together?

6. WHY AM I SUCH A CHEAP ASS?!
So, when I bought new quick strut assemblies, I bought the cheapest ones NAPA had to offer. Now my car takes bumps like an 1800's war wagon. Anyone know of a good, softer ride strut? I know the FE3 suspensions are notoriously rough riding, but the stock struts felt like a dream in comparison.

Has anyone experienced and solved these issues? If you have any questions about how I fixed something, or a solution to my problems, please feel free to ask / tell!

Welcome to the Impala forum! @TheCodeMan
Second that on the LED’s. I’m in the process of swapping all mine over. Just have turns left at this point.
On the trans I would suspect a PCS solenoid. That would cause it to rev and then slam into gear. What happens is the gunk gets past the filter and clogs up the solenoid. Also replace the other solenoids while you are in there.
Don’t know about the other stuff so sorry :/
Whereabouts in MI are you? I’m from the Flint area myself.

Good evening!

I'm from the Canton area probably about 30 minutes from Detroit.

Probably a good idea to just go ahead and replace 'em all. (the solenoids) Since it's a daily driver, I've been considering buying a rebuilt trans from like A1 Cardone, taking it to a shop, and renting a car to drive back an forth for a day or two. I would hate to have someone else work on it, but since I can't just occasionally work on it in my driveway, and work doesn't allow me to have enough time to do the project at home, it's probably my only choice if I wanna get it done fast.

Thanks for the recommendation!

Welcome!!


Nice 'Pala!

Need MOAR pics!


Booze??

I sight have mum....

Attached Images

 

Clunking up front could be the front swaybar. If it's cracked or broken replace it with the Dorman 927-100 and Moog Poly end links.
I seem to remember a TSB or PIC on gas tank mounting causing a rear end clunk. Could be the swaybar too... Moving up to the FE3 15mm swaybar or an Addco 639 18mm and Moog Endlinks will not make the ride any stiffer but it will flatten it out some on corners.

Transmission:

The slamming is still intermittent. Before you replace the transmission do the magnet replacement TSB and add a transmission cooler.
GM TSB 08-07-30-040C

You can also replace the solenoids but you have to drop the LH end of the engine cradle... The side cover gasket is a reusable part. If you're doing the steering shaft you're probably already in there.

You really want the trans temps down lower than the engine coolant temp. 210°F is too darn high. You want the temps in the 160°-180°F range. This requires that you install an aux transmission cooler.

There are a couple threads on using the 9C1 9C3 cop car transmission coolers and hoses. The Delco coolers use the GM Jiffy-Tite cooler fittings and the whole shebang bolts up. Really too bad this wasn't available as a dealer installed option.
New from AC Delco 9Cx coolers are usually between $100 & $200. I have seen them as cheap as $35 from Delco tho.
I used the 2012 rad to AUX Cooler line and the cooler output half of the 2012 AUX Cooler to trans line.
I used a Magnefine 3/8" transmission filter to splice the 2012 AUX return to the 2009 4T65E return line with SAE J1019 trans cooler hose and four spring band clamps.
This thread has some discussion with the various part numbers and the GM parts books exploded views of both the 06-11 4T65E & 12-16 6T75 systems.
https://www.impalaforums.com/8th-gen-...mpala-ltz.html

The Hayden LPD and other aftermarket coolers will need brackets fabbed and you'll need to run a section of SAE J1019 Trans cooler hose and spring band clamps to couple it to some kind of line that mates with the transmission and radiator.
You could form 3/8" steel line with a Mastercool Hydraulic Flare Tool and the 3/8" GM Jiffy-Tite trans line dies or chop up a set of GM aluminum lines. I'd roll a bead at the aftermarket cooler end of the lines to keep the hose in place.


Brakes:

There are two possible issues at work on your brakes. Either they really are developing hard spots from thermal damage or the hubs are not running perfectly perpendicular to the splined center hole... excessive hub runout... or both.

If it's heat you can replace the front brakes with the much larger 2012 cop brakes and install the cop dust shield in place of the civilian part.
This is the GM service bulletin on replacing the dust shields.PIC5268C
This is one of the 12.7" 2012-2016 cop brakes thread.https://www.impalaforums.com/8th-gen-...ers-parts.html
Here's the one with a bunch of discussion.https://www.impalaforums.com/8th-gen-...rake-info.html

Here's a post on a Chevy forum about using Raybestos Brake-Align shim plates to correct hub runout.
The article he cites is spread across two GM Tech-Link magazines about two years apart. You can download the original magazines here if the GM Tech-Link site no longer has them in the archive.http://www.mediafire.com/folder/206j.../Impala_Brakes

The thumping in back could be your victim waking up. Next time use a



.......oh, wait.....HEY! You're Not Bones and Paulie!!!

Welcome to the forum





T you know very well mine never wake......... and I want my shovel back

Welcome to the asylum. That front rattle just might be the (secondary steering output shaft). There was a newer designed piece after 2006, but you can never tell. The triple click in the back when I stop has been with me since 2007. It is like an old friend now and I just accept its presence. Some real sharp folks here (and a couple of strange ones too). Nice having you here. Enjoy.
Hatzie is a frustrated author.