Mechanics

GUTTURAL NOISE ON ACCELERATION

2008 Buick Lucerne • 6 cylinder FWD Automatic • 25,000 miles

Hi,

I am going crazy with this. I bought a used 2008 Buick Lucerne with a 3.8 engine. I never noticed the loud raspy/ gutteral acceleration sound. I am convinced that this is not normal. At times I have to raise the radio volume and crack the window to drown out the sound! I have driven the EXACT same car sitting at the dealer and this sound is NOT present in that car but I can't seem to get any of 3 different appointments I have made at 2 different dealers to hear this. PLEASE. ANY SUGGESTIONS WILL BE APPRECIATED.

YOU CAN ONLY HEAR THIS FROM THE DRIVERS SEAT.(Passenger seat is quiet)
IT DOES VARY IN LOUDNESS (Of course it is always quiet when I take it in)
IF I ACCELERATE AROUND A CORNER THE SOUND WILL BRIEFLY DISAPPEAR UNTIL IT STRAIGHTENS OUT. (They told me that the engine and the exhaust don't move independently) Then why is there a flex pipe? They just shrug their shoulders.
THE HEAT SHIELD AROUND THE EXHAUST ON THE DRIVERS SIDE HAD 2 OF THE BOLTS ALMOST COMPLETELY OUT WHEN INSPECTED.
( implying in my thoughts that someone was in the flex joint of the exhaust)

Dealers have stated that the loose bolts means nothing. Probably weren't put in at factory. No work was reported being done in that area. They said if it was an exhaust leak it would be present at all times. I have begged them to disassemble the flex joint and inspect the pipes and gaskets. They haven't and obviously don't think it is necessary.

This spring I will most likely do this my self to rule this out.

What else could this be if not the exhaust

ANY IDEAS?

Avatar
Dseibert
January 16, 2011.



This is a tough one. The one thing you mentioned that got my attention is the fact that when you accelerate around a turn, it goes away. To me that sounds more like a wheel / hub bearing issue. It would cause a growing sound. I don't know if you have noticed if it goes away in one direction and gets worse in the other, but pay attention to that and let me know. As far as the flex joint, take a close look at it. If there is a leak coming from there, the leaking area will have a black carbon like powder on it. That is the same on any part of the exhaust system. One other thought, check the air intake system. Start at the air filter and inspect the plastic housing and breather pipes that go to the throttle body for cracks / leaks that can cause noise.

If you notice the change in sounds that I mentioned when turning, have the front wheel bearings checked. Let me know what direction makes it worse and I'll tell you which bearing is bad.

Hi, Thanks for the reply. The sound is always attached to acceleration. Starts around 2,000 rpm. Even when cruising at 65 mph. A slight acceleration, (200 rpm's), will cause the sound.

The reason I bring up the cornering as my thoughts are that the centrifugal force of the turn causes the engine to shift and the leak temporarily seals. I bring this up to my service people and they just look at me. They tell me that is what the flex pipe would take care of if that was the case. I tell them yes, but what if it is cracked. They looked at the 1 surface they can see from under the car and tell me all is well. If it was cracked you would always hear it. The black carbon would tell the story if I could get them to disassemble it. Maybe they have x ray vision.

This fall I inspected the air cleaner area and the chamber attached to it and didn't see anything. We seem to think alike here. I was thinking about covering the entire area with a packing blanket to see if that muffles the air intake area. If it did, that would maybe lead me to a solution. Wanted to do the same with the exhaust area also.(Not with a blanket though) Wouldn't know what to use there. Not a lot of space down there anyway.

I will say though that you can torque the car all you want and there isn't the sound. Kind of puts a kink in the theory. Or does it?

I am at the point that I will take the 4,000 loss as it is really making me crazy.

Any other thoughts?

Is there anyway of finding out if there is a problem with acceleration noise and the flex joint on the Buick's?

Tiny
Dseibert
Jan 16, 2011.
Please be careful if you cover any engine or exhaust parts. They get hot and can cause a fire. As far as the leak, yes I understand you. Considering the exhaust system is basically mounted to the vehicle with rubber hangers, there is always movement. Try this. Start the engine and have a helper plug the tail pipe with his / her foot. If there is an exhaust leak, you will hear air escaping from the system. Tell your friend to only do this for a couple seconds at a time. It will get hot on the foot and make sure you are outside when you do it.

Thanks, I will try that. Will advise.

Tiny
Dseibert
Jan 16, 2011.
Well, No luck with anything. 2 dealerships, 3 different service writers just shrug their shoulders and proclaim. It will eventually break and then we can fix it. HA HA HA. They laugh. We test drive the same exact cars on their lot and they are always dead quiet. Mine always makes the noise but they can't hear it as it is always somewhat quiet when I take it in. I'm starting to see that if it breaks, no problem. Diagnosis. Not so much.

Like the fact that the engine uses 2 qts of oil in between oil changes and they proclaimed that GM feels that 2 qts between oil changes is acceptable. They replaced valve guides. No change. I so regret buying a GM car.

Anyways. Enough of the rant. I guess It is up to me figure this out. And good hearted folks that are here of course.

New clue: Traveling down the road and hearing the noise. Remember: I have to turn up the radio and crack the window to drown out this noise when it acts up. I only hear the noise in the drivers seat. If I shift the car in neutral (60 mph) the noise virtually goes away while revving the engine so I don't think it is engine related as I originally thought. It is only under power with the car ROLLING at around 2,000 rpms. Can't hear it revving in park, can't hear it torquing the car up at 2,000 rpms. I have heard bad bearings and this sounds nothing like that. A friend that was a mechanic in a different life heard the noise and said it sounds like air noise like the car didn't have an air filter to baffle the intake noise and that the "wooden ball bouncing around in a plastic box" was a carberation noise. The air intake system was checked.

Any other ideas.

Tiny
Dseibert
Oct 23, 2011.
I had/have the same problem. Got the car this last spring. Did not notice the noise at first. Got progressively louder. Only happened on mild acceleration. Louder in back seat.

Buick dealer finally figured it was exhaust after replacing some other parts. Their proof/trial was to install some kind of factory supplied counterweights to the exhaust right after the manifold. The factory told them how to orient the weights and, noise was gone. Once verified, they replaced the complete exhaust system under factory warranty.

Now, it is starting up again. Haven't contacted dealer yet.

If they will not cover it under warranty again, I will ask if they will install the weights again and just leave them on. If all else fails, I'll either get rid of the car or see if complete exhaust replacement by local muffler shop does the job. Depends on the cost.

While waiting for the new exhaust system parts, I showed the (installed) weight things to the local service shop. They said they had seen that type of stuff on other cars before (not all were GM cars.) But never knew what they were for. Must be a widespread problem/solution.

I must frequently transport my 90+ year old ****** around. She says the noise in the back seat is very loud. To the point she asks to trade seats with my sweet wife.
Wife says the same thing.

Nothing like our old Park Avenue.

Tiny
Lawalkowski
Nov 24, 2011.
Thanks for you response. I will show this to them. Nothing will come of it because that would imply they didn't do their job right in the first place and they most likely will dismiss it.
You are right when you imply these Buick's are not what they used to be. Plastic dashboards. Never again. GM is dead to me now. If I wasn't so cheap and didn't mind taking the $5,000 hit trading this in, it would be long gone.

Have a nice Thanksgiving

Tiny
Dseibert
Nov 24, 2011.
Dseibert, have you found a remedy for this, besides a louder stereo?

In one of your last posts, you said that you don't hear the noise when in park, only while rolling and accelerating. What happens if you're rolling and you shift into neutral?

Have you tried lifting the vehicle's front end and seeing if the noise is made? This would eliminate road noise and bearings.

Rivermikerat
Dec 31, 2011.
No, The problem is still there.

When I'm traveling 65 mph and shift into neutral the sound goes away.

Someone on a different site mentioned the torque converter?

I have an appointment this Tuesday. They will shrug their shoulders like they have the last 3 times. (2 different dealers). This car is a total disappointment. I can't afford to take a 4,000 hit in trading it in. I bought the car used. The sound wasn't there for the first few months. The sound isn't there when I test drive other 2008, 3.8 cars on their lots.

I'm totally disappointed in Buick, GM and the service centers I have at my disposal.

Did I mention that the car loses 2 qts of oil in between oil changes. They found a tsb and changed something. No help. Then they stated that 2 qts of oil is considered "acceptable" by GM.

And we wonder why people buy foreign.

Tiny
Dseibert
Dec 31, 2011.
I was going to mention the torque converter when you said it goes away when shifted into neutral.

Either find a shop that will test transmission fluid pressure for free, or a parts store that will loan or rent a gauge for free and test the pump output pressure and let me know what you get.

2 quarts of oil used to be acceptable to only Harley-Davidson. Now not even racers consider it acceptable. They're being lazy.

My thinking is it's either a problem within the torque converter or the transmission itself. Check online or in the phone book for a good transmission shop, like Aamco, if you can.

Rivermikerat
Dec 31, 2011.
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