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Very odd Buick Century noise, everyone please read!!!


Hennessy_Viper
08-27-2005, 04:40 PM
Sup everyone
I'm new to this but I got in here to ask a question, and I needed to know because my Century is everything to me. First off, I use it to drive 60 miles a day to/fro work 6 days a week, plus any other errands. It's been an awesome car, has great power and everything I can need. But recently I have noticed a problem with the engine I'm guessing. For about a year, when I drive in residential speeds between 10-25 mph, without any pressure on the accelerator the engine will seem to surge, or I should say seem to bog down and it does repeatedly until i either go at a higher speed or give it gas. Well, now when I start my engine there is a very noticeable knock in it, but it's a loud, almost like someone is hitting a hammer on metal kind of noise, and it will do it for about 5 seconds. What is weird is sometimes it will do it, sometimes it won't, sometimes if it does it's very quiet, other times the engine revs up very high and it's loud as hell. Another thing I notice is while I'm on the highway, the car shakes now, because I can't put the accelerator to the floor because it gets stuck. If I leave it close to where it gets stuck, the engine kicks back almost violently and I immediately lay off. Usually to give my car more power on the highway I let off the accelerator and get back on it, but it still is stuck. All of these issues to me seem related possibly, I had it taken a mechanic, they think the noise is from the tranny. Another mechanic said he's been workin with trannys for 30 years, he has never heard one make the noise and thinks it's the crankshaft. OK, but here is what's weird everyone: the oil and tranny fluid looks, smells, and doesn't burn at all, never has, and I change both when they need to be changed. Another weird thing. When I leave my car in park, pop the hood, I'll push on the accelerator cable and when I let it go, the engine makes the loud knocking noise. One time I did it it moved the engine, scared me bad. So my idea is the problem lies within the engine revving down. I even showed this to the 30 yr tranny mechanic, he didn't think it was a tranny problem. Where do I go from here, does anyone have an even small idea to what it might be? Thanks again for any help
Ryan

GTP Dad
08-27-2005, 05:36 PM
Welcome to the forum! I have to agree with the tranny guy that this has nothing to do with the transmission. It sounds more like you may have a problem with general engine wear. If you drive as far as you say on a daily basis, this has to be a high mileage car. The first thing I would do is replace the throttle cable and possibly replace the throttle body. Both the cable and the throttle body return spring could be worn out and causing the throttle to stick.

As for the engine making the noises you state there is a good possibility you could have piston wear problems. I really don't know since I haven't heard the engine run but you may want to take it to a mechanic you trust and have it evaluated he may be able to give you a simple solution but you may be forced to replace a few parts to eliminate the problem. If it is very high mileage a used engine may be a better choice. Good luck!

Hennessy_Viper
08-28-2005, 05:02 PM
Welcome to the forum! I have to agree with the tranny guy that this has nothing to do with the transmission. It sounds more like you may have a problem with general engine wear. If you drive as far as you say on a daily basis, this has to be a high mileage car. The first thing I would do is replace the throttle cable and possibly replace the throttle body. Both the cable and the throttle body return spring could be worn out and causing the throttle to stick.

As for the engine making the noises you state there is a good possibility you could have piston wear problems. I really don't know since I haven't heard the engine run but you may want to take it to a mechanic you trust and have it evaluated he may be able to give you a simple solution but you may be forced to replace a few parts to eliminate the problem. If it is very high mileage a used engine may be a better choice. Good luck!

Thanks alot for the help, any advice rught now really helps me. But just today on the way home, my engine (I'm guessing that's what was shaking) rocked back and forth violently for about 5 seconds, or at least something rattled terribly for that long. It made the engine kinda pause, very weird. But everyone this is odd, because no smoke appeared anywhere, it was overheating a little, but nothing out of the ordinary happened. I'm really starting to wonder if theres bearings and crap bad with the engine, and it's just a matter of miles before its done. When the engine is running, I can hear from the top intake plenum some rattling inside the engine. Like i said, no smoke, no indication to my knowledge that anything is burning, please anyone with any advice it would help alot!!
Thanks everyone

Hennessy_Viper
08-28-2005, 05:18 PM
Thanks alot for the help, any advice rught now really helps me. But just today on the way home, my engine (I'm guessing that's what was shaking) rocked back and forth violently for about 5 seconds, or at least something rattled terribly for that long. It made the engine kinda pause, very weird. But everyone this is odd, because no smoke appeared anywhere, it was overheating a little, but nothing out of the ordinary happened. I'm really starting to wonder if theres bearings and crap bad with the engine, and it's just a matter of miles before its done. When the engine is running, I can hear from the top intake plenum some rattling inside the engine. Like i said, no smoke, no indication to my knowledge that anything is burning, please anyone with any advice it would help alot!!
Thanks everyone

Ok 2 more things everyone. The car knocks or kinda 'pops' when turning to the left, and I only have 122,000 miles on the car!!

tri-power
08-28-2005, 10:27 PM
This is kind of a reach but I'd take it to someone who can check your motor for cylinder comprssion and to make sure all cylinders are both equalized and firing. It's a slim possibility that you might have a bad rod bearing or maybe a broken connecting rod thats hitting the crank. However before you attack that, make sure that you have a dead cylinder first.

Hennessy_Viper
09-15-2005, 03:20 PM
I just had my car looked at by an ASE certified mechanic, my brother and a manager at my job have gone to him and said he is very good at what he does. After a few hours, I still could not pinpoint exactly where and what was causing the noise. It seems likely to be in the valvetrain though, just by the type of noise and the fact that is goes away after starting and decelerating after revving. I had the cylinder compression checked, everything came ok good, and with the battery disconnected and all, we hooked up a device that started the car but didnt, it actually showed the rocker arms and cylinders moving up and down, and everything seemed good. The rocker arms had normal wear and tear, the rods didnt seem corroded or burnt in any way. So I'm back to square one it seems like. However, it seems to be an exhaust problem, because upon deceleration the noise appears. If anyone knows enough about GM cars to give maybe something similar happening, it would be greatly appreciated. The car still runs really good, so I'm still driving it!!

HotZ28
09-15-2005, 08:00 PM
If the throttle is sticking, it could be your transmission mounts. Also if it is surging, check ignition system. An engine that surges or rapidly cuts off/on, plays havoc on the balancer!

Open the link below and see if this could be it;

http://www.buickforums.com/forums/showthread.php?t=1439 :screwy:

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