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2003 Buick Century engine knocking


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wrightpaint
New User

Feb 1, 2017, 2:55 PM

Post #1 of 7 (334 views)
2003 Buick Century engine knocking Sign In

I have an 03 buick century with the 3.8l v6. on monday the engine started a sudden loud knock that speeds up with more throttle. I was going to look at it last night but it died on my wife on her way to work. I charged the battery and it started fine so I loaded it onto the trailer and brought it home. We started the engine to try and pinpoint the noise and it sounded as if it was coming from the firewall side of the engine, I engine pulled the valve covers and everything looked fine, a couple of the rods had maybe 1mm of up/down play. turning the car over didnt produce a knock so I pulled the intake and nothing stands out to me. Rods don't look bent or anything. charging the battery right now so I can turn it over again and see if I can locate a problem. As for right now though i'm perplexed, it sounds like it should be obvious but its not. It was low on oil, which is bad< but it started so suddenly and the additive I put in made no change.
I think the alternator is bad also, I had read that they can produce a loud knocking sound when they go bad so i pulled the fan belt and it changed nothing.
I have replaced 2 injectors and put new gaskets on the intake manifold maybe 2 years ago. There hasn't been any noticeable noise other then the water pump. Its gone out 2 times once 3 years ago and then about 6 months later which I believe was a faulty pump. No problems since. can't think of anything else to add. let me know if you need any other info


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Feb 1, 2017, 3:41 PM

Post #2 of 7 (324 views)
Re: 2003 Buick Century engine knocking Sign In

I don't get this.............

Your car had a bad knock but your wife took it to work anyway............... not too smart.

Now, with no idea what the problem is, you start taking the intake off.

What's the point in asking now?



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



wrightpaint
New User

Feb 1, 2017, 3:56 PM

Post #3 of 7 (316 views)
Re: 2003 Buick Century engine knocking Sign In

your right, Know it wasn't smart and the reasons are immaterial at this point. its not any worse than when it started. what I'm looking for are Ideas as to where to go from here not condemnation. Something like idk, lifters, engines shot, check the cam shaft.
I don't have any Idea now, I thought it might be a bent rod or something which is why I tore it down. wasn't a big deal to do.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Feb 1, 2017, 3:59 PM

Post #4 of 7 (312 views)
Re: 2003 Buick Century engine knocking Sign In

Any diagnostic ideas you may have gotten from us would have required having a running engine.

Now that you have ripped the top of the engine apart, your options are pretty much, ...................... replace the engine.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



wrightpaint
New User

Feb 1, 2017, 4:03 PM

Post #5 of 7 (308 views)
Re: 2003 Buick Century engine knocking Sign In

It'll only take about an hour and a half to put it back together. are you saying its a waste of time? I don't get it what questions would you have asked if it was running?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Feb 1, 2017, 4:09 PM

Post #6 of 7 (306 views)
Re: 2003 Buick Century engine knocking Sign In

There are things you can do to isolate the source of the noise with a running engine like killing cylinders, using a stethoscope, examining plugs, doing a compression check, monitoring data in a scan tool, etc

All things considered though, if the noise is as loud and extreme as you describe, there is a very low chance it would be repairable if the damage was in the lower end or even dropped a valve or anything like that.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



wrightpaint
New User

Feb 1, 2017, 4:19 PM

Post #7 of 7 (302 views)
Re: 2003 Buick Century engine knocking Sign In

Ok, that helps. I can still check compression by turning the engine over right? I can also check the plugs and inside the cylinders through the spark plug sockets. we did use a poor mans stethoscope (a long handled screw driver) and while not as good still helps to localize things. If its in the block like the cam or crank shafts I would have to pull the motor anyway.






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