Knock when accelerating, especially up hills.

G

gmssage

New Member

Mar 9, 2004

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Mar 9, 2004

#1

• Mar 9, 2004

• #1

My 1997 Mustang has a noticeable, but not overly loud knock when accelerating, especially when going up hills. It is not quite so loud when on a flat road.

I just changed the spark plugs, thinking that it would be due to spark knock, but I didn't change the wires. After having the plug changed, the sound still continued.

I also tried running a higher octane gas (went from 87 to 93), but that made no change.

Any help in diagnosing and fixing this would be much appreciated.

 

xneox

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Jan 14, 2004

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Mar 9, 2004

#2

• Mar 9, 2004

• #2

This is one of those things that's nearly impossible to diagnose thru the 'net. Could be anything from an alternator bearing to a main bearing.

How many miles?

Oil change intervals?

Spark knock & bottom-end knock sound nothing alike, so if you can't distinguish between the two maybe you have a bud that's into cars & will go for a ride w/you to help nail this one down.....?

 

J

Jamez

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Mar 2, 2000

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Tulsa, Ok

Mar 9, 2004

#3

• Mar 9, 2004

• #3

Mine sounded like it was knocking when one of the primary tubes cracked.

 

G

gmssage

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Mar 9, 2004

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#4

• Mar 9, 2004

• #4

63,500 miles, with oil changes every 3,000 miles using Pennzoil 5W-30.

It's more of a higher pitched, extremely rapid knocking sound, and it doesn't happen at all while in park/neutral.

 

Mach428

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Dec 7, 2003

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Mar 9, 2004

#5

• Mar 9, 2004

• #5

Answer these questions for me, Is it one loud knock and do you have an auto?

 

98CobraClone

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Feb 28, 2003

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Ripley, Ohio

Mar 10, 2004

#6

• Mar 10, 2004

• #6

extremely rapid..........valve lash??????

 

G

gmssage

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Mar 9, 2004

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Mar 10, 2004

#7

• Mar 10, 2004

• #7

Yes, it's an automatic.

No, it's not one loud knock. It sounds like a lot of semi-quiet little knocks, rather rapid, probably about 7-10 little knocks a second while accelerating.

 

xneox

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Jan 14, 2004

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Mar 10, 2004

#8

• Mar 10, 2004

• #8

98CobraClone said:

extremely rapid..........valve lash??????

Click to expand...

Sounds like top-end from what he's describing.....but I've heard belt/chain tensioners & accessory bearings make that kind of noise too....

 

Mach428

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Dec 7, 2003

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Mar 10, 2004

#9

• Mar 10, 2004

• #9

I know on my v6, after 50,000 miles, the trans like to make all funny little knocks, every think you might be hearing something from the trans downshifting?

 

G

gmssage

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Mar 9, 2004

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Mar 10, 2004

#10

• Mar 10, 2004

• #10

If it was the transmission, wouldn't it just be while it was shifting then, instead of constant?

 

Mach428

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Dec 7, 2003

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Mar 10, 2004

#11

• Mar 10, 2004

• #11

allot of the v6 trans like to do funny crap, i'm not sure