What would cause a knock..

SXYXC

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Apr 22, 2007

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Apr 15, 2008

#1

• Apr 15, 2008

• #1

trying to help a friend.. He has a knock in his lightning.. the guy before him brought it and had some engine work done, a week after he sold him the car a knock formed. What are causes of knocks? how bad can they be? how can you fix them? Don't know anything but it had work done then a knock formed.. and he can't get a hold of the last owner... I want to know most of the common causes of knocks and how to fix them.. and about the price range to fix one..

Thanks in advance

Steven

 

BlackenedSVT

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Apr 15, 2008

#2

• Apr 15, 2008

• #2

too much or too little timing can cause a knock. A bent rod could also cause a knock. How is the compression the cylinders? Was the vehicle ever dynoed at all?

A knock could be a simple fix or it could be expensive

 

Winters98GT

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#3

• Apr 15, 2008

• #3

a 5.4 swap might fix it, but I guess he already has one.....

I saw your thread in that other forum where you "had to win" and you guys were dogging stangnet. maybe they can help you a bit more than this site

 

SXYXC

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Apr 16, 2008

#4

• Apr 16, 2008

• #4

Winters98GT said:

a 5.4 swap might fix it, but I guess he already has one.....

I saw your thread in that other forum where you "had to win" and you guys were dogging stangnet. maybe they can help you a bit more than this site

Click to expand...

ouch low blow... but i guess i deserve it... how long ago was that whole thing though, its been a while since i been on the board) yeah most of the guys there are very partial to mustangboards.. but i posted the same thing over there. and on sn95forums.com to see if i can get a mixed idea of things to try...

i have thought of a few more ideas
please tell me if i am wrong on this one.
1) If the wrong fuel was used (not premium) the engine would denotate and then knock right??
2) if the cam was removed then put back in but no degreed it would cause a knock?
3) if the timing chain had jumped it would knock??
4) if the engine was about to dump because a rod was bad it would knock,\?
5) if its running to lean or rich it would denotate and knock (said something similar to that)
6) timing was retarded or advanced it would knock?
7) and finally just a bad valve would cause knocking??

Are those all ways knocking would happen.. and are there more??

 

geoffsgt

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Apr 16, 2008

#5

• Apr 16, 2008

• #5

well, #1 is correct, #2 is possible, #5 - lean, yes... rich, i don't think so. #6 is true

don't know about the rest.

 

SXYXC

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Apr 16, 2008

#6

• Apr 16, 2008

• #6

so from your thoughts,
a 99 lighting with 95K miles on it, goes to a ford dealer for work, guy trades it in, friend buys it, a week later it starts to knock... its was at the ford dealership for about 2 weeks. do you think they could have just put wrong fuel in it... because they had it a week before it started to knock...
i was thinking probably fuel (not right octane)
or the repairs messed with the timing.. (but would that take about 3 weeks for it to start knocking. that seems like a long time..

do you think the truck is still good??

 

geoffsgt

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Apr 16, 2008

#7

• Apr 16, 2008

• #7

Maybe.

Is it possible the guy had the computer tuned for whatever setup he was running, and when he traded it to the dealership, they reflashed the computer to stock settings, changing the ignition timing and causing the knock?

Seems like it could happen, but I don't know if that's common practice for dealers when they receive modified cars.

I'm sure the truck is fine, unless it was run wide open with the knock. The knock definitely needs fixing though.

I had a slight knock before i got the KB. I ran it wide open through 3rd gear 3 times (noticed a sound the first time, listened for it the 2nd time, showed a friend the 3rd time), and I have no apparent damage. I run it wide open now with the KB pretty regularly with no problems, and it's running strong.

 

mustang50v8

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Apr 16, 2008

#8

• Apr 16, 2008

• #8

could be a bad or worn bearing on the crank does it sound like a rod knock?

 

SXYXC

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Apr 16, 2008

#9

• Apr 16, 2008

• #9

well i have only been told about it, he doesn't live near me, but knows i am good with engines so he asked

 

Winters98GT

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#10

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• #10

ouch low blow... but i guess i deserve it... how long ago was that whole thing though, its been a while since i been on the board) yeah most of the guys there are very partial to mustangboards.. but i posted the same thing over there. and on sn95forums.com to see if i can get a mixed idea of things to try...

Click to expand...

its all good man! Just had to get one stab in.

good luck figuring the problem out

Mark

 

d98gt

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#11

• Apr 16, 2008

• #11

Knock knock knocking on heavens door Could very well be the motor on its way out..

Actual engine knocks aren't usually a sign of an easy fix. A video of the noise would be helpful. He should bring it back to the dealer and let them find the problem. No way in hell I would purchase something that is broke.

 

SXYXC

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Apr 22, 2007

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Apr 16, 2008

#12

• Apr 16, 2008

• #12

Winters98GT said:

its all good man! Just had to get one stab in.

Mark

Click to expand...

its all good, i was just like WTF bringing that up again. that was a while back...

 

jgorm

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Apr 17, 2008

#13

• Apr 17, 2008

• #13

Lightnings are sometimes prone to tip in knock. There are a bunch of changes you can do in the tune to eliminate this, but it is a fairly common problem. Check out my link on detonation for all kinds of info on what will cause knock. NEVER let it knock!!!
http://www.tricktuners.com/detonation_explained.htm

 

C

cobravader

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Mar 16, 2009

#14

• Mar 16, 2009

• #14

What would cause a knock noise from the passenger side valve cover, only between 2,000 and 2,500 rpms? This has me stumped. Its on a 2001 cobra by the way.