knoking+ some noise when car makes a turn

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  #1  
Old 06-04-05, 12:58 PM
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knocking+ some noise when car makes a turn

Hi all.
1990 Merc Cougar, 165000 Mi, V6, makes knocking sound when accelerating. Was a lot worse before a tune up. I changed plugs, wires, cup and rotor, plus replaced cats. Also I hear something loud when car makes a left hand turn. The noise is coming from rear-left.Any ideas what it could be? Also, what else could I do about knocking and to improuve acceleration?
Thanks. Irina
 

Last edited by Irina; 06-04-05 at 02:15 PM.
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  #2  
Old 06-04-05, 06:55 PM
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Engine knock is a sign of worn bearings. I doubt that a tune up has any effect whatsoever, aside from psychological.

The left hand turn noise is often a speed relative knocking noise also. It is most often a bad cv joint on the drivers side (front, not rear as you suggest). Driver side cv's go bad because they are shorter than the passenger side cv joint axle. The shorter axle means shorter cv joint life.
 
  #3  
Old 06-04-05, 07:52 PM
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OK, maybe noise is not exactly knocking in the front end, but I feel and hear it when accelerate from start to 40 MPH or so, then acceleration a bit slaggish, but noise is never there. Tuning up definetely made a diffference. Could it be the timing chain? When I was changing plugs had a little trouble removing one (something melted over it) + plugs were pretty bad, it've been a while since last change. I'm really concerned about it. Please, help.
Irina
 
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Old 06-05-05, 05:53 AM
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Left hand turns verses 0 to 40 mph? Im confused. Maybe you could describe just one noise per post, including what it sounds like and when it occurs.
 
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Old 06-05-05, 04:39 PM
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Sorry. First, noise in the front end. It's hard to describe what it sounds like. Rolling- rattling maybe. But it's very subtle. Had a guy from the tranny shop test drive the car, he didn't pick it up. Occurs only on the low speed, mostly when under load, as if going up the hill, or sometimes when accelerating hard from the stop.To make it go away I have to let up on the gas pedal. Acceleration is slow overall, especially noticeble on the highway. When I rev up the engine it sounds great, noise is not there.

Second, you suggested that noise from the back is really from front- CV joint.Is it possible that CV joint sounds like the whole rear part is folling apart?Sounds like something is lose and banging on the car's body. Not every left turn car makes a noise, only when I accelerate during the turn.

Third, are these related? I don't see how, but figured I'll ask pros. Thanks.
Irina
 
  #6  
Old 06-05-05, 07:50 PM
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The noise under the hood, from your description, sounds pretty much like engine ping. A tune up, as you stated, may have reduced the pinging. Are you using the same gas that you have always used?

The noise in the rear is not so easy to determine. I could only offer different guesses, starting with the easiest thing to check, the muffler brackets. See if you can wiggle the tail pipe or muffler with your hand. The entire exhaust system should be tight, and not be loose anywhere.
 
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Old 06-05-05, 08:53 PM
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Well, I'm using the same gas. What can be done and what's causing it? I have check engine light coming on briefly once in a while. Is changing O2 sensors will make any difference? My cats were changed and accelerating power improved, but sensors are old, possibly original.
Checked the muffler and it's tight.
 
  #8  
Old 06-06-05, 06:42 AM
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Replaceing 02 sensors on a hunch is not a good idea.

My two thoughts are:
1. Pull the codes which will guide you in problem diagnosis. Driveability problems can be complicated to resolve and the trouble codes are a key part of any driveability problem.

2. Your engine pinging could be due the engine not being able to produce enought horsepower for a number of internal reasons, i.e. weak valves, etc, or could be as simple as a lean fuel ratio. A lean fuel ratio can be solved once the codes are pulled.
 
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Old 06-06-05, 08:46 AM
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We couldn't pull any codes. The light is not on, test says no codes stored. The hook up was in the trunk ( we also tryed to pull brake code, without success). Is that the correct way to test engine codes?
 
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Old 06-06-05, 09:46 AM
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Negative, the hook up is under the dash, or under the hood, depending on whether it is obd1 or obd2. 1995 was a transitional year, but I would guess it is obd1 with connector in the engine compartment.
 
  #11  
Old 06-06-05, 06:29 PM
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It sounds kind of stupid, but could it be any of your heat shields making that noise. Thats what happened on my car. One of the head shields had came loose and would cause noise.
 
  #12  
Old 06-07-05, 12:43 AM
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1990 mercury cougar. That a rear wheel drive right?Vibration up hills? and under load only? Maybe it could be your driveshaft.The U-joints maybe worn out. Is it a vibrating noise up hills only?
 
  #13  
Old 06-08-05, 01:19 PM
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No, but it never failed to make it when going up the hill.
 
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Old 06-10-05, 07:37 PM
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Cleaning the fuel ingectors seems to solve the problem. Thanks, all!
 
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