Tapping sound ... Can't diagnose

M

MAK507

Active Member
Joined
Mar 29, 2013
Hey guys, started experiencing this sound.. Can't figure it out. Thought it was from the flexplate or tranny but it's not.

I was thinking cam sensor?? It starts up while driving. Sometimes I'll go the distance (about three miles to work) and it won't start. It's really annoying since its 50/50 that it'll do it.




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I would try to use a stethoscope or pipe and diagnose if it is coming from top or bottomend. It could be a rod bearing, flywheel bolts loosened up, bad lifter, flattened cam ,there are multiple things until u find where the noise is coming from
 
Pwt said:
Sounds like rod knock.
Click to expand...
Yeah I was thinking that. Fearing that.

Is there a way to test for this?
And wouldn't that be constant? Today I drove it to work (about 2 miles) and it didn't do this sound at all.

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How have you been MAK507?
Have you checked the belt tensioner? Sounds like it might be bottoming out.
 
Jerryl said:
How have you been MAK507?
Have you checked the belt tensioner? Sounds like it might be bottoming out.
Click to expand...
I've been good up until this point! Haha. I thought everything was finally done with this car. Mechanical and paint. I *have* noticed a recent whine on the belt, serpentine belt was replaced about three months ago. How does it bottom out and how do I check it?


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Good to hear man.
Easy way is to remove the belt and see if the noise goes away. If it does . . . I would look if the pointer on the tensioner is not at the end of its travel and for markings where it may be hitting the aluminum bracket, and, look for cracks at the mounting ears of the tensioner casting.

Let us know what you find.
 
Sounds like belt tensioner to me as well.
As belt stretches the tension can hit its stop.
Just replaced in my Durango and I think my wife's Mitsubishi Outlander is doing the same.
How long could you have rod knock before failure? Wouldn't something like that get worse fast?
Never had thank goodness.
Joel
 
Agree on belt tensioner. Look at the bracket of the tensioner down from the cam sensor side and you will see a window and the line from the tensioner should be in that window. If not or its at the far end (loose) side of the window you need a shorter belt. Also very common and makes the exact same noise and lends itself to a bottom end noise...i.e. get louder when hot and higher revs is a cracked flex plate. Pull cover from convertor area and use a light and look at the flex plate where it bolts to the crank and look for cracks from the bolts to the surrounding holes in plate.
 
What part number belt did you use? If it was a dayco from autozone their listing is wrong and the belt is too long which puts the tensioner at the end of its travel and will make the noise described. This same situation cost me a week of aggravation, a tensioner that didnt need to be replaced, and a hatchet wound in my otherwise perfect hood liner... and a pair of underoos when it threw a belt after a hard pull and i had no brakes (at the time i had an 84 hydroboost with no accumulator- no belt=no stoppy) hahaha
 
Look at the gap between the belt and the A/C pulley. I found a bunch of Goodyear Gatorbacks that were shorter than stock and even though my tentioner wasn't bottomed out I installed it anyway.
Photo1517a.jpg


Note the distance between the belt and the stainless nut on the compressor.


Look in that area on your car while it's making the noise and see if you see the idler pulley jumping in unison. Also, pop the belt off and put your hands on that pulley. The bearing in there is most likely 30 years old and a little sloppy too.
 
I wish I knew how accurate my TV speakers are compared to the actual noise the car is making...

Years ago I had a car in the intercooler bolt was stripped and made a noise almost exactly like I hear on my end. What stands out to me with your car is the consistent inconsistent rhythm of the noise.

Is it the same sound byte played in a loop with GN pictures by chance?
 
Pull the belt tension loose, and see if you can wiggle the front balancer pulley. They can crack and rattle like that. Have to remove it to see if the sleeve is cracked. Usually its right on the keyway.
 
earlbrown said:
I wish I knew how accurate my TV speakers are compared to the actual noise the car is making...

Years ago I had a car in the intercooler bolt was stripped and made a noise almost exactly like I hear on my end. What stands out to me with your car is the consistent inconsistent rhythm of the noise.

Is it the same sound byte played in a loop with GN pictures by chance?
Click to expand...

Yes the sound is looped. [emoji28]

Thanks guys for all the input. I'm going to pray it's the belt tensioner! I'll check it out tomorrow


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One time I replaced a tensioner but it turned out to be the belt because of a similar noise. Run it without the belt to rule out the other pulleys.
 
If it is the belt tensioner, where do I pick up a new one? Part#?


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If tensioner likely hitting stop because belt is stretched.
I had to replace my durango's tensioner as the belt was squealing as tensioner was not holding tight.
As advised earlier. Start motor and watch tensioner you'll know quickly if it is the problem. Be sure to have nothing hanging on that could get grabbed by spinning stuff. Easy to get careless.
 
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