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Cause of knock?

Kalal92
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Kalal92 Comanche Fan

Kalal92

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Do you have access to a mechanics stethoscope? 

I do not. Long story sure local mechanic said piston pin and Engine will need to be rebuilt or replaced I do have it in, I need to pick up and pay for it if not then they ship it back just wondering if this is less major and don’t need the engine replacement. Pretty much looking for another opinion


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yxmj MJ Junkie

yxmj

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Yes....that is were I am going.....if you had a stethoscope you could pinpoint the exact origin of the noise....no guessing involved.

 

IMHO....if it were a piston you would hear it when the motor was cool cool and all through the rev.....

My money is on

1) Ring Gear/Flywheel

2) Harmonic balancer

mjeff87 Obsessive Comanche Disorder

mjeff87

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Doubtful it's a wrist pin, but you can check quick and dirty like to see.  With the engine running and knocking, pull a plug wire off of each plug one at a time and see if the sound diminishes or goes away.  If it does, it indicates a worn wrist pin.

 

My 2.5 developed a clickity-clack sound when warmed up.  Not quite as deep sounding as yours, but it ended up being a worn out timing chain tensioner that allowed the chain to start slapping the inside of the timing cover.  Pull your distributor cap and watch the rotor tip as you carefully rotate the engine via a breaker bar/socket on the harmonic balancer bolt.  If you get more than about 10 degrees of movement on the crank without the rotor moving, I'd say you have a worn out timing chain and/or tensioner.  How many miles are on the engine?

Kalal92 Comanche Fan

Kalal92

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  • Author
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Doubtful it's a wrist pin, but you can check quick and dirty like to see.  With the engine running and knocking, pull a plug wire off of each plug one at a time and see if the sound diminishes or goes away.  If it does, it indicates a worn wrist pin.
 
My 2.5 developed a clickity-clack sound when warmed up.  Not quite as deep sounding as yours, but it ended up being a worn out timing chain tensioner that allowed the chain to start slapping the inside of the timing cover.  Pull your distributor cap and watch the rotor tip as you carefully rotate the engine via a breaker bar/socket on the harmonic balancer bolt.  If you get more than about 10 degrees of movement on the crank without the rotor moving, I'd say you have a worn out timing chain and/or tensioner.  How many miles are on the engine?

60 K on the engine. Before I started tearing it apart I pulled the spark plugs while running didn’t change any sound or knock


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sinkrun Comanche Fanatic

sinkrun

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Sounds like busted piston skirt to me and I have done A few however they  sounded that way cold also. Not sure how hard it is to pull the pan on 2.5 but that would tell you if you find a piece of skirt. Listen to some busted skirt videos on you tube see what you think. I have done them with the engine in that was 4.0 never worked on 2.5.

mjeff87 Obsessive Comanche Disorder

mjeff87

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At 60K I doubt it's a timing chain issue.  Shorting each cylinder like you did sort of proved its not a wrist pin or rod bearing issue, most likely.  Drop the pan like sinkrun suggests, what you might find will probably point you in the right direction.

 

Do you have dummy gauges in your cluster, or full gauges?  If gauge, what's your oil pressure look like?

Kalal92 Comanche Fan

Kalal92

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At 60K I doubt it's a timing chain issue.  Shorting each cylinder like you did sort of proved its not a wrist pin or rod bearing issue, most likely.  Drop the pan like sinkrun suggests, what you might find will probably point you in the right direction.
 
Do you have dummy gauges in your cluster, or full gauges?  If gauge, what's your oil pressure look like?

Light gauges if my oil pressure was to drop you think the light would come on ( light works on start up)


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mjeff87 Obsessive Comanche Disorder

mjeff87

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ummmm.....yeah.  That would do it.

 

You can pull the lifter(s) out without pulling the head.  Just make sure you use the type of lifter puller with the little "ears" on the end of the rod that lock into the top of the lifter versus a magnetic type.  They are a very tight squeeze to pull up through the head, so much so that you have to use the tool to physically pull them.  Use the same tool to reinstall to make sure the lifter drops back into it's bore, otherwise they will fall over and roll around inside the lifter valley.  It's a beoitch to get them picked back up and positioned correctly when they do that.  Ask me how I know......:laugh:

Eagle Obsessive Comanche Disorder

Eagle

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On 12/4/2018 at 5:56 PM, sinkrun said:

Sounds like busted piston skirt to me and I have done A few however they  sounded that way cold also. Not sure how hard it is to pull the pan on 2.5 but that would tell you if you find a piece of skirt. Listen to some busted skirt videos on you tube see what you think. I have done them with the engine in that was 4.0 never worked on 2.5.

 

A friend across town just went through this with his 2.5L Wrangler. Number 3 piston self-destructed.

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