YACT: what can i do about a rod knock? **NOW with WAV file**

[RgrPark]

So my car started making this rattling noise around 1500-2500 rpm...
Had a master mechanic look at it and he says it's definitely the sound of a rod going...
So what are my options? I've already added MOA, supposedly the only additive that works...
How much would it cost?

 

[Nutdotnet]

Isn't a rod knock meaning you'll need to do a rebuild?

 

[Kilgor]

Rebuild the engine or put a new or used one in nothing you dump in the crankcase will fix it. Cost depends on what kind of engine.

 

[woodie1]

You can reduce the noise by using straight 40W oil.

 

[Zenmervolt]

Originally posted by: RgrPark
I've already added MOA, supposedly the only additive that works...

HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

ZV

 

[DurocShark]

Originally posted by: Zenmervolt

Originally posted by: RgrPark
I've already added MOA, supposedly the only additive that works...

HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

ZV

A rod knock (if it's a connecting rod) is unrepairable without tearing the engine down. It's broken metal.

 

[FrustratedUser]

fill it with crazy glue

 

[Eli]

The only thing you can do is run heavier oil.

Good luck finding straight 40 weight oil. That would be a bad idea anyway, as startup lubrication would be almost non existant.

Your best bet is 20W-50.

There is also a product called Motor Honey, it is a very thick, viscous oil additive.. but I recommend staying away from oil additives, as they can cause more harm than good.

Are you sure it's not lifter tap or something along those lines?

 

[Quixfire]

Start saving you monies for a engine rebuild or a good used engine, or trade it in before it gets a worst.

 

[GalvanizedYankee]

I have lurked for three months on aol and Roger was right. You guys do not post enough info to
make a real diagnosis.
Main bearings will knock under heavy load.
Rods will knock on the over-run,at the shift point or when backing out of the throttle.
Pistons slap when cold and generally quiet a little at warm-up.
Lifters clatter at start-up and tic constantly after warm-up.
The acceptable limit for crank journal out of round and tapper is .0005".
Good luck on what ever you do to resolve this...John

 

[geno]

Rebuild/replace the motor

 

[Zenmervolt]

Originally posted by: galvanizedyankee
I have lurked for three months on aol and Roger was right. You guys do not post enough info to
make a real diagnosis.
Main bearings will knock under heavy load.
Rods will knock on the over-run,at the shift point or when backing out of the throttle.
Pistons slap when cold and generally quiet a little at warm-up.
Lifters clatter at start-up and tic constantly after warm-up.
The acceptable limit for crank journal out of round and tapper is .0005".
Good luck on what ever you do to resolve this...John

You're a friend of Roger's? Into the Typ IV and old Porsches too?

ZV

 

[StageLeft]

Originally posted by: galvanizedyankee
I have lurked for three months on aol and Roger was right. You guys do not post enough info to
make a real diagnosis.
Main bearings will knock under heavy load.
Rods will knock on the over-run,at the shift point or when backing out of the throttle.
Pistons slap when cold and generally quiet a little at warm-up.
Lifters clatter at start-up and tic constantly after warm-up.
The acceptable limit for crank journal out of round and tapper is .0005".
Good luck on what ever you do to resolve this...John

Why the new username...? Are you going to come into all the YACT threads and help out? if so, whoo hoo!

 

[DivideBYZero]

Rod Knock *smirk*

 

[Eli]

Originally posted by: DivideBYZero
Rod Knock *smirk*

 

[RgrPark]

Recored the sound my engine makes at low rev while parked...
Goes away at high rev....

wav file

 

[RgrPark]

bump

 

[DivideBYZero]

Yeah, sounds bad.

 

OK, I can't hold back from not posting anymore, if you listen closely you will notice the knock is not continuous, I suspect either a loose piston pin, excessive side clearance on a connecting rod or a cracked/broken piston skirt.

Here's how to identify which cylinder is causing the noise, loosen but do not remove all the spark plug cables, start engine, carefully remove one plug wire at a time until the noise stops.

If the noise continues, it's a broken or cracked piston skirt, if the noise stops, it's either a loose piston pin, excessive side clearance on the rod, it just may be a loose rod bearing.

Warm up the engine, drain the oil and inspect it very closely for "glitter" (small metal fragments), If there are metal fragments in the oil, try applying a magnet to them, if they cling, then it's a connecting rod side clearance issue, if they do not cling, then it's either bearing material or piston material.

Mind you that this diagnoses is from listening to the WAV file which incidentily is not that clear.


Oh, by the way, PLEASE, PLEASE, PLEASE