Strange Metallic Whirring Noise

-
MOPARJ

MOPARJ

What can I upgrade now?
Joined
Nov 3, 2006
Messages
861
Reaction score
7
Location
Thousand Oaks, Ca
For the last year, the my warmed over 318 has been making an odd whirring noise from what seems to be the lower rear vicinity of the engine. Oil pressure has been great and I have racked up over 4000 miles on the engine ever since I began noticing it. Also adding to things, it may occur or be noticeable one moment, but gone at the next stop sign. Power has not changed any and oil consumption is good. Motor is a little rough, but not that alarming, especially considering that it is running an XE268 cam. Oil has remained clean and free of debris. The best way to describe the noise is almost like a noisey pulley or wheel, but it is coming from the rear portion of the engine from what I can tell.

Everything on the front of the engine including pulleys and accessories checked out ok. The transmission is a 4 speed and everything from the flywheel back is fine and as it should be.

The engine has 47k on it since the last rebuild and has headers. Any ideas about this? Due to the somewhat intermittent nature of this, I have a hard time believing it to be a bearing, but who knows.
 
Sounds like a throw out bearing or pilot bushing What effect does depressing and releasing the clutch have?
 
This sound could be thrust bearing wear. What happens is the crank walks back and the counter weight hits the rear of the block at the pan rail.

I have seen this on a couple motors especially when heavy metal slugs are welded in for balancing. The welds are never cleaned off properly and tend to hit with just a small amount of play. This noise will come and go depending if you hit the brakes hard or accelerate hard.

Easy check is move the crank front and back and measure the distance it moves. I'm guessing you will find to much play. Replacing the thrust bearing is easy. I know guys that just put the cap side only in. But both can be done in the car with just lowering the rear of the crank.

Pan can be dropped in car with 1 and 2 counter weights up. Otherwise the pan will hit coming out in the front.
 
RustyRatRod said:
Sounds like a throw out bearing or pilot bushing What effect does depressing and releasing the clutch have?
Click to expand...

This was recently converted over to 4 speed. The same noise was heard long before the 4 speed went in, with the 904. Clutch depress doesn't have much effect on things. Will come and go and will quiet or go away if it is left idling for a few minutes.
 
Oldmanmopar said:
This sound could be thrust bearing wear. What happens is the crank walks back and the counter weight hits the rear of the block at the pan rail.

I have seen this on a couple motors especially when heavy metal slugs are welded in for balancing. The welds are never cleaned off properly and tend to hit with just a small amount of play. This noise will come and go depending if you hit the brakes hard or accelerate hard.

Easy check is move the crank front and back and measure the distance it moves. I'm guessing you will find to much play. Replacing the thrust bearing is easy. I know guys that just put the cap side only in. But both can be done in the car with just lowering the rear of the crank.

Pan can be dropped in car with 1 and 2 counter weights up. Otherwise the pan will hit coming out in the front.
Click to expand...

Thinking it's possible. Just surprised that drive ability has not changed whatsoever in the year or so that it has been making the noise.
 
FWIW.....I have an odd whirrr from my /6's crankcase. I think that the oil pickup is juuuuust touching the pan and is being vibrated juuuuust slightly, and the movement of the pickup on the pan is making a low level noise that will come and go. Everything was solid and in spec at the rebuild with new timing chain and thrust bearing, so that is all I can figure. The /6 assembly instructions are to have a 1/8" interference between pan and pickup; that's probably to avoid this noise that probably has driven owners and mechanics crazy in the past.
 
Noticed today that the noise didn't begin until a few minutes after start up and driving for a block or two. Also, if it idles for a minute or two, the noise goes away.
 
Check the crankshaft endplay like OMM suggested. You can do this with a prybar and dial indicator under the car. Is the timing mark steady when you use a light on it?
 
Oil pump driver and bushing replaced at rebuild ? You can get a noise from the gear mesh there, like differential gear noise, gear drive timing setups, etc...
 
MOPARJ said:
I couldn't see how. Not characteristic of a noise it would make. Seems to be originating from lower than that.
Click to expand...

Is easy to check. The shaft connects to the center of the engine making it sound liked it's lower, distributors don't last forever. As with any trouble shooting, check the easy stuff first. Good luck.
 
RedFish said:
Oil pump driver and bushing replaced at rebuild ? You can get a noise from the gear mesh there, like differential gear noise, gear drive timing setups, etc...
Click to expand...

That's what prompted my timing question....
 
Do/did you have the tin dust covers on the front of both bellhousings?

If so, remove it, and see if the noise is gone.
 
inertia said:
Do/did you have the tin dust covers on the front of both bellhousings?

If so, remove it, and see if the noise is gone.
Click to expand...

Dust cover not there. Wasn't on the 904 before the 4-speed swap either. the noise was occurring with the 904 in the car as well.
 
MOA said:
Is easy to check. The shaft connects to the center of the engine making it sound liked it's lower, distributors don't last forever. As with any trouble shooting, check the easy stuff first. Good luck.
Click to expand...

Could swap back in one of my spare distributors to double check. Put an FBO unit it about a year and a half ago, just before the noise started occurring.
 
MOPARJ said:
Could swap back in one of my spare distributors to double check. Put an FBO unit it about a year and a half ago, just before the noise started occurring.
Click to expand...

A clue perhaps.... An advance weight sticking or rubbing?
 
[ame="https://www.youtube.com/watch?v=oeoDAjDApkU"]Strange noise #1 - YouTube[/ame]


Here is a link to a video of the noise. Again, this has occurred for the past year, with the previous 904 and with the current A-833. Oil pressure has remained the same and great. Will start quiet in the morning, but noise begins a minute or two after out of the garage. If you let it idle for a few moments, the noise will stop again, until you revs are brought up, or you begin driving. Clutch depress has no effect on it. I do not notice any debris in oil and no visual movement of the crank upon revving the engine in neutral.


When the noise does occur, it varies speed with engine speed.
 
Since we seem to be making a SWAG at this, here's mine. Return spring on starter Bendix drive working properly? Is the starter gear staying in place when not in use? Check starter gear for unusual or excessive wear pattern,
 
2 Darts said:
Since we seem to be making a SWAG at this, here's mine. Return spring on starter Bendix drive working properly? Is the starter gear staying in place when not in use? Check starter gear for unusual or excessive wear pattern,
Click to expand...

Good suggestion but tried a new starter a while ago. No change.
 
Almost sounds like piston slap.
 
You must log in or register to reply here.
-

Back
Top