Rod Knock... is this an indication of the future?

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09-14-2011, 06:16 PM

#11

69MustangCoupe393cid

4th Gear Member

Thread Starter

Join Date: Nov 2006

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Posts: 1,229

My main concern right now is the fact that it's getting close to winter, and I don't have the money for a termi drivetrain yet haha.

09-15-2011, 01:48 AM

#12

TOMMY01GT

2nd Gear Member

Join Date: Mar 2011

Location: FLorida

Posts: 334

Quote:

Originally Posted by 69MustangCoupe393cid

I know they have piston slap from what I hear, don't know about the timing chains

Yeah I know rod knock, I think I just freaked and it was really valve train, but still I never got it before with the many oil changes I have done on this car. I'm a sho owner and no stranger to rod knock, lost 2 sho engines that way haha.

Embed fail.

Rod knock... SHO style...

Link:

http://s34.photobucket.com/albums/d1...t=shoknock.mp4

See above haha. But as far as rod knock I agree but disagree. You can get rod knock with a failing oil pump, but with a replaced pump the engine could be saved. That was more my worry over truly worn rod bearings

If your oil pump has failed to the point that the rods are knocking...a new pump "might" fix the oil pressure issue...but the mains and rod bearings are toast. Metal should never touch metal..as soon as it does, its too late.

I had a SBC 350, running down the road, hit the brakes from 55..oil pressure was a solid 55psi, pressure dropped to 2 psi, I got the trans in neutral, cut the engine off...coasted to a gas station. checked oil...not on stick. Added 3 quarts...pulled hot wire from coil, cranked for 10 seconds, put coil wire back on..fired up engine..all 16 lifters were collapsed but pumped back up within a minute...but I had some bottom end chatter...oil pressure was down to..oh about 20psi crusing and 5psi idle...

Pulled engine and 2 of the mains were trashed and started to spin, multiple rods bearings were wiped/transfered....

Just a few seconds of low oil pressure did all that damage, under 1500 rpms...and it was a healthy motor!

Rod knock and engine noise from low oil pressure are not one in the same...once you have rod knock, it does not go away until you repair the damaged bearings.

These 4.6's have hydraulic snubbers under each rocker, also the chains are tensioned by oil pressure...if anything leaks down...it takes a second to pump back up, but it makes noise. Piston slap, also a problem...makes noise.