Knocking noise....checking bearings? - Ford Muscle Forums : Ford Muscle Cars Tech Forum

Vinyl66 · 10-23-2007, 07:15 PM

My engine has a knock that sounds very much like rod knock. I have heard rod knock in the past and do not want to run the engine for another minute before trying to find the problem.

When I first heard the noise it was not coming from the valve covers but it sounded like it was coming from the bottom end and rear of the engine.

Anyway, what I want to know is what is the best way to check the bearings? I guess I should check main and rod bearings. The pan is already off. Do I just remove one cap at a time, check for scoring or wear, if none then torque it back? What is the torque spec for mains and rods? It uses arp bolts.

I am bearing scared since this happeed to me with my previous engine when a oil galley plug popped out.

boss302isback · 10-23-2007, 07:31 PM

i would pull the motor to check the bearings. i had this problem too :'( this is a chance to build it bigger :-D

mustang42782 · 10-23-2007, 08:58 PM

Roll them out, measure it all up, get the correct bearings new and replace them all

FEandGoingBroke · 10-23-2007, 09:02 PM

Pop each one one at a time like you sugested

Call the local machine shop for torque rating for the rods & mains, ARP torque specs are DIFFRENT than standard book #'s/

FE

PaulS1950 · 10-23-2007, 10:36 PM

Before you pull the bearings out try this:
start the car and put it in drive at an idle. if the knocking goes away then you probably have a broken drive plate. Fords with automatics sometimes break the drive plate that connects the cranck to the converter. It sounds like a rod or main bearing knock that is ready to come apart. Check the drive plate for cracks before you tear the engine down.
None of the above applies if you have a manual transmission.

64bird410 · 10-24-2007, 02:49 AM

check the bearings as said but also look elsewhere for something not having proper clearence. does the knock increase in frequency as you rev it? check the pan baffle for indication of being hit by the rotating assymbly.

68fastang · 10-24-2007, 03:32 AM

Why not cut the oil filter open and look for debris before you pull the motor?

dennis111 · 10-24-2007, 03:58 AM

As 68fastang mentioned, checking the oil filter would be a great next step.

Since the pan is off, you should go ahead and remove each rod cap and check it out. Take pics and post if you are unsure. Also check out what size rod bearings are installed and post it (std, .010, .020.)

I have had success diagnosing an idling motor for rod knock by removing the plug wires on by one until the sound went away. Then I knew right away which rod cap to remove first.

Vinyl66 · 10-24-2007, 06:09 AM

When I took the oil pan off last night, in the bottom there was a good bit of fine copper looking material. I think with a new engine that some metal material should be expected. It's just the noise has me worried.

I got the torque specs of 45-50 ft/lbs for the rod bolts and 65 ft/lbs for the mains using arp moly lube and 70-75 tops for mains using oil.

I wil take pics tonight when I remove one cap at a time. The engine has only run for a very short time since I heard the noise so hopefully there is not too much damage. With my luck with cars though.........

1bad6t · 10-24-2007, 06:13 AM

A loose Main Bearing is a powerful dull thud or knock that take place regularly every other revolution. The knock can be confirmed by disconnecting the plug wire next to this cylinder. The knock would be less audible.

Loose Rod Bearing is a metallic knock that can be heard the loudest at about 30 mph. The knock can be reduced or eliminated by disconnecting the plug wire to this cylinder.

Loose Flywheel is a thud or click which is usually irregular. To test, idle the engine fast and shut off the ignition. If a thud is heard, the flywheel is loose.

Loose Piston Pin is a sharp double knock which is usually heard when idling. Severity of knock should increase when the plug wire is removed to this cylinder

Mikes66 · 10-24-2007, 06:15 AM

Wasn't there a recent rash of china stroker cranks that had a machining cross-hatch pattern at the (third main) thrust bearing, where the cross hatch was griding down the thrust bearing with-in 500 miles, and leaving copper all over the oil-pan?

Also I hope a high quaility torque wrench was used. Dry rod bolts vs a light film of oil on them helps to torque bolts to spec better. I use a lot of thick STP on main bearings surfaces for assembly.

Vinyl66 · 10-24-2007, 08:26 AM

Quote:

Originally Posted by Mikes66

Wasn't there a recent rash of china stroker cranks that had a machining cross-hatch pattern at the (third main) thrust bearing, where the cross hatch was griding down the thrust bearing with-in 500 miles, and leaving copper all over the oil-pan?

Also I hope a high quaility torque wrench was used. Dry rod bolts vs a light film of oil on them helps to torque bolts to spec better. I use a lot of thick STP on main bearings surfaces for assembly.

I am using a SCAT crank. Aren't they made in China now? The motor has somewhere around 400 miles on it. Hmmm....

Thanks for the tip, I do have some STP with ZDDP at home to use when I put the bearings back in. That stuff is thick and stays on there.

I wish I would have tried the spark plug wire thing before I removed the oil pan, but that's the way I do things.... wrong.