[Haywood69]

I have a friend with a 454 in his truck. It has always had a light tapping sound, but I borrowed it the other day and took it on the freeway for about 10 miles at 70 MPH and when I got off the freeway the tapping sound was really loud.

I looked in the forums here and found that it might have been the flexplate, so I took off the inspection cover and unbolted the torque converter and tapped the flexplate with a small hammer and it rang like a bell. Then we started the engine with the torque converter unbolted and backed off the flexplate and the tapping was the same.

Next I thought that it might be a bent push rod. Took off the valve cover and removed them all but they were fine.

Now to the question....Does anyone else have another idea of what this could be before we take the motor out and tear it down? I was wondering if it could be the fuel pump, since it was on the side that was the loudest?

Any advise would be appreciated!

Thanks

 

[Randy 67EC]

I had a 350 that tapped real loud on the fuel pump side, it got louder as the rpms went up. Still did it after rebuilding the 350. Replaced the fuel pump, noise gone. It seems the fuel pump arm was sticking some and caused the loud tap. It's cheap enough and easy to change, can't hurt trying it.

 

[kettbo]

Yes, if the noise is on the passenger side, the fuel pump is the #1 suspect.
Usually the diaphram breaks and you get a fuel leak..... Sounds like your FP has mechanical failure. How many miles on the engine/FP?

 

[Chicken Coupe]

The ghost of Michael Jackson trying to get out? l

 

[SAMMYSEVEN]

I still have a tapping type noise in my 70 chevelle 454 sounds like the right side, sounds like exhaust leak but ive replaced just about everything , comes on around 1400 rpm under load up to about 2200 rpm . Tried the ring gear ,torque conv , headers , cyl heads , intake , fuel pump , exhaust system, o/hauled engine twice but always used comp cams . Started with xe284 now 280h flat tappet. Running out of patience . I dont know if same sound or not but ive tried about everything

 

[Haywood69]

I'm not sure about the pump, but the truck has about 120,000 miles on it. I am pretty sure that it would have been replaced at least once, wouldn't it?

 

[ironhead]

You can kill cyls to help isolate the noise.If it sounds like an upper cyl knock..the piston skirt is most likely cracked at that mileage.

 

[kettbo]

I'm not sure about the pump, but the truck has about 120,000 miles on it. I am pretty sure that it would have been replaced at least once, wouldn't it?

People do not replace stuff that is not broken....
Could be the pump, could be a piston skirt as mentioned, that or any of 15 other things.....

 

[matt's66]

Could be a bad plug wire arcing under the insulation. That happened to me once. It was so loud it sounded like a bad lifter or rocker out of adjustment. Especially with HEI ignition, puts out a lot of juice.

 

[Motorhead62]

The ghost of Michael Jackson trying to get out? l

YouTube - You Know Who I Am

Ha Ha, your killin me with that one! l