A new theory on engine noise... - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

Kevin69Mach1 · 07-07-2004, 07:29

I have been trying to find a strange noise in my 351C that I suspected was in the roller rockers.
I have a new theory after I changed out my fuel pump this weekend. Is it possible that the double roller timing chain could be smacking the fuel pump arm? I reached in through the fuel pump hole and the chain has about 1/2" play in it which would slap around abit. The noise is a slight click/knock noise that I can't tell where its coming from.
Any thoughts????

Thanks....Kevin

TruBlu351 · 07-08-2004, 08:11

Is the sound just as noisy at the rear of the motor? ie: is it just isolated to around the front where the pump is?

Is it the same on both sides? Is it continuous? (problem with rocker chatter I think would be continuous?).

Never tried this, but there is a special trick to isolating where the noises come from that people swear by..............

Get a long heavy duty screw driver and put it on the part you think is noisy and then place your ear up to the handle........this apparantly amplifies the small noises. Kind of like a doctor's stethoscope! Then try it on different parts of the engine and compare!! Don't get your hair caught in the fan belt!!

Are you running a solid or hydraulic cam? You could easily pull a rocker cover and check the valve lash. Shouldn't be any movement in the rockers with a hyd cam (~zero lash). I've had "chattering" rocker arms. Obvious loose movement due to my previous owner having major issues with pushrod lengths.

Cheers

svo347 · 07-08-2004, 19:45

you can buy a mechanics sethoscope for around $15, comes in real handy too.

Rhett · 07-08-2004, 21:34

I'd be a bit concerned about the half an inch play. Can't be good for accurate timing.

I use a stethoscope now, but before that I used half a broom handle in the same way that TruBlu suggested. A screwdriver can get your head a bit close to moving parts.

svo347 · 07-08-2004, 22:20

Depends on what side the pump goes into, meaning one side of the slack chain would always be under tension the otherside would be floppy but not that bad..
If it went into the drivers side then that side would always be loose as the crank would pull the chain clockwise.

svo347 · 07-08-2004, 22:21

Ive had my engine rebuilt 4 times since Ive had it & never had that much play..

Nod · 07-09-2004, 18:44

1/2 inch play is the maximum allowable deflection. It may be time to buy a new chain.