Topic: "Knocking" noise ideas/diagnosis -- VIDEO inside! ***SOLVED w/ DAMAGE!!!***

[OrigOwner77]

Anyone want to throw some ideas out there as to what the noise in the following video sounds like / could be? Car in question is my 80 T/A.

http://www.my80ta.com/videos/80noise.wmv

Don't know how much diagnosis I'm going to actually do (may have another motor going in this year, don't know yet). But...it has always had me curious.

To note, car pulls VERY strong, noise is most prevalent at idle (can't hear it above 1500-ish rpms), and the car has great oil pressure. No adverse effects seem to be a result. Also, noise 'seems' more prevalent on the driver's side of the vehicle. Torque converter bolts are tight also.

Thanks!

[RPO_Z06]

I can't seem to get the video to work.

[rhino33]

maybe a really noisy fuel pump to check it get a broom handle and listen through it when you put it on the fuel pump, to check if its in the lower end get a axe handle or some hardwood and force it against the front pully or the torque converter to push the whole rotating crank in and out a bit to see if the sound stops when doing it

[OrigOwner77]

I can't seem to get the video to work.

Video works for everyone on the PerformanceYears board. Standard Windows Media video, not encoded in any fancy way, shape or form.


And thanks for the idea rhino33....a fuel pump was suggested on PY. I may, as it is a cheap enough test, swap it and see what happens.

[jjr]

 Kinda sounds like a "something or other" rattling.

 It's may be rpm dependent, which support a vibrational mode.

 When I am at that point I use my "garden hose" tool.

 About 5 feet of cut off hose (both ends) with one end up to
my ear and the other slowly snooping the engine compartment.

 The hose localizes sounds allowing me to pin point the source
of sounds. It's one of my best tools... <grin>

 Joe

[Rick]

Vid works for me too.  Jamie, see if you can open it with the Windows Media Player.

[OrigOwner77]

 Kinda sounds like a "something or other" rattling.

 It's may be rpm dependent, which support a vibrational mode.

 When I am at that point I use my "garden hose" tool.

 About 5 feet of cut off hose (both ends) with one end up to
my ear and the other slowly snooping the engine compartment.

 The hose localizes sounds allowing me to pin point the source
of sounds. It's one of my best tools... <grin>

 Joe

If I get ambitious, I may "borrow" a reproduction of that tool and poke around to see if I can narrow the sound down.

[transam dave]

Anyone want to throw some ideas out there as to what the noise in the following video sounds like / could be? Car in question is my 80 T/A.

http://www.my80ta.com/videos/80noise.wmv

Don't know how much diagnosis I'm going to actually do (may have another motor going in this year, don't know yet). But...it has always had me curious.

To note, car pulls VERY strong, noise is most prevalent at idle (can't hear it above 1500-ish rpms), and the car has great oil pressure. No adverse effects seem to be a result. Also, noise 'seems' more prevalent on the driver's side of the vehicle. Torque converter bolts are tight also.

Thanks!

could try the water pump its a start dave.

[OrigOwner77]

could try the water pump its a start dave.

Thanks for the idea Dave...my waterpump is actually chattering a little bit, but noise from the water pump would be too high up and on the wrong side. This noise is most prevalent from the Driver's side and down low.

[RPO_Z06]

Strange, the video works fine today. 
Try removing spark plug wires one at a time on that side to see if it makes a difference, that will help tell if its a rod.

[4SPEED]

check your convertor bolts.

[4SPEED]

I only say that because the bolt may not be the right ones and are bottoming out agents the convertor. I had that sound on mine and that was the problem.

[OrigOwner77]

Thanks for the ideas guys. RE: TQ bolts...not a bad theory, but the noise wasn't there when the car was purchased 4-5 years ago...have noticed it in the last couple years (not getting worse either). And they're tight.

I'll get a plug boot puller (so I don't get zapped w/50,000 volts lol) and see if that makes a change/difference with the noise. Should they be pulled from the cap or the plug end?

---

Another thought...this weekend I re-jetted my carb. The car had been sitting for a week, and when I pulled my dual-feed line, there was no fuel in it after the pump. Maybe the anti-drainback check valve is bad in my fuel pump (even though the pump isn't that old)? I disconnected the coil and cranked it. After 2 revolutions (maybe 1 second on the starter tops) the pump was shooting fuel out of the line, so it is working well, just allowing drainback.

Maybe this is pointing more and more to a noisy fuel pump? Or do some pumps allow drainback?

[rhino33]

just get a wooden broom handle and put one end on the pump and the other on your ear, its the best way to isolate a knock and you can use a 12v lighted tester to short out the cyls, all you do is clip it onto the ground and then you poke it into the caps each of the wires one at a time on the distrubuter
the fuel pump runs on a cam and sometimes they get really noisy but work good otherwise

[OrigOwner77]

***UPDATE: 4/18/09***

Found some more info on the knocking noise in the video above.

If I pull the manifold vacuum line off my Holley that goes to the transmission modulator, the idle goes up a couple hundred rpms (expected), but the noise goes away.

Can a trans modulator make noise? Or is there something inside the trans that is vacuum controlled that can make a noise like this?