New tapping/knocking noise! scaring the heck out of me

[Mrlee75]

So this happened yesterday after a full week of odd noises. First it was a timing belt screech, second the brakes started screeching, third the odd shudder which i've posted about already. However this one is unique and quote honestly has me worried to drive it. The timing belt screech started Sunday, sprayed it down with belt conditioner and WD-40. Up until Wednesday the screech was bearable until I started hearing a light tapping/knocking sound coming from behind the middle of the dash. The tapping/knocking is very mild and faint, not consistent with anything and sounds like something loose is rolling around. The closest description I can think of is it sounding like you had a 12" plastic tube, put 3-4 pieces of small plastic pieces in it. A very faint tapping on plastic sound. Very hard to explain and describe catching it on film would be nearly impossible.

It's not a very deep knocking, but noticeable. At low speeds or when my foot is off the gas you don't hear it, however under acceleration you would definitely hear it. Once in a while when you let off the gas you still hear it, but very faintly.

Not sure what it is. It's an entirely new sound. This happened on my way back from work after I had filled it up with gas. Switched from 89 to 91 recently, the tank before this I used STP super concentrated fuel injector cleaner (used the entire bottle), Lucas Oil transmission fix (used maybe 60-70% of the bottle) and steering stop leak, along with filling up the radiator coolant reservoir. Doubt the last two had anything to do with it.

I have a 1997 5.0L EB.

Please, I'd like to make that noise go away. Open to any take on it and quite honestly fearing that driving it any longer would create more damage.

Thanks!

 

[windsors03cobra]

Sounds like a bad front driveshaft you need to get under there and inspect it for any slop or play, and have a good look at the rest of the front end as well.
Odds are there are several worn pieces in that front end that could be replaced to make it more roadworthy.

Also you do not have a timing belt you have a serpentine belt on an accessory drive and WD40 should never be sprayed on the belt. Probably half the reason its squealing.
I would start by throwing the belt you have away, inspecting the accessories in the drive for bad bearing and or noise, replacing whats bad there and you'll probably be good to go. Could be as little as a bad idler or tensioner. Could be a screwed water pump, either way if the belt comes off and you overheat the motor or run out of battery juice you'll be really disappointed.

Brakes, sounds like you need a brake job, 90% of used cars do in the first year of ownership. You've got something that is 14 years old with what probably half a million miles ? Shes gonna need some TLC all over...........

 

[ragajungle]

I just had a belt tensioner go out on my sisters 97 awd 5.0L and it scared the shizzle out of me. It sounded like a main bearing getting ready to let go. VERY inconsistent. my vote is belt tensioner.

+1 on the wd40 on the belt-bad idea

 

[Mrlee75]

Yea, sorry for the mix up. I meant serpentine belt. I couldn't stand the noise anymore so I took it out and replaced it yesterday.

I had more time yesterday to drive it around after I replaced the serpentine belt. I thought the two were related, but after the fix the light tapping/knocking sound was still there. As I was driving around trying to pinpoint the noise, I leaned forward towards the Head Unit and it seemed as if the noise was coming straight ahead of me through the firewall or that I was directly over it. (I know it doesn't make sense, but it's one of those odd noises) It's like small pieces of plastic being tossed around in a blender on slow.

I'll definitely have to check out the front driveshaft when I have time.
Could it possibly be a valve issue instead?

I'm hoping I can get her to see half a million miles! Just broke 170,000 miles 2 weeks ago. I really don't want to see the explorer go, it's one of the few cars that I have actually liked driving...minus the thirsty appetite for fuel, that part I hate.

 

[Mrlee75]

Yea I checked all the pulleys and tensioner when I replaced the belt. Everything seemed fine. The noise didn't seem like it was coming from the front of the engine, more so from the back. Probably anywhere from the throttle body and back, maybe even as far back as the egr valve.

 

[lounge lizard]

ding! ding! ding!

on the back of the motor ( in most cases ) there should be a tube ( most cases it's metal ) that ties into your exhaust and your intake manifold.
usually this tube rusts through and you begin to get a tapping noise. I got it right now on my 5.0 v-8.
now sometimes ( on mine) it will go away while your driving it. around as it heats up. and then sometimes if you start and stop the truck ( turn on and off the truck ) it will come and go.

may not be your deal but I know it is mine.

 

[Mrlee75]

Yea. I already have that problem too. haha. EGR tube is cracked, right side exhaust manifold is in bad shape (been seeing a lot of threads on this issue and confirmed with people telling me I have an exhaust leak)

However, this one is a bit different. The ticking from the EGR tube is noticeably louder on the right side and consistent with the engine rpm and has a certain rhythm. This is a bit softer and sporadic. Sounds like pieces of plastic are just blowing around in the back of intake manifold, rocker arm, or valve springs. Maybe it's a bad front driveshaft as Windsor said, don't know for sure, but I'm hoping it's just a bad tensioner. I would be the happiest person if it were.

 

[windsors03cobra]

Bad tensioner randomly chirping ? Uh huh.

Does it do it while just sitting idling ? You wont hear "plastic blowing around" as you describe.
Could be a spun bearing, Could be anything at this point.

 

[Joe Dirt]

Glad you changed the belt- Spraying WD40 on a serpentine belt is not a good idea at all- it will only create slippage and more issues...

 

[explodertime2013]

Your timing chain is bad.... you need a new motor.... I know exactly what noise your talking about because mine snapped in 2 after 3 months of making the noise and it getting louder... and no one wants to fix it because its on the rear of the motor