Metal grinding type sound at 3200 RMPs

[matt12305]

https://imgur.com/a/HTTLtf2

Hey so as the title states, my ranger makes a weird grinding type sound at 3200 RPM's. It sounds like the sound is coming from the transmission area or the rear of the engine. It happens in park, neutral, and drive, I'm not certain if it makes the sound in reverse cause I never need the engine to go that high.

For some information:
1988 Ford ranger XLT 2wd
2.9l V6 engine
Auto 4 speed OD transmission

I'm really not sure where to start with diagnosing the sound, I really think it could be the transmission but I don't know what to check so I can find the problem and fix it. Also it's worth noting, I did check the transmission fluid level after having driven around for 20 or so minutes and with the engine at normal temp. I checked it over and over just to be sure, it looks like there's too much fluid in there. The fluid is still a brownish red color, although the truck has been sitting for 14 years up until last October when I started working on it.

If anyone can give guesses of what the sound could be or offer advice of what to check for and how to diagnose it'd help me out tons. The link attached is a video of the screeching/grinding sound.
Thanks for your time.

 

[alwaysFlOoReD]

I wonder if something got caught up in the driveshaft? It's not a sound I've heard before.

 

[Uncle Gump]

It kinda sounds like a heat shield rattle. But with most of these sound clips... it's hard to tell.

It does sound like it's hammering pretty good just before you let of the gas.

 

[Shran]

Heat shield on the catalytic converter would be my first guess. I would bet some part of the exhaust system is loose or something else is loose and rattling against the exhaust.

Those noises are hard to nail down sometimes. My buddy was chasing one that sounded like marbles inside a coffee can... a couple of the nuts holding the torque converter to the flywheel backed off and one was rubbing on the block plate, and another was floating around inside the bellhousing.

 

[matt12305]

Thanks, I'll have to check the exhaust. With how long it sat it's possible some stuff rusted off and isn't securing it properly.

I also plan on checking the motor mounts, now I'm not sure if that would cause this sound but considering it sat outside for 14 years they're probably not looking too good. Thanks for your response

 

[matt12305]

I shook the exhaust pipes and heat shields pretty good and didn't notice any movement. I'm thinking, could it be the engine mounts?

https://imgur.com/a/YgGHz3x

That's a video of the engine vibration as seen from the mounts, it causes a lot of vibration on the engine and tranny and in the cabin, could it be hitting on something to cause that sound?

 

[Uncle Gump]

Rubber engine mounts are designed to absorb those vibrations. That looks pretty normal to me.

 

[matt12305]

Are you sure? I'm able to shake the engine with my hands when it's not running, and when it is running I put it in drive and held the brake while applying throttle and it definitely moved quite a bit. Also I put it on jack stands and started it up, at idle it also shakes quite violently and it seems to shake the transmission as well.

I'm not sure how much movement is okay just after 14 years in the weather plus it's actual age I expected them to be bad

 

[Uncle Gump]

I can only comment on what I see. They're rubber mounts... they are not ridgid...

Put it on drive and brake torque it a bit. If a mount is broken... the engine will pull away from the frame and want to flip over.

Maybe someone else will say something different then my view point.

 

[matt12305]

https://imgur.com/a/5sPT5HP

That's the test with the brake and gas while in drive, it definitely seems to be moving a bit

 

[Uncle Gump]

To me it looks normal. If a mount was broken... it would move way more then that.

Another thing that happens with bad mounts... is the cooling fan will come up and hit the fan shroud. Check for damage there.

 

[matt12305]

Oooh okay yeah I haven't even thought of that, I will check that for sure

 

[Shran]

Yeah that looks normal to me although it appears to be running pretty rough!

I have broken several 4 cylinder driver side engine mounts and have had to use a ratchet strap to keep the engine in place while driving back home. The engine will flop sideways several inches, a LOT more than in your videos.

Just saw that you have an automatic, you should also check the transmission cooler lines, they could be rubbing on something and they are metal so they could make a sound like that.

 

[paddy1998]

If you haven't chased it down yet, my opinion is that it's a heat shield or other part of the exhaust.

Chased the exact same thing down on my 92 4x4 this morning; upper heat shield on catalytic converter.

You're not looking for a loose bolt. What you have is something that rattles when the vibration frequncy of the engine matches the piece of metal that's vibrating. Get under there and have one of your operatives rev the engine to recreate the rattle. You'll find it.

Look at the heat shields first, they're just held in by bent tabs and when they get a little loose (little enough that you can't tell just by feeling them) then they'll vibrate and rattle. Get under there with a pair of channel locks and when you hear the rattle press the tool against the heat shields. When the rattle stops you found it.