Can’t figure out rattle sound from Ford Ranger engine
 

I have a 2008 Ranger 3.0 RWD I bought in February with 118K miles. (see attached video)

A few weeks after I bought it a rattle sound started coming from beneath the engine that wasn’t there the first few weeks I had it. I’ve been wondering if it’s an issue or not and I believe it may have gotten slightly louder progressively since the. It’s definitely the loudest on a cold start but becomes much quieter or goes away once the truck has been running for a bit. I got under the truck and found that it’s most likely coming from above/ around the oil pan area of the engine. I’ve noticed a rattle sound now coming when I accelerate too and I think it’s whatever this is but not positive.

A few tidbits, the car was only driven <300 miles for 2 years before I bought it. I have consistently maintained a healthy level of oil during my ownership. There’s a whining sound I can hear when I accelerate between 45-50 MPH that started at the same time as this, it sounds like it’s coming from the same area but I’m not positive and I’m unsure if they’re related.

I’m really hoping it’s nothing major like timing chain but want to make sure my engine isn’t going to randomly die at any point. I only need ~3 years out of the truck before I get something else

Not much to go on

For sure not the timing chain on a 3.0l Vulcan engine, they were bulletproof
Manual or Automatic?

Do this test
Stone cold engine, i.e. been unused for 6 hours or more
Remove fan belt from crank pulley, so no fan or accessory noise, leave hood open
Start engine, Battery Light will stay on, thats OK
Engine bay will now be VERY QUIET
Start looking for the noise, you have 90 seconds which is quite a long time, there is no water pump operating so don't run the engine without fan belt any longer, but you can repeat this test as many times as needed after engine cools back down, 6 hours

If there is no noise then it was coming from an accessory, so check/spin any pullies, after shutting engine off

If you hear the noise then try to localize it, should be easier now that's its quiet
Starter motors can rattle
Loose exhaust can rattle

Engines don't usually "rattle", they have a "tick" or "knock", I know semantics, but your gut description of "rattle" means a lot because you are there

Thanks Ron.

I've listened for the sound from the front of my engine & am 100% confident it's not coming from anything pulley associated. Do you know what car components are located around the oil pan? It's an automatic as well.

Also, how hard is it to remove the fan belt from the crank pulley? I have no experience specifically doing this.

Just use a wrench to move the belt tensioner to relieve tension on the belt, then pull the belt off one of the pulleys and it will then be loose and can no longer be turned by crank pulley
So same procedure as if you were changing the fan belt
And have a look at the belt, if you see cracks it might be a good time to change it

You said it would make the noise when cold, so this is a good test to see if you can locate the noise
Engine bay is a metal container so very very hard to locate where a noise is coming from exactly, sounds are reflected so can trick your ears

I just want to make sure I'm fully understanding. You're just saying to remove the serpentine belt & then run the engine for <90 seconds right? It will be easier to locate the noise that way etc

Yes, engine bay will be VERY QUIET with no fan or accessories moving, you will be surprised how quiet, lol

But also no water pump, so you need to shut off engine before the 90 second time limit
But as said this test can be repeated as much as you like AFTER engine is cold again

And you can put fan belt back on and drive like normal after the test, don't have to wait for it to cool off or anything like that

okay so I ran with with no belt and definitely determined the rattle is coming somewhere around the item in the attached picture. It’s tough for me to be able to nail down if it’s coming from inside of it or around it. I know for fact it’s in that general area. Again, it’s the loudest by far on a cold start and is quiet/ not noticeable once the truck warms up
https://cimg1.ibsrv.net/gimg/www.ran...cd1814a78e.png

@RonD thoughts?

Starter motor is all that comes to mind

is it normal for the start motor to rattle once the truck is running?

Almost sounds like an exhaust leak.

This is what I'm hoping for tbh. I just need reliability from the truck & if it's just exhaust I'm just fine with that

Also I forgot to mention, I notice the sound getting louder when I accelerate too no matter how hot the truck is