2005 mustang 4.0 making weird noise

I have a 2005 mustang 4.0, and its making a weird noise on cold start but slowly goes away once the car warms up, the car runs completely fine and don’t seem off at all, sounds like it’s underneath the car I can’t be 100% sure tho, some people have suggested the torque converter, buts it’s not acting up at all and shifts completely normal. It’s like a whining noise

Automatic transmission?
How many miles on it?
Is the noise a whine at the front of the car or under the floor at the center?
Has the transmission fluid ever been changed?

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I’m not sure on the mileage, it’s been replaced before, I bought the car not to long ago, it’s an automatic transmission, and I’m not sure if the fluid has been changed before

Guessing it is the pump in the transmission, not the convertor. Might be the power steering pump… lift the hood during a cold start and listen.

I’d suggest you check fluid levels in the trans and power steering. Wipe the trans fluid on a white paper towel. If it looks brown and smells burnt the trans may be on its way out.

Or ignore it until it never goes away even when hot. It will be easier to find.


I think you nailed it Mustangman…
If it was the older OHV engine I would say the cam synchronizer, but pretty sure this does not have one…

One simple/quick way to find out if it is front accessory related (alt, PS pump, etc) or internal engine/transmission related, just remove the serp belt and start it and see if the noise is still there or not… Idf the noise went away then put the belt right back on and retest to make sure noise comes back… Don’t want a false positive…

You don’t know how many miles are on your vehicle?? 10K, 50K, 100K, 150K just a rough guess??..

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Both trans and motor have been replaced from previous owner

OK wasn’t sure if you meant the odometer or…

Is there not any paperwork on the replacements?? Even used units the salvage yard will tell you about how many miles on the donor vehicle… Just figured there was some kind of a paper trail…

He never told me, he just gave me a guess which was about 150, never said anything about the tranny, I bought this car and already planned on rebuilding the motor and tranny but don’t have the means to do so at the moment so I would like to have it fixed in the mean time until I can rebuild it

If it is the front pump (bushing) in the transmission then you are already getting up there in price and that metal went somewhere, there is a chance the filter caught all the material from the front pump and or bushing then you can just replace those bad parts, but it is a chance you have to take… But if I am opening the transmission up, other than the pan and or valve body, I’m going all the way myself… I blew the stator up bad in my torque converter and destroyed the converter beyond repair and after seeing all the metal caught in the filter (I run an all metal mess filter) I figured some made it past the filter so I torn it 100% apart (as well as some racing friends that build racing transmission said it had to of gone all through the trans) and found 0 metal anywhere, so technically It wasn’t required but I built it anyway…
Point is if it is something internal you might be building one of them anyway…

But like already said, you can just keep driving it until it gets way worse or leaves you walking one…

But again 1st thing you have to do is find out if the noise is internal or not which is a pretty simple check to do…

How can I tell if it’s internal or not? Any tips on diagnosing where the noise is coming from?

As stated in my 1st reply… remove the serp belt and start vehicle to see if noise goes away or not… Just don’t run it long if the water pump is belt driven…

Both Mustangman and Dave’s Mopar have provided ideas.
My take:
Change the transmission fluid and cross your fingers.
Listen to the power steering pump on startup.
Remove serpentine belt, start the car, does the noise disappear? With engine off check all pulleys the serpentine belt drives.
Change the oil.
Put the front of the car on jack stands, start the car, turn the steering wheel fully left and right, is the noise still present?

Note, I mentioned change the engine oil, as I recall, this beastie has three timing chains, you want to keep them intact until you pull the engine&tranny for your rebuilding project.

If the source of the noise is the transmission, changing the fluid might buy you some more time.

Good luck, I had an 06 with the 4.0 and Pony Package, I liked it, served me well for 150,000 miles.



OK… now it’s more clear. In any event, if you don’t know when the trans fluid was last changed, that means it is time to do it.
Will that help? Maybe yes, maybe no, but… it’s worth a try.

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