peter p

Hello,
I'm looking to buy a 2003 F150 supercrew with a 4.6 and automatic transmission.
While test driving it in 4x4 high at about 50 km's an hour it makes some kind of humming noise. It does it at the higher speeds and as soon as the 4x4 is disengaged the humming noise goes away. The noise is pretty loud and I have no Idea where it's coming from (I think the front).
Anyone know what this could be?

LovetheTide

Were you driving on pavement, if so that could be the problem.

peter p

Yes I was driving on pavement.
I was checking out the vehicle because I wanted to buy it. I put the 4x4 on high and drove for awhile when I noticed the noise.

So it's normal for the truck to make that noise?
I have a jeep cherokee that also makes a humming sound when in 4x4 high on pavement but not as loud as the f150.

LovetheTide

The truck will have a different so to say ride when in 4x4 and on pavement, but im not sure how bad of a vibration yo are having so i cant tell you if its normal or not.

Jbrew

Well , "humming" is somewhat normal. You have the 4R70w trans - the loudest one lol. Anyway , humming usually comes from the the rear. If it's bothersome , Ford makes a kit for this to fix completely , theres also a TSB on it explaining the whats involved. People usually only get this done if there under warranty - it's exspensive!!.

Your 4x4 driveshaft has "Volocity Joints" - Theres a rubber seal on these that you can inject grease into (it's a service item) Also the splines have been known to dry up. You have to pull the shaft , clean the splines with brake fluid cleaner and applie a thin coat of teflon grease . This eliminates allot of friction and stress.

The T-case fluid gets dirty fast , The spec use to be 2 quarts of Mercon in the t-case. Use a synthetic like Mercon V or I use Amsoil everywhere , but it's pricey . The best thing about using Amsoil was that it reduced my temp in the trans 40 degrees and it's constant.

1998 Ford updated all seals in there builds to give them the ability to handle "RAW" Synthetics. Synthetics are tammer today and can be used without compromising seals, so , no more worries there.

Inthe rear end use 140w 90w 100% syn - that's spec , along with 4-8 ounces of friction modifier..

These are the cheapest things you can do to keep the noise and vibrations down.

YellowFX4

Its most likely your universal joints cause I had a 01 f150 with some driveline vibration and once they were changed it was gone.

Jbrew

Yellow , I'm not sure the privet messaging went thru - I have the info you asked for - what you need to do in order to receive the kit. I PM'ed you my email address, send me an email and I'll send you the info .. I tried to do - I had to many characters or something lol , idunno..