Hey, this morning on my way to work i noticed a very,
very ugly sound. It started after I shifted out of 4wd
and hit about 55mph. It was kind of "thunkthunkthunkthunkthunk".
I slowed way down, then put it in neutral but the sound didn't go
away. Then I tried shifting back into 4wd. The sound disappeared! I've noticed it shifting rough between 4w and 2w before but
nothing like this.
I drive a '97 F150. Does anyone have an idea what's going on?

Thanks!

 

gee, thanks for all the help.

 

Hey,
Since no one answered you, Is it still
happening?

 

idaho_girl,

Sorry, I just noticed your post. What surface were you driving on in 4x4. Where is the noise coming from? What kind of T-case do you have, electric or manual?

Regards

Jean Marc Chartier

------------------
00 F-150 XLT SC Flairside 4x4 4.6 w/5spd 3.55LSD
Warn XD9000i, skid plates, Draw tite class III,
Rancho RSX Reflex shocks,
BFG 285/75 R16 MTs,
Borla Cat Back, Headman Headers,
Modified Air Cleaner Outlet Tube
and air box, Ported Throttle body,
Shortened MAF sensor tower,
K&N air filter,
Superchips

 

Hi,

I think you would have had better initial response if you had titled the thread with something more descriptive than just "Help." "4WD going Thunk Thunk Thunk" would have gotten you a much better response.

You really need to answer JMC's question about what transfer case (t-case) you have. Do you have the 4WD shifter on the floor (manual) or the **** on the dash (electric). It would also help if you could tell us what kind of road you were driving on while in 4WD and what the approx. temperature was.

 

Dennis said:
I think you would have had better initial response if you had titled the thread with something more descriptive than just "Help."
________________________________________
That's exactly what I was going to say. I usually don't bother looking at threads titled "Help"...."Need Help",,, etc.
Give us a clue in the subject line.

 

the noise hasn't recurred. it stopped after
i shifted into 4w, then back to 2w. The truck has an automatic transmission and i was
driving on the hwy. i'm not sure where the sound came from. it _seemed_ to be from the
transmission, but I'm not a mechanic. I would like to get some idea of what this might mean.

Thanks!

 

...i was on the highway, blacktop. it was
morning, probably between 20 and 40 degrees.

Thanks!

 

using 4WD on dry pavement is not good on your truck. the gears can get all bound up, and can eventually cause damage.

my guess it that once your truck worked its way back into 2WD, everything returned to normal.

watch using 4WD on dry pavement!!

------------------
'99 Ford F-150 Lariat Supercab 4x4
5.4L Triton V-8
Deep Wedgewood Blue



MODS TO COME:
K&N FIPK
Gibson Swept Side Exhaust
Hard Tonneau Cover

 

I wasn't driving on dry pavement in 4w. I shifted out of 4w as soon as i got onto dry pavement. after shifting into 2w, i sped up and the sound started. the sound continued until i tried shifting back into
4w. then it was gone. i NEVER drive on the hwy in 4w.

 

It could be something as simple as a sticky linkage between the shifter and the transfer case. Could be ice had built up and kept the transfer case from fully disengaging. Test the system at home or near a dealer, just in case it really breaks. So long as you only drive in a straight line, you can test the system on dry pavement at low speeds.

If it ever happens again, I'd suggest you pull over and go thru the gears on the 4WD. In other words, go all the way to 4Lo and move forward and back a bit. Then into 4Hi and move the truck again. Then into 2WD and see if the sound persists.

Suggest you review the procedures for shifting and using 4WD in your manuals.

 

idaho_girl,

I would suspect the following. 1st- Misaligned/loose shift linkage. You could be borderline on the exact position of 4Hi disengagement or if the linkage is loose which will cause the T-case to stay in 4hi. Shifting back into 4hi then 2hi might have been enough to disengage 4hi. Have the linkage looked at.

2nd- Malfunctioning vacuum shift motor or shift fork on the front differential. This could cause the coupler cluster gear to not completely disengage and produce the noise. Have the motor tested.

3rd- Least likely, driver error. Shifting out of 4hi too late and driving on dry pavement. Correct driving habits

Kindest regards

Jean Marc Chartier

------------------
00 F-150 XLT SC Flairside 4x4 4.6 w/5spd 3.55LSD
Warn XD9000i, skid plates, Draw tite class III,
Rancho RSX Reflex shocks, MAC 8.8 Axle Girdle
BFG 285/75 R16 MTs,
Borla Cat Back, Headman Headers,
Custom air intake system with modified
air box, Ported Throttle body,
Shortened MAF sensor tower,
K&N air filter,
Superchips

 

hmm, i don't know what a transfer case is,
let alone what kind i have. the 4wd shifter
is on the floor. i have 4w high, which
can be shifted in gear. and 4w low. i have
to put the transmission in neutral to shift
into 4w low. let me know if i missed any
questions.

 

Thanks everyone! I really appreciate
the help!!

p.s. I'll be more descriptive on the
next headline, should I have another
question.

 

Hey Idaho Girl, welcome to the board.
I am in Idaho, myself...
Around where do you live?

theone