Hey Folks, I have a 1997 F-150, 4.2L 5-speed manual with 350,000 miles. Bought it new. Engine rebuilt at 300,000 (that lower intake manual gasket leak finally got me). Been a long time (12 years) since I re-installed the engine. Replaced the pilot bearing and I think put in a new clutch plate since I had apart. I do not drive it near as much as I used to. 17 MPG highway new and still 17 MPG. Salesman said if gas mileage seems low to wait for it to "break in". DOH!!

Have noticed over the last few years a noise developing that sounds like it is coming from the clutch, but could be in the tranny. Clutch and tranny work as they should. No jingling, chatter, rattle or grinding noises. Tranny shifts fine. Had the clutch replaced once, but not sure what all they replaced. LONG time ago. The tranny is original. I checked the fluid level and is OK and fluid looks fine.

When I am driving it, there is a sort of whining/whirring sound that gets higher pitched and louder the faster I go. It is also louder with a heavier load or going up hill. It seems to mostly disappear when the clutch is engaged or am "coasting" down a hill in such a manner that no load really applied to the drive train. Put my son in the back and he said very loud between the cab and the bed.

I am thinking a bearing in there somewhere, but thought there would be some sort of grinding or even jingling sound if worn out.

Was hoping someone on here might have experienced the same "noise". Before I pull the tranny out, want to be sure there is not something "simple" I overlooked.

Thanks for any help! Stay safe!

 

Have you changed the fluid in the rear end?

 

Yes. I had to replace the seals in the rear axle so changed the fluid at that time. Couple of years ago? I had my son (in his 30's) in the bed of the truck while driving it and he listened at the back and at the cab. Said he could hear it at the back, but was MUCH louder between the cab and the bed.

 

Is the noise constant? Does it vary in different transmission gears?

 

Roadie, I believe the sound is consistent in each gear. I have to take it out to get some things and will drive it in various gears for a longer time to see. Generally just accelerating from 1st to 5th, or at least 4th. I will see what I can tell and get back this afternoon. Will be easy to tell driving in 4th or in 5th.

I guess I should have said when I go faster in a particular gear, but have been listening in particular in 5th. Driving down I-85 at 70 MPH annoyingly loud. The pitch does go up the faster I go. I keep thinking that the sound was there to some extent even when new, just normal truck sound, but nothing like this. If that helps.

Good question - RPM's or Velocity.

 

Roadie, just got back. Ran it through a number of paces. Sorry for the novel, but I figure in this case more info the better.

1st gear - cannot really tell anything. Lots of engine noise, so hard to hear much.
2nd gear - about the same as 1st, but can begin hearing the noise.
3rd gear - hear it more
4th & 5th - cannot really distinguish any difference at same speed. I think 4th and 5th are very close in gearing.

In 4th & 5th, when there is basically no load on the drive train, essentially no sound. That is, on basically level ground, let off the gas some and essentially rolling along, but still in gear, sound almost goes away. I did notice that when I engage (depress clutch pedal) the clutch at speed, the sound is still there, but much diminished. When I slowly released the clutch, the volume definitely went way up as soon as it began engaging the transmission. When driving along at say 40 or 50 and let off gas altogether, sound drops about an octave and less of a whine, but definitely still there.

At about 25 MPH I put in neutral and let coast and sound was there, but lower frequency and diminished.

One thing I did notice I had not really noticed before is that when coasting to a stop with clutch engaged (by engaged, I mean pedal depressed), the sound is still there but the whir gets slower and slower til I stop almost like it is the driveshaft turning. Hmmm. right?

When I was originally trying to assess the problem, I was thinking along the lines of ManualF150, maybe the differential. That is why I threw the boy in the back. LOL

Is it possible that a U-Joint could make that sound? I replaced them just because 50,000 miles ago at about 300,000 since I had to drop the tranny to get the engine out. Any U-joint I ever had go bad over my much younger years made a clanking noise.

To answer ur question, I would say the sound has more to do with Velocity than RPM's. The higher RPM's at lower gears did not generate the same sound. It was only at the higher speeds - 4th or 5th gear it got higher pitched and more pronounced. Lot's of engine noise trying to generate much speed at lower gears so cannot be certain, but... That would seem to point away from the clutch huh. Rear bearing in tranny, U-joint or differential.

Interested in ur and other thoughts!

 

What axle code you do have? Does it have Limited Slip?

 

Just wild guessing but I suspect it's a bearing towards the rear of the transmission. I'm a shadetree mechanic, not a pro, for 62yrs.

 

Manual, not limited slip. Sure got stuck in "backyard" easily. Where is axle code at?

 

Roadie, no worries. I am a pecan tree mechanic in GA. LOL That is what I am thinking. Before anything else, will replace U-joints and double check differential as ManualF150 suggests, but sounds like replace or rebuild tranny. At 350,000 miles, hard to complain. No idea typical mileage to expect out of them.

Any suggestions where to get one or have AAMCO do a rebuild? Near Athens, GA, so not even sure if there is an AAMCO around here.

I do not trust shops and especially now. May have "trained mechanics", but not experienced. They just follow the bouncing ball on some online troubleshooting guide, just to come up with the wrong answer. The one thing I like about this forum, is folks who really think about stuff and ask the right questions.

Not sure when I will get done. Have a '94 Dodge Dakota my Dad gave me for my youngest son to use, so may be a bit. Whenever I get repaired, will let y'all know. Trying to get a garden in at the moment.

Thanks to u and ManualF150 for making me re-think where I am at. Been pondering for 2 or 3 years now. LOL

Thanks again, Mark

 

Door jamb sticker. Mine is H9, which is 3.55 limited slip. 19 would be 3.55 non limited slip.

Go to car-part.com and search for used/rebuilt transmissions. 1997 and 1998 4.2 transmissions are compatible, 2wd is not compatible with 4wd. V8 transmissions are not compatible.

 

The axle code is on the sticker in the door jam and on a tag on the rear diff cover.
I don't know where to get a manual trans rebuilt. Aamco may be fine now but I still have a bad taste in my mouth from all the ripoffs they used to do. They were so bad that the attorney generals of 12 states got together and went after them.

 

Door jamb sticker says axle I-9 so not limited slip per GLC. I thought not. Wish it was...

Truck was built in 12/96. I think manufactured in Canada.

Had an AAMCO in WV rebuild an automatic tranny in an Aerostar about 30 years ago. One of the seals blew out midways of 500 mile trip going up a mountain on I-77 southern WV. Kind of at anyone's mercy at that point. Certainly not free, but no problems afterwards.

Sounds like GLC is saying to get a re-manufactured one.

Thanks again gentlemen!

 

Thanks GLC. Yeah, is I-9.

So re-manufactured the way to go? Good experience with car-part.com?

 

Oh, I see that is a junk-yard site. $300 and basically next door! That would work. Do the 97's and 98's both have the same connections? I would replace all the clutch stuff. Recommend OEM or aftermarket work? Looks like they have them with 150,000 miles on them. Should give me another 50 or 100k without worry unless abused. At my age, doubt will drive it more than another 100k if that.

Take care!