1986 F-150 unidentified noise
 

My truck hasn't lived for about 3 1/2 years so this could be related to sitting up so long. When I get her on the road, I have a noise that begins around 45 -50 MPH. After it begins, it will do it at slower speeds. The noise ONLY happens when in gear and letting off the accelerator or coasting. If I push the clutch and / or take it out of gear, I do not have a noise. When I'm increasing speed, I do not have the noise. Whatever this is, I feel it slightly through the seat. (Yeah, I listen and feel my truck) Please help. I need her running but I don't want to mess her up and have to park her again.

Welcome to the forum, Lymira! :)

Hmmm... this will likely take a few guesses from members and is difficult over the Internet. A 1986 manual transmission has a hydraulic clutch, which offers no adjustment since the throw-out bearing is always in contact. Sometimes there is a slight squeal or chirping due to this. In my experience, this occurs when idling with the transmission in neutral and the clutch all the way out. If pressure is applied to the clutch pedal, the noise stops. The same happens when cruising with little strain on the drive train. While cruising, if you just touch the clutch pedal lightly, the noise stops. Also, at that point [cruising], if you accelerate [places stress on the drive train] the noise lessens or stops.

I do not feel anything through the seat, as you have mentioned. Normally, "feeling" something means a vibration due to reciprocating parts [i.e. u-joints, drive shaft, wheels out of balance or tires out of round, etc.]. Did the truck sit on the tires for the 3 1/2 year period? Could there be flat spots?

Does this sound anything like what you are experiencing?

Great description of this elusive, subtle "chirping" noise. I have heard it in my '85 when idling and it is exactly as you described it, going away with the slightest pressure on the clutch pedal. I'm glad to know what it is now!

The truck did sit on these tires while not running. I don't have noise while idle at all. It doesn't start until I'm up to speeds over 45 or so and let off the accelerator but stay in gear. After starting, it will do it at lower speeds. Pressing the clutch or out of gear stops the noise, or slowing to about 25 or less. My exhaust has broken loose from the muffler so the truck is loud and I can hear this over that.

Well, you're going to have to be a LOT more descriptive and specific as to what "the noise" actually sounds like; by virtue of feeling it, and experiencing it only with the driveline under load, that eliminates small things such as fan belts.

But this could be a lot of different things... my personal suspicion involves bearings in the rear end, but the "noise" in my mind is a bearing whine... and I have no idea if you're talking about a whine or a clunk or a chirp or what....

In any event, best for you to take it to a local shop and put it on a rack or dyno; sure, people here can ask questions and throw out ideas on what to maybe look at, but asking the Internet - people who can't hear and feel and see it themselves - for help is going to give you only so much help....

It's nothing quiet or faint. Metal on metal roaring. I can feel the roughness through the seat, but you are right. I'm out of work so I was looking for ideas that I could check. Thank you everyone for your help. I guess she sits a while longer.

Since I can't ask for help, moderator, can you tell me how to delete my thread?

You can ask for all the help you want, I'm not trying to discourage you, mostly trying to point out that noises are like smells - you need to describe them as best you can for people to get an idea of what you're experiencing.

Even with that, though, it's really hard for others by remote.

Maybe @Gary Lewis or one of the others can help...

You say it's not nearing whine, and this apparently began after having sat for 3 years... metal on metal... which makes me suspect something that is normally supposed to move (like brakes) is stuck... but only on deceleration? Hmmmm.....

I think you may have a worn out drive shaft. But, you haven't told us much about your truck so I'm not sure what kind of drive shaft you have. (I make it a habit to not respond to threads where people don't tell us more than we could possibly need to know about their truck, but Chris asked me to join.)

Anyway, if your drive shaft has a slip joint about 9" behind the transmission I'd bet that joint is worn out. I had that on one of my trucks and it came in much like you described - when coasting but not letting off completely.

If your shaft has the slip joint, try pushing it sideways or up/down. If it deflects at all then you need to pull the shaft off and pull the slip joint off to check the splines.

:)

I asked you to join because he's a noob[1] and I'm afraid that I "set the tone" that we can't help because of too little information (besides the fact that none of us have heard it), and I really don't mean to do that....

Just noticed something, it doesn't make the noise with the transmission disengaged - which eliminates the brakes as a possibility...

[1]And he writes well, none of this im-id-iv-u-textese crap...

Good points! So, there's hope for him. ;)

Anyway, my experience is that no one lubes the splines and that causes serious wear that allows the shaft to "bend". That means you have a vibration, which is right under you so it comes through the seat.

My first thought was a tailshaft bushing.
Though I have a slip yoke in the transfer case and not a slip joint in the driveshaft like Gary suggested.

The symptoms all fit.
Trailing throttle, disengaging the clutch takes the bind off the driveline and the shaft stops shuddering.

Sorry guys. There is no hope for me I'm sure. I'm not a "him". :-)

I have talked to a local mechanic, and his first response was throw out bearing, which it's not. I have replaced the entire clutch assembly before, and I know what that sounds like.

I pulled the transmission and took it somewhere before she went down and got bearings replaced. I've talked to him since it seemed transmission related or transmission activated. He suggested engine mounts. I have given them a visual, but I intend to get the engine pressure off them Monday and get a good look.

I don't remember the driveshaft like that, unless I'm not visualizing what you are saying. It's been a while since I've played with the driveshaft after all - 4 years. I remember just solid driveshaft after the slip yoke but I will crawl under Monday and check that, along with the universals. Family coming over and all this weekend so Monday will be my day.

Thank you for any and all help. I am a noob but I've had to work on my own stuff since I started driving. I bought this truck because 1) She was all I could afford after my divorce. (He got it all) 2) She has a carburetor therefore I can work on her and 3) She's a Ford and absolutely the prettiest hunk of junk I've ever owned. Sorry if I don't give specs on my truck, but I'm learning a lot of this as I go. By the time I'm done, she'll be fully restored and I'll be able to tell you every piece on her.

You will have either/or.
Never a slip yoke *and* a slip shaft.
With the wheels chocked and truck in neutral try pushing the yoke sideways in all directions.
If you pull it out you may see the wear pattern in the brass bushing.

Another thought would have been the transmission mount, but if you've had the gearbox out I'd imagine you would have noticed it was wasted or the bolts were loose.

Nice to see another woman who jumps right in to working on her truck. :)
We have a few here on the forum.
Sorry to hear of the circumstance that necessitated it.

Sorry about the "him". We don't get many "hers", so I assumed, which is not right. Especially ones that can work on a carb. In fact, few "hims" can work on a carb these days. Again, sorry.

I believe there are three styles of drive shafts:

• Solid: Typically used on a 2wd truck, these have the slip-yoke Jim was talking about at the output of the tranny.
• Slip-joint: Frequently used on a 4wd truck, these have a short piece with internal splines bolted to the tranny, and a long drive shaft with external splines from there to the rear axle.
• 2-piece: Typically used on the longer trucks, these have a u-joint in the center.

The problem Jim and I are talking about happens most frequently on trailing throttle, meaning you aren't truly coasting with the throttle off, but aren't using much throttle to maintain speed either. Like when going down a long hill.

So, check your drive shaft where it connects to the transmission to see if there is any play - either in the slip yoke or joint, or in the u-joint.

I have the 2wd with the solid driveshaft. I will check Monday and update what I do or don't find.

Lymira,

I just noticed your location... I am just across the river. If I can be of help, let me know. I have a Ford trained mechanic friend who can figure out anything and cut his teeth on these trucks.

That would be AMAZING. I will take any and all help I can get.

BTW, as of writing this, I cannot write nor respond to private messages. I can read them, but that's it, so I cannot get in touch with you except here for now.

An email was just sent, Lymira.

1986F150six, I don't know if it takes a while, or maybe the ones I got were because of who they came from, but I haven't got anything. ctubutis wrote and I received it, but nothing from you yet. Yeah, I'm bummed now.

I sent it just as I posted. If it does not go through, post again.

It says I'm not suppose to be able to use private messaging until I've been here for 10 days. I guess that's it. I'm sure in 4 days, I'll get them all at once. I did send a visitor message on your page. That's all I can do it looks like.

Message sent; contact made.

UPDATE - 1986F150six met me today to listen to my truck and help identify my noise. We met around 1 and in the parking lot where we met, he rebuilt my differential, replaced the universals, all in time to get back home to see the game at 3 and did not get dirty at all. I was amazed.

OK, that sounds WAY better than the truth. Sometimes when you are looking for a problem, you don't look at the simple things.

It appears like someone liked my back tires, and attempted to take them. I haven't touched them so I did not look at them at all. Both back tires were loose, but I was not far from losing the driver rear all together. Driving the little bit I have worked the lug nuts loose, VERY much so on the driver side. The driver rim is so worn, it will have to be replaced along with the studs. I will be buying a pair for the back. He tightened them up in the parking lot and TADA, no noise.

Yes, after this, I feel very dumb for overlooking the simple and obvious but maybe by sharing, someone else can be smarter.

A HUGE thank you to 1986F150six for driving all the way out my direction to show me something I really should have seen. I hope the football game goes your way. ;-)

That's our David/1986F150six! I'd rep him, but am in rep jail, so maybe y'all can. Well done, David!

I can't rep him, either, but thank you, David! :)

Thank you, Gary and Chris.

The holes on the driver's side wheel were wallowed, so the wheel needs replacing and probably the lugs as well. Some of the threads were damaged, but I was able to tighten the lug nuts all the way, but they squeaked.

Lymira is not afraid to tackle any mechanical need and is going to be a contributing forum member. She has pulled the transmission and replaced the clutch as well as rebuilding the front brakes.

Lymira, I ran into my friend [Ford trained mechanic] at church and he has a 1986 F150 which we have stripped for parts. It has 4 factory steel rims with old tires. He has offered to GIVE you the 4 rims, if you want them. Let me know.

By the way, my team won!

Cool! Well done!

Yes, I did see where they won. Congrats !!

I would love the rims and tires. Please let me know where to go and I'm there. And thank you for the vote of confidence on contributions to the forum. I'm no mechanic, obviously. I wanted to be but parental guidance shoved me another direction so I play one when I can. :-)

Lymira,

The wheels will possibly be taken off the truck this afternoon. He will notify me when he can do it and I'll pick them up. I'll let you know and we can meet someplace for the transfer.

Lymira,

The wheels were picked up, yesterday afternoon. PM me.