Topic: Strange clacking noise

[Lewis Hein]

Hey all,

Yesterday my truck started making a clack-clack-clack-clack noise at low speeds, say 5-10 MPH when I am stepping on the clutch pedal (in or out). My ideas so far are:

--Bad throwout bearing (would expect this to be more of a growl)
--Bad transmission input bearing (same, only I would also expect it to always be there
--Could a bad clutch somehow make this noise? I tried putting it in 4th with the rear brake on and letting out the clutch, and the engine died instantly.

Also of note. I've been having problems with surging going up hills is 4th and 5th. I would say this is definitely a clutch problem, but it also happens going down hills, just less often. Also the front brakes are failing to release properly.

I recognize the impossibility of making diagnoses online, so I'm mainly just looking for ideas and input

[Dingman.]

Is this noise only when manipulating the clutch pedal?   Does it make the noise when you are stopped? Truck off? Etc.
If you put your truck in low range, does the frequency of the knocking increase? Or the same frequency of noise?

As far as surging while driving, I’m not sure why it would be clutch related and only be in 4th and 5th gear unless it is related to engine load with the higher gearing of the transmission at that point.

How old is this clutch assembly?

[Lewis Hein [OP]]

It came with the truck, so no idea. I can accelerate as hard as the 22R will push it, with no problem or slippage.

It makes this noise with the truck moving in 2WD and front hubs unlocked at low speeds while manipulating the clutch pedal. It almost sounds like the the clutch fork was hitting the cover plate fingers: I know this is astronomically unlikely, I'm thinking throwout bearing right now.

Also the front brakes are sticking. I can brake, but to make them unlock from the rotors I have to use a pair of pliers (!) I suspect this may be involved with the lurching problem.

[Dingman.]

It sounds like you are going to have to drop your transmission, I wonder if something came loose (pressure plate bolts, flywheel, etc)

You could also try getting a camera and see if you can get in there to see if there is any markings that show what might be happening.  If there is contact you would hopefully be able to see it.

(I have used this type of camera, and while not GREAT, it does work “okay”)
https://www.amazon.com/Semi-rigid-Endoscope-Borescope-Inspection-Smartphone/dp/B0785H3XR7/ref=sr_1_4?keywords=Borescope&qid=1560441156&s=electronics&sr=1-4

[Snowtoy]

It makes this noise with the truck moving in 2WD and front hubs unlocked at low speeds while manipulating the clutch pedal. It almost sounds like the the clutch fork was hitting the cover plate fingers: I know this is astronomically unlikely, I'm thinking throwout bearing right now.

To try and narrow down the issue, I would put the t-case in neutral, see if you can reproduce the noise w/o the truck moving, as well as if it does it throughout the gears.

Also the front brakes are sticking. I can brake, but to make them unlock from the rotors I have to use a pair of pliers (!) I suspect this may be involved with the lurching problem.

Assuming you mean you use the pliers to push the pads off the rotors, and not something else, it would indicate sticking pistons, and you need to rebuild the calipers, which involves little more than about $10 and your time.

[Lewis Hein [OP]]

To keep things coherent here:

My engine developed a loud, definite rod knock. I think there is likely a spun bearing that was causing the original problem.

The brakes are still bad. The clutch may have its issues. But I think the main issue may have been engine all along. I'm no mechanic so take this all with a grain of salt.

[Lewis Hein [OP]]

I just realized that I never posted the conclusion to this episode.


We towed the thing home and opened up the hood, only to find a loose piece of copper tubing that is part of an OBA system in progress

I also replaced the 34 year old fuel filter and adjusted the clutch pedal freeplay which seemed a little tight but nothing drastic. It is now a little loose.

I removed it and the clacking noise went away. It's now been some 1100 more miles with no engine trouble, lurching, or sudden loss of power.