irv

I have a 1986 4wd extended cab pickup with the G52 five speed transmission. It has recently started making an unhealthy sound that is most noticeable when downshifting/engine braking. It's also heard when accelerating but not as prominent. I've shot a little 13 second video showing downshifting into 2nd and 1st gear and the noise that is made. Any idea on what this noise is and where it's coming from?

knobs

Does it make the noise when the clutch pedal is depressed?

irv

No it does not. It disappears when the clutch pedal is depressed. It only appears when the clutch is engaged during downshifting/engine braking and during acceleration.

knobs

ya to me that is either a throw-out bearing or a pilot bearing, more than likely that its a throw-out bearing. Pretty common with high mileage clutchs

irv

Are these bearings part of the clutch assembly? Or are the contained within the tranny?

knobs

all part of the clutch assembly. If you buy a clutch kit, those bearings should all be included. throw-out is on the input shaft, pilot is in the back of the crank and the nose of the trans input shaft rests in it. once you get the trans out, throw-out is very easy to replace, the pilot is a little more difficult to replace, but absolutely worth it to do

irv

Yeah I was just looking at this kit and I see the two bearings that you're referring to. I believe my truck has the original 1986 clutch. Truck has 160k miles.

https://www.marlincrawler.com/clutch...-lb-clutch-kit

However, just because the noise goes away when the clutch is depressed that doesn't necessarily rule out internal problems with the tranny or transfer case does it?

knobs

if it was anything in the trans, youd know because the bearings are all still spinning in the trans even when the clutch is depressed, so you would still notice the noise, The throw-out stops spinning when clutch is depressed. That is a good kit from Marlin, but a little excessive unless youre doing a lot of wheeling. id just get a Luk clutch kit from Napa and call it good, $120 less and ive used plenty of them and never had a problem, very good quality

irv

When the clutch is depressed doesn't the transmission and transfer case cease to move inside? Is this ceasing of internal movement not what allows you to shift?

knobs

nope its all still spinning, its like youre idling, its all still spinning. the throw-out stops though. ive replace quite a few for this very reason that you are explaining.

knobs

**** the throw-out is the only bearing that stops when the clutch pedal is depressed

irv

Thanks for the info. Between you, google and youtube I've got an ok grasp on it now. Looks like a new clutch will be not too far off for me.

Is any type of catastrophic failure possible from continuing to drive on a worn throw out/pilot bearing?

knobs

It will put wear on the fingers of your pressure plate, i wouldnt let it go too long. If the bearing "lets go", then youre clutch wont disengage properly and shifting will be extremely difficult. Not like a slave cylinder failure (which i would also replace when doing the clutch, about $20), but similar i guess

knobs

Power shuft when possible maybe? Haha

irv

Just replaced slave cylinder last summer, so good to go there. But good to know that it is went bad it won't ruin my entire tranny or anything like that.

millball

This is full-blown wrong. The opposite is true.

The throw-out bearing is stopped when the pedal is up, and spinning at engine speed while the clutch is depressed.

While it may be true that the tranny turns some even when the clutch is depressed, it is only turning if in neutral and it is turning at less than engine speed and can be easily stopped by the tranny syncros.

This is why it is often easier to select reverse by selecting a forward gear first, then going for reverse before the tranny starts to turn again. (reverse has no syncros, so it grinds easily)

Don't listen to knobs, he's wrong.

Very likely that you have a tranny mainshaft, or countershaft bearing, that is worn, and is failing to maintain correct end-play.

eventually your tranny will probably begin to pop out of one, or more gears, or maybe you will not be able to be select into them.

It is certainly possible that you need clutch work, but I think your tranny issue will remain.

knobs

I appologize if im wrong about the compressed/decrompressed error with the throw-out bearing. My mistake. Im just putting info out from what ive found from the same issue. Nothing wrong with intelligent, helpful conversation. Thanks for the good info millball.

millball

I would also add that the very, very first place to look is to the driveshaft.

U-joint faults are often ignored until just before the driveline grenades.

millball

Any noise news???

irv

Still noisy. Will probably be a while before I tackle it. The truck has 168 thousand miles and goes great overall but leaks lots of fluids, could use a clutch and a timing chain soon and also has this tranny noise. So at some point in the next year I'll be taking the whole motor out and overhauling a bunch of things.