My first car, an 89 k1500

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Road Trip

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So do you guys think it's a throw out bearing? It works just fine, it's just noisy

Greetings Gordy_,

I'm a big fan of driving standard transmission vehicles, and since it's the
well-used stuff that normally follows me home, I've had plenty of hands-on
practice in this area over the years.

And when it comes to troubleshooting clutches and standard transmissions,
it's all about following the sound. More specifically, exactly which parts are
rotating when the noise presents itself, and furthermore, which parts are not
moving when it's noisy?

Thanks to your video, I think I've got a pretty good idea of where your noise
is coming from, so without further ado let's dig in.

The first step is to see if there's a noisy manual transmission/clutch troubleshooting
section in the '89 FSM? (Factory Service Manual) Check this out:

You must be registered for see images attach

(source: '89 Factory Service Manual)

From what you played us on your video, the transmission is noisy in Neutral, but goes quiet when you depress the clutch?

The Throwout Bearing -- the first part to be isolated as not contributing to the noise heard in your video:

NOTE: Before we start to follow the manual, I'd like to point out that you have already proven that in your situation the
throwout bearing is actually OK? How do we know this? Well, when the clutch pedal is released, *this* is when the throwout
bearing is NOT rotating, for when your foot is off the clutch pedal, the release bearing has been pulled back (away) from the
pressure plate fingers. In other words, the throwout bearing is still, and also quiet, good or bad. Guess what, a bad throwout
bearing is quiet with the clutch out, but becomes *noisy* when your foot pushes it forward into the spinning pressure plate
fingers, and the noise starts when the throwout bearing also starts spinning. (!)

In English, IF the throwout bearing was bad, then we would hear the exact opposite of your video. Quiet with clutch OUT,
noisy with clutch IN. So allow me to take the throwout bearing off of the troubleshooting table for now.

****

After reading the 'Noisy Neutral' section of the 'Diagnosis of Manual Transmission' page,
let's see if we can find a diagram to look at:


You must be registered for see images attach


OK, remember that moving vs non-moving rule? When the clutch is out, the transmission input shaft is spinning
at the exact same speed as the pilot bearing that it is inserted into. (#131 in the diagram above.) No relative
speed difference = no noise, right? But when you depress the clutch pedal, now the transmission input shaft
comes to a stop. Meanwhile, since the engine is still idling, the pilot bearing is now rotating around the input shaft.

But wait a minute, your truck is quiet with the clutch pedal depressed? Yup, we've just eliminated the 2nd part
as a source of your current noise. So now we have no choice but to leave the clutch area and head downstream
to the transmission.

You must be registered for see images attach


During the '88-'92 era, the 5-speed manual transmission was referred to as the HM290 Getrag.
'93+ models switched over to the NV3500. (New Venture manufactured with improvements?
Disclaimer: I do not consider myself a NV3500 guru at all, so if I'm misleading with the above
would someone please chime in with a correction?)

Anyway, this input shaft bearing comes to a HALT whenever you depress the clutch all the way in.
IF you have one of these transmissions that is noisy in neutral, but goes quiet with the clutch
pushed in, here is where your repair effort will start.

If you read what I put inside the arrows, I am trying to get you to visualize that clutch
disc sitting in the splines, and in order for that disc (and also everything else splined onto
the input shaft inside the transmission) to run quiet & smooth this input shaft bearing
must be dead smooth. And when they wear, they get exactly as noisy as your truck currently is.

NOTE: If you were to replace the input bearing on the transmission, I would strongly recommend
that you also renew the pilot bearing in the crankshaft. If there's excess wear/sloppy fit between
the pilot bushing (bearing?) and the nose of the transmission input shaft, then there will be
lateral play/excess stress communicated back into your new input shaft bearing. So if you
are in there, change both.

Last and least, here's a quick view of what the transmission will look like when you first pull it.
The input shaft bearing will be hiding underneath the associated bolted down retainer/cover:

You must be registered for see images attach

(Sharp-eyed viewers will see unmistakable signs of a leaky rear main seal on the near-side periphery of the bellhousing.)

****

So there you have it. Thanks to the clarity of your video I have confidence in my noise diagnosis.

Where to go from here?

* A skilled mechanic on a *too tight* budget may elect to just replace the input shaft bearing, pilot bearing,
and put it all back together. Not recommended.

* A skilled mechanic on a realistic budget would buy a rebuild kit with all new bearings, synchos, etc.
Rebuilding a manual transmission is actually fun, and driving an old tranny with new synchros and bearings
is a smooth shifting, quiet running pleasure.
NOTE: This is one of those legit 'while I'm in there' moments. Unless the clutch was recently replaced, it only
makes sense to install a new clutch kit, which will future-proof the clutch disk, pressure plate, throwout bearing, etc.

* A still-learning mechanic may elect to exchange his worn out transmission for a remanufactured unit, and do the
clutch himself right before he stuffs the rebuilt tranny in. Assuming a good rebuild was performed, this is a one & done
situation. If they missed something, then you will be relying upon their warranty...which means doing this all over
a 2nd time?

****

Final thouhts. In it's current noisy state, I would keep it close to home & drive it gently. If you haven't already
drained & refilled the transmission fluid, I'd do that just to see what comes out, and with the hope that fresh
lubricant will stretch out the life just a little longer.

By the same token, I would not recommend a long, cross country trip in it's current condition. Sounds kinda
gnarly, especially given the close tolerances that all these spinning parts are running. (Especially inside the tranny. (!)

Apologies for the length, but your video was compelling, and I also wanted to elaborate a
bit on the whole 'following the noise' thing when troubleshooting in this area.

If you have any other questions on all this, don't hesitate to ask.

And be sure to let us know what solution you finally choose & implement.

Best of luck.

Cheers --
 
Last edited:

Gordy_

OBS Enthusiast
Joined
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Location
East Oregon
Greetings Gordy_,

I'm a big fan of driving standard transmission vehicles, and since it's the
well-used stuff that normally follows me home, I've had plenty of hands-on
practice in this area over the years.

And when it comes to troubleshooting clutches and standard transmissions,
it's all about following the sound. More specifically, exactly which parts are
rotating when the noise presents itself, and furthermore, which parts are not
moving when it's noisy?

Thanks to your video, I think I've got a pretty good idea of where your noise
is coming from, so without further ado let's dig in.

The first step is to see if there's a noisy manual transmission/clutch troubleshooting
section in the '89 FSM? (Factory Service Manual) Check this out:

You must be registered for see images attach

(source: '89 Factory Service Manual)

From what you played us on your video, the transmission is noisy in Neutral, but goes quiet when you depress the clutch?

The Throwout Bearing -- the first part to be isolated as not contributing to the noise heard in your video:

NOTE: Before we start to follow the manual, I'd like to point out that you have already proven that in your situation the
throwout bearing is actually OK? How do we know this? Well, when the clutch pedal is released, *this* is when the throwout
bearing is NOT rotating, for when your foot is off the clutch pedal, the release bearing has been pulled back (away) from the
pressure plate fingers. In other words, the throwout bearing is still, and also quiet, good or bad. Guess what, a bad throwout
bearing is quiet with the clutch out, but becomes *noisy* when your foot pushes it forward into the spinning pressure plate
fingers, and the noise starts when the throwout bearing also starts spinning. (!)

In English, IF the throwout bearing was bad, then we would hear the exact opposite of your video. Quiet with clutch OUT,
noisy with clutch IN. So allow me to take the throwout bearing off of the troubleshooting table for now.

****

After reading the 'Noisy Neutral' section of the 'Diagnosis of Manual Transmission' page,
let's see if we can find a diagram to look at:


You must be registered for see images attach


OK, remember that moving vs non-moving rule? When the clutch is out, the transmission input shaft is spinning
at the exact same speed as the pilot bearing that it is inserted into. (#131 in the diagram above.) No relative
speed difference = no noise, right? But when you depress the clutch pedal, now the transmission input shaft
comes to a stop. Meanwhile, since the engine is still idling, the pilot bearing is now rotating around the input shaft.

But wait a minute, your truck is quiet with the clutch pedal depressed? Yup, we've just eliminated the 2nd part
as a source of your current noise. So now we have no choice but to leave the clutch area and head downstream
to the transmission.

You must be registered for see images attach


During the '88-'92 era, the 5-speed manual transmission was referred to as the HM290 Getrag.
'93+ models switched over to the NV3500. (New Venture manufactured with improvements?
Disclaimer: I do not consider myself a NV3500 guru at all, so if I'm misleading with the above
would someone please chime in with a correction?)

Anyway, this input shaft bearing comes to a HALT whenever you depress the clutch all the way in.
IF you have one of these transmissions that is noisy in neutral, but goes quiet with the clutch
pushed in, here is where your repair effort will start.

If you read what I put inside the arrows, I am trying to get you to visualize that clutch
disc sitting in the splines, and in order for that disc (and also everything else splined onto
the input shaft inside the transmission) to run quiet & smooth this input shaft bearing
must be dead smooth. And when they wear, they get exactly as noisy as your truck currently is.

NOTE: If you were to replace the input bearing on the transmission, I would strongly recommend
that you also renew the pilot bearing in the crankshaft. If there's excess wear/sloppy fit between
the pilot bushing (bearing?) and the nose of the transmission input shaft, then there will be
lateral play/excess stress communicated back into your new input shaft bearing. So if you
are in there, change both.

Last and least, here's a quick view of what the transmission will look like when you first pull it.
The input shaft bearing will be hiding underneath the associated bolted down retainer/cover:

You must be registered for see images attach

(Sharp-eyed viewers will see unmistakable signs of a leaky rear main seal on the near-side periphery of the bellhousing.)

****

So there you have it. Thanks to the clarity of your video I have confidence in my noise diagnosis.

Where to go from here?

* A skilled mechanic on a *too tight* budget may elect to just replace the input shaft bearing, pilot bearing,
and put it all back together. Not recommended.

* A skilled mechanic on a realistic budget would buy a rebuild kit with all new bearings, synchos, etc.
Rebuilding a manual transmission is actually fun, and driving an old tranny with new synchros and bearings
is a smooth shifting, quiet running pleasure.
NOTE: This is one of those legit 'while I'm in there' moments. Unless the clutch was recently replaced, it only
makes sense to install a new clutch kit, which will future-proof the clutch disk, pressure plate, throwout bearing, etc.

* A still-learning mechanic may elect to exchange his worn out transmission for a rebuilt unit, and do the clutch
himself right before he stuffs the rebuilt tranny in. Assuming a good rebuild was performed, this is a one & done
situation. If they missed something, then you will be relying upon their warranty...which means doing this all over
a 2nd time?

****

Final thouhts. In it's current noisy state, I would keep it close to home & drive it gently. If you haven't already
drained & refilled the transmission fluid, I'd do that just to see what comes out, and with the hope that fresh
lubricant will stretch out the life just a little longer.

By the same token, I would not recommend a long, cross country trip in it's current condition. Sounds kinda
gnarly, especially given the close tolerances that all these spinning parts are running. (Especially inside the tranny. (!)

Apologies for the length, but your video was compelling, and I also wanted to elaborate a
bit on the whole 'following the noise' thing when troubleshooting in this area.

If you have any other questions on all this, don't hesitate to ask.

And be sure to let us know what solution you finally choose & implement.

Best of luck.

Cheers --
Thank you! I was partially convinced it was something other than the throughout bearing. I plan to dup the gear oil and put new in soon. The most of it's trips have been about 50 miles round trip and it hasn't been a large issue aside from the noise. Once it is warmed up the sound isn't very bad at all if that helps. I unfortunately don't have the spare time to replace the bearing, let alone rebuild the transmission, and I definitely can't afford to replace the transmission. All I can do right now is keep driving it.
 

movietvet

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Are you saying you have no other transpo if you remove the manual transmission to inspect?
 

Gordy_

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Are you saying you have no other transpo if you remove the manual transmission to inspect?
Yup, me and my dad have been switching off driving it with nothing else to drive, and it's also a matter of time. I have almost no spare time to drop the transmission out let alone rebuild it.
 

Erik the Awful

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Does anyone have experience with dying seats? I am considering dying these red to match the interior. Thanks!
No, but I've painted my carpet with vinyl interior paint. I have to touch it up about once a year because the color gets rubbed off - in the pic below you can see that the paint looks thin in some places. I would recommend getting some seats that are in a color that matches. I put tan leather seats into my black interior - they match close enough for my tastes.

You must be registered for see images attach
 

Road Trip

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If anyone has any advice or pointers to keep this teuck going as long as I can, I'm all ears. This truck, although it isn't fast by any means, is a riot to drive and is easy to work on, and I would like to keep it in the fleet as long as I can.

I've already done fluids, hub bearings are good, I checked those when I did the brakes. The water pump is in great shape and the I replaced the thermostat. I flushed the coolant too. The accessory belt is new, the power steering pump leaks a bit, but I'm not too concerned about it. There is no compressor pump as the truck didn't come with AC. The suspension is decent, and the cv axles looked good. I've basically done everything I could think of to get the truck in road-worthy condition after sitting in a field for 8 years. I even went as far as replacing the vacuum lines.

Also, does anyone know anything about the noise in the transmission? It rattles pretty loud when in neutral and in higher rpms in gear. Is this something I should be worried about? This truck might have to make a 3000 mile road trip with a trailer in a few months and I want to have it in top shape before then.


Yup, me and my dad have been switching off driving it with nothing else to drive, and it's also a matter of time. I have almost no spare time to drop the transmission out let alone rebuild it.

Hello again Gordy,

I just reread your thread, and I like the overall vibe. Possibly because you sound a bit like
myself when I was first starting out. For example, I for one would have wouldn't have hesitated
to buy a $500 truck out of a field, swapped out the cracked transfer case, and in general try to
make the most of what I have to work with.

I share this with you so that you understand I'm not trying to badger you into spending time & money
on something that's currently getting the job done for you and your dad.

On the other hand, the idea of putting a tired, light duty transmission through a 3000 mile
road trip with a trailer attached is a scary proposition. Some of the most expensive $/mile trips
occur when the vehicle breaks, you are halfway across country in a repair shop where the mechanic
can smell the "I'm a long way from home and at your mercy" cologne that you are wearing. All of
sudden the repair estimate sounds like it was generated in the Emergency Room at the local hospital? :-(

And if you absolutely can't refresh your 5-speed but must make the trip? That's why they make
rental cars. Or U-Haul. It's actually the best solution for when all you have is a good enuf for
local use DD, but the time comes when you really need something that is road trip ready.

****

So the rest of this is basically for others reading your thread because they also have a noisy 5-speed
Getrag (NV3500) and are trying to figure out what their options are?

In a previous response I mentioned that it would be possible to just change the transmission
input bearing and the crank pilot bearing and make the situation a lot better than it is. In a
$500 truck rescued from slumbering in a field, this might actually get the trans to no longer be
the weakest link in your drivetrain?

And once upon a time I would fix like this simply because diapers & baby formula took priority.
While it would make me feel like a troublesniper instead of just a normal troubleshooter, I would
usually regret the decision down the road, because the 'next most worn' part would step up and
make it's presence known. Given this, I'm still not recommending this approach, so how to identify
the specific front input shaft bearing part number is an exercise left up to the reader. :0)

****

Now that the table is set, let's get on with what I really wanted to share.

I just checked to see what a complete bearings kit for your trans will set you back:

You must be registered for see images attach



NOTE: This is a valid $189.00 choice IF your existing synchros are working well.

Synchros worn / gear clashing during everyday driving? For another $86.00 you can get
the kit that includes the new brass circles:


You must be registered for see images attach



As for the clutch, bringing this area back to new at the 'while you are in there' price of just over $100:


You must be registered for see images attach



There you have it. Assuming that your synchronizers are still OK, for the total cost of ~$300
in parts (+ new tranny fluid) you can make the middle of your drivetrain road trip ready.

Or you can get a cool sounding exhaust & rent a U-Haul for the longer trips. By the way, I'm
not goofing on you, for I've been at the same fork in the road in the past and stood there
pondering which path I prefer to take. (And for the record, I'm guilty of changing exhaust
systems for a 3% performance improvement while chasing after the finest motor tone in
the neighborhood. :0)

That's all I got. And while I'm here I'd like to salute you for saving one more GMT400 from
the boneyard. Well played, sir.

Here's to safe, reliable travels.

Cheers --
 
Last edited:

Gordy_

OBS Enthusiast
Joined
Feb 2, 2024
Messages
88
Reaction score
128
Location
East Oregon
Hello again Gordy,

I just reread your thread, and I like the overall vibe. Possibly because you sound a bit like
myself when I was first starting out. For example, I for one would have wouldn't have hesitated
to buy a $500 truck out of a field, swapped out the cracked transfer case, and in general try to
make the most of what I have to work with.

I share this with you so that you understand I'm not trying to badger you into spending time & money
on something that's currently getting the job done for you and your dad.

On the other hand, the idea of putting a tired, light duty transmission through a 3000 mile
road trip with a trailer attached is a scary proposition. Some of the most expensive $/mile trips
occur when the vehicle breaks, you are halfway across country in a repair shop where the mechanic
can smell the "I'm a long way from home and at your mercy" cologne that you are wearing. All of
sudden the repair estimate sounds like it was generated in the Emergency Room at the local hospital? :-(

And if you absolutely can't refresh your 5-speed but must make the trip? That's why they make
rental cars. Or U-Haul. It's actually the best solution for when all you have is a good enuf for
local use DD, but the time comes when you really need something that is road trip ready.

****

So the rest of this is basically for others reading your thread because they also have a noisy 5-speed
Getrag (NV3500) and are trying to figure out what their options are?

In a previous response I mentioned that it would be possible to just change the transmission
input bearing and the crank pilot bearing and make the situation a lot better than it is. In a
$500 truck rescued from slumbering in a field, this might actually get the trans to work as well
as the rest of the vehicle?

And once upon a time I would fix like this simply because diapers & baby formula took priority.
While it would make me feel like a troublesniper instead of just a normal troubleshooter, I would
usually regret the decision down the road, because the 'next most worn' part would step up and
make it's presence known. Given this, I'm still not recommending this approach, so how to identify
the specific front input shaft bearing part number is an exercise left up to the reader. :0)

****

Now that the table is set, let's get on with what I really wanted to share.

I just checked to see what a complete bearings kit for your trans will set you back:

You must be registered for see images attach



NOTE: This is a valid choice $189.00 choice IF your existing synchros are working well.

Synchro worn / gear clashing during everyday driving? For another $86.00 you can get
the kit that includes the new brass circles:


You must be registered for see images attach



As for the clutch, bringing this area back to new at the 'while you are in there' price of just over $100:


You must be registered for see images attach



There you have it. Assuming that your synchronizers are still OK, for the total cost of ~$300
in parts (+ new tranny fluid) you can make the middle of your drivetrain road trip ready.

Or you can get a cool sounding exhaust & rent a U-Haul for the longer trips. By the way, I'm
not goofing on you, for I've been at the same fork in the road in the past and stood there
pondering which path I prefer to take. (And for the record, I'm guilty of changing exhaust
systems for a 3% performance improvement while chasing after the finest motor tone in
the neighborhood. :0)

That's all I got. And while I'm here I'd like to salute you for saving one more GMT400 from
the boneyard. Well played, sir.

Here's to safe, reliable travels.

Cheers --
If I can do it, I will atleast replace the input and guide bearings as well as the clutch. The transmission shifts beautifully and has no issues with the synchros. I do understand the idea that doing this is a temporary solution and will likely cause another problem to arise. Are these bearings replaceable while leaving the transmission in place and just unboolting it and sliding it back? Or is this something I would have to remove the transmission?

Another part is my dad doesn't want to waste what limited time and space we have to fix this. We have a rented shop in the next town over, but it has my dad's 2500 and his chevy luv taking the space up right now. Maybe after we are done with his 2500 and he has something to drive I can work on repairing the transmission. I don't think I can replace all the bearings however.

I can probably get all those parts far cheaper because my mom works at NAPA and I can get a heavy discount on parts. I will get a price quote and go from there.

And about the exaust, it's not a huge priority, it was just a question I have because my muffler is rotted out. I might be able to get a nice Flowmaster muffler soon, or I'll just throw a 20 dollar glass pack under it.

I really appreciate your help, you have helped me clarify a major worry of mine about the truck and I am very grateful. I will keep you guys updated on ehat I end up doing!
 

Gordy_

OBS Enthusiast
Joined
Feb 2, 2024
Messages
88
Reaction score
128
Location
East Oregon
No, but I've painted my carpet with vinyl interior paint. I have to touch it up about once a year because the color gets rubbed off - in the pic below you can see that the paint looks thin in some places. I would recommend getting some seats that are in a color that matches. I put tan leather seats into my black interior - they match close enough for my tastes.

You must be registered for see images attach
I really don't mind the blue, I will likely get some seat covers, but for 50 bucks I can't complain about the color
 
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