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"But how do it know?"
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Discussion Starter · #1 ·
Hi All, :welcome:

Recently picked up a '94 Chevy 1500 with almost 320k miles. I'll be doing a full tune up and servicing the transmission.

Having never done a transmission service myself before, I have a few questions. The plan is to, at the very least, drop the pan and replace the fluid and filter. Should I go as far as doing a full flush?

Also, should I just stick with the regular Dex/Mercon fluid, or would the high mileage stuff from Valvoline be a better choice?

Thanks in advance! :thumbup:
 

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4L60E service

Be prepared for transmission failure. With high mileage like that what happens is the grit will actually adhere to the clutches and create friction. New, clean fluid will wash the grit away and slip city. With that many miles it's time for an overhaul.
 

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Wrench Turner
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If the fluid is dirty, or, appears burnt, then yes, I would definitely consider a proper flush, along with a new filter & a quality brand fluid.If you don't know much about it's maintenance history, you really don't have any idea how old, how often it has been serviced.If it's been serviced on any regular basis, changing it shouldn't hurt anything.If it hasn't & the fluid appears excessively dirty/burnt, changing it along with a proper flush is needed, but, it can cause you problems in some cases, but, no more than doing nothing will.
 

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"But how do it know?"
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Discussion Starter · #4 ·
Be prepared for transmission failure. With high mileage like that what happens is the grit will actually adhere to the clutches and create friction. New, clean fluid will wash the grit away and slip city. With that many miles it's time for an overhaul.
If the fluid is dirty, or, appears burnt, then yes, I would definitely consider a proper flush, along with a new filter & a quality brand fluid.If you don't know much about it's maintenance history, you really don't have any idea how old, how often it has been serviced.If it's been serviced on any regular basis, changing it shouldn't hurt anything.If it hasn't & the fluid appears excessively dirty/burnt, changing it along with a proper flush is needed, but, it can cause you problems in some cases, but, no more than doing nothing will.
Hey 39 master and jokerZ71,

Thank you both for the replies.

When I was researching this online, the thing about a possible transmission failure after doing a flush came up often.

I do not have any service history available on this truck. However, both the engine and transmission are surprisingly smooth considering the age and mileage.

A quick check shows the transmission fluid is dark in color and appears to be dirty when wiped on a cloth. Not sure what burnt fluid looks like.
 

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Hey 39 master and jokerZ71,

Thank you both for the replies.

When I was researching this online, the thing about a possible transmission failure after doing a flush came up often.

I do not have any service history available on this truck. However, both the engine and transmission are surprisingly smooth considering the age and mileage.

A quick check shows the transmission fluid is dark in color and appears to be dirty when wiped on a cloth. Not sure what burnt fluid looks like.
You say that the trans is very smooth, I would not do much to disturb it: change the fluid and filter and leave well enough alone.
Or do a full rebuild for peace of mind.
Anything in between is just a shot in the dark and asking for trouble.
 

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If you drop the pan n filter, break open the filter. Look inside. Sometimes it is very eye opening to the health of the trans
 

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Hi All, :welcome:

Recently picked up a '94 Chevy 1500 with almost 320k miles. I'll be doing a full tune up and servicing the transmission.

Having never done a transmission service myself before, I have a few questions. The plan is to, at the very least, drop the pan and replace the fluid and filter. Should I go as far as doing a full flush?

Also, should I just stick with the regular Dex/Mercon fluid, or would the high mileage stuff from Valvoline be a better choice?

Thanks in advance! :thumbup:
If it works properly and has no leaks I would just leave it alone. The 4L60E is one of those things where "if it ain't broke don't fix it".

Bogie
 

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"But how do it know?"
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Discussion Starter · #8 ·
You say that the trans is very smooth, I would not do much to disturb it: change the fluid and filter and leave well enough alone.
Or do a full rebuild for peace of mind.
Anything in between is just a shot in the dark and asking for trouble.
If you drop the pan n filter, break open the filter. Look inside. Sometimes it is very eye opening to the health of the trans
If it works properly and has no leaks I would just leave it alone. The 4L60E is one of those things where "if it ain't broke don't fix it".

Bogie
Hey Gents,

Yes, the transmission is shifting fine and there seem to be no leaks.

It is the dirty fluid that has me concerned. I mean that fluid has to be changed at some point before it becomes harmful and/or useless? Plus I figure replacing the filter can only help.

My thinking is that, instead of doing a full flush, change the filter and fluid in the transmission for now, and see how it runs while also monitoring the fluid. If after a few months the transmission continues to shift fine but the fluid becomes dirty, then to replace it again. By then, I should have enough saved up for a proper rebuild.
 

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Hey Gents,

Yes, the transmission is shifting fine and there seem to be no leaks.

It is the dirty fluid that has me concerned. I mean that fluid has to be changed at some point before it becomes harmful and/or useless? Plus I figure replacing the filter can only help.

My thinking is that, instead of doing a full flush, change the filter and fluid in the transmission for now, and see how it runs while also monitoring the fluid. If after a few months the transmission continues to shift fine but the fluid becomes dirty, then to replace it again. By then, I should have enough saved up for a proper rebuild.
You need to determine if the fluid is really dirty or just brown in color. I'd put some drops from the dip stick on a clean white paper towel to see if it's gritty or just brown in color.

Bogie
 

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Wrench Turner
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During a simple drain, filter, refill, you are only draining about half of the fluid, so you will only be adding approx 5 quarts of clean/new fluid to about the same amount of old/dirty fluid.
 

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If it truly is the original unit, and it really has that many miles on it, that would SHATTER the existing record for my shop for mileage from a factory unit.

Look it over carefully. Is the case painted? Does it have a GM REMANNED sticker on it somewhere? I know it's possible that it is original, but it is just not likely.

I'm with the poster above-LEAVE IT ALONE, or pull it and rebuild it. Doing anything else is just wasted time & money.

Fluid discolors due to clutch/friction dust. Putting new fluid into the trans does not replace the lost friction material from the clutches or band. It is not "liquid renew" as many would like to believe. You can put new fluid & a filter in it if you would like but the reality is that if the trans is on it's way out-it is still going to fail. If the trans was not going to fail before the service, then you will not have helped, or hurt it in that regard either.

At 320K miles you are TWICE the average failure point of the majority of 4L60E's that come through our shop. If it were mine, and I planned on keeping it, I would just go ahead and pull it and rebuild it.
 

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If it truly is the original unit, and it really has that many miles on it, that would SHATTER the existing record for my shop for mileage from a factory unit.

Look it over carefully. Is the case painted? Does it have a GM REMANNED sticker on it somewhere? I know it's possible that it is original, but it is just not likely.

I'm with the poster above-LEAVE IT ALONE, or pull it and rebuild it. Doing anything else is just wasted time & money.

Fluid discolors due to clutch/friction dust. Putting new fluid into the trans does not replace the lost friction material from the clutches or band. It is not "liquid renew" as many would like to believe. You can put new fluid & a filter in it if you would like but the reality is that if the trans is on it's way out-it is still going to fail. If the trans was not going to fail before the service, then you will not have helped, or hurt it in that regard either.

At 320K miles you are TWICE the average failure point of the majority of 4L60E's that come through our shop. If it were mine, and I planned on keeping it, I would just go ahead and pull it and rebuild it.
Good grief I've got 420,000 on mine behind a breathed on 350 in an S15 and I do a lot of tire squealing starts with it. Admittedly it is blowing a little pressure oil out the vent (toasted it pretty good in city traffic last summer so I expect the pump warped) and the lock up converter clutch ain't what it used to be but does work; the fluid is still red.

Bogie
 

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Wrench Turner
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If it truly is the original unit, and it really has that many miles on it, that would SHATTER the existing record for my shop for mileage from a factory unit.

Look it over carefully. Is the case painted? Does it have a GM REMANNED sticker on it somewhere? I know it's possible that it is original, but it is just not likely.

I'm with the poster above-LEAVE IT ALONE, or pull it and rebuild it. Doing anything else is just wasted time & money.

Fluid discolors due to clutch/friction dust. Putting new fluid into the trans does not replace the lost friction material from the clutches or band. It is not "liquid renew" as many would like to believe. You can put new fluid & a filter in it if you would like but the reality is that if the trans is on it's way out-it is still going to fail. If the trans was not going to fail before the service, then you will not have helped, or hurt it in that regard either.

At 320K miles you are TWICE the average failure point of the majority of 4L60E's that come



through our shop. If it were mine, and I planned on keeping it, I would just go ahead and pull it and rebuild it.
My original 4L60E went 418,000 miles troublefree.The rebuilt unit that replaced it went 198,000 before blowing the seal between the transmission & transfer case causing bearing fs ilure.It's fairly common, at least around here for these to go 300 to 400,000 miles if maintained & taken care of.
 

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"But how do it know?"
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Discussion Starter · #14 ·
Hey Gents,


Thank you all for the continued help!




You need to determine if the fluid is really dirty or just brown in color. I'd put some drops from the dip stick on a clean white paper towel to see if it's gritty or just brown in color.

Bogie
I checked the fluid again this morning.


First I checked it a few moments after starting the truck.









Then I checked it again about a minute or so later. It came out a lot cleaner than when I first checked it a couple weeks ago.










During a simple drain, filter, refill, you are only draining about half of the fluid, so you will only be adding approx 5 quarts of clean/new fluid to about the same amount of old/dirty fluid.
Yeah, that is about what I am budgeting on for a regular oil and filter change. Thank you for the heads up on the quantity.. The local Auto Zone carries Valvoline High Mileage Dex/Merc ATF and Castrol/Dex/Merc ATF. Will one of these work just fine?




If it truly is the original unit, and it really has that many miles on it, that would SHATTER the existing record for my shop for mileage from a factory unit.

Look it over carefully. Is the case painted? Does it have a GM REMANNED sticker on it somewhere? I know it's possible that it is original, but it is just not likely.

I'm with the poster above-LEAVE IT ALONE, or pull it and rebuild it. Doing anything else is just wasted time & money.

Fluid discolors due to clutch/friction dust. Putting new fluid into the trans does not replace the lost friction material from the clutches or band. It is not "liquid renew" as many would like to believe. You can put new fluid & a filter in it if you would like but the reality is that if the trans is on it's way out-it is still going to fail. If the trans was not going to fail before the service, then you will not have helped, or hurt it in that regard either.

At 320K miles you are TWICE the average failure point of the majority of 4L60E's that come through our shop. If it were mine, and I planned on keeping it, I would just go ahead and pull it and rebuild it.
Duly noted. I'll check the case to see if it has been painted or if there is a re-manufactured label somewhere.




Good grief I've got 420,000 on mine behind a breathed on 350 in an S15 and I do a lot of tire squealing starts with it. Admittedly it is blowing a little pressure oil out the vent (toasted it pretty good in city traffic last summer so I expect the pump warped) and the lock up converter clutch ain't what it used to be but does work; the fluid is still red.

Bogie
My original 4L60E went 418,000 miles troublefree.The rebuilt unit that replaced it went 198,000 before blowing the seal between the transmission & transfer case causing bearing fs ilure.It's fairly common, at least around here for these to go 300 to 400,000 miles if maintained & taken care of.
Wow, those are some serious miles!
 

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That fluid looks not bad too me. The 1st wipe was just cleaning crap off the dipstick, that's why the 2nd check was cleaner in appearance.

I'd just drop the pan, change the filter and refill with 4-5 liters or whatever it takes. Yes, you aren't getting all the old fluid out doing this, but that might be an advantage in such a high mileage unit.

The idea is to drop the pan, change filter and refill starting when the mileage is lower. Doing this will on average keep the quality of the fluid high, rather than a power flush. I had a 60e go out on me shortly after a flush. Now I just drop the pan, change filter, wash out the pan, and replace. But do so more often. Maybe every 50,000 miles. I use Dexron-6 Delco stuff from the GM parts counter.
I'm at 260,000 miles now.

peace
Hog
 

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Burnt out transmission tech.
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Hi All, :welcome:

Recently picked up a '94 Chevy 1500 with almost 320k miles. I'll be doing a full tune up and servicing the transmission.

Having never done a transmission service myself before, I have a few questions. The plan is to, at the very least, drop the pan and replace the fluid and filter. Should I go as far as doing a full flush?

Also, should I just stick with the regular Dex/Mercon fluid, or would the high mileage stuff from Valvoline be a better choice?

Thanks in advance! :thumbup:
If it is true mileage leave it alone.
What you showed on the dipstick tells me this is not original fluid.
If, as you say, it is shifting fine leave it alone.
This comes from over 50 years of building transmissions. :pimp:
 

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Hey Gents,


Thank you all for the continued help!






I checked the fluid again this morning.


First I checked it a few moments after starting the truck.









Then I checked it again about a minute or so later. It came out a lot cleaner than when I first checked it a couple weeks ago.











Yeah, that is about what I am budgeting on for a regular oil and filter change. Thank you for the heads up on the quantity.. The local Auto Zone carries Valvoline High Mileage Dex/Merc ATF and Castrol/Dex/Merc ATF. Will one of these work just fine?





Duly noted. I'll check the case to see if it has been painted or if there is a re-manufactured label somewhere.







Wow, those are some serious miles!
That looks pretty decent to me, I put the dipstick back in and call it good.

Bogie
 

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Wrench Turner
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Another option you have is, if you're just really worried about it, drain the fluid as much as possible into a clean container.Drop the pan, change filter,&, refill with the drained fluid.Top it off with some new fluid as you are bound to lose some amount during the drain.This would be a PITA, but would be no more harmful than adding fluid to top it off at any other time.IMO, I don't think hou'll have any problems by doing a basic fluid/filter change.
Most ppl end up changing the fluid when they detect a problem as a 1st course of action.By then, it's usually too late & the trans goes out soon after.The failure then gets blamed on the fluid/filter change.Looking at the pics, I dkn't think you'll have any problems. If you do, they were already present before the service most likely.
 

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Discussion Starter · #19 ·
Hey Gents,

That fluid looks not bad too me. The 1st wipe was just cleaning crap off the dipstick, that's why the 2nd check was cleaner in appearance.

I'd just drop the pan, change the filter and refill with 4-5 liters or whatever it takes. Yes, you aren't getting all the old fluid out doing this, but that might be an advantage in such a high mileage unit.

The idea is to drop the pan, change filter and refill starting when the mileage is lower. Doing this will on average keep the quality of the fluid high, rather than a power flush. I had a 60e go out on me shortly after a flush. Now I just drop the pan, change filter, wash out the pan, and replace. But do so more often. Maybe every 50,000 miles. I use Dexron-6 Delco stuff from the GM parts counter.
I'm at 260,000 miles now.

peace
Hog
If it is true mileage leave it alone.
What you showed on the dipstick tells me this is not original fluid.
If, as you say, it is shifting fine leave it alone.
This comes from over 50 years of building transmissions. :pimp:
That looks pretty decent to me, I put the dipstick back in and call it good.

Bogie
Another option you have is, if you're just really worried about it, drain the fluid as much as possible into a clean container.Drop the pan, change filter,&, refill with the drained fluid.Top it off with some new fluid as you are bound to lose some amount during the drain.This would be a PITA, but would be no more harmful than adding fluid to top it off at any other time.IMO, I don't think hou'll have any problems by doing a basic fluid/filter change.
Most ppl end up changing the fluid when they detect a problem as a 1st course of action.By then, it's usually too late & the trans goes out soon after.The failure then gets blamed on the fluid/filter change.Looking at the pics, I dkn't think you'll have any problems. If you do, they were already present before the service most likely.
Going by the feedback provided by all of you, I'm going to leave things as they are for now.


I have to get the truck ready for a smog check asap, so I'm just going to focus on that for now. Afterwards, if there is any concern about the ATF, I'll look into doing just a basic fluid and filter change.


Thanks again for all your help! :thumbup:
 
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