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Transmission fluid changes for 4t60E

12K views 37 replies 9 participants last post by  GetOffMyLawn 
#1 ·
Just wondering how religious some of you are out there with trans fluid changes...Or maybe not so religious? :) I have 66k on my 91 ETC. Trans is shifting SUPERBLY. Shifts as smooth as a hot knife through butter and virtually seamless....But i wonder about the condition of fluid. Its not the nice Magenta color but a light brown almost identical to clean motor oil. No burnt smell, In fact, smells the same as new fluid.
One might suggest to change it...But i am one who is hung up on all the transmission myths out there. One being if its working fine leave it be. I think i am spooked by two incidents in my trans. fluid change history. Changed fluid on a 1975 Mercury Cougar i had way back when at about 96K miles.....Next few days following, Trans. started slipping. Buddy of mine changed fluid on his 91 Lincoln LSC at higher miles...within a few days...trans slipped as well. Coincidence maybe.

As much is argued about flushes as well, But i think a fluid change by pan drop and filter change the best way. Just looking for thoughts
Thanks!
 
#8 ·
Right. Owner neglects transmission (or it just gets old), transmission starts acting up, owner has fluid changed to try and fix the proem. Transmission eventually fails, and the owner blames the fluid change.

FLUSHING is another story. Pressurized fluid stirring up sediment that wasn't doing any harm and/or junk from the last car that was hooked up to the machine can kill a transmission in a hurry.

The myth is that draining and filling with clean fluid will damage the transmission in any way.
 
#10 ·
Question: Why should I not believe the Transmission Fluid sensor and GM's claims of lifetime transmission fluid (except when the sensor says otherwise)? (I don't know about a '91 ETC, but this has been so on all my above models iirc)

I haven't found any official schedule calling for fluid replacement. The only time I see draining and replacement suggested in the manual/TSB's (omitting major problems/procedures) is either when operated outside of normal conditions (overheating tranny) which the sensor is supposed to detect, or in the case of fluid contamination ("strawberry milkshake").

It's of course plausible that the fluid will degrade over an extended period of time and that may itself lead to problems, but where's the hard data or manufacturer recommendations? That's the only real way to fight the myths.
 
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#13 ·
Actually the 91 came with Dex II ... So i actually wanted to get DEX IV but the parts guy from a small parts shop that has been in my city for 70 years has an old dude working there since as long as i can remember and im 52 adamantly talked me out of DEX IV His argument didnt seem to be of incompatibility but unnecessary.There was a cost difference i didnt care about.... He seemed to more than me.... I just needed compatibility as my thoughts are any fluid (thats compatible) has a better quality than what the factory installed 23 years ago even if i used a generic brand...But this should do right?
 
#16 · (Edited)
Curious about how a shop fully drains a 4T80-E without doing a flush - I presume they would get out all 12-14L, not just the 7L you get from pulling the drain plug. Is there a machine for fully draining that won't stir up or pass the sediment the way a flush can, or do they do the same DIY hose & engine running in P trick mentioned in other threads, or...? All I've found in the manual is the full flush procedure so far, nothing specifically for drain & replace besides a mention. Makes me think the full drain is just the last 1/3rd of the flush procedure which is pretty much the same as the engine in P? Other threads also contain many anecdotes about not trusting the dealer to not use the flush machine, welcome input from anybody who's done this.
 
#17 ·
They use a machine for what they call a "fluid exchange". It basically pumps fluid through the trans until fresh stuff comes out. Kind of like flushing your brake lines. You could accomplish the same thing by running the engine with the pan removed to pump out the TC. Shut down when the fluid stops. Another way is to make an adapter to fit on the trans fluid cooler return line and put a hose on it and run that into a bucket and pump it dry.
 
#19 ·
JimD posted the necessary fittings a couple of years ago. You make up an adapter and hose for the upper fluid cooler return line. Stick it in a 5 gallon drywall mud bucket and idle the engine until the discharge fluid bubbles and sputters. Refill properly. You'll get 12 quarts or so (of the 15 total) out this way.
 
#22 ·
Now that's an interesting question: The risk of leaving a growing layer of sediment (there's a TSB about the magnet becoming saturated), vs the risk of a problem caused by dropping the pan (gasket doesn't reseal properly?). And that TSB has me scratching my head about what exactly is going on with change intervals, just leaving it alone now seems to be a risk as well, so much for dispelling that myth. :rant2:
 
#23 ·
I'm new, but why not flush? Is there a way of emptying the converter without flushing? If you are just dropping the pan, I was told you are really just adding a few quarts of new to the large volume of old fluid. On my Reatta, I did the flush which emptied the converter. If you are just opening the return line from the radiator to empty the old fluid, and running new fluid in as the engine runs and until it runs clear or new color, how does it stir up anything?
 
#24 ·
A flush involves sending water-based solvents through the system with air pressure, in both directions. GM instructions say it generally is never needed on this transmission, but if it is it should be done with the special GM parts with the transmission entirely dismounted. You're describing just a fluid exchange - see above previous posts for the various fluid exchange methods - I had the same question above.
 
#26 ·
The instructions are in the manual directly from GM. Go to your AllDataDIY, Vehicle - Transmission and Drivetrain - Automatic Transmission/Transaxle - Testing and Inspection - Component Tests and General Diagnostics - Oil Cooler Flushing and Flow Test. There are also several related TSBs.
 
#29 ·
That's fine, believe what you want about the authors if you don't understand how manuals are written, but unless you've performed the solvent-based cleaning in the procedure, you haven't actually "flushed" the system, you've just exchanged the fluid using whatever procedure suited you. Cycling fluid is not considered a flush by the GM definition, and GM released TSB 04-06-01-029G specifically stating not to use external aftermarket machines for fluid exchange or flush. While I have tracked down the flush procedure as above, I am still trying to track down the official fluid replacement procedure (which is referenced in several places in the manual).

What's also still unresolved is the contradictory TSB information I pointed out in post #18.
 
#30 ·
I can't swear to it because no dealer has ever touched my trans. I have always dropped the pan and changed my own fluid (so far), but that is time consuming and messy and I would bet that most dealers use some sore of fluid exchange machine. They (and I) would probably consider that a "flush". Now whether that machine would be considered an "aftermarket machine" I do not know, but that would seem to fly in the face of the TSB you posted. :noidea:

What's also still unresolved is the contradictory TSB information I pointed out in post #18.
Their trans fluid change recommendations seem to vary. I can remember when it was 30K, then 50K, then 100K and finally lifetime (under "normal" driving conditions).
 
#31 · (Edited)
Yes, there is a general lack of clarity. That certainly does not help clear up myths and confusion.

But I may have connected at least a few dots: (or skip to conclusions below if you don't want to read)

There are at minimum two distinct types of transmission flushes referred to in GM documents, pre-2003 with the J-35944-A machine, and post-2003 with the J-45096 machine (TSB 99-07-30-017A). Both procedures share the characteristic of being designed to stir up and vacate sediment - that's a fair definition of a flush when compared to an exchange, and still fits with GM's terminology. Both machines are (unsurprisingly) hooked up to the cooling lines. Both procedures are only recommended (or required, depending on the document) after the transmission has been pulled for overhaul. The older procedure cycles a water-based solution with air agitation, the newer procedure cycles Dexron VI with air agitation. The manual for our cars lists the older flush procedure as do the J-39544-A instructions (find an alternate set here), while TSB 02-07-30-052I describes the newer flush procedure (another description here).

I have also found the official fluid exchange procedure in the AllData. It's under Vehicle - Transmission and Drivetrain - Automatic Transmission/Transaxle - Service and Repair - Removal and Replacement - On Vehicle Service - Scavenge Screens and Seals Replacement. DUH! These instructions are - you guessed it - the traditional bottom pan drop and drain plug, no usage of a machine anywhere.

Now here's the interesting bit: The J-45096 manual contains a procedure for filling the transmission fluid using Flow mode which makes complete sense. I would guess the J-39544-A can do the same. TSB 04-06-01-029G is written for a response to customer service specifically regarding flushing, and says never to use aftermarket machines ever, to never flush the transmission fluid, and to never use any machine for flush or exchange... but then it leaves the ambiguous statement that J-45096 "is recommended for GM vehicles." There is also the Service Information manual referenced by the TSB's, which may contain yet more/different information, but that manual is behind a wall at ACDelco Technical Delivery System for non-GM-affiliated folks like us - it is possible that information resolves some of these ambiguities.

This is to say nothing of the different methods and terminology outside the GM world, which further confuses the situation. For this discussion, that's ignorable.

Conclusions so far regarding doing a fluid exchange in a GM-compliant manner:
  • The JimD procedure is compliant since it's basically the last stage ("Flow Check") of the flush procedure.
  • The pan drop ("Scavenge Screens and Seals Replacement") + JimD procedure is a clever combination and still compliant.
  • Machines besides the J-45096 are forbidden, while J-45096 usage is suspect. It would seem less risky to avoid any procedure involving a machine altogether.

I need a :alchi:

Edit #1: The Flow Check sub-procedure can be found in the AllData, Vehicle - Transmission and Drivetrain - Automatic Transmission/Transaxle - Testing and Inspection - Component Tests and General Diagnostics - Oil Cooler Flushing and Flow Test
 
#33 ·
Yes, there is a general lack of clarity. That certainly does not help clear up myths and confusion.

But I may have connected at least a few dots: (or skip to conclusions)

There are at minimum two distinct types of transmission flushes referred to in GM documents, pre-2003 with the J-35944-A machine, and post-2003 with the J-45096 machine (TSB 99-07-30-017A). Both procedures share the characteristic of being designed to stir up and vacate sediment - that's a fair definition of a flush when compared to an exchange, and still fits with GM's terminology. Both machines are (unsurprisingly) hooked up to the cooling lines. Both procedures are only recommended (or required, depending on the document) after the transmission has been pulled for overhaul. The older procedure cycles a water-based solution with air agitation, the newer procedure cycles Dexron VI with air agitation. The manual for our cars lists the older flush procedure as do the J-39544-A instructions (find an alternate set here), while TSB 02-07-30-052I describes the newer flush procedure (another description here).

I have also found the official fluid exchange procedure in the AllData. It's under Vehicle - Transmission and Drivetrain - Automatic Transmission/Transaxle - Service and Repair - Removal and Replacement - On Vehicle Service - Scavenge Screens and Seals Replacement. DUH! These instructions are - you guessed it - the traditional bottom pan drop and drain plug, no usage of a machine anywhere.

Now here's the interesting bit: The J-45096 manual contains a procedure for filling the transmission fluid using Flow mode which makes complete sense. I would guess the J-39544-A can do the same. TSB 04-06-01-029G is written for a response to customer service specifically regarding flushing, and says never to use aftermarket machines ever, to never flush the transmission fluid, and to never use any machine for flush or exchange... but then it leaves the ambiguous statement that J-45096 "is recommended for GM vehicles." There is also the Service Information manual referenced by the TSB's, which may contain yet more/different information, but that manual is behind a wall at ACDelco Technical Delivery System for non-GM-affiliated folks like us - it is possible that information resolves some of these ambiguities.

This is to say nothing of the different methods and terminology outside the GM world, which further confuses the situation. For this discussion, that's ignorable.

Conclusions so far regarding doing a fluid exchange in a GM-compliant manner:
  • The JimD procedure is compliant since it's basically the last stage ("Flow Check") of the flush procedure.
  • The pan drop (Scavenge Screens and Seals Replacement) + JimD procedure is a clever combination and still compliant.
  • Machines besides the J-45096 are forbidden, while J-45096 usage is suspect. It would seem less risky to avoid any procedure involving a machine altogether.

I need a :alchi:
Holy crap.
 
#35 ·
I'll just stick with a simple pan drop and using the engine to pump what I can out of the TC.
Yes, that seems the safest way to drain all fluid, remove pan sediment / clean magnets, and still be sure of compliance with GM procedures. This is the combination of the Scavenge Screens and Seals Replacement and the Flow Check (2nd bullet-point in Conclusions above).

I would choose the same method, as leaving collected sediment and dirty magnets seems riskier than dropping the pan (presuming everything else is in good working order). TSB 08-07-30-040C is specifically about dirty magnets and new replacement magnets which are round (instead of the original squares) - here's the text that makes dropping the pan seem worth doing:


A new transmission oil pan magnet, P/N 29535617, was released for service. The current square transmission oil pan magnet may become saturated with normal ferrous sediment and the Pressure Control Solenoid (PCS) is now collecting ferrous sediment, making it vary from design. For a given current the PCS electromagnet is stronger, causing the line pressure to be less than needed.
 
#34 ·
Its without a doubt ....which prompted my initial post...That transmission fluid, changes, exchanges, flushes definitely have a ton of controversy over them and its good to get guys talking and clarify. Ultimately what i did was the pan drop, clean, replace gasket , fluid and thats it. In rereading my owners manual...I have the recommendation of "normal driving conditions, Transmission fluid service is not necessary until after 100,000 miles" My thought was although my 91 ETC appears to have been extremely well cared for, I could not guarantee previous owner drove under normal conditions and had to assume the fluid was never changed (as owner may have been following the manual recommendation) I figured that the age of the fluid may have an affect .. I have no proof of that. But i figured after getting some input, It could not hurt to change what i could and "freshen" it up. The fluid that i had in the car was brown, However the coloring of trans. fluid is a dye..It may have just faded after so many years? Just a guess.... It came out of the pan smelling like the new fluid i was going to put in. No burnt smells and although brown, It was a transparent brown on the dipstick. I got out only what was in the pan which amounted to 5.5 quarts. A total overhaul, According to the manual says 8 quarts....So i mixed 5.5 new with 2.5 old. Seeing as how the old fluid although was colored brown but still had the smell of new fluid and the trans. shifted immaculately before the change and just as well now with 67 k miles. Or maybe the placebo effect of feeling like it shifts a little better with new fluid. I am ok with having changed it the way i did.
 
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