96 4L60E Too Flush or Not

[east302]

When cold it sometimes has a hard shift into second but otherwise shifts smooth.

A broken spring in the 1-2 accumulator can cause a hard 1-2 shift under light throttle. Mine was so bad it shook the dash but went away as it warmed up. It’s an easy thing to check (and fix) with the pan dropped, check YouTube for videos.

New spring pair on left, original on right on a 98.

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[gyver]

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Ok 96 K1500 just hit 50,000. At 46k I dropped pan/new filter and replaced what came out. Fluid looks clean! When cold it sometimes has a hard shift into second but otherwise shifts smooth. Any thoughts on whether to do anything like fluid exchange through cooling lines, transmission flush/fill(at transmission shop) or just leave it be? I’d say aside from fluid I replaced, the rest is 25 year old OE fluid.
Btw-I did just add auxiliary cooler!

I bought my 1998 Chevy truck new in 1997. After a few years I went to change my transmission oil and the guy said if you haven’t changed your transmission oil by 50,000 miles don’t change it because it will start having problems. So, now I have 233,000 miles and never changed the fluid. So far it works just fine. It’s my daily driver.

 

[df2x4]

the guy said if you haven’t changed your transmission oil by 50,000 miles don’t change it because it will start having problems.

Glad you haven't had any issues, but IMO this is terrible advice. A fluid and filter change (not flush) isn't going to hurt anything. If it does, that trans was not long for this world anyway.

 

[alpinecrick]

Glad you haven't had any issues, but IMO this is terrible advice. A fluid and filter change (not flush) isn't going to hurt anything. If it does, that trans was not long for this world anyway.

This^^^ In spades........!!!

 

[alpinecrick]

I bought my 1998 Chevy truck new in 1997. After a few years I went to change my transmission oil and the guy said if you haven’t changed your transmission oil by 50,000 miles don’t change it because it will start having problems. So, now I have 233,000 miles and never changed the fluid. So far it works just fine. It’s my daily driver.

mmmmm........

 

[Caman96]

Well I dropped pan at 46k so I’ve avoided the 50k cutoff already. I prefer to get new fluid in there. Let me change hard shift occasionally into second to “harder shift” occasionally. PCM is off to Black Bear tomorrow!

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[alpinecrick]

Well I dropped pan at 46k so I’ve avoided the 50k cutoff already. I prefer to get new fluid in there. Let me change hard shift occasionally into second to “harder shift” occasionally. PCM is off to Black Bear tomorrow!

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When you get the PCM back from BB let us know how things go!

 

[oldchevylover]

numerous times over the years, I have resolved poor transmission performance by simply changing the fluid. I am convinced that these transmissions NEED clean fresh fluid in order to operate properly. There is absolutely no reason to pay someone to "flush" the transmission fluid. I always do a complete replacement by disconnecting one of the cooler lines and letting the old out while pouring in the new.

 

[Night Bomber]

1 - Loosen and disconnect the transmission cooling tube connected to the UPPER radiator outlet port.
2 - Install a short piece of tubing with the correct fitting into that radiator outlet and run a length of CLEAR tubing down into a pail.
3 - Start your engine and watch the color of the oil flowing in the clear tube. Dark Red=OLD. Bright Red=NEW.
4 - Let the transmission pump oil out until you see bubbles in the clear tubing or until it sputters oil into the pail.
5 - Stop the engine and add appropriate amount of new transmission oil.
6 - Go back to step 3 and repeat. Once the oil comes out bright red you have flushed your transmission without disturbing the leak prone fittings at your transmission.
7 - Remember to check your transmission oil level a couple times once you have brought the level back up to the correct amount.

 

[Schurkey]

^^^ Almost.

Steps 1--4 are perfect except to start with buying two, 12-quart cases of trans fluid and a correct trans filter (and gasket if needed. The newer GM gaskets are reusable and better than the cork ones commonly sold in the trans filter kits.)

Half of step 5 is good. Once the fluid sputters into the pail, stop the engine, REMOVE THE TRANS PAN, CLEAN THE PAN AND MAGNET, AND INSTALL A FRESH TRANS FILTER. REPLACE PAN, ADD 5 QUARTS OF FLUID. OPEN ANOTHER TEN QUARTS SO THEY'RE READY TO POUR.

START THE ENGINE, ADD MORE FLUID AS FAST AS YOU CAN POUR IT IN THE FUNNEL.

WATCH THE FLUID COLOR SHOOTING OUT OF THE DRAIN HOSE. WHEN IT LOOKS VIRGIN-NEW, SHUT OFF ENGINE. You've replaced 95% of the old, depleted trans fluid AND the trans filter, AND removed all the grit from the pan.

RECONNECT TRANS COOLER TUBE.

START ENGINE, ADJUST FLUID LEVEL AS NEEDED.

POUR OLD FLUID INTO EMPTY BOTTLES FOR RECYCLING. Screw the caps on tight so they don't leak in your vehicle on the way back to the recycling station--which is probably the parts store you bought the fluid at.

HAVE A CELEBRATORY BEVERAGE. When you've recovered, return the unused quarts of fluid and the old, recyclable fluid to the parts store.