To flush....... or not to flush! THAT is the question!

[Supreme Pizza]

You know the deal... Unknown trans maintenance. 250'ish on the old clock. Trans fluid is in the "yellow" stage - Not green or red, but sitting in that yellow stage. Trans works and shifts fine. Should I drop the fluid and shock the tranny with a new batch? Should I drop a quart and add a quart once a week? Should I leave it the **** alone, cuz ya shouldn't fix something that ain't broke? I am well aware of the new fluid ghosts, as well as what is involved in a tranny swap. Thoughts?

[sefiroxx]

Willing to gamble. It's not proven, but theory has it that the old fluid is carrying fine particles that are adding to the friction of the clutches and a flush remove that material - or it doesn't.

 

What color is it?

 

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[Supreme Pizza]

My fluid is in the middle ground. Its brown. Lost the pink, but its not sporting a black or silver tint yet. I do not believe that the fluid is supporting the friction plates. My concern is that the new detergent will mess up the valve body.

[Boardmember]

Pardon, but what are the pictures of?

[007matman]

Which tranny? What year?

 

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[diyer2]

Too little too late IMO.

Drive until it dies, replace.

[KARNUT]

On a newer transmission I would pull a line and flush. On a older transmission I would change the filter without flushing, just replace lost fluid.

 

 

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[Supreme Pizza]

My rig is a 2002 Suburban with a 5.3. Not sure on what trans it is. If I did anything at all, I would drop the drain plug, and re-fill, drive it a few miles and repeat. I would not pull the filter or do a "flush". The exhaust would have to come down to do the filter - not happening.. My concern is that the valve body will get messed up because of the new fluid and detergents. I think the new fluid would benefit the trans but that the detergent might do harm. I'm leaning toward just leaving it alone. If I ever put a brand new transmission in, I will change the fluid on a regular basis for the life of the vehicle.

[Nanotech Environmental]

My rig is a 2002 Suburban with a 5.3. Not sure on what trans it is. If I did anything at all, I would drop the drain plug, and re-fill, drive it a few miles and repeat. I would not pull the filter or do a "flush". The exhaust would have to come down to do the filter - not happening.. My concern is that the valve body will get messed up because of the new fluid and detergents. I think the new fluid would benefit the trans but that the detergent might do harm. I'm leaning toward just leaving it alone. If I ever put a brand new transmission in, I will change the fluid on a regular basis for the life of the vehicle.

A passive flush is completely harmless and is the best way to freshen fluid in a trans. Forced flushes, such as the ones done in car shops are the ones that cause all the problems. Passive flushes are done using the 2 cooling lines and the trans pump. New fluid will not mess with the valve body.

[Supreme Pizza]

My concern about the valve body is that there may be crud stuck to the internal parts, and the new detergent may break that crud loose, clogging up the valve body passages. I have heard that the forced flushes are a bad idea. I'm just not sure if the new fluid will cause more harm than good. The current fluid is clean, so I don't believe that the clutches will slip with new fluid.

[Nanotech Environmental]

My concern about the valve body is that there may be crud stuck to the internal parts, and the new detergent may break that crud loose, clogging up the valve body passages. I have heard that the forced flushes are a bad idea. I'm just not sure if the new fluid will cause more harm than good. The current fluid is clean, so I don't believe that the clutches will slip with new fluid.

If you replace the fluid via a passive flush and something goes bad, it was going to fail anyways.

[Supreme Pizza]

You might be right. My goal of course is to get the most amount of life out of the trans. Just cant decide if new fluid will extend the life or shorten the life.

[T1Kaiju]

Dealership told me they do passive flush with motor moving the fluid. So for $150 I said go for it at 50k miles. About a month later, I started having issues with shutter and what felt like tires going over rumble strips on occasion - usually after driving for 30 min. Thought it was my new michelins, so I rotated early, but it wasn't that. Then I had them check autoride, but not that either (was hoping to get that covered free). It got worse, and I finally found out it was torque converter. Didn't malfunction until tranny temp was over 160, but then shuttered pretty bad. They replaced it under gmpp, flushed the lines, and changed the filter; now it runs perfect. I had zero issues before that fluid exchange so I think Ill just drop and change filter from now on out...

 

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[Supreme Pizza]

I think your right man. Leave well enough alone and just drive it.

[swathdiver]

Well as for me and my truck, it was purchased a few months ago and now has 117K. The Tech2 said the fluid life was 35% but I wanted to change the fluid anyway, it was beginning to turn brown but not burnt. Dealership has that special machine that back flushes the filter and then exchanges all fluid when they reverse the lines and they do not do the pan drops anymore, so I went with that. Seemed a little slow on the way home, made a funny shift but now, several hundred miles later, it's driving fine, as if it had to relearn. I used my Tech2 to reset the transmission fluid life. Temps seem to be the same but upon reflection, that day was 103 outside while I was driving it.

 

As for the OP, some JB Weld here and there and that thing will be good to go!