To Flush or Not, 4L80E

[Big T]

What's involved in flushing the transmission? Is it really all that it's cracked up to be, or is it just a way for shops to get your $$$. How much does it cost on the 4L80E? How often should it be done?

 

[THEFERMANATOR]

Flushing can be a double edged sword. If you drop your pan every 30K miles and change the filter you shouldn't ever need to flush it out. On the other hand, if you don't service your fluid and filter clutch material builds up and teh flush will clean it out. The kicker is though, many times when all the clutch material comes loose it will go into the valve body and plug it up and take the trans out. It is mostly just a money making service as it really isn't that intensive to do. The only time it is really beneficial is if you are changing from say dino oil to synthetic and want to get all of the old fluid out when you do it.

 

[Big T]

Thanks for the clarity on this matter.

 

[3500GMC]

The whole 100,000 mile transmission fluid change interval thing is just asking for it.

You won't get but half the fluid out on a pan drop filter change, but if you are regular about it, it's not a big deal.

I've seen it a hundred times, guys will wait until the fluid is burnt (too late) and then think, "I know how to fix THAT, I'll just drain it and pour new stuff in!" Uhh, NOT..

Trans failure right around the corner.

 

[Brooklyn Tow]

What about if your Rad Crapped out and you have coolant in the Trans?.......Happened to me sat. afternoon, pulled the stick and it looked like a strawberry milkshake.

So I parked the truck and waiting for a rad, then I NEED to flush......It's my only hope to save the tranny:mad2:

 

[THEFERMANATOR]

DEFINATELY flush it if coolant got in it. Unfortunately though, anti-freeze eats the glue that bonds teh clutch pad material to the clutch plates so get it out ASAP!

 

[WarWagon]

May be cheaper to just do the trans now and save the tow bill later... Some clutch linings are paper. Then the moisture coolant mix will rust and lock up bearings. The bearings then spin and damage the case adding to the repair bill. Been there done that with a pinhole leak in the trans oil inter-cooler. Plug both holes in the radiator for the trans oil intercooler and run a air to oil cooler 2x bigger than stock. I have had good luck doing this in the past. Common failure point.

Flushing does not get the debris off the bottom of the pan or change the dirty trans filter. Drop the pan and clean it out, new filter, then flush it.

In the case of water the torque converter is a blender and will throw the water to the outer rim. The oil enters and exits through the center. Not easy to get the coolant out.

 

[Brooklyn Tow]

May be cheaper to just do the trans now and save the tow bill later... Some clutch linings are paper. Then the moisture coolant mix will rust and lock up bearings. The bearings then spin and damage the case adding to the repair bill. Been there done that with a pinhole leak in the trans oil inter-cooler. Plug both holes in the radiator for the trans oil intercooler and run a air to oil cooler 2x bigger than stock. I have had good luck doing this in the past. Common failure point.

Flushing does not get the debris off the bottom of the pan or change the dirty trans filter. Drop the pan and clean it out, new filter, then flush it.

In the case of water the torque converter is a blender and will throw the water to the outer rim. The oil enters and exits through the center. Not easy to get the coolant out.

Already have a external Trans cooler OEM (3500HD).....

Lets be optimistic.....Change rad and flush cooling system, Flush tranny with machine, drop pan, change filter, and flush again after it drives for a week or two.....

Need some good Karma!!

 

[Brooklyn Tow]

Flushed everything and swapped filter Friday, refilled......Truck seems OK....Will drop the pan again Monday and replace filter and fluid as needed.