99 tranny flush or fill?

[jeff99]

i have a 99 tahoe with 200k on it. at times it shifts kind of hard between 1 and 2nd then it will go a way. only really happens at frist start up and goes a way. not a everyday thing just once and awhile. happens in the winter and summer as well. i would like to flush and fill the tranny but i have heard some good and some bad. one guy told me he did it to his k1500 and the tranny blew up two weeks later. i also heard that you should only put fluid in and not replace all at once. the build up in the tranny is what is holding it together.

i dont want to have it flushed at the instant oil change just b/c i think they are out for a buck. i have read that doing a flush and fill 4 or 5 times. taking only a few quarts at a time is the best way.

so what is the best way to go about this? drop the pan and replace the fluids? drain and refill? should i stick to the reg fluid or go to the high miles. should i replace the fliter as well.

i havent gotten under the hoe to see if there is a drian? or would i have to drop the pan. i have read about guys running the motor and taking off the tranny lines and letting the fluid pump out vs dropping the pan or using a drain plug.

if anyone can help please do so..thanks alot

jeff

 

[S.V.T.]

i'd say flush, because it's a pressurized system that will get more deposits and gunk out of the trans, trans cooler, lines, etc, than just a drain and fill.
when i wrenched we had one of those machines, it worked great.. it is expensive but you're replacing ALL the fluid with new fluid, where as with a drain and fill you are not.

now there is a drain and fill bolt on your trans. so you could do that; however, how long has it been since you changed the tranny pan filter? i would change the filter, it's really easy to do.

now you are correct, the build up from old fluid can be helping your tranny, all new fluid could cause parts that are out of spec, alignment, not to have 'wiggle' room. this could be a result -- tranny failure if you do a flush, although a fill could do that as well.
the best thing to do is what's required. flush it, if it fails you can rebuild or buy another. i know it's not cheap, but it'll happen either way eventually (knock on wood that it doesn't).

 

[telmd]

I personally would just filter and fluid change. Have read that flushing can do more damage than good in older transmissions.

 

[freyguy]

Dropping the pan and changing the filter, and that fluid is a good start. I wouldn't flush either with that many miles. Normally when the problem is there, it's a bit late, but good fluid will help it last longer. What I like to do is to drop the pan and change the filter, clean the pan, and put it all back together. Fill up with the pan capacity. Then find the tranny lines that go to the radiator. Pull off a line, and attatch a hose that goes to a bucket with lines on it. Normally 2 or 3 quarts is good. Be carefull here. I thought the top hose would be going into the radiator, but it was actually going out. So I had a good bit of fluid on the floor. Then, have a buddy watch the pan, start the truck, and slowly shift through gears. When you hit 2 quarts, shut down the truck, put 2 quarts in, and repeat. Keep going until you replace all 14 quarts or whatever the capacity is, and even do it an extra time or two for safe measure.

As far as fluid, anything is good, but I like Amsoil ATF myself.

 

[tspain]

Do what freyguy says and drop the pan, change the filter and top off the fluid. With that many miles, if you have it flushed, it will probably cause some problems in the long run.

 

[ADP1326]

i would not flush or changed the filter (unless you've had several trans services already). the new fluid has conditioners in it and may cause more damage. go to napa and get an additive called lube gaurd. part #61910 its the black bottle. i use this at my repair shop and works wonders. good luck

 

[jeff99]

thanks alot guys....

 

[stbeverlin]

I used the BG service with the complete flush at 79K. I had already done two at 30K and 55K. After the 79K flush my xmission went south in 4 thousand miles at 83K.
Lessons learned are: do pan drops and filter change every 25K. Forget complete flushes as they don't pick up the shavings in the pan or the magnet (in the pan).
They only get the small particles flowing in the fluid.