OK, I have 98 Blazer 203,000 miles. Tranny seems to be fine, I was thinking of changing the fluid and filter. yes or no and why?

 

Hello, Bueller? anyone?

 

check the fluid for color and smell first, if its still red and dosent smell burnt leave it alone

 

Okay.. you asked one of the toughest questions there is to answer on here.

I am a firm believer in "if it's hi-mile and working right, leave it the hell alone" school. I have anecdotes to back that up.

However.. if your dipstick doesnt show dark or cloudy fluid {like very weak tea at the most} and there's no burnt smell, then a little PM wont hurt as long as you have plenty of patience and are very careful it wont hurt anything to do it and you'll get a good idea of the health of the transmission.

Two of the three things that can go wrong are:

1 You break shift solenoids removing or installing the pan.

2 The pan has a lot of wear solids in it. If it's like a tablespoon or less, you're in pretty good shape. 3 tablespoons or more.. no matter what you do, good chance of the trans acting up after:
- Sometimes it seems the fluid being full of minute solids is what keeps the trans working. I think there's something to that. But you're sorta screwed no matter what you do from that point. Go ahead clean the pan good, replace the filter - see below - and when you refill leave room for a bottle of Lucas AT fix, put in while warmed and running... or mix it with fluid first.

Replacing filter..IMPORTANT!!!! Lots of people have trans shifting problems a short time after replacing the filter. In a worn transmission you cannot just pull it out and shove a new one in.

The reason is deposits build up around the filter neck seal / o-ring. Disturbing that seal breaks them loose and they may or may not lodge in a narrow place in the valve body.

Even accidently knocking against the filter can do that. When you pull the filter out make sure the o-ring comes with it. If it stays, you have to make a hook out of something that wont scratch the bore it sits in. Be very careful not to push crud up into the fluid passage.
THEN find or make something that will cover and block that passage hole ... think of a small ball on a stick.. and spray into the bore with wd-40 or choke cleaner to clean out the crud. Q-tips help, just spray out after.
The trick is getting the blocking thing up to cover the passage without carrying crud up with it. Maybe a stiff paper 'funnel' removed once the passage blocker is in place?

If you're successful at all that and dont break something in the process, you're in good shape for a while.

That's how I would do and have done it. Any variation at all might alter the consequences. Above ALL, DO NOT get a trans flush unless that pan is clean when you take it off. And you do the full filter change process I described above, first.

 

So what do you think of them apples "Joker"

 

Thanks guys, I`ve got a lot of dont do its, especially if everything is fine. The old, if it aint broke, dont fix it thing. So I think the route I`m going is to do nothing unless it starts acting up. Again, thanks for the info. I love this forum