I've had my truck about a year and it just rolled 90k, on the original transmission fluid, should i change it now or could it possibly do more damage than good?

 

Change it and the filter. 90k on the trans fluid??????

 

I was somewhat shocked when i found that out, when i was looking through the paperwork that came with the truck just now i noticed oil changes EVERY 6,000 and tires 3 times but guess it slipped my mind when i should have looked for paperwork from a transmission shop

 

Yep. Get it changed or change it yourself.

 

I heard never change it or it could cause problems...but I couldnt believe it so I changed trans fluid and filter, within 30 days I lost 4th gear, no shift into OD... now I run around in limp mode 3rd until I can afford a $4,000 dollar fix... you better keep asking around!

 

I've heard of crappy oilchange service flushing trans fluid without removing the pan and then trans went, but never with a proper filter change and fluid replacement.

What's wrong with your trans. How come no overdrive. Does it slip or shudder.
What fluid did you use.

 

no slipping or shuddering, had a blown maxi, and the codes point to shift solenoid...taking it in for a pinout, but they are saying new trans... I used fluid from ford

 

If the shift solenoid is bad or shorted, causing no overdrive, then why not try replacing it or the valve body after you know the wiring is good/bad after the pinout/wiring check.
Fluid from ford would have been merconV. Not an issue other then cost. But if you didn't change filter and clean out the sludge from bottom of pan, then that was your issue.
Trans filters are more to keep chunks out of the valvebody. When you have old fluid the particles fall out of suspension because the fluid already is suspending its max already. Big particles fall down and settle. If you only flush new fluid into the pan, then it will pull particles off pan and cycle it through the trans, causing solenoids to stick or check ***** to clog up or whatever else happens.

Hopefully it's an easy fix that only requires a 300$ valvebody.

 

Got it changed yesterday and put about a hundred miles on it and nothing but smooth as smooth could be shifts

 

Geez...90k. Is that all? My mother had 120k or so on her 1997 Merc Mountaineer...original mercon trans fluid. I did a cooler line flush a few months ago and put in Mercon V and it shifted better than ever. 5000 miles later still shifts beautifully.

 

About 220k on my fluid.
Original owner said it was never changed.
It was black and smelled burnt and stained anything it got on.
I dropped the pan and it was nearly clean on the inside.
I changed filter and flushed fluid and I'm guessing it's good for at least another 50k.
Or until I put my new valvebody in (that I don't have yet)