Bought 98 F150 v8 4.6 w/ auto transmission.after our mech checked out OK. Changed trans fluid 1st time. Auto parts store said truck used Dextron III. Got in & started to drive when trans. emits high pitched whine & slipped bet. 1 & 2nd gears. Had mech. look at old fluid & said nothing was in fluid to suggest trans was "doctored" & no metal in it. Has no idea what's going on. We have not driven over 5 miles until we can figure out something. Help!!! We're dumb on this. Have we bought a lemon? What suggestions do you have to solve?

 

What tranny? Look on your door jam code sticker as it does matter.

U would be the 4R70w which NEEDs Mercon V.

E would be the E4OD or 4R100 which NEEDs Mercon. Mercon is Fords name, Dexron III is the GM equivilant.

Adrianspeeder

Adrians

 

Mercon can be up graded to Mercon V. Are you sure the filter screen was installed correct. also recheck the fluid level because the torque holds alot.

 

No, Mercon V has a friction modifier that the 4R70w requires, and will damage the E4OD/4R100.

Adrianspeeder

 

I highly suggest you stay away from both the Autoparts store and your mech. Both are idiots if they can't figure out that Dextron is for GM vehicles and that Ford requires Mercon or Mercon V.
Suggest you completely drain and flush out the GM fluid. That means the pan, the torque converter all the lines and the cooler. Look in your owners manual or on the tranny dipstick to see if you need Mercon or Mercon V - don't interchange. Then install the correct Ford juice. Then flush it all out again to make sure.

Fritz

 

DEXRON III is not the problem. DEXRON III and MERCON are so close that you won't be able to find a MERCON fluid that doesn't also say DEXRON II, except at a Ford dealer.

You have a 4R70W trans. It takes MERCON V fluid, not MERCON. The wrong fluid will not cause it to slip, it will cause it to shudder several thousand miles down the road.

Did you change the filter when you changed the fluid? Your symptoms sound like the filter was not installed correctly.

 

Dextron = Mercon

Don't look at the dipstick, as origionally the 4R70w called for Mercon, but it actually was determined to require a friction modifier which is what Mercon V has. ALL 4R70w's (trans code U) from 94 to 03 NEED Mercon V.

If you have the E4OD/4R100 (I doubt it though) it is trans code E, the Dextron is fine.

Adrianspeeder

 

Listen to Adrianspeeder. from what I have seen on the forums here, he knows what he is talking about. And in this case I agree....

 

Well the problem you are having is somewhat simalr to what my old truck was doing the last week I owned it with a few other problems from time to time durring that week with the tranny that forced me to buy a New 05 truck almost a month ago.

 

Did you change the oil yourself? Did you drain torque convertor and check to be sure trans is completely full? Its possible that the filter dropped off where trans is only picking up air.

 

It sounds like a low fluid level to me. Lots of fords (and all others for that matter) will get real finicky when the fluid is low. In order to check it, it must be at operating temperature, and then shift it into reverse and sit for say 15 seconds, then drive for 15 seconds, and 3, 2, and 1 for another 15 seconds each. Then leave it running and check the level. If its not in the crosshatched area then this is most likely your problem. Mercon/Dexrton was and is commonly used in most vehicles, but the newer fords require the Newer Mercon V.

 

I have 112,000 on my 97 4r70w with no problems. I change the fluid every 25K.

 

Oh, and I only use Mercon! Have had no problems.

 

Sounds like it's low or the filter fell into the pan and it's starving for fluid.