I have a 97 F150 Super Cab 4x4 with the 4.6 auto and a 3.55. I just bought it a couple of weeks ago with 42000 on the clock. When going up hills (mild grade) and keeping the truck at about 40mph (3rd gear approx 1400-1600rpms - requires light throttle), the truck makes a vibration that feels like I'm going over shallow rumble strips - like the ones on the side of the road. If I take my foot off the gas completely the "rumbling" stops. Anybody have any idea what could be causing this or experience this with their truck?

 

Converter problem, I don't work on 4R70s, but I know it's a common problem with them, had it in my 94 T-bird and a new converter fixed it, I think it has something to do with the lockup clutch. Mark Kovalsky would know better than anyone.

G

 

I posted this in the engine section also.
I had a simular problem and found that changing my PCV valve all but cured it. I did the blow test and the old valve seemed to be working but it obviously was not. Now my tranny down shifts out of torque converter lock-up when on these grades. It probably wasen't able to produce enough vacume with the bad PCV to unlock the torque converter. Costs only $3 to find out. Could be a cheep fix.

 

I have the same type of thing, same setup; 30K miles. But it didn't start until I had the transmission serviced. Changed all fluid. Now it does this especially when cold or going up a grade with some load. Noticed it on drive home from service and thought about taking it back! The old lube was better, figured I'd let the new oil age a bit. Can someone out there that understands this auto box fill us in

thanks, arl

 

I had a slight vibration for a while thouth it was my old set of tires as right after I had them put on I didn't notice a vibration but now that it has gotten colder I notice it not as bad as it was before the new tires I was thinking it may be the shocks but now I may have to have the trany looked at after reading this thread.

 

Just got back from the Ford garage. My torque converter is bad. Because of my warranty, they are replacing the entire transmission.

 

I done a test today and it seems it is the trany deal not the shocks after all.

 

Yo Doc,

At least you were under warranty. Had that problem at about
40,000 miles too. Dealer said Torque Converter, I said no thank
you to 900 $$$$$$$$ replacement, Warranty gone!

Found tranny guru in area, suggested changing fluid first, going
from Mercon to "slippery" Dextron. Took away that annoying
mid throttle vibration.

Been back to Mercon since because Tranny calls for fliud change
every 30,000 miles for my 4R70. about 91,000 miles on it now
and no problems since, same Converter going strong.

Keep in mind when warranties over, just change the fluid, and
make sure to drain the converter as well.

Happy New Year to All
Cantpay

 

The most common cause of the rumble strip vibration is worn out transmission fluid. Change the fluid using MERCON V and it usually will go away.

I have seen a few vehicles that had bad plug wires that also had the rumble strip vibration. My brother-in-law's '92 Grand Marquis (4.6L/AODE trans) had the rumble. We changed the fluid and it still did it. New plug wires fixed it.

Mark

 

One common mistake is we confuse Mercon from Mercon V which the 4R70 calls for. Putting "Mercon only" can cause these trannies to shudder as the additive to make is more slippery in Mercon V is missing. Drain you ATF and put Mercon V and it should fix it. By the way, Mercon V is also semi-symthetic. Hope this helps.

 

Mercon and Mercon V are not interchangable. There can be some confusion about what to use because Ford changed the specifications for the 4R70W Automatic in 1998.

Ford specifically states that using Mercon V in a transmission requiring Mercon may cause internal damage.



You may want to look into using Amsoil or Redline Synthetic. Neither one will cause a problem.

 

I had this problem too - the Ford mech. knew exactly the problem - torque converter - swapped - problem fixed. (and it was under warranty).