Automatic transmission thunp problem on lock-out
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New User
Joined: Jan 2004
Posts: 3
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From: Olympia, WA
Automatic transmission thunp problem on lock-out
I have a 1999 Ranger Supercab 4x4 4.0L with the 5 speed automatic transmission. I purchased it used and I'm noticing what a percieve may be a problem. At around 45mph the transmission "locks out" into overdrive. If I give slightly more gas the engine sounds almost as if it is borderline lugging. Anyway, If I let of the accelerator while it is doing this a light jolt accompanied by an audible thump results. I have serviced the transmission (pan drain and filter) and cleaned the MAF sensor. Any idea as to why it is behaving like this? I suspect something wiht the electronics. Any help would be appreciated.
Post Fiend
Joined: Jan 2003
Posts: 9,748
Likes: 16
From: Connecticut
Hi taz, welcome to FTE!
I'm not much on trannies, but it sounds like yours might have a problem with the torque convertor improperly locking/unlocking.
Did you make sure to use a Mercon V-rated ATF and nothing else when you dropped the pan and changed the fluid? It is imperative that your tranny have only Mercon V in there.
Also, keep in mind that the dropping-the-pan method only gets about 1/3-1/2 of the old fluid out ...the only way to change all the fluid is to have a flush done.
I'm not much on trannies, but it sounds like yours might have a problem with the torque convertor improperly locking/unlocking.
Did you make sure to use a Mercon V-rated ATF and nothing else when you dropped the pan and changed the fluid? It is imperative that your tranny have only Mercon V in there.
Also, keep in mind that the dropping-the-pan method only gets about 1/3-1/2 of the old fluid out ...the only way to change all the fluid is to have a flush done.
Logistics Pro
Joined: Sep 2002
Posts: 4,410
Likes: 1,016
From: Central KY
The symptoms he is describing are a "normal" feature of the 5-speed tranny in my opinion. I am not saying that they SHOULD do that, but it seems that they all do. I have owned two of them now, and both of them behave exactly as you indicated.
Sometimes I wish Ford had just stuck with a traditional 4-speed automatic. Those don't seem to be constantly searching for a gear like these 5-speeds do. One thing you can do to help it a little is let your Ford dealer perform a "powerflush" on the transmission in which they flush out all the junk and refill it all with fresh fluid. This is different than a typical drain and fill.
Sometimes I wish Ford had just stuck with a traditional 4-speed automatic. Those don't seem to be constantly searching for a gear like these 5-speeds do. One thing you can do to help it a little is let your Ford dealer perform a "powerflush" on the transmission in which they flush out all the junk and refill it all with fresh fluid. This is different than a typical drain and fill.
New User
Joined: Apr 2004
Posts: 2
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Hi Taz,
My 99 Ranger had the same problem, along with a slip from 2-3. After several trips to the dealer, to no avail, I found a thread on here that mentioned a gasket problem with these trannys. Anyway, I mention that to the Ford mechanic and he immediately jumped on the Tourque converter gasket! He said he has replaced lots of these on Rangers and Explorers, same drivetrain, with very good success. So, with that, I had him replace mine, about $500, and the problem is all but gone.
My 99 Ranger had the same problem, along with a slip from 2-3. After several trips to the dealer, to no avail, I found a thread on here that mentioned a gasket problem with these trannys. Anyway, I mention that to the Ford mechanic and he immediately jumped on the Tourque converter gasket! He said he has replaced lots of these on Rangers and Explorers, same drivetrain, with very good success. So, with that, I had him replace mine, about $500, and the problem is all but gone.
