TRANSMISSION OR TORQ CONV?
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More Turbo
Joined: Feb 2004
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From: Findlay, Il
TRANSMISSION OR TORQ CONV?
New to me 2003 7.3 PSD A/T 150K. The problem; when I put the transmission in gear, the rpm will drop some and then all of a sudden the transmission will grab a hold and take off (better have foot on the brake or it will get up and go). Does this in D or R. Also, when coming to a stop, sometimes, the trans will downshift fine, then while sitting, it will lock up and do the same as described. Trans fluid is full and cherry red. I installed a new trans oil cooler(the big one, dorman) this summer. Noticing also, that it is take the trans quit a while to come to operating temp, comparing this to my other trucks. (Six miles to one mile). This problem didn't show up until this cold weather started. Problem exists whither trans is up to op temps or cold. So the question is, what's happening?
Posting Guru
Joined: May 2006
Posts: 1,427
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From: Bryson City NC
I am not a trans guru by no means !
smarter guys here for sure. But sounds like TC locking up but thats me! As far as your trans temps go if you put on a bigger cooler it will most likely read cooler both summer and winter. In winter mine runs very cool and unless I load it will stay cool. Cooler doing its job!
Smokie
smarter guys here for sure. But sounds like TC locking up but thats me! As far as your trans temps go if you put on a bigger cooler it will most likely read cooler both summer and winter. In winter mine runs very cool and unless I load it will stay cool. Cooler doing its job!Smokie
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,722
Likes: 2,648
From: SE Florida
I suspect the torque converter clutch is drifting on. This will happen is line pressure dips.
Get a 0-350 PSI gauge with a 1/8" NPT thread. Put it in the test port on the driver's side of the trans, towards the front of the trans, just above the pan. There is a black hex head plug in there from the factory.
Record pressures in P, R, N, D, 2, and 1 at idle, and R, D, 2, and 1 at WOT with the truck held against the brakes. DO NOT HOLD WOT FOR MORE THAN 5 SECONDS. Then idle in park for at least 10 seconds before going to the next position.
Get a 0-350 PSI gauge with a 1/8" NPT thread. Put it in the test port on the driver's side of the trans, towards the front of the trans, just above the pan. There is a black hex head plug in there from the factory.
Record pressures in P, R, N, D, 2, and 1 at idle, and R, D, 2, and 1 at WOT with the truck held against the brakes. DO NOT HOLD WOT FOR MORE THAN 5 SECONDS. Then idle in park for at least 10 seconds before going to the next position.
Senior User
Joined: Nov 2004
Posts: 101
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I had one where the pump was wearing to the point that the jackets were bleeding one to another causing a similar symptom. Mine however, only did this in reverse while applying throttle. When a little bit of throttle was applied, it would in essence force fluid in the lock-up jacket, and at such a low speed the engine would die, or at least stumble.
Thread Starter
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More Turbo
Joined: Feb 2004
Posts: 509
Likes: 3
From: Findlay, Il
I suspect the torque converter clutch is drifting on. This will happen is line pressure dips.
Get a 0-350 PSI gauge with a 1/8" NPT thread. Put it in the test port on the driver's side of the trans, towards the front of the trans, just above the pan. There is a black hex head plug in there from the factory.
Record pressures in P, R, N, D, 2, and 1 at idle, and R, D, 2, and 1 at WOT with the truck held against the brakes. DO NOT HOLD WOT FOR MORE THAN 5 SECONDS. Then idle in park for at least 10 seconds before going to the next position.
Get a 0-350 PSI gauge with a 1/8" NPT thread. Put it in the test port on the driver's side of the trans, towards the front of the trans, just above the pan. There is a black hex head plug in there from the factory.
Record pressures in P, R, N, D, 2, and 1 at idle, and R, D, 2, and 1 at WOT with the truck held against the brakes. DO NOT HOLD WOT FOR MORE THAN 5 SECONDS. Then idle in park for at least 10 seconds before going to the next position.
This problem is a lot worst in R than in D.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,722
Likes: 2,648
From: SE Florida
The problem is always worse in reverse. Reverse has a high pressure requirement, so the pump works harder. A weak pump can't keep up.
If the pump is bad the trans has to come out.
If the pump is bad the trans has to come out.
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More Turbo
Joined: Feb 2004
Posts: 509
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From: Findlay, Il
The apparent fix: installed new cooler this past summer, since cold weather, apparently the connections loosened, allowing the pressure to back off enough to engage torque converter. Also, had lost a little fluid.
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