high tranny temps
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,740
Likes: 2,669
From: SE Florida
Don't block the bypass. If there is a restriction and you don't have a bypass the rear of the trans won't get any lube and the trans will fail instead of run hot. It's more likely that you have a restriction in the cooler circuit than you have a failed bypass valve.
Posting Guru
Joined: Sep 2005
Posts: 2,476
Likes: 2
From: Monroe Michigan
Don't block the bypass. If there is a restriction and you don't have a bypass the rear of the trans won't get any lube and the trans will fail instead of run hot. It's more likely that you have a restriction in the cooler circuit than you have a failed bypass valve.
Elder User
Joined: Aug 2007
Posts: 502
Likes: 0
Travis was talking about the spacers in the lower right hand picture.Those who didn't want to braze up there own could buy spacers from john wood. Read the acticalFord Super Duty 4R100 Tranny Bypass Line Photo
Thread Starter
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Senior User
Joined: Sep 2006
Posts: 357
Likes: 0
From: Kailua Hawaii
Thanks for all the help. NAPA didnt have the part but I wasn't really expecting them to so I called the dealer and they will order it tomorrow and it should be here by Mon or Tues. More expensive than I expected, $74, Oh well price you gotta pay out here. Thanks again
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,740
Likes: 2,669
From: SE Florida
After you put it on you need to run a flow test on the coolers.
Warm the trans up first. That will take a minimum of 10 miles of city type driving.
Have two buckets under the truck. Disconnect the cooler line at the rear of the trans. Put the line in one of the buckets. Have someone start the engine, and as soon as the flow is steady put the line in the second bucket for exactly 15 seconds, then put the line back in the first bucket and shut the engine off.
If you have at least one quart in the second bucket the flow is fine. I suspect you'll have fluid spraying out of the open port on the trans where you disconnected the line, which means either the coolers or cooler lines are restricted, or the new bypass is also bad.
Warm the trans up first. That will take a minimum of 10 miles of city type driving.
Have two buckets under the truck. Disconnect the cooler line at the rear of the trans. Put the line in one of the buckets. Have someone start the engine, and as soon as the flow is steady put the line in the second bucket for exactly 15 seconds, then put the line back in the first bucket and shut the engine off.
If you have at least one quart in the second bucket the flow is fine. I suspect you'll have fluid spraying out of the open port on the trans where you disconnected the line, which means either the coolers or cooler lines are restricted, or the new bypass is also bad.
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Elder User
Joined: May 2002
Posts: 858
Likes: 0
From: Robbinsville NJ
Thanks for all the help. NAPA didnt have the part but I wasn't really expecting them to so I called the dealer and they will order it tomorrow and it should be here by Mon or Tues. More expensive than I expected, $74, Oh well price you gotta pay out here. Thanks again
I bought one this summer from a local Ford dealer. I think it was about $55, took me 30 minutes to install / cleanup and only lost a few drops of fluid.
