Tranny overheating :)

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Jan 12, 2011 | 06:50 AM

#16

Ponyboychris

Lead Driver

Joined: Jan 2007

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From: Kiowa CO

Quote:

Originally Posted by Billyclub

So I understand you. Your saying that if The original transmission is replaced then a new bypass must be installed. Was the bypass in the old transmission inside the transmission and nothing that can be seen without tearing into the tranny. I've poked around under the truck and don't see anything that resembles a bypass. If the new HD4R100 doesn't have one I should probably install the one that came with the Tru-Cool. What you think?

The factory bypass is on the passenger side of the tranny. Look to where the two lines coming to and from the cooler and into the body. You will see the steel line that runs along the tranny body. That's the bypass line.

Jan 12, 2011 | 07:04 AM

#17

psd76

Freshman User

Joined: Nov 2006

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My truck is an 03, it has a bypass valve on the passenger side of the tranny. My tranny was running in the 210 degree range so i put a 6.0 tranny cooler in and it brought the temps down to about 160-180 degrees. I did more research on tranny temps on another forum site and learned that this bypass vale could possibly go bad and contribute to high tranny temps. So i replaced the bypass valve and now i see temps no higher than 160 degrees during the summer heat. Im not a mechanic just learning as much info from these forum sites as i can so far it has worked well for me and the setup im running on my truck. Not sure if that helps. Im guessing if thats a ford tranny it already has the bypass valve on it

Jan 12, 2011 | 07:30 AM

#18

Billyclub

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Joined: Apr 2006

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I may be mistaken but the bypass tube that is on the passenger side of the trans. is pressure regulated and not temp. I've read that the bypass tube opens in case the line to the cooler gets plugged. the pressure increases and opens the spring gate valve in the tube and allows transmission fluid to continue to circulate. They're maybe a temp related valve in there but I'm not aware of one.

Jan 12, 2011 | 08:05 AM

#19

psd76

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Joined: Nov 2006

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You are probably right, its not temp related but if that check valve gets buggered up somehow from debris or fails from cold temps or something, the fliud bypasses the cooler and and just goes back into lubrication circulation. Hot is better than nothing i guess.

Jan 12, 2011 | 02:28 PM

#20

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

Posts: 24,739

Likes: 2,669

From: SE Florida

There is no temperature related valve in a 4R100. The bypass is on the passenger's side of the transmission. It is inside the tube that is between the two cooler lines.

Jan 12, 2011 | 08:50 PM

#21

Firefighter 1406

Thread Starter

Lead Driver

Joined: Mar 2004

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From: Northern Indiana

Alright, I bought a cooler from the parts house and went to install it on my truck. Come to find out I already have a quite large tranny cooler installed on my truck. So now I have a truck with a extra cooler that is still getting too hot.

so could the cooler be clogged? Could that little small filter that ford put on when they changed the tranny be clogged? Would a power flush be helpful? Any help?

Jan 13, 2011 | 03:05 AM

#22

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

Posts: 24,739

Likes: 2,669

From: SE Florida

Quote:

Originally Posted by Firefighter 1406

so could the cooler be clogged?

Yes.

Quote:

Originally Posted by Firefighter 1406

Could that little small filter that ford put on when they changed the tranny be clogged?

Yes.

Quote:

Originally Posted by Firefighter 1406

Would a power flush be helpful? Any help?

Maybe. I'm not sure what a power flush is. I've never seen a power flush machine. I have seen fluid exchange machines, but they don't power flush. I don't know how one would power flush a transmission.

Jan 13, 2011 | 09:13 AM

#23

damicofuel

Senior User

Joined: Dec 2009

Posts: 438

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From: Columbus, Ohio

when I was fleshing system out by unhooking return line(rear line) I gor a lot of fluid comming out of rear port on transmission. Replaced bypass valve assembly and very little fluid came out of rear port and now transmission runs about 60 degrees cooler! I would replace bypass and blow out cooler.