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Mr Richter I humbly ask for your expertise...

10437 Views 93 Replies 22 Participants Last post by  Dysfunctional
My trans temps have gone WAY up in the last two weeks. Prior to this, the highest temp I've ever seen was 180* driving like a PRICK on a 118* day over the crooked and steep mountain road I drive daily. Today I hit 230* in the morning with outside temps in the 50's :poke:

Tonight I came home, hooked up a snap-on MODIS I'm borrowing from a friend and went for a test drive. Trans temps with the scanner are +/- 10* of what my autometer gauge says, I even got it up to 240* with ambient in the high 90's. You can monitor alot with this scanner, but I just locked in trans temp, TCC%, TorqueConverterClutch (on/off) and gear. When I LUGGED it on hills with TC locked in 3rd, TCC% shows 100%. A downshift, TCC% drops to about 60% momentarily (this seems ok). If I climb a grade with 2nd gear manually selected, the TC never locks according to the scanner (TCC shows OFF the entire time to any MPH) and my temps rise FAST.

IMO something is wrong... My temps are sky high out of nowhere. So the other weekend I bypassed the bypass valve on the trans by removing it and adding fittings to adapt back to the threads in the trans. After that temps seemed lower and stayed in check a few days.

When I got back tonight and my trans temp was 240*!!! I started feeling the cooler lines and I didn't not burn myself. Seems to me with fluid that hot I should have 2nd degree burns on my hands right?

Tomorrow I'm going to my friends shop to have the transmission flushed with a machine, 10 times if necessary.

Short version of this babble... I'm thinking I have a blockage...? :swordfight:
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This is for all of you to understand how the trans works. Ford had installed the bypass before the superduty. Yes It will open if the cooler becomesplugged.But if your cooler is plugged then the trans has already failed! Ford used the bypass on the superduty to warm the fluid up on the early years with no rad coolers. I have seen a lot of posts about not using rad cooling. You must use engine temp to bring trans fluid to operating temp. The more even the trans fluid stays the longer the life of the trans.


The bypass is not there to warm the fluid. It is there to provide lubricant to the rear of the transmission in case there is a flow restriction thru the coolers, for whatever reason.

The radiator cooler is not there to bring the fluid to operating temp. It is there to cool the fluid.
and you know this how?? you build trannies now too? still wondering what you HAVE done.
Your concern is out of focus. You shouldn't focus on someone who doesn't build transmissions yet understands a couple of simple features about them. I'd be more concerned about those that do build them yet don't understand those simple things.
So, noted on my 99.5 that it has the OTA cooler and the radiator has the OTW cooler, but it was never hooked up. Was this factory or did someone disconnect this earlier in its life?
The radiator has been changed using a later model radiator. They didn't have both coolers from the factory until about March 2000.
So, when I upgrade to a larger OTA cooler, it would be beneficial to run thru the radiator and remove the by-pass? Or leave it be?
Has the radiator cooler been sealed or left open? Even though I can count the number of radiator cooler failures I've seen on one hand, I do get some satisfaction from knowing that the trans fluid can't get into the coolant. But if it was clean I'd use it. I'd also leave the bypass on it.
Hey if you want to believe the cooler in the bottom of the radiator is there to bring the trans fluid up to operating temp, that's fine with me.
i want to believe that someone who has over 300 high performance transmissions with an impeccable reputation knows more about the simple things than you. nice dodge on answering simple questions though.
I've had times when I wanted to believe things that weren't correct too. But the feelings will pass. What simple question did I dodge?
Didn't realize that was a real question. I thought it was an attempt to be supercilious. But since it's a real question, I drive and have driven one but not very often. BTW I thought we were talking about transmission coolers.
exactly. you've done nothing except type. maybe go out and live a little. back to the original thread...

p.s. could we at least get a pic of your rig?
And yet I know how a few things work, how they really work. A picture? My truck looks like an F-250. Not much you will learn from a picture. You act like you think I'm trying to prove something or impress someone like you are trying to do. I'm not trying to do either. I'm simply providing the correct info. You can do whatever you want with that info.

But just for the record, what do you think the cooler in the bottom of the radiator is for? To cool the fluid, or to raise the fluid to operating temp.
Here's an original idea, put a temp sender in the bottom of the radiator and another one in the converter out line.
You obviously didn't read my post.

The bypass almost caused complete distruction on the trans I was talking about, and this was a brand new bypass unit!
I read it. You say it almost ruined your transmission because it didn't bypass enough fluid. Then you say toss it.

The only way it will do more damage than not having one is if it bypasses too much fluid.
I thought it was there in case of a cooler restriction. Why didn't it work?
I don't know why it didn't work. Do you still have it? If you do take it apart and look at it.

You were right. I shouldn't have been such a jerk.

: IIRC the bypass was added to the 4R100 to solve a problem, maybe when they went to the OTA/OTW combo coolers ... again a complete WAG
Vehicles that have only an OTA cooler have them too.
Aint that right 444? :rockwoot:
That sums it up pretty well. Especially the crotchety old bastard part.
ed- can you give us any background into who u are or what u do? that would be a nice change from the other site...breaks the monotiny of anonimity...
I thought it was well known on that other site that I've spent the last 40 years involved in some facet of vehicle repair.

As it pertains to this thread, I have never overhauled a 4r100. I haven't done an auto of any kind in probably 20 years. But the 20 years prior to that I probably did more than 300 of them. That would only be about 1 per month, I'm sure I averaged more than that. That wasn't just one type of trans but a variety of mfg. However they all had one thing in common, a cooler in the radiator.

You take your pick of vehicles that have only an OTW cooler in the radiator. Now disconnect both lines from the radiator and connect them together with a rubber hose. I don't think you have to have any experience in auto repair to understand your fluid is not going to stay too cool.
I thought that was Kan man...... :hehe:
You might be half right, Kanman isn't old and isn't in Oklahoma. But half right will raise your average.
in my best imitation of Dr. Suise...

"that 444-d, that 444-d, I do not like that 444-d..."
Don't expect you to. It would be tough for you to like anyone who has the facts straight. You can't even get the user name right.
I got to ask...

How do you walk with a head that big? You must fall over alot right? Do you have your truck modded to fit a head that big? Do you have to go thru the garage door to get in the house? Or can you still use the slider?
The biggest heads,such as yours, are the ones overloaded with a bunch of phony inaccurate BS. I only care about the facts regardless of what they are or who they offend. I know it's hard for you to understand.
*mod hat on*

You boys be nice....
That's asking a lot from a bigheaded typist.
So should I re-install the bypass valve or not?
At temps above zero your cooler will not quit flowing because your fluid is too cold.
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