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Discussion Starter #1
What could cause a 4r100 to run abnormally hot all of a sudden? I can hit 200-215* on a 20 minute drive into town, now it is hot here with temps hitting triple digits mid day but i used to barely hit 190 on the same trip a month ago.

Bad cooler?
Stopped up lines?
Internal issues?

Im not looking for "Oh just throw a 6.0 or trucool on it", I know how to keep it cool, i want to know why it just started running hotter than normal "overnight"

I may just take it in to the shop that rebuilt it and take full advantage of my warranty :D
 

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A Ghost these days...
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Might try a flush and filter change.... When is the last time that it had one?

Can you feel your converter slipping? That will definatly cause it to heat up.
 

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"Smoke A Lil Smoke"
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I am willing to bet your tranny cooler crossover line is not opening and letting oil through to the cooler.check this test out to check it.
from thediesel site
Detailed Description
The Ford R4100 automatic transmission has this device installed on the passenger side between the two cooler lines. It's designed to bypass the cooler when fluid temps are cold to aid in quicker warming to operating temps. It will also bypass fluid if the coolers are blocking flow for any reason. This device can fail at some time. If you find yourself having higher than normal operating temps or temps climbing out of control while your towing, chances are this little device is your problem. It's an easy install. It takes about 20 minutes and you lose very little transmission fluid. See below how to tell if this is your problem.

*****Important Note: We get questions from time to time about the validity of removing this device to eliminate having the replace it from time to time. This is FOOLISH! While it may be an inconvenience that it failed, the worst thing that it cost you is a little time, a new valve and new fluid. If you removed it and the cooler were blocked, you'd lose the transmission in a matter of seconds.





Q: How do I tell if my bypass valve is faulty?



Read the following answer as how to test the coolers and bypass valves.

A: IMPORTANT! The temps should be measured in the pressure port in the driver side of the transmission body. If you are measuring temps from a tee in the output line, temps will read about 30 degrees hotter than temps read from the pressure port.

TESTING:

Bring the transmission up to temperature. It needs to be at least 100 degrees for this test.
Turn the truck off.
Remove the rear line from the transmission and place it into a bucket or similar container so that you can measure volume of your flow.
Have someone turn the truck on.
At idle (in park), you should measure 32 ounces of fluid in your bucket - in 15 seconds or less. This is an absolute minimum number. A properly working transmission will flow that amount in about 10 seconds or less. You should not see ANY fluid pumping out of the rear transmission port.
TEST RESULTS:

If you have the proper amount of flow, your transmission pump and coolers are working fine. SO, if you are running hot and have the proper flow (with no fluid coming out of the rear transmission port), you most likely have a mechanical problem causing high heat. This could be torque converter slippage or one of many other internal problems. You may have to see a professional at this point to help diagnose the problem.
If you do not have proper flow, OR you have fluid coming out of the transmission rear port, you either have a cooler blockage, OR a faulty cooler bypass valve. Here's how to tell.
Trace the forward transmission line to the front of the truck.
Remove the line from the 1st place it enters a cooler or the radiator (if so equipped).
Now, do the same flow test checking flow at this point.
There are two outcomes.
The first is that you now have enough fluid flow- this means your cooler /coolers are partially blocked. To determine which cooler is plugged you would perform the same flow test through one cooler at a time.
The second outcome will be that you don't have enough flow even with all coolers disconnected. This means you have an internal pump problem.
IMPORTANT! The outcome of this test assumes that you have NO fluid exiting the rear port of the transmission. If you perform a flow test with the coolers disconnected and you get fluid from the rear port on the transmission, your cooler bypass valve is bad.

 

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28 cent #2
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If you have a warranty I'd take it to the builder and let them have at it. As you said might as well take advantage of the warranty while you have it.
 

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Former Ford Trans Engr.
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I am willing to bet your tranny cooler crossover line is not opening and letting oil through to the cooler.check this test out to check it.
It needs to be closed to send fluid to the cooler. When it's open fluid bypasses the cooler.

It's designed to bypass the cooler when fluid temps are cold to aid in quicker warming to operating temps. It will also bypass fluid if the coolers are blocking flow for any reason........

If you perform a flow test with the coolers disconnected and you get fluid from the rear port on the transmission, your cooler bypass valve is bad.
The bypass DOES NOT aid in warming up the trans. It's sole purpose is to maintain flow to the lubrication circuit in the rear half of the trans if there is a restriction in the cooler circuit.

If you get fluid from the rear port during this test it is possible that the bypass is stuck open. It is more likely that there is a restriction in the cooler circuit causing the bypass to open.
 

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"Smoke A Lil Smoke"
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thats all from Bob at dieselsite.com So your saying Bob is wrong and doesn't know what he is talking about?And if it takes over 100 degrees to open then I would assume it is because of temps as stated .If that was the case it wouldn't need to wait to open when trans is up to temp.And FYI I did the delete of mine per John woods instructions years ago.John aslo said it was for helping the temps get up to operating quicker.
 

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Discussion Starter #10
Might try a flush and filter change.... When is the last time that it had one?

Can you feel your converter slipping? That will definatly cause it to heat up.
I will be flushing it sometime in the next 2 weeks. Is mercon all that can be used? Nothing off the "aftermarket" any better?

I manually lock my converter 90% of the time, when i dont it still locks just fine, no slipping
 

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Discussion Starter #11
thats all from Bob at dieselsite.com So your saying Bob is wrong and doesn't know what he is talking about?And if it takes over 100 degrees to open then I would assume it is because of temps as stated .If that was the case it wouldn't need to wait to open when trans is up to temp.And FYI I did the delete of mine per John woods instructions years ago.John aslo said it was for helping the temps get up to operating quicker.
The guys a Former Ford Tranny Engineer, he prolly knows his chit:poke:

Bob does too though:D
 

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"Smoke A Lil Smoke"
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Enineers are the worst.Only they can take a perfectly good object and screw it up.Look at all the stock trannys for instance that get rebuilt properly by john woods and bts. there ideas (screw ups) are endless.And because they designed it doesn't meen they know how it works. :poke:
 

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"Smoke A Lil Smoke"
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Caption This
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If you want to know the way stuff really works, don't believe everything you read on the dieselsite website.
 

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Discussion Starter #15
If you want to know the way stuff really works, don't believe everything you read on the dieselsite website.
My remark was made on the assumption that most of you can pick up on sarcasam:poke:
 

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Former Ford Trans Engr.
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thats all from Bob at dieselsite.com So your saying Bob is wrong and doesn't know what he is talking about?
That's exactly what I'm saying.

And if it takes over 100 degrees to open then I would assume it is because of temps as stated .If that was the case it wouldn't need to wait to open when trans is up to temp.
There is nothing in the bypass that detects temperature. All it can detect is pressure. If the pressure in the cooler line is too high it overcomes the spring pressure and pushes the ball off the seat. That allows fluid to flow through the bypass instead of going to the cooler.

And FYI I did the delete of mine per John woods instructions years ago.John aslo said it was for helping the temps get up to operating quicker.
Then he's wrong, too. I was there when it was designed. I know why it was installed on the trans and how it works. They're wrong.
 

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Former Ford Trans Engr.
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I will be flushing it sometime in the next 2 weeks. Is mercon all that can be used? Nothing off the "aftermarket" any better?
You can use MERCON V. I prefer Mobil 1 synthetic ATF. It has a MERCON V rating.
 

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Discussion Starter #18
Thanks
 

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Caption This
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John aslo said it was for helping the temps get up to operating quicker.
John also said the cooler in the bottom of the radiator warmed the fluid.
 
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