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Discussion Starter #1
Hello All,


New to the forum, but have been lurking and researching here since I bought my '02 F250 SRW 7.3. I am hoping that some of the folks here can provide some additional insight into the issue that I am seeing.


To start, I have an '02 7.3 F250 with 256k on it and it is essentially stock other than the Superchips 1805 programmer installed. I had the transmission rebuilt at 165k and the shop installed a higher stall torque converter (2800 rpm). I had the transmission rebuilt again at 254k (March of this year) using the same converter. I do not tow anymore (used to tow 20ft trailer and Jeep), but see no reason to get rid of the truck as it is paid for and has plenty of life left in it.


Historically the stock in dash gauge (no after market gauges installed) has rarely ever moved from dead center. After the initial rebuild the only time it went up was long trips at higher mph (usually when carrying ATV in bed). Since the second rebuild earlier this year, I have seen the gauge climb more frequently after driving for about 45 min and when in slower traffic. I have not noticed any slipping or other issues and have not thrown any codes. For perspective, I do live in Florida and the temps have been in the mid to upper 90s lately.



I have recently upgraded the stock cooler to the Mishimoto 6.0/7.3 37 row cooler. I have since performed a flow test with mixed results. The first test blew ATF out the hole where the rear line was attached. I then installed the bypass delete kit to the front line, eliminating the bypass as a variable. I tested again and the flow was solid and quick from the input line to the transmission, with nothing exiting the transmission itself. This leads me to believe the bypass valve was the culprit and that the coolant flow is not an issue. I rebuilt the bypass valve today using the Sonnex rebuild kit and plan to test it again tomorrow. My intention is to keep the bypass in place once I resolve the heating issue. The ATF is still a nice light pink color on the dipstick.


I have also checked for leaks and do not see any and the fluid level appears correct. I added two quarts after installing the new cooler and coolant flow test. One for lost fluid and one for the additional capacity of the new cooler (per Mishimoto specs).


To date the factory dash gauge has gotten to yellow, but not red. Based upon what I have read, that is in the 200-225 range and I should be running less with the new cooler. From what I have read, with the new cooler I should be seeing 60-90 degrees above ambient (so up to 190 would seem appropriate given recent temps here in North FL???).



Questions at the moment

1) Should the front banjo bolt should also be replaced at the same time?
2) If after rebuilding the bypass valve I see the same results with flow test, what else should I investigate?
3) Should I install an electric fan in front of the condenser to force more air toward the cooler?
4) Why would the dash gauge all of a sudden be more responsive?



Thanks in advance for any input or direction that will help in figuring this out.
 

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[QUOTE=itsnunyabzns;4664434








Historically the stock in dash gauge (no after market gauges installed) has rarely ever moved from dead center. After the initial rebuild the only time it went up was long trips at higher mph (usually when carrying ATV in bed). Since the second rebuild earlier this year, I have seen the gauge climb more frequently after driving for about 45 min and when in slower traffic. I have not noticed any slipping or other issues and have not thrown any codes. For perspective, I do live in Florida and the temps have been in the mid to upper 90s lately.





Welcome to the forum. I too had a by-pass that I had to rebuild (discovered while following Marks’ write up for 4R100 Flush/Fill). With the lines apart I blew low pressure air (10psi) through the supply line, OTW cooler in the radiator, stock OTA cooler, and out return to be sure there were no blockages (advice from this group). With no problems found, then replaced OTA cooler with the Mishimoto 6.0/7.3 cooler, and added a A/T Temperature Gauge. I don’t believe I would rely on the in dash gauge for any degree of accuracy. Also, those assumed A/T temps do not seem normal even with ambient temps in the upper 90’s. I’ve seen no increase of over 160* driving 4 hours in the same temps as you mention with a light tow. I’m sure more experienced members will be along shortly with some advice. Good Luck.
 

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Not sure why anyone would want a 2800 rpm stall converter for towing...it's usually a lower stall to get the boost built sooner. You are almost out of the power band stalling that high.
And yeah, get a real gage.
 

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I had the transmission rebuilt at 165k and the shop installed a higher stall torque converter (2800 rpm).
That was a mistake. A lower stall converter is MUCH better. In my opinion the stock converter stalls too high for this engine.

I had the transmission rebuilt again at 254k (March of this year) using the same converter.
That was a BIG mistake unless they cut the converter open and cleaned it out.

Historically the stock in dash gauge (no after market gauges installed) has rarely ever moved from dead center.
The stock gauge will stay dead center when the transmission is warmer than 50°F and colder than 230°F. It won't move at all if the temps are in that range.
 

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Discussion Starter #5
That was a mistake. A lower stall converter is MUCH better. In my opinion the stock converter stalls too high for this engine.


That was a BIG mistake unless they cut the converter open and cleaned it out.

So, given the predicament I am in, aside from another complete rebuild replacing the TC with a lower stall, is there anything I can do in the interim to help keep the temp down? I was not aware of the TC stall recommendations for Diesels at the time of the rebuild and took the shop at their word (obviously a mistake on my part).





The stock gauge will stay dead center when the transmission is warmer than 50°F and colder than 230°F. It won't move at all if the temps are in that range.

I was basing the temps for the stock gauge on an old post here from SmokeyWren in 2001. Are you saying that if it is getting to the yellow that it is well above the 230 range?



If it has in fact ran well above 230, would draining and replacing with synthetic help?



Any thoughts on the front banjo bolt replacement for the bypass valve ($20 if ordered through local Ford dealership)? I have already rebuilt the valve itself.
 

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So, given the predicament I am in, aside from another complete rebuild replacing the TC with a lower stall, is there anything I can do in the interim to help keep the temp down? I was not aware of the TC stall recommendations for Diesels at the time of the rebuild and took the shop at their word (obviously a mistake on my part).
A lower stall will produce much less heat when the converter is unlocked. When locked it doesn't make any difference.

I was basing the temps for the stock gauge on an old post here from SmokeyWren in 2001. Are you saying that if it is getting to the yellow that it is well above the 230 range?
It moves into the yellow at 230°F. It moves to red at 260°F. When in the yellow all you can tell is that it is warmer than 230 and cooler than 260.

If it has in fact ran well above 230, would draining and replacing with synthetic help?
It will, a little. It won't make a big difference.

Any thoughts on the front banjo bolt replacement for the bypass valve ($20 if ordered through local Ford dealership)? I have already rebuilt the valve itself.
My SWAG is that your bypass is opening, reducing the flow to the coolers. I don't know if a new banjo will help or not.
 

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Discussion Starter #7
My SWAG is that your bypass is opening, reducing the flow to the coolers. I don't know if a new banjo will help or not.
Flow test with bypass in place fails with it open and fluid exiting side of transmission. It is still heating up after 45 min or so with the bypass delete in place.

At this point I am debating whether I should try adding a fan in front of the condenser to force more air or just take it back to the shop and demand that they investigate why it is overheating when the flow test is more than sufficient. I would like to tell them to just install a lower stall converter, but I doubt they will do that under the warranty (12mo/12k from 3/19). I was not having these consistent heating/cooling issues until the rebuild in March.

What is the likelihood that the issue is reusing the 2800 stall converter with debris from prior trans failure and that changing the TC would solve the issue?

I realize that after hitting yellow on the factory gauge a couple times that the fluid should probably be replaced, but need to fix the root cause in the process.
 

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Flow test with bypass in place fails with it open and fluid exiting side of transmission. It is still heating up after 45 min or so with the bypass delete in place.
This points towards a restricted cooler circuit. A pinched cooler line or a partially plugged cooler.

At this point I am debating whether I should try adding a fan in front of the condenser to force more air
That will probably make a very small difference. I don't think there is enough fluid flowing through the cooler.

What is the likelihood that the issue is reusing the 2800 stall converter with debris from prior trans failure and that changing the TC would solve the issue?
Almost zero.

I realize that after hitting yellow on the factory gauge a couple times that the fluid should probably be replaced, but need to fix the root cause in the process.
Why should it be replaced? That's within it's operating range.
 

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Discussion Starter #10 (Edited)
With the fact the flow test was strong with the delete in place, I did not consider the OTW via radiator as a problem.


As for fluid, I figured that since it was reaching into the 230+ range it should be replaced since I read above 225 was damaging fluid.
 

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It's probably worthwhile to run a cooler flow test.

Warm the trans up. It should be at least 150°F.
Have two containers, each at least one gallon.
Get a hose that will fit over the cooler return line at the rear of the trans.
Remove the return line where it enters the rear of the trans.
Put the hose on the return line and put it into container #1.
Have a helper start the engine and leave it in park and at idle.
When the flow is steady out of the hose (that should only take a few seconds) move the hose to container #2 for EXACTLY 15 seconds, then put it back in container #1.
Shut the engine off.

Results:
If fluid sprayed out of the transmission, the test fails. A small dribble is fine, but spraying is not.
If there is less than a quart in container #2 the test fails.

If the test fails either the cooler bypass valve is stuck open or there is a restriction in the cooler circuit.

It doesn't destroy the fluid to be hotter than 225°F. That's an internet myth that just won't die.
 

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Discussion Starter #12
Apologies for the late follow up on the thread, work travel and such has kept me busy and unable to tend to the truck.


Coolant test was successful with Bypass Delete in place, with more than 1 qt of fluid in the 15sec time frame. Temp still rises after about 30-45 min driving time on interstate or city streets.



After further thought about other occurrences/symptoms, I am looking to replace the TC. I have talked to the shop and they will check the seals and such when they drop the transmission to inspect it.

Symptoms:
- Temp rising at higher speeds (85-90mph) for long periods of time (2+ hrs) at ~2200rpm (this was occurring periodically since the rebuild in 2010 when 2800 stall TC was installed, TC was kept after March rebuild as well)
- Stalling in Reverse and Manual 1st after transmission is warmed up over a few miles.
---- Symptoms found listed were fluid level (checked good), seals, pump, or converter (Thanks to some responses by Mark K. in other threads/forums)

- Trans temp rising after 30-45 min driving time (despite new higher capacity cooler and successful coolant flow test)
----Stock Gauge will rise to Yellow and approach Red if I do not stop and let it run to cool down.


Any reason why the TC could not be the culprit given the information above?


At this point in I am looking at the following TCs considering that my 7.3 is stock other than the Superchips programmer (stated at 385hp/730lb on Performance setting). I am also planning on replacing/upgrading injectors in the near future since the stock ones are leaking and resulting in cold rough starts.



Options:
- Diamond T Triple Disc Billet

- Diesel Site Triple Disc Billet
- Thor Heavy Hammer Lvl 2 Single Disc Billet

- RacerX Eagle
- Hughes



Probably a stupid question: Will converters not listed as "Diesel" work or will they not be adequate? (e.g. some of the Thor or Hughes TCs for the 4R100)
 

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The ones not listed as diesel will have four studs, not six, and will not fit.
 

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Discussion Starter #14
Thanks for the clarification Mark. I was looking at the 6 stud, but was not sure the difference in application with the 4 stud - makes sense now.
 

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Discussion Starter #15
So my transmission issues have been addressed with the replacement of the torque converter. I got rid of the high stall converter and installed a 1700 stall multi-disk billet converter. Several hundred miles on it since and not one issue.

Now on to replacing my injectors and some feedback on direction, but that is for another thread.

Thanks for the input and direction with the transmission issues.
 

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So which converter did you get and what do they go for? I'm interested in an upgrade myself.
 
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