**Also posted in 7.3 PS forum**

Okay guys,

I own a 2003 f-550 crewcab 7.3 PS, 4r100, 4.88, Gear Vendor with an 11' service bed and HD rack. With tools, my truck weighs in about 12,500 lbs.
I drive up a grade everyday back from the Palm Springs area (very hot).

When the truck was new I put a trans temp gauge in and it would peak at about 225 during the summer. I then installed a deep Mag pan and cooler with a fan. The max temp seemed to drop about 20 degrees, awesome!

At 33k Ford found overdrive slip codes, and rebuilt tranny for free (lucky me) still no problems.

At about 65k I had trans flushed and requested the correct fluid (Mercon V or Mercon, can't at the moment remember which is correct)My truck seemd to run abut 20 degrees hotter after being flushed. I found out they used a bulk fluid with additives that were supposed to equal the "wrong Mercon fluid"
I took it back, they then flushed it with the correct Mercon, tranny still ran hotter than before.

At 70k the truck was getting a bad vibration and growl on the freeway, (possible U-joint), By the time I got back it was blowing fluid. I had a local transmission shop (highly recommended) rebuild it with a shift kit and a heavy duty TC installed. The trans body had been cracked so it was also replaced (crack was so hairline they actually rebuilt trans before finding crack and then had to replaced body.

On the road I felt a slight shudder, then a vibration. The shop then replaced a U-joint and that corrected problem. Still can't stop thinking that a U-joint cost me about $3300.00 (U-joint killed tranny?)

The rebuilt trans works fine (fine for a soft shifting, gear changing, TC unlocking 4r100, just like the stock trans)
It does run hot though, I am reaching temps of 245 to 250 at the end of that long grade (outside temp is 112-120+).
It also takes a long time to for trans cool down (maybe 15 degrees after a 10 minute decent)
Trans guy checked fluid, said it looks fine, agrees that is hot, but assured me that the temp gauge was in the hottest location and that everything was fine.
I do trust the tranny guy, he seems very professional.
Truck also seems too shift funny (shifts too soon, maybe slip?) after trans is hot

What do you think?
Why is it running hotter than stock trans.
I do run double overdrive on grade, but I always did.
Tranny also seems to take longer to shift into reverse ( is that becuase of the new Heavy Duty TC?)

Sorry for the book, but thought I should tell all if I am asking for complete answers.

Thanks to all

Scott

 

Hey Guys,

I really need some input
Ran at 250 again today, fluid has very slight smokey smell

Scott

 

sorry scott i don't have any answers for you? i was just scanning to see if i could find some answers for my trans woes in my x i surprised somebody has given you something to go on. you already did a cooler mod ahve you thought about some of these trans additives that claim cooler operating temps. hasd your transmssion guys put a set of pressure gauges on your trans and ran it to see the actual working pressures? if not i don't think they are really trying to help you find the problem. just waiting for you to get out of warranty and rebuild your trans again thats what there in business for! anyway good luck and big howdy from texas! one quick question about your gearvendor why did you decide to get it and has it paid for itself? thks toolboxjunky!

 

No problem,

Guys here at the forum figured it out. It was my pressure bypass valve that was stuck open. Very little fluid was traveling thru coolers.

All is good now!

 

that's great scott glad to hear you found the problem. i have really enjoyed the ford forums since i registered in and have learned alot and still going! how about the gearvendor questions and info to share?

 

I drive like a maniac, so the Gear Vendor was a must have.
I'm sure it has paid for itself just in fuel as well as RPM wear to motor. Don't get one if you intend on getting an exhaust brake though. I believe US Gear would be the better choice with brake. As always check with the forum.
Later,
Scott