Trans running hot

Hi All,

I've got a '95 F-350 with 275K miles on it. When I bought the truck about 5 years ago, the PO told me it had a recent transmission rebuild and a shift kit but he didn't know which one. And overall the trans feels very strong. At that time it was shifting VERY hard ... like throw your back out hard. After a lot of troubleshooting it ended up being the barometric pressure sensor. Replaced that and it's been great for the most part.

Last summer I bought a fairly heavy 5th wheel trailer so did a bunch of stuff to get the truck up to speed, one of which was to put in an intercooler. At that time we didn't feel like the intercooler and the 2 trans coolers by the radiator would all fit, so we removed those coolers and put in a remote frame mounted Derale cooler. Also put in a Mag-Hytec deep pan. With the pan and the remote mounted cooler, it has a LOT of fluid.

Since then, the trans has been running pretty hot. It will settle in at 200 or so unloaded just running around down as my daily driver and 225 when towing through the mountains. Last trip it started throwing a P1728 when it gets hot.

Things I have tried:

• The Derale cooler was set up to pull air from above the cooler vs. push it through. I reversed the polarity to switch it to pushing through. This made no difference.
  
• The cooler has a thermostat that turns on the fan at 180*. I bypassed this on my last trip towing to just have the fan always run when the ignition is on. This made no difference either.

Questions / Next Steps

I read somewhere that there is a theory that the deep pans are a bad thing in that the fluid takes longer to get hot, but once it does, the cooler just can't keep up. If this is the case, should I go back to the stock pan? Add more cooling? I want to change the fluid anyway since it's been running so hot so changing the pan would be pretty easy to see if that helps.

I'm also wondering about the torque converter. I don't know if it was replaced when they rebuilt the trans and I know these can be a weak point. Long term I'd like to put a built trans like a BTS or JW in. But that's a lot of $ so I'd like to put it off as long as I can. Wondering if replacing the TC with a better one (like the one from Precision Industries for example) would make sense? Maybe do a valve body at the same time so I know what it is?

Any other suggestions appreciated.

To see if you need to replace the torque converter look at the front face of the converter. This is the end facing the engine. If the surface shows heat, especially bluing, then it is slipping and needs to be replaced.

With the poor cooling system that you have I'm not surprised by your temperatures. If this were my truck I'd lose the Derale cooler. Unless you have a MONSTER fan the cooler isn't doing much for you. You need a cooler that is in the airflow, not one tucked under the truck. The air under the truck is HOT. A cooler that is sucking in hot air isn't going to cool the trans very well.

The large pan isn't helping you. I can't really say it's hurting you, but it does NOTHING to help cool the trans. Once the trans does get hot it will take a lot longer to cool because of all the extra fluid.

The best transmission cooling system is from the front of the trans to the radiator cooler, then to a cooler from a 6.0L truck, then back to the rear of the trans. If you can fit this in your cooling problems will be over.

Mark Kovalsky said:

The best transmission cooling system is from the front of the trans to the radiator cooler, then to a cooler from a 6.0L truck, then back to the rear of the trans. If you can fit this in your cooling problems will be over.

Click to expand...

That is the problem. With the A/C and Intercooler there's not much room. In another thread someone mentioned putting the 6.0 cooler behind the bumper? So lower than you'd normally want it. Guess that would be better airflow wise than the frame mounted one.

The V-10 or 4739 Tru-Cool coolers go in the bumper.

Peroni said:

The V-10 or 4739 Tru-Cool coolers go in the bumper.

Click to expand...

Yep, fit great and work good. http://www.powerstroke.org/forum/94...l-4739-1-transmission-cooler.html#post3242675

Well that was an adventure.

Took the truck to my local tranny shop to see what they thought about putting in a better cooler. At a minimum I wanted to get the fluid changed since it had been running hot. Their recommendation was to switch to synthetic fluid and see if that helped. And if not work on getting another cooler in after our trip to OR. Did that and took off for OR.

About three hours into the trip (right outside the beautiful garden spot of Wendover, NV), the tranny went. Vented all the fluid out the top. Got a tow into Wendover the next morning (after sleeping in the 5'er on the side of I-80 overnight) to what seemed to be a pretty decent tranny shop. They also towed the 5'er to a campground so we were set that way.

Anyway the verdict was that it was shot and needed to be rebuilt. It would have cost $500 per vehicle (truck and trailer) to tow it home so I had them go ahead and rebuild it. Which sucks because I was saving for a BTS. I did at least have them put in a triple disc billet converter. The other thing they did was route the cooling through the radiator in addition to the Derale. After it was done it was still running a little hot but we figured I could at least get it home and then address the cooling issue.

The other thing they said is that the valve body had a "half assed" shift kit. It had always shifted pretty hard so that didn't surprise me. They put a real shift kit in as well.

Made it home just fine, though it did run pretty hot (up to 215 across the desert). Parked the rig in front of the house and went to bed.

The next morning I went out to park the trailer and there was a sizable puddle of tranny fluid on the ground. Got under there and discovered it was a leaky cooling line. The lines that were in place for the Derale are 5/16" rubber lines. The guys in Wendover had pushed those over the steel lines going to the radiator and secured it with hose clamps. Anyway it was leaking out of that junction.

I have an appointment at a highly recommended shop in the area to install my new HPOP (terminator T500) tomorrow so tonight I went and got a couple more hose clamps and really tightened it up at that junction, topped off the tranny fluid and let it run for about a half hour. No leaking so went to take it for a test drive only to discover that it won't shift from 1st to 2nd. Only gears I have are Reverse and 1st.

Per my Infiniti, the PCM is commanding 2nd gear but the transmission is not shifting.

Two questions:

I'm wondering if this is a valve body / shift kit issue? Given the suspect nature of the original shift kit and by extension the valve body.

The shop is a pretty good distance from my house (about 20 miles). Do I risk doing additional damage driving it that far in first? Should I have it towed there? Or if it's just the valve body I could probably handle a valve body install at home.

Thanks for the help.

Just had a thought and went out and tried shifting into 2nd manually with the gearshift. That works. But it won't go into third and of course there is not a manual position for that. But I could drive it to the shop in 2nd at least.

rknight said:

I'm wondering if this is a valve body / shift kit issue? Given the suspect nature of the original shift kit and by extension the valve body.

Click to expand...

It's either the valve body or a problem with the intermediate clutch or intermediate one way clutch. What happens if you shift to 2 to get it into 2nd gear, then once you speed up shift to OD? Will it upshift then?

Nope. Drove it in 2nd 20 miles to the shop this morning.

rknight said:

That is the problem. With the A/C and Intercooler there's not much room. In another thread someone mentioned putting the 6.0 cooler behind the bumper? So lower than you'd normally want it. Guess that would be better airflow wise than the frame mounted one.

Click to expand...

You sure about that oke:

http://powerstrokenation.com/forums/showthread.php?t=140448

Billy T.
[email protected]