Transmission temp

micahjbun · 08-11-2017, 10:14 AM

I have a 98' Ford 5.4L RB, full SMB build out with a penthouse top, iron cross front bumper and custom rear bumper with box. Needless to say the van is a heavy beast. My question is what temp should my transmission running at normally?

carringb · 08-11-2017, 12:12 PM

Mine runs about 70F above ambient not towing, and it weighs 8500 pounds empty with plenty of anti-aero additions (grill guard, rack, awnings, giant rear fenders etc) Towing it runs about 100F above ambient. In either case, add about 30F on top of that when pulling a long steep pass. Last weekend when it was 92 degrees at 5,000 ft (104F at the bottom) and I was at 23,000 combined, it maxed out at 230F. Still within the safe zone for the 4R100. I did just about max out the diff temp gauge, but I don't think a stock 5.4L could overheat the diff.

86Scotty · 08-11-2017, 12:22 PM

I've had about the same experience as CarringB above. Usually around 150 until it gets warm out. In the Southwest loaded for a trip (no trailer) and I'll see around 200 -225 on long passes. I hit 230 once and got worried and then Ramsey (BajaSportsmobile) told me race trucks see like 275 and their trannies last for awhile if not run that way for long. When your fluid starts smelling burnt then worry.

wadewaydo · 08-11-2017, 01:45 PM

TexomaPowerboater · 08-11-2017, 02:23 PM

I read the hood louvers (vent inserts) will help lower transmission temperature. Anybody know if there is any truth in that?

Have a hard time believing the chart. I've run vehicles up to 190K and transmission still seemed in good shape.

JoeH · 08-11-2017, 03:20 PM

I have hood louvers and I doubt they have much effect on transmission temp. Wrapping the downpipe might help more.

I think the chart is a overly conservative as well. Before I added a bigger transmission cooler I once hit 275F going over Imogene. I changed the oil when I got home and it was clear red and didn't smell burned. Hitting 230F was pretty normal off road. I have a 5R110 but generally what I've read is that seals and such don't really start cooking until your at 290 or 300F.

From reading posts by Mark Kowalski on the diesel forums (Ford tranny engineer) it sounds like you can run 220°F all day long and go up to 250°F for short periods (no more than a half hour at a time). That might vary depending on tranny but also keep in mind that it also depends on where the temp is being measured. The pan is the coldest and on my rig varies from what the PCM is reading by ~12-15F. Ideally (obviously

) you want to know what the internal temp of the trans is and the test port on the side of the trans is the place. I think the PCM sensor on a 6.0 psd is in the solenoid and that is good too.

rallypanam · 08-11-2017, 04:46 PM

Quote:

Originally Posted by TexomaPowerboater

I read the hood louvers (vent inserts) will help lower transmission temperature. Anybody know if there is any truth in that?

Definitely untrue.. at least for my 7.3.

Bbasso · 08-11-2017, 05:44 PM

On my current rig, 7.3 PSD and 4R110 I routinely see an avg temp of 163 in Florida's summer. Once in a while I'll see a max of 185, but not often. Do to the odd ball mounting location of the trans cooler- undeneath the passenger side seat parallel to the ground. It works well and no complaints.

MadScience · 08-11-2017, 11:35 PM

I've pulled the entire hood off trying to get things under control while towing over donner pass on a hot day. That did nothing to stop the heat from building up.

Stopping at a car wash and spraying the cooler for a while did wonders to bring things way back down and start over.

**BroncoHauler** · 08-12-2017, 10:17 AM

Quote:

Originally Posted by TexomaPowerboater

I read the hood louvers (vent inserts) will help lower transmission temperature. Anybody know if there is any truth in that?...

In theory it could help because it should increase air flow through the radiator and trans cooler, but I think you'd achieve better results (trans cooling) with just a larger trans cooler. Don't know if the configuration is the same, but on my 7.3L Excursion I had the 7.3L-based trans cooler swapped for the 6.0L-based trans cooler which is substantially larger. I wanted this done purely as a preventative measure.

Quote:

Originally Posted by TexomaPowerboater

...Have a hard time believing the chart. I've run vehicles up to 190K and transmission still seemed in good shape.

Does seem like a very conservative chart.

Herb