Surprised at low trans temp while towing.

[44dwarf]

Hi gang.

Last month I finally got around to doing some service on my 96 f150 xlt with tow package. It has 163,000 on it. As far as i know the trans had only an oil and filter done right before i got it at 152,000. It had the shutter everyone complains about and a can of conversion fluid (dexron to mercon V) seem to fix it for a month or so.

Anyway. things i did were.

1) Replaced both Accumulator valves with bonded rubber units.
2) Mild J-MOD on the valve body plate.
3) Sunnex SURE CURE kit parts in the valve body only didn't due the seals it came with.
4) Heat Buster 4 core Copper radiator.
5) Upper and lower hoses
6) power flushed the cooler with 2 cans of flush stuff and compressed air after.
7) Added drain plug
8) Added second drain plug kit and fitted a trans temp unit in the pan.
9) Royal purple MAX ATF (5 gallon pail)

I've been towing a 6300lbs trailer with it and the max temp i've seen was 160 deg!
I have no shutter anymore! I'm getting 15.6 mpg up 1.5 from before the service with just the truck full of stuff in the bed. still get around 10.5 while towing.

I'm so surprised at the trans temp but then again the big rad the motor never get hot at all. maybe to the "R" in NORMAL going up the vermont hills.



44

[MudTerrain]

Very nice!!!

[glc]

Which engine and trans do you have?

[44dwarf]

302 with 4r70w and 3.55 open rear. Most of the time the OD is off and on hills i put it in 2nd before I have too to try to maintain speed but don't rev the heck out of it. So hill you just know no matter what you do your going to down to 40mph at the top so just relax put it in 2nd and back off the throttle.
I used to use a school bus as a hauler for the race car it was slow on hills too.

I've though about going to 3.73 or 4.10s to help with hills but no $$ with gas at $4.09

[Galaxy]

The reason you are seeing such cool tranny temps is because you have the temp probe in the pan...arguably the coolest fluid in the system. Does not really give you a good indicator of the tranny temp and far from the hottest temps the fluid will see. Majority of people place the probe in the cooler line that runs FROM the tranny TO the cooler. This is the hottest temp the fluid will see in its route through the tranny, and the reason it's monitored here is because it's the hottest. I'm not saying this is happening to you but theoretically you could be cooking the crap out of your fluid and if your radiator/cooler is efficient enough, it wold be that cool by the time it got back to the pan.

[44dwarf]

My trany guy said best place was the pan cause thats where in fulid it picked up to lube the trans. I've thought about putting a thremo couple in the in and out trans lines too just to see how good it is.
But i'm happy.

[spike747]

Originally Posted by Galaxy

The reason you are seeing such cool tranny temps is because you have the temp probe in the pan...arguably the coolest fluid in the system. Does not really give you a good indicator of the tranny temp and far from the hottest temps the fluid will see. Majority of people place the probe in the cooler line that runs FROM the tranny TO the cooler. This is the hottest temp the fluid will see in its route through the tranny, and the reason it's monitored here is because it's the hottest. I'm not saying this is happening to you but theoretically you could be cooking the crap out of your fluid and if your radiator/cooler is efficient enough, it wold be that cool by the time it got back to the pan.

I hear this alot about the "coolest" oil not being a good place to measure. I think it might be cooler then the outlet line, but I believe the temperature is a fixed number of degrees less. Say 20 F. I can't think of any reason why the outlet temp would fluctuate wildly without the pan temp fluctuating also. So I think that if the pan temp is well within the temp range of tranny fluid then who cares what the outlet temperature is. The two numbers can't be that far off from each other.

Or I could be wrong.

[Galaxy]

Yes..you could be wrong!! The outlet line temps fluctuate GREATLY and in a manner that will not cause an immediate and equal change in the temp of the fluid in the pan. When your converter is unlocked that generates A LOT of heat. If you're driving for any amount (or towing) with the converter unlocked, that fluid temp rises much, and rises fast, and continues to go until you get that converter locked up. I've seen a 40-50+ temp increase over the matter of a minute just from driving like that. By the time the fluid makes it's rounds, and remember the very next place it goes is to the cooler, it's likely you wouldn't see much of that temp change. Because you can watch it instantly drop back off when the converter lockes up. And when that fluid in the out line starts to warm up from the converter, it's an instant reading on your needle. Anything in the pan is most likely going to be a gradual fluid warm up. It would not reflect those spikes you get during converter lock/unlock conditions because there's soo much fluid in the pan that would have to be warmed up. You say you think the fluid in the pan is a fixed number of degrees less...say 20?? Sounds like you're making stuff up to make yourself feel better, because that's not the case.

Besides, even if you were right, I personally wouldn't want to have to drive around doing the math all the time.