Trans Temp regulator valve???
Thread Starter
|
PMS: an obsession
Joined: Jul 2007
Posts: 804
Likes: 0
From: Kamloops
Trans Temp regulator valve???
Can anyone tell me if there is a reason why my tranny gets warmer in the winter time than it does in the summer while towing? The temps are as low as -22*C and my tranny can climb up to 160* with my TRU-Cool while, it babrely ever hit that while tugging in the 30*+ weather of the summer. Is there some kind of cooler block valve in the tranny that shuts the flow to the cooler? If so how does this work? Thanks to anyone in the know.
Elder User
Joined: Sep 2006
Posts: 679
Likes: 0
From: NW Burbs of Illinois
It was explained to me that its not a thermal bypass, its a over pressure reliefe valve. I just replced that part on my trans. So if the fluid gets too thick and slow moving, the fluid will pop open the valve, bypass the coolers and fluid will still get to the back of the trans so it doesnt melt down.
Post Fiend
Joined: Feb 2007
Posts: 14,541
Likes: 2
From: Dallas-Ft. Worth
It was explained to me that its not a thermal bypass, its a over pressure reliefe valve. I just replced that part on my trans. So if the fluid gets too thick and slow moving, the fluid will pop open the valve, bypass the coolers and fluid will still get to the back of the trans so it doesnt melt down.
Also make sure the cooler fins are clean -- crud getting in there can keep them from working as well.
You can read about the bypass valve here:
http://www.dieselsite.com/index.asp?...ROD&ProdID=172
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,705
Likes: 2,626
From: SE Florida
It does NOT do both. It is ONLY a pressure bypass. Dieselsite believes otherwise, and I've tried to explain it to Bob, but Bob knows what he knows and is not open to those that might know more about transmissions than he does.
All that is in there is a spring and a ball. If there is too much pressure going to the cooler the ball pushes off it's seat and allows flow to bypass the cooler. When the pressure goes back down the spring pushes the ball back onto it's seat and all flow goes to the cooler. There is no thermostatic device in the 4R100 at all.
At -22C (-8F) it might be cold enough that dino ATF is getting too thick to go through the coolers, especially if there is any restriction in the coolers or the lines. This will make the bypass open. If it is opening because of this it will not close again until the ambient temperature rises. Even if the trans gets really hot the coolers won't see the hot ATF and will remain clogged. Once the bypass opens there is very little pressure in the cooler lines to push out the thick ATF.
All that is in there is a spring and a ball. If there is too much pressure going to the cooler the ball pushes off it's seat and allows flow to bypass the cooler. When the pressure goes back down the spring pushes the ball back onto it's seat and all flow goes to the cooler. There is no thermostatic device in the 4R100 at all.
At -22C (-8F) it might be cold enough that dino ATF is getting too thick to go through the coolers, especially if there is any restriction in the coolers or the lines. This will make the bypass open. If it is opening because of this it will not close again until the ambient temperature rises. Even if the trans gets really hot the coolers won't see the hot ATF and will remain clogged. Once the bypass opens there is very little pressure in the cooler lines to push out the thick ATF.
New User
Joined: Dec 2008
Posts: 2
Likes: 0
Mark,
That's kind of confusing when it doesn't have to be. It's not reall important how it works, it was designed and installed to divert converter out flow to rear lube when the ambient temp is cold. WHile there isn't any kind of thermostat or thermocouple in it, the differences in fluid viscosity caused by air temps is why it works. Bottom line is, when it's cold outside, your converter out is sent back to rear lube in without going to the cooler, when it's real cold, it never opens up to the cooler at all and this is why sometimes you can run higher temps in the winter than in the summer. And if you cooler is clogged in any weather, it just might save your tranny by allowing some flow where a clogged cooler could shut of flow completely.
That's kind of confusing when it doesn't have to be. It's not reall important how it works, it was designed and installed to divert converter out flow to rear lube when the ambient temp is cold. WHile there isn't any kind of thermostat or thermocouple in it, the differences in fluid viscosity caused by air temps is why it works. Bottom line is, when it's cold outside, your converter out is sent back to rear lube in without going to the cooler, when it's real cold, it never opens up to the cooler at all and this is why sometimes you can run higher temps in the winter than in the summer. And if you cooler is clogged in any weather, it just might save your tranny by allowing some flow where a clogged cooler could shut of flow completely.
Fleet Owner
Joined: Mar 2007
Posts: 28,287
Likes: 6
From: BLT, MN
Mark,
That's kind of confusing when it doesn't have to be. It's not reall important how it works, it was designed and installed to divert converter out flow to rear lube when the ambient temp is cold. WHile there isn't any kind of thermostat or thermocouple in it, the differences in fluid viscosity caused by air temps is why it works. Bottom line is, when it's cold outside, your converter out is sent back to rear lube in without going to the cooler, when it's real cold, it never opens up to the cooler at all and this is why sometimes you can run higher temps in the winter than in the summer. And if you cooler is clogged in any weather, it just might save your tranny by allowing some flow where a clogged cooler could shut of flow completely.
That's kind of confusing when it doesn't have to be. It's not reall important how it works, it was designed and installed to divert converter out flow to rear lube when the ambient temp is cold. WHile there isn't any kind of thermostat or thermocouple in it, the differences in fluid viscosity caused by air temps is why it works. Bottom line is, when it's cold outside, your converter out is sent back to rear lube in without going to the cooler, when it's real cold, it never opens up to the cooler at all and this is why sometimes you can run higher temps in the winter than in the summer. And if you cooler is clogged in any weather, it just might save your tranny by allowing some flow where a clogged cooler could shut of flow completely.
Trending Topics
Thread Starter
|
PMS: an obsession
Joined: Jul 2007
Posts: 804
Likes: 0
From: Kamloops
Thanks for all the responses fellas. I was never concerned about the 160 degree temps, just curious as to how and why this occurred. Thanks for the insight Mark. I was actually hoping you would chime in on this as I know from past posts that you are in the "know" with transmissions, and I respect your posts very much.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Post Fiend
Joined: Feb 2007
Posts: 14,541
Likes: 2
From: Dallas-Ft. Worth
Interesting. I missed this whole thing today. So it's PURELY based on cooler restriction -- good enough... That actually makes more sense, considering somewhat common failure that thing is. The sucky part is Mark's last paragraph. If dino fluid is cold enough to cause the bypass to open, it might never close again since the fluid will never be pushed through (also an EXCELLENT reason to run syn ATF!). I wonder if those of us with the tranny cooler in the radiator won't have the problem because eventually, the fluid in the lines WILL get warm from the hot coolant.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,705
Likes: 2,626
From: SE Florida
If you want to know why, do a search. I've typed it WAY too many times lately and I don't want to type it again.
Post Fiend
Joined: Feb 2007
Posts: 14,541
Likes: 2
From: Dallas-Ft. Worth
I'm not that interested, really. But it makes sense to me that if it's really cold out, as the truck warms up to temp, that some of that warmth in there will make it to the fluid. I'll take your word for it, but there has to be some heat transfer, if indeed the bypass is closed and there is no warm fluid from the tranny making it there.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,705
Likes: 2,626
From: SE Florida
When it's really cold out the ATF can gel in the aux cooler. There isn't enough pressure in the cooler lines to blow it through before the bypass opens. Once the bypass opens there is very little pressure in the cooler lines, so there is even less pressure trying to force the gelled fluid through the cooler. Meanwhile the aux cooler is out front in the air stream, so even if heat reached it the below zero air rushing over it will keep it below zero, and the fluid stays gelled until the ambient warms up.
Senior User
Joined: Nov 2003
Posts: 423
Likes: 0
From: Providence, RI
After it has warmed up so the coolant has risen to operating temperature, the engine oil will have warmed up to about 100ºF, and the tranny fluid will be reading about 50ºF.
You're saying the 40ºF in tranny-fluid temp is NOT connected with that fluid circulating through the now-warmed radiator?
As to the original topic, the 6.0L cooler may not have the same kind of restriction, as my tranny-fluid seems to circulate even when very cold; driving around town, it will eventually get up to the 110º-120ºF range, but no higher.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,705
Likes: 2,626
From: SE Florida
No, I'm saying the radiator doesn't warm up. The engine warms up, but the radiator does not. The thermostat keeps the engine warm, but the radiator doesn't get hot. It cools the coolant inside. Since the thermostat is limiting the flow of coolant to the radiator the coolant spends a lot of time sitting in the radiator cooling down. Cold coolant in the radiator can't heat the trans fluid. Engine oil doesn't enter into this at all.