ATS trans cooler bypass valve

[CAROLINA CUMMINS]

175 isnt bad. Just wondering what it'll be at 100+ ambient with a load or working it harder.

Guess I'll find out this summer.

 

[Cummins12V98]

What's wrong with 175°?

Absolutely NOTHING!!!

 

[CAROLINA CUMMINS]

Absolutely NOTHING!!!

I'm happy with 175, just curious what it will do on rough FS roads where it got close to 200 last time. No one really references those experiences that I have seen. I'll try some stuff next time, 1st vs 2nd, also 4 Hi vs. 4-Lo

This is my 4th Cummins but 1st auto trans so still learning. I miss the 5-spds sometimes

 

[gsbrockman]

What's wrong with 175°?

EVERYTHING........if you are a retailer like ATS or RevMax

 

[RVTRKN]

The tolerances are designed for certain temperatures, and is why I allways warm up my vehicles before driving. If the bypass is prone to failure, then replacing them would be warranted, but for the 14 years I been posting on TDR, this is the first I've heard of this. After a little research, they have leaked and some failures, it would warrant replacement if it helps with your worring about it. I would not eliminate the bypass though, for the low cost of an aftermarket bypass.

 

[TFucili]

I think what has driven this is that beyond the thermostatic valve controlling flow to the cooler, I have read they now they run coolant through to warm the fluid more quickly. I have seen reports of some pretty high temps, especially on the ZF 8 speed in the 1/2 tons. They are now using a beefed up ZF in the HD gassers.

 

[lilbxl]

Just had a discussion with a transmission shop that does a lot of 68RFE builds. He said the cooler the better. He also brought up about keeping the cooler clean of debris for optimal cooling.

 

[TCDiesel]

http://www.txchange.com/heatchrt.htm

#ad

 

[CAROLINA CUMMINS]

Very few reviews on the TBV Delete, here is a thread with some temps I finally found.

https://www.ramforum.com/threads/recorded-68rfe-temps-after-the-ttbv-block-delete.140448/page-4

I'm itching now to get out and try some FS roads to see what my trans temps are with ambient temps in the 90s+

 

[AH64ID]

http://www.txchange.com/heatchrt.htm

#ad

I've been seeing that chart for 20 years, or more, and seriously doubt it has any bearing on modern synthetic ATF+4 or ASRC.

When I first started seeing that chart synthetic fluids were rare, and now they are OE.

 

[TCDiesel]

Yep, todays lube/Fluids are even More robust....

 

[kthaxton]

He said the cooler the better.

To a point....i.e. running at 170 is going to be better than running at 120 for example.

 

[sag2]

My 1500 8 speed had a trans heater and kept the temps above 190 all the time.

 

[TCDiesel]

Back in the day our pulling trucks had trans heaters also...If that fluid was not above 160F , prepare for the carnage and wallet suck up $$$$

 

[Ozymandias]

I saw 174° on a couple mile steep pull in 1/2 at approx 18K GCW on a 80° day.

I'll have some more slow and steep pulls this fall to see how hot it gets.

I have also tried 4Lo to get into a higher gear so the TQ converter would lock but it wouldn't lock below 20 mph regardless of gear... there goes my idea of 4.10's helping at low speeds get to TQ lock sooner.

That's interesting, my old box locks up at around 10mph in 2nd Gear 4lo. And stays locked till down to around 7mph.
All with EB switched ON.

 

[AH64ID]

That's interesting, my old box locks up at around 10mph in 2nd Gear 4lo. And stays locked till down to around 7mph.
All with EB switched ON.

I’ve only messed with it once. I do need a little more time to see what she’ll do. But so far it looks like 20mph is a limit.

 

[AH64ID]

Did a little more slow towing last weekend and 20 mph does seem like the program limit for lockup, but I didn't try 4LO.

Trans temps got up to 175° for me at ~18K GCW, and 188° for dad at ~21K GCW.

So that got me thinking, what temps are programmed for the fan in relation to trans temp.

Here is what I found on the stock file for a 2018. Aisin and 68RFE are the same.

Fan engages at at trans temp of 194°F.
Fan maxes at a trans temp of 234°F

Fan engages at a TQ Converter outlet temp of 237°F
Fan maxes at a TQ Converter oulet temp of 275°F

Bottom line... Ram doesn't seem that concerned about any of the temps we are seeing, and then some.


I can't look at the Aisin programming as it's stand alone, but the 68RFE requires 1250 rpm on the turbine output shaft to go into lockup (~35 mph)... that seems really high!

 

[lilbxl]

Did a little more slow towing last weekend and 20 mph does seem like the program limit for lockup, but I didn't try 4LO.

Trans temps got up to 175° for me at ~18K GCW, and 188° for dad at ~21K GCW.

So that got me thinking, what temps are programmed for the fan in relation to trans temp.

Here is what I found on the stock file for a 2018. Aisin and 68RFE are the same.

Fan engages at at trans temp of 194°F.
Fan maxes at a trans temp of 234°F

Fan engages at a TQ Converter outlet temp of 237°F
Fan maxes at a TQ Converter oulet temp of 275°F

Bottom line... Ram doesn't seem that concerned about any of the temps we are seeing, and then some.


I can't look at the Aisin programming as it's stand alone, but the 68RFE requires 1250 rpm on the turbine output shaft to go into lockup (~35 mph)... that seems really high!

Installed the bypass today. Am I going to see any negative effects from doing so?

 

[AH64ID]

Installed the bypass today. Am I going to see any negative effects from doing so?

Depends on the climate you live in, even then it will take longer to warm up and my 0.02 is that’s not good.

I’m still not certain it’s a real issue, but rather a marketing gimmick.

I think adding a thermostatic bypass to the trans was a big benefit over older transmission cooling systems.

There is a reason thermostats are used for many different applications.

 

[lilbxl]

Depends on the climate you live in, even then it will take longer to warm up and my 0.02 is that’s not good.

I’m still not certain it’s a real issue, but rather a marketing gimmick.

I think adding a thermostatic bypass to the trans was a big benefit over older transmission cooling systems.

There is a reason thermostats are used for many different applications.

Well, guess I’ll see how it goes. I can always reinstall the stock valve.