Transmission temp top hot?

[Wild one]

I know a lot of posts are calling it "too hot," but are those responses reasonable? Regardless of what transmission you have, a couple of questions need to be answered. First, does the transmission have the ability to report "too hot"? Second, at what fluid temperature does the transmission fluid offer its best lubricity?

250 degrees is too hot for a transmission like the 68RFE, but is it too hot for the ZF 8-speed? The point being: each transmission has minimum and maximum operating temperatures at which the transmission fluid offers its best lubricity. It sounded like your dealer answered that question.

Googling operating temperatures and based on your dealer's response, it appears you have the ZF 8-speed. Its operating temperature typically ranges from 190°F to 210°F. Its maximum safe operating temperature is around 220°F to 230°F. You may want to do some additional research and approach your dealer again.

You have the Maxcare lifetime; relax. Maxcare has your back. FYI, if the tranny does go, Maxcare could total your truck and pay you the market value if that number is less than the repair cost.

If you go by what the 6.4 trucks run their 8 speeds at,and they use the same basic 8 speed as the 1500's,it appears like between 160 and 170 are better transmission temps. The majority of 2500's with the 6.4/8 speed combo will tow 7,000+lbs and stay between 160 to 170 on transmission temps

 

[Dean2]

If you go by what the 6.4 trucks run their 8 speeds at,and they use the same basic 8 speed as the 1500's,it appears like between 160 and 170 are better transmission temps. The majority of 2500's with the 6.4/8 speed combo will tow 7,000+lbs and stay between 160 to 170 on transmission temps

Spot on, my 2021 2500 with the 8 speed never goes above 170 F, even on really hot days. Most of the time it runs just under 160.

 

[CanuckRam1313]

The @caulk04 bypass valve upgrade will drop trans temps by up to 30 deg/c and the engine temps by 3 to 5 deg/c (as evidenced on my current and previous trucks), plus confirmation from the half dozen peeps I've recommend them to that have purchased them here in Ontario as well.

@BossHogg - I hear what you're saying from a purely textbook point of view, but if you're one who drives and knows vehicles past the OEM specifications, one can easily feel how ones transmission acts when it's too warm vs when it's running a bit cooler, especially in 40 to 50 deg/c ambient summer temps.

One could also toss out that running too cool utilizing this bypass upgrade could negatively affect this 8spd transmission, and to that I, and I'm sure anyone on this platform who utilize it will tell you, that their transmissions be it winter or summer, operates much better overall.

Just having a warranty is good, however IMPO, being proactive and predictive in ones vehicle upkeep will ensure that you're not broken down and waiting for who knows how long it takes to get a new (reman) transmission from the dealership.

 

[Wild one]

Spot on, my 2021 2500 with the 8 speed never goes above 170 F, even on really hot days. Most of the time it runs just under 160.

According to Jeremy Satera and Jon Sipple the ideal temps for the 8 speed is right about 160/165F,and they should know. I also trust their advice,especially Sipples when it comes to the 8 speed,plus after doing some testing at the track,and finding out the transmission can be over cooled,as it acts a bit wonky at temps under 150F on full throttle shifts at the dragstrip,i'm pretty inclined to think they know what they're talking about.

 

[CanuckRam1313]

According to Jeremy Satera and Jon Sipple the ideal temps for the 8 speed is right about 160/165F,and they should know. I also trust their advice,especially Sipples when it comes to the 8 speed,plus after doing some testing at the track,and finding out the transmission can be over cooled,as it acts a bit wonky at temps under 150F on full throttle shifts at the dragstrip,i'm pretty inclined to think they know what they're talking about.

Agreed, and with @caulk04 bypass I see between 71 to 74 deg/c as my average daily "full operating temp" range in the summer months.

However, I did see 77 last week here in Ontario as I was driving spiritedly on the highway during our near 50 deg/c days, and then having some fun in town

I have also never had temps at 65 deg/c when at full operating temp in the dead of winter here, and that includes in the Ottawa Valley and QC winters, too.

Tells me that the bypass was designed properly to optimize the 8spd transmission

 

[Wild one]

Agreed, and with @caulk04 bypass I see between 71 to 74 deg/c as my average daily "full operating temp" range in the summer months.

However, I did see 77 last week here in Ontario as I was driving spiritedly on the highway during our near 50 deg/c days, and then having some fun in town

I have also never had temps at 65 deg/c when at full operating temp in the dead of winter here, and that includes in the Ottawa Valley and QC winters, too.

Tells me that the bypass was designed properly to optimize the 8spd transmission

Swap your Evic over so it shows farenheight temps,i might be Canuck,but anything over 30C i have to still look up,lol. When it comes to oil/transmission/coolant temps,i'm still old school and use farenheight as 180F means alot more to me then 82.2C does,lol.

65C/149F is a bit on the cold side for the 8 speed to be real happy,especially if you floor it,

71C /160F to 74C /165F is pretty well the ideal temps for the 8 speed,that's where they're the happiest

If i was running Jesse's bypass in Canada in the winter,i'd seriously look into adding one of Improved Racings stand alone high flow thermostats,just so the transmission will come up to temp.I know after removing the TMU on my trucks 8 speed and removing the thermostat,the tranny wasn't really happy when it was cold out,as it would consistently run right around 130F on the days i did drive it in the winter,i babied it to the moon and back the few times i did use the truck when the temps were under 0C

High-Flow Engine & Transmission Oil Cooler Thermostat

Improved Racing's Flow Series Motor Sport (FSM) oil thermostat is a universal solution that can be used with any oil cooler on any vehicle or industrial application flowing up to 20 GPM (75.71 LPM). Trusted by professional race teams, OEM's, and military contractors. Accelerates fluid warmup...

www.improvedracing.com

 

[Tominator223]

Ime high trans temps on higher mile vehicles . End up causing rear main seal on the engine to start leaking. Seems that the t-stat they’ve put in line is an issue. To me it looks like they've turned an old a/c expansion valve in to a trans t-stat. I had a s-pack go out on my 545. Got so hot the id sticker on the side of trans melted & dripped off. No joke. Rear seal on engine started leaking as soon as trans cooked. If the t-stat is lazy I’d remove it. If it’s sticky sea-foam has a trans additive for Trans only that works well. I’ve used it a few times , in vehicles that wouldn’t shift into OD. One GM & one ford also in one 545 that I driving now. Seafoam trans additive. Not regular seafoam

 

[RingSteel]

Is there anyone near Houston that installs the caulk04 bypass valve?

I've looked at the location on the transmission, and I'm challenged with only partial use of my right hand; just seems like it would be a real challenge for me to do it.

 

[DILLIGAF]

170xxx Your about 3x overdue for a oil change...lol...

Do an oil change with PPE pan , Maxxlife and caulk04 bypass

I did the improved racing thermostat myself instead. because having coolant line run to a transmission is ******* retarded.

 

[HEMIMANN]

Screwing around with engines for miniscule mileage improvement was bad enough - going after transmissions also is just insane. You guys likely saved my RFE.

So they just can't leave well enough alone and made the ZF even more of a kluge. In addition to the German's a*n*a*l lack of serviceability for home wrenchers. I see cray stuff on the Japanese vehicles too.

 

[DILLIGAF]

How is the ZF a kluge when its to go to transmission on a ton of swaps now , handles 800hp stock, can be used stand alone with only 3 inputs, now that is actually pretty cool (RPM, Throttle Position, and Brake Signal) . and you can service it at home in your driveway. Taking the Valve body apart for upgrades dosent require specialty tools. Heck guys have it behind 12 valves now.

The fact dodge spec it out with no drain plug, with that stupid cooler isnt on ZF. ZF actually say to change the oil in them and ZF confirmed Maxxlife as an oil for it...

The 6 speed is the actual POS here lets no kid ourselves.