RevMax 8 speed thermostat bypass

[Different Drummer]

Its kind of a balancing act.

Cooler temperatures are always better. But cooler fluid is (slightly) thicker, which will technically cause more friction and drag.

Now....do the 1500 transmissions run hotter because its better? Or because FCA wants to eek another 0.00000001 mpg out of them and so the hotter, thinner fluid helps with their goals at the cost of long term durability?

Personally I think its all about FCA making their CAFE targets....the fact they call it "lifetime fluid" makes me think they just want it to make it to the end of the warranty and to hell with the customer.

Can't say I disagree with any of that.

 

[Wild one]

If after a good solid drive the temp returns to the 180s I’ll probably reinstall the tstat to aid in faster warmup. Very amused though. I’ll have to see. It still warmed relatively fast due to not removing the coolant lines however it was a bit longer. If it remains in the 170 range I’ll be extremely happy, though being cooler out right now may change the temps too

I forget what engine thermostat your running,but i'm wondering if the tranny will still eventually match the engines temp with the coolant lines hooked up.It would make sense that it'll take a bit longer to warm up,and if you're running a 180 or 195 thermostat the tranny will match the engines temp after the trucks been in operation long enough to have everything up to operating temp. I don't suppose you have a set of hose pinching clamps laying around ,and would you be up to pinching the hose that feeds coolant to the heater assembly as an experiment.I know the guys running the kit as option #3 with the plate are reporting tranny temps in the mid 140's,so it looks like the thermal heater,might effect the tranny fluids temp,more then we think. Now i'm leaning even more towards putting a manual heater control valve inline with the coolant line feeding the heater assembly,so i can control the amount of heat fed to the thermal heater.

 

[crazykid1994]

I forget what engine thermostat your running,but i'm wondering if the tranny will still eventually match the engines temp with the coolant lines hooked up.It would make sense that it'll take a bit longer to warm up,and if you're running a 180 or 195 thermostat the tranny will match the engines temp after the trucks been in operation long enough to have everything up to operating temp. I don't suppose you have a set of hose pinching clamps laying around ,and would you be up to pinching the hose that feeds coolant to the heater assembly as an experiment.I know the guys running the kit as option #3 with the plate are reporting tranny temps in the mid 140's,so it looks like the thermal heater,might effect the tranny fluids temp,more then we think. Now i'm leaning even more towards putting a manual heater control valve inline with the coolant line feeding the heater assembly,so i can control the amount of heat fed to the thermal heater.

190 tstat but my trans never saw temps over 187° unless I was racing. I do not have hose crimps.

 

[Wild one]

190 tstat but my trans never saw temps over 187° unless I was racing. I do not have hose crimps.

I'm betting then the tranny will still eventually match your old temps with the coolant hoses still hooked up Kristopher,as nothings changed in the coolant temps fed to the thermal unit,it'll just take it a bit longer to get to the same temp.If you have a pair of vise grips,wrap the jaws with some black tape,so they don't cut into the heater hose feeding the thermal unit,and they'll accomplish the same thing as a set of hose pinch off pliars will if you clamp one onto the hot side feed of the thermal unit.Only do it,if you're interested in seeing what the differance in temps will be,as i'm already asking you to do way more then i should,lol

 

[Different Drummer]

Couple of pieces of hardwood or HDPE with 2 , 1/4" matching holes drilled in each. 2, 1/4" bolts with nuts and washers. = one hose clamping device.

Note that the engine coolant used to warm the transmission fluid via heat exchange in the Transmission thermal management unit, Never does get cycled through the radiator via thermostat. It is routed from the engine to the 3 way diverting valve then, to the TTMU and then back into the engine. Cycle then repeats itself. I realize that in theory it would mix with coolant in the engine and exit the engine at engine coolant operating Temp. However, I wonder if in reality it is not warmer than what the thermostat in use is rated for.

 

[Wild one]

Couple of pieces of hardwood or HDPE with 2 , 1/4" matching holes drilled in each. 2, 1/4" bolts with nuts and washers. = one hose clamping device.

A little wood clamp would probably work to,lol.

IRWIN QUICK-GRIP Bar Clamp, One-Handed Mini, 6-Inch, 2-Pack (1964743) - - Amazon.com

 

[Wild one]

190 tstat but my trans never saw temps over 187° unless I was racing. I do not have hose crimps.

I forgot to ask if you had tried it with the interior heat turned on? I know on the 3 way valve equipped trucks,the heater core recieves the majority of coolant flow,till a certain interior temp is reached,then the valve redirects flow to the thermal unit.In theory turning the interior heat on should accomplish close to the same thing as the plate does till the interior is warmed up.Wonder if turning the interior heater on and driving around with the windows down would be the cheapest / easiest way to bypass the coolant heating the tranny fluid,for a short test,lol

 

[crazykid1994]

I forgot to ask if you had tried it with the interior heat turned on? I know on the 3 way valve equipped trucks,the heater core recieves the majority of coolant flow,till a certain interior temp is reached,then the valve redirects flow to the thermal unit.In theory turning the interior heat on should accomplish close to the same thing as the plate does till the interior is warmed up.Wonder if turning the interior heater on and driving around with the windows down would be the cheapest / easiest way to bypass the coolant heating the tranny fluid,for a short test,lol

I do not have the 3 way valve. Also have a custom fan setup that runs at low speed unless needed which helps my temps warm up faster and given that it’s cold out my fan hardly runs. It runs off the temp of the coolant going back into the engine. I have a bimetallic temp sensor in the radiator out hose.

 

[Wild one]

I do not have the 3 way valve. Also have a custom fan setup that runs at low speed unless needed which helps my temps warm up faster and given that it’s cold out my fan hardly runs. It runs off the temp of the coolant going back into the engine. I have a bimetallic temp sensor in the radiator out hose.

I'm not sure how they route the coolant to the heater core and the thermal unit on the trucks with-out the 3 way valve,but it's my understanding,the heater core still gets the majority of coolant flow,till the interior of the truck hits a certain temp.I don't think your engine fan set-up would affect how the coolant is routed to either the heater core or the thermal unit. It's just a thought to try ,if you get a chance to crank up the interior heat .

 

[crazykid1994]

I'm not sure how they route the coolant to the heater core and the thermal unit on the trucks with-out the 3 way valve,but it's my understanding,the heater core still gets the majority of coolant flow,till the interior of the truck hits a certain temp.I don't think your engine fan set-up would affect how the coolant is routed to either the heater core or the thermal unit. It's just a thought to try ,if you get a chance to crank up the interior heat .

Coolant has direct open flow to the trans unit as well as the heater core. There is no diverted valve that I’m aware of. Just a splitter that allows full flow but I will double check tomorrow. And sorry I didn’t mean my fan changes the coolant flow. Just meant my coolant heats up faster because my fan doesn’t run until my coolant is over 165° leaving the engine and I can adjust fan speed as well so that could be affecting trans temps because air flow is lower. If I turn my radiator fan speed up I wonder if it would help keep temps lower

 

[Wild one]

Coolant has direct open flow to the trans unit as well as the heater core. There is no diverted valve that I’m aware of. Just a splitter that allows full flow but I will double check tomorrow. And sorry I didn’t mean my fan changes the coolant flow. Just meant my coolant heats up faster because my fan doesn’t run until my coolant is over 165° leaving the engine and I can adjust fan speed as well so that could be affecting trans temps because air flow is lower. If I turn my radiator fan speed up I wonder if it would help keep temps lower

I haven't been able to find anything on how they route the coolant to the heater core or the thermal unit on the trucks with-out the diverter valve,there's info floating around about the earlier trucks with the 3 way diverter valve,but nothing on the later trucks,at least nothing i've been able to find.

 

[crazykid1994]

For everyone’s knowledge and enjoyment I went out this morning in under 50° weather and traced out all the hoses for the heater, engine oil heat exchanger, and the transmission heat exchanger.
Picture 1 is the splitter on the cold side of the radiator that the engine oil heat exchanger and the transmission heat exchanger return to.

Picture 2 is the water pump and tstat housing. If you notice the tstat housing has a fitting on the side of it. That fitting is the hot side out to the transmission. Above the tstat housing are 2 more hoses. 1 is attached to a black tube that connects just before the tstat housing for hot out to the heater core. The other attaches to a fitting that is on the cold side of the water pump for the heater core return.

The 3rd picture. Above the tstat housing in this picture is a small hose leaving the water pump housing and connects to that hard line heading down. That hard line then changes again to a rubber line and connects to the engine oil heat exchanger that is sandwiched between the oil filter and the engine block.

So to note: the trans heat exchanger is fed from after the engine coolant thermostat, the engine oil heat exchanger is fed from before the engine coolant thermostat, the heater core is also fed from before the engine coolant thermostat.
What that means is the heater core and engine oil always have constant coolant flow to them but the trans does not get coolant flow until the thermostat opens.

 

[Wild one]

For everyone’s knowledge and enjoyment I went out this morning in under 50° weather and traced out all the hoses for the heater, engine oil heat exchanger, and the transmission heat exchanger.
Picture 1 is the splitter on the cold side of the radiator that the engine oil heat exchanger and the transmission heat exchanger return to.
View attachment 234230
Picture 2 is the water pump and tstat housing. If you notice the tstat housing has a fitting on the side of it. That fitting is the hot side out to the transmission. Above the tstat housing are 2 more hoses. 1 is attached to a black tube that connects just before the tstat housing for hot out to the heater core. The other attaches to a fitting that is on the cold side of the water pump for the heater core return.
View attachment 234231
The 3rd picture. Above the tstat housing in this picture is a small hose leaving the water pump housing and connects to that hard line heading down. That hard line then changes again to a rubber line and connects to the engine oil heat exchanger that is sandwiched between the oil filter and the engine block.
View attachment 234232
So to note: the trans heat exchanger is fed from after the engine coolant thermostat, the engine oil heat exchanger is fed from before the engine coolant thermostat, the heater core is also fed from before the engine coolant thermostat.
What that means is the heater core and engine oil always have constant coolant flow to them but the trans does not get coolant flow until the thermostat opens.

Wow things got a lot more complicated hose wise when they added the engine oil pre-heater,lol. But it looks like you could clamp off the hose after the thermostat pretty easily to see if there's much differance in the tranny temp with no coolant feed to the trannies thermal heater. The upside is no 3 way valve to give you issues though,as it appears to occassionally cause an issue by going south on some trucks

 

[Wild one]

Damn 50F that's t-shirt and shorts weather for a Canuck at this time of year, we'd be sweating up here at those temps in Jan,lol

 

[crazykid1994]

For me it’s not so bad at 50s. Lol. Used to live in Maryland in the northeast United States. I wear sweat pants and a tank top and everyone thinks I’m crazy.

 

[Wild one]

For me it’s not so bad at 50s. Lol. Used to live in Maryland in the northeast United States. I wear sweat pants and a tank top and everyone thinks I’m crazy.

Now i know where your handle on here comes from,lol

 

[Musky Mike]

For everyone’s knowledge and enjoyment I went out this morning in under 50° weather and traced out all the hoses for the heater, engine oil heat exchanger, and the transmission heat exchanger.
Picture 1 is the splitter on the cold side of the radiator that the engine oil heat exchanger and the transmission heat exchanger return to.
View attachment 234230
Picture 2 is the water pump and tstat housing. If you notice the tstat housing has a fitting on the side of it. That fitting is the hot side out to the transmission. Above the tstat housing are 2 more hoses. 1 is attached to a black tube that connects just before the tstat housing for hot out to the heater core. The other attaches to a fitting that is on the cold side of the water pump for the heater core return.
View attachment 234231
The 3rd picture. Above the tstat housing in this picture is a small hose leaving the water pump housing and connects to that hard line heading down. That hard line then changes again to a rubber line and connects to the engine oil heat exchanger that is sandwiched between the oil filter and the engine block.
View attachment 234232
So to note: the trans heat exchanger is fed from after the engine coolant thermostat, the engine oil heat exchanger is fed from before the engine coolant thermostat, the heater core is also fed from before the engine coolant thermostat.
What that means is the heater core and engine oil always have constant coolant flow to them but the trans does not get coolant flow until the thermostat opens.

Would be easy to get a brass plug the same diameter as the hose, take the hose off, slide in the brass plug with a restricter hole drilled in it (maybe starting at .25") and see what the tranny temps do. If the temps are too low, you could drill the hole size a little bigger until you get what tranny temp you want. This way the system would still function, but at a reduced heating rate and the flow restricter inside the hose would never been seen...

 

[crazykid1994]

Took another short drive today. What regulates oil flow to the cooler vs being bypassed back to the transmission? I know the thermostat was supposed to regulate oil to the cooler. This was only a 30 minute drive and I hit 185. Not sure if it would have kept climbing on a longer drive. I know the oil is hot at the radiator and cold leaving the radiator as I felt the lines up front. How can I prevent oil from bypassing the cooler still?

 

[Wild one]

Took another short drive today. What regulates oil flow to the cooler vs being bypassed back to the transmission? I know the thermostat was supposed to regulate oil to the cooler. This was only a 30 minute drive and I hit 185. Not sure if it would have kept climbing on a longer drive. I know the oil is hot at the radiator and cold leaving the radiator as I felt the lines up front. How can I prevent oil from bypassing the cooler still?

View attachment 234529

I'm starting to wonder if removing the thermostat might not be the best way to go now. I checked mine again today,and noticed the inlet line to the tranny cooler was hot,but the return wasn't as hot as i thought it should be,which makes me wonder if removing the thermostat leaves both the bypass passage and the cooler passage both open at the same time,which makes me wonder if it's not sending all the fluid through the cooler . I'm starting to think the brass plug needs a revision ,so it'll block off the internal bypass passage,so the pump forces all the fluid through the cooler passage,instead of through both passages.Sound German has a version,that gets rid of the thermal heater totally,but it entails building/fabbing up a line adapter.

 

[crazykid1994]

I'm starting to wonder if removing the thermostat might not be the best way to go now. I checked mine again today,and noticed the inlet line to the tranny cooler was hot,but the return wasn't as hot as i thought it should be,which makes me wonder if removing the thermostat leaves both the bypass passage and the cooler passage both open at the same time,which makes me wonder if it's not sending all the fluid through the cooler . I'm starting to think the brass plug needs a revision ,so it'll block off the internal bypass passage,so the pump forces all the fluid through the cooler passage,instead of through both passages.Sound German has a version,that gets rid of the thermal heater totally,but it entails building/fabbing up a line adapter.

Yea. Kinda annoying. I’m thinking I may email them and see if I can return this since it’s pointless. I don’t really feel like digging into the heater to find out how it directs oil flow to remove the bypass but if I must I will. It would require me to completely remove the thermal block from the transmission which I don’t really feel like doing as that would require me to check fluid level after and could pose possible leak points.