I have read multiple threads about Trans temp and now that I have my scanguage 2 hooked up I'm more curious. Usually on the highway it doesn't go above 110 but today it was 40 deg out and it didn't go above 95 deg. I have a b&m waiting to be installed but I'm wondering what temp does the fluid need to be to properly libricate. Some people say 90-110 other 150-185 so just want some clarity
Trans temp
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ajonesnv
New member
It is safe to say the high temps are very bad, but low temps are up to each others interpretation...unfortunately. I like to follow the FSM as well as possible, which is around the 110* mark.
There are a few things to consider; the oil needs to be able to flow, but keep in mind 90* may be considered cold when talking about truck temps, but if you had a bottle of 90* oil out of the truck it would clearly be warm enough to flow smoothly, so I would assume it is warm enough to flow through the transmission. The counter to that is that some of the tranny ports are so small that the viscosity needs to be so much so that it is not hindered at these ports. My point is I doubt you will get a more straight answer than the FSM.
I have a B&M cooler that is 8x11x1.5 (it is huge), but when I am in close to 0* temps the tranny temps don't even register, so at the time I used card board to cover a good bit of it. Since I have added the TruCool bypass and now it stays in spec. I would recommend that with the install. This is all based off the assumption you are bypassing the radiator, which if you are not you might want to consider. BUT if you are not the bypass won't do much more than what the radiator already does.
There are a few things to consider; the oil needs to be able to flow, but keep in mind 90* may be considered cold when talking about truck temps, but if you had a bottle of 90* oil out of the truck it would clearly be warm enough to flow smoothly, so I would assume it is warm enough to flow through the transmission. The counter to that is that some of the tranny ports are so small that the viscosity needs to be so much so that it is not hindered at these ports. My point is I doubt you will get a more straight answer than the FSM.
I have a B&M cooler that is 8x11x1.5 (it is huge), but when I am in close to 0* temps the tranny temps don't even register, so at the time I used card board to cover a good bit of it. Since I have added the TruCool bypass and now it stays in spec. I would recommend that with the install. This is all based off the assumption you are bypassing the radiator, which if you are not you might want to consider. BUT if you are not the bypass won't do much more than what the radiator already does.
Mgyver1
Member
This article from YotaTech seems to think the external bypass is unecessary.
Transmission coolers - low temps and bypass thermostats - Tests and results - YotaTech Forums
Also [MENTION=73515]ajonesnv[/MENTION] I believe your particular B&M did not have the low pressure drop design like most models do. So in your case you fluid is always being fully cooled unless you have your external thermal bypass, so in ultra cold climates it probably is a good idea.
Transmission coolers - low temps and bypass thermostats - Tests and results - YotaTech Forums
Also [MENTION=73515]ajonesnv[/MENTION] I believe your particular B&M did not have the low pressure drop design like most models do. So in your case you fluid is always being fully cooled unless you have your external thermal bypass, so in ultra cold climates it probably is a good idea.
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19963.4lsr5
New member
I like seeing 130 to 160 degrees F. But it's personal preference like oil and filters. and I don't have a cow if I see 180 either.
So I got my b&m 70268 installed tonight. Highway temps are higher than before at 116 range and in town temps are at 140 max so far. So there is less temp change roughly 25 degrees previously I would see temp of 105-160 so that is less but I think the 70268 might be a little small or I need I look at my airflow. I think my grill restricts a lot due to placement.
19963.4lsr5
New member
My temps are about the same in Chicago's stop and go traffic. 160-180 on a warm day and up to 200 on a blistering hot humid day. Stable 160 on the highway at 70mph with a/c on, fully loaded (either 5 people or fully stuffed cargo area, seats folded).
I have the BM 70268 installed, bypassing the radiator and measuring temps with a mechanical gauge.
jgue467
Senior Member
Slides, how long do you drive when you take your readings?
I get similar readings to Tdaz in austin, tx (mild hills of 100-200 ft climbs here and there) during august when its 105. But my runner won't get to those temps until at least a 30-40 minute drive, anything less leads to lower readings for me.
When i drove the rockies between steamboat and denver in july i got 167 in 80 degrees (engine was working hard for the $ that day), so outside temps clearly make a big difference, for me anyway. :cheers:
I get similar readings to Tdaz in austin, tx (mild hills of 100-200 ft climbs here and there) during august when its 105. But my runner won't get to those temps until at least a 30-40 minute drive, anything less leads to lower readings for me.
When i drove the rockies between steamboat and denver in july i got 167 in 80 degrees (engine was working hard for the $ that day), so outside temps clearly make a big difference, for me anyway. :cheers:
I would say after 20 min of driving it gets up to the 116-120 range on the highway. Last night after driving for an hr I got off the highway with city driving it went up to 140 and sat there Untill I got home. I have if mounted sideways and you can feel the air getting sucked in by the fan it's basically right in front.
I'm not concerned I'm curious I figure as long as it's not near 190+ I'm fine.
I'm not concerned I'm curious I figure as long as it's not near 190+ I'm fine.
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19963.4lsr5
New member
I guess it would be important to know where everyone is sensing their temp from. The trans factory temp sensor position is inside the trans and is rumored to sense oil temp comming from the torque converter.
Putting a temp sensor in the cooler line comming from the trans to the cooler is basically measuring oil pan temp cause the flow is pan to pump to cooler to trans. And the coolest readings would be putting the sensor in the return line after the cooler.
Putting a temp sensor in the cooler line comming from the trans to the cooler is basically measuring oil pan temp cause the flow is pan to pump to cooler to trans. And the coolest readings would be putting the sensor in the return line after the cooler.
slapdappy
Banned
my '99 temp sensor takes its reading where the fluid is hottest, just before it flows out of the case and into the send line. red X in photo.
from member kball http://www.toyota-4runner.org/605605-post4.html:
from member kball http://www.toyota-4runner.org/605605-post4.html:
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19963.4lsr5
New member
Most transmissions pump fluid out of sump and to the cooler. From the cooler it goes to the valve body and does its work.
Edit:
On the jeep forums I'm reading that the oil pan oil is post cooler on the AW4 which is basically the A340. So I found a AW4 service manual pdf and am looking for the hydraulic schematic to see where the cooler is in the oil path.
slapdappy
Banned
My '99 (and subsequent year 3rd gens) sensor doesn't just trigger an idiot light at a preset temperature, it measures the actual temperature and sends this info to my scanguage. I believe it is located so that it measures the fluid at its highest temp.
I think the reason trans fluid temp is relevant is because it starts to break down at an increasing rate above a certain temp, which shortens its service life. So the temp after it is cooled and it enters the trans isn't relevant. The highest temp at any given time is what's relevant.
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