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Bad to run an auto tranny too cold?

Metalhead47

Metalhead47

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I tried posting this over on a Nissan forum but never got a response, but it's relevant to my 'Burb project too. Anyway, my wife has an '06 Nissan Frontier with an auto tranny. I bypassed the in-radiator cooler (they've been known to fail), and added a second auxiliary cooler & temp gauge. I've noticed on my long o-dark-30 drives this fall that the temp barely registers above 100* most of the trip.

Any potential problems with this? I was thinking of running a similar setup on my Suburban (no radiator cooler).
 
yup.... i know firsthand.. you need the trans to get up to about 150 degrees to burn off any condensation.. it killed my 700r4.. it's not an overnight thing, but it's not good for the trans... did awesome when it was hot, trans would run right about 175, 180.. winter i had trouble getting it to break 100.....
 
Where do you have the temp sensor located? What is the average outside temp lately when you are driving?
 
right now its in a port on the side of the transmission suggested by those more familiar, tho shortly ill be moving it to the pan. been in the 40s/30s for most of these drives, hundred mile cruise on hiways & interstates, so very little speed changes.

never thought about condensation being an issue. ill have to ask my wife what the gauge does during her drives with alot more stop n go.
 
That port may be a stagnant oil source and not a true indicator
of true fluid temp. I wouldn't make any assumptions about the
system or temps till the sender is relocated, you may just be reading
case temperature where it is now.
 
My 4l80E in my 99 never gets up to 150, unless I'm towing. (factory gauge)
I just drove back from Chicago Sunday, and it only got to 120 or a little less, and that was 150 miles.
That trans has 185K on it now.
 
Heh, kinda sad when I post a Nissan question on a GM forum & get more responses in 4 hours than the other forum gave me in several days now.:D
:thumb: to the CK5 crew!

Greg Ducato said:
That port may be a stagnant oil source and not a true indicator
of true fluid temp. I wouldn't make any assumptions about the
system or temps till the sender is relocated, you may just be reading
case temperature where it is now.
Click to expand...

From what I've read it's a pressure port, and the usual mounting spot for temp senders since doing anything with the pan is a pain (I had to order a drain plug adapter all the friggin way from England). During the summer the temp range was as it should be, 150-170 pretty consistently, think a touch over 180 when towing a couple thousand pounds. I'll step up getting the sender relocated. I can make up a blockoff plate for the addon cooler easily enough, any advice on long-term solutions? Replacing the radiator is probably not an option, as I hear Nissan has been dragging it feet about acknowledging the issue. Anyone make a 12vdc pan heater?
 
I don't think you need to go to the extreme of a heated pan, with the sensor in a pressure port you are not getting a true oil temp of fluid returned to the pan. I would run it as is and put the sensor in the pan as time and money allow. You are almost assuredly running at or near the normal temp of this unit as the air to oil cooler is probably not as good as water to oil in most circumstances. At least this has been our observation over the years.
 
an air cooled cooler doesn't heat the fluid the way the rad does.. the rad is gonna bring it up to thermostat temp/operating temp...
 
ryoken said:
an air cooled cooler doesn't heat the fluid the way the rad does.. the rad is gonna bring it up to thermostat temp/operating temp...
Click to expand...

Exactly. Lots of people forget about this double purpose of the radiator "cooler" .
 
ryoken said:
an air cooled cooler doesn't heat the fluid the way the rad does.. the rad is gonna bring it up to thermostat temp/operating temp...
Click to expand...
DING DING DING DING, ryoken win's again.:bow::bow::thumb::thumb: I was gonna mention this, but, once again I lost.:D:D
 
yup, I learn my lessons... it was killer on hot summer days... but having the cooler just cooling off the rad warmed fluid in the winter is the way to go... might not run quite as cool on hot days as the aftermarket only setup does, but when it was 20 degrees out that stuff took FOREVER to get some heat to it with just an aftermarket.... I'd drive for an hr and it'd be at like 110...
 
Yip, I agree with all that is said. I have my temp gauge sending unit in the port on drivers side just above the pan. When my TQ wasnt locking up, my temps would go alot higher than when it locked up, so I know this location sees the differences in temps.

Ive got an aux cooler in the front of rad. but ive still got the factory cooler running thru radiator..My trans stays at a nice temp and I can idle and put around in the woods for hours with no issues.
 
Soaking all this up here... are there any alternatives to keeping the tranny warm enough without the radiator cooler? I'm getting the plumbing for my suburban diesel swap planned out, and was planning to skip the radiator cooler there too, among other oddities. Just seems to inefficient to me to try to cram a radiator, ac evaporator, tranny cooler, oil cooler, PS cooler, intercooler:laugh:, etc, all into the same few square feet of grill space. And after hearing about the issues with the Nissan cooler leaking antifreeze into the tranny, I'm really leery about the mixing of fluids too (the part of me that's seen Red Dawn one too many times doesn't like the idea of having to replace the tranny too when if the radiator gets all shot up by Russian paratroopers :doah:). The 'burb's got a TH400 anyway, so without a lockup converter lack of heat might not even be an issue.
 
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there was talk awhile back about running a thermostatically controlled bypass... which to me sounds like a horrible idea... talk about fail points and a nuked, literally, trans waiting to happen..

it's possible running just a cooler out of direct airflow may let the temp come up, but after my experience, I'm doubting it..
 
ryoken said:
there was talk awhile back about running a thermostatically controlled bypass... which to me sounds like a horrible idea... talk about fail points and a nuked, literally, trans waiting to happen..

it's possible running just a cooler out of direct airflow may let the temp come up, but after my experience, I'm doubting it..
Click to expand...

Yeah I see "DOH!" written all over that too. I was thinking something like a plug-in pan heater, only DC & temp & master switch controlled.

Speaking of out of direct airflow... On my burb I'm planning to mount the tranny & oil coolers under the truck, between the drivetrain & framerail, at an angle with great big fans. They put bus radiators on the side with great big fans, can't be that outlandish...?:D
 
I see your points, but really, the stock style radiator cooler is the best method to heat the fluid.
 
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