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Trans temp gauge installed...temp seems low.

1K views 11 replies 6 participants last post by  Casey_1 
#1 ·
I did the shotgun method, so I have no previous data. I installed a new PML oversized trans pan (with cooling veins), drilled and tapped the pan for the sensor, installed the sensor and new temp gauge (in a nice new A-pillar). Checked that the gauge was getting voltage. Have all the grounds at the same terminal, meaning the gauge lights with the ground used. and voltage is going to the other positive terminal that I figure does the temp reading. Today on the way to work (only 25 miles, 45mph typical speed) the trans temp MAYBE got to 100, which is the low end of the gauge. Basically, the gauge barely moved, but did move the smallest of bits. Temp in the AM was around 39 DEGF. This sound reasonable? I have not installed any larger cooler yet, but was planning to do that. But now I wonder if I need a larger cooler. Can you have too much cooling? Meaning, is too cool a bad thing? Is my gauge working? How do I tell other than drive it longer, on a hotter day?
Thanks.
 
#2 ·
Sounds normal to me. Mine seldom gets over 100 on short trips at this time of year unless I am towing. I doubt Virginia at this time of year is that much warmer than SE Michigan. Wait 'til next summer. You will have no problem seeing the gauge move. If you cannot wait, you might hook up to your nearest heavy trailer and pull some hills.
 
#4 ·
Thanks. Great. Now, second question.... I saw a post, I think in the mods section, where someone said only install an extra cooler IF you need it and ONLY IF. What is that all about? I hadn't read that before I ordered my extra cooler (of course), so I have it and was going to install it........
 
#6 ·
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Thanks. Great. Now, second question.... I saw a post, I think in the mods section, where someone said only install an extra cooler IF you need it and ONLY IF. What is that all about? I hadn't read that before I ordered my extra cooler (of course), so I have it and was going to install it........

[/ QUOTE ]Well, an additional cooler could add a significant restriction to your flow of ATF. It would depend on your flow rate. So I would not add it unless you have evidence that you need it. I am sure Casey_1 knows of other good reasons.
 
#8 ·
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The extra restriction is the biggie. Getting your trans fluid too cold in very cold weather can be a problem, too. It IS possible to get the trans fluid too cold. Been there, done that, a C6 trans on fire!

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Now I know why my tranny temps read unusually higher in the winter months compared to the summer. But isn't there a by-pass in the stock coolers for when it's cold to keep the temps warmer? Now I'm confused. /ubbthreads/images/graemlins/shrug.gif
 
#9 ·
Well, I've got a very nice cooler I purchased sitting on the shelf in my shop. I guess now I wait until summer to see if it is needed....or maybe replace the stock cooler with this larger one. Where I bought the cooler stated on their web to purchase the NON-BYPASS version for my truck. Maybe I should have purchased the bypass version..... seems like there are many variables to consider. Oh well, it was only money.
 
#10 ·
BikeRider, you might want to add a sig with your truck details - it will help folks answer your questions. Pre-2001 trucks, like mine, don't have the 'in radiator' OTW tranny cooler, just an OTA external cooler that is smaller than the V10 or 6.0L versions some upgrade to. The OTW cooler improves hot weather, high temp performance [e.g., when the tranny temp gets to 200F or so ....]. Like you, I have a nice replacement OTA cooler sitting in the garage. Despite hauling a GCVW [with horsetrailer] of 16-18k], I've only seen temps exceeding 200 on rare occasions [hauling heavy, slow, uphill, ambient temps in th3 90s] and hit 230 maybe once, for maybe ten minutes. Even towing, I'm usually only +70f over ambient - no where near the 220f+ that would lead me to add cooling power. Chill out and see what your tranny temps are on the hot days next summer, when you are towing heavy and slow; that will tell you whether you need to take additional steps.
 
#12 ·
[ QUOTE ]

Now I know why my tranny temps read unusually higher in the winter months compared to the summer. But isn't there a by-pass in the stock coolers for when it's cold to keep the temps warmer?

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The 4R100 does have a bypass that will keep fluid flowing to the lube circuit if the fluid is too cold to flow through the coolers. The reason it can get hotter when it's cold is that the fluid can jell in the cooler and nothing will flow through it. Now all the fluid bypasses the coolers and the trans operates with no cooling. If you are working the trans it needs cooling, even in the cold.
 
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