What happens if I cut the transmission cooler line?

Glend · **Posted:** Sun Jan 17, 2010 6:11 pm

Strange subject line I know. I am about to fit my B&M tranny cooler (auxiliary to the stock primary one). I will also be puttng in a Temperature gauge (probably on the return line to the tranny). When I go to cut the line what should I expect? Will it hold pressure, will it drain the entire tranny? I have heard that there is a valve that stops cooler line flow when the vehicle is in park, neutral, off etc, so am I only going to have to deal with the tranny fluid in the lines and primary cooler? Just trying to get an idea of how big a mess to expect. Anyone have some experience with this?

:?:

dthdcrd · **Posted:** Sun Jan 17, 2010 7:13 pm

I just installed one. Just a few drips no big deal. I used brass barbed fittings and had them ready. Cut the line slipped the hose clamps over and pushed on to the fitting.

Good luck.

kskj · **Posted:** Sun Jan 17, 2010 11:37 pm

Same here just made sure I had all the connectors ready and only had a few drips.

geordi · **Posted:** Mon Jan 18, 2010 12:57 am

which line is the outlet from the transmission to the cooler, so the fluid is the hottest for a temp probe?

Silverdiesel · **Posted:** Mon Jan 18, 2010 1:34 am

Yep just a few drops...

If you run an aux cooler may I suggest to run the new cooler in series AFTER the stock one. IOW to cut and connect to the return line. Way to tell is run Engine for a few minutes and then hand feel for the colder line. Another way is that the return(Colder) line always exits the radiator assy (radiator,CAC,A/C condenser,trans cooler block of finned stuff) furthest away from the top opening (radiator cap or line to expansion bottle).
An Aux cooler is just that. Let the system do its thing then help it further with this mod. This allows the Aux cooler to be mounted in front of everything including the electric fan.

Roland

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

Geordi,

The top trans line on the 45RFE is the "hot" line. The most accurate temp reading is a sensor located in the transmission sump. The trans pump is not always delivering the same flow rate through the cooler lines, it depends on the trans fluid temps and if the trans is in "lock-up" or not.

geordi · **Posted:** Tue Jan 19, 2010 8:29 pm

Hmm. I was thinking of the cooler lines b/c that would be an easy place to locate a probe, rather than poking holes in the pan. I do admit that the pan would be the most accurate place to read from... Is there a specific spot on the pan that is safe to locate a probe that will poke into the sump of fluid without hitting anything? That is what scares me the most - I want to know it will fit BEFORE poking any holes into a perfectly good tranny pan.

Or... Does the PML pan come with a bung for a temp probe... And maybe a real drain plug?

Glend · **Posted:** Tue Jan 19, 2010 10:06 pm

Yeah I get what GDE is saying, however tapping into the fluid return line with a T fitting is a way less work (and way less messy) than dropping the pan to place a fitting in there. I can't see how you could put a probe into that thin metal pan without a nut on inside. In my thinking the fluid coming back from the cooler is going into the pan anyway. However, I am going to get the fluid changed anyway since installing my B&M auxiliary transmission cooler, so maybe that represents a chance to put the probe in there. So as Geordi says, where is the best spot for it?

What happens if I cut the transmission cooler line?

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