NSBU switch leaking fluid? - Diesel Truck Forum - TheDieselGarage.com
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post #1 of 6 (permalink) Old 03-10-2010, 05:20 PM Thread Starter
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NSBU switch leaking fluid?

Has anyone experienced the NSBU switch leaking transmission fluid? I either have a bad transmission pan gasket (is getting replaced this week) or the NSBU gasket or seal is leaking. Those are the only 2 things I can figure out that is leaking cause of the location of the leak. It isn't leaking very much fluid and only when I am moving.

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post #2 of 6 (permalink) Old 03-10-2010, 07:14 PM
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Have you checked the lines going to the cooler, I know they leak on newer trucks not sure on a '03.

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post #3 of 6 (permalink) Old 03-10-2010, 11:34 PM
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The LB7s arent known for leaking cooler lines, i'd bet its your pan gasket.


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post #4 of 6 (permalink) Old 03-11-2010, 01:34 AM
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Mine has a small leak there as well. It's the shift shaft seal. I've replaced mine 3 times now and it still leaks. I ended up putting 2 seals into it and it just barely drips now every once in awhile.

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post #5 of 6 (permalink) Old 03-12-2010, 07:38 PM Thread Starter
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Thanks for all the suggestions and comments, I have replaced the seal and am waiting now to finish my transfer case rebuild to fill it up. I also noticed that there had at one time a leak from the top of the transmission, guessing there is an overflow of some sort up there or breather, but that is all dirty and not clean. That or the PTO cover has had a leak. I will keep replacing a seal at time till she stays dry I guess. Thanks again guys. don't feel it is coming from the cooling lines, it is coming from the other side of the transmission.

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post #6 of 6 (permalink) Old 12-08-2010, 03:45 AM
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Did you ever resolve this? I seem to have the same problem on my 05 2500, ATF looks to be coming from behind the NSBU switch, and pooling all around the lip of the transmission oil pan before dripping off the back. Sure would like to hear about how it turned out.
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