What would cause the transmission to indicate fluid over fill & blow out vent when the proper amount of fluid was put in (& even after draining a quart after that?


Asked by Feb 04, 2014 at 06:18 PM about the 2001 GMC Sierra 1500 SL 4WD Extended Cab SB

Question type: Maintenance & Repair

2001 GMCz71 w/ 207,000 miles, well cared for.
mech tells me my xfer case has a little leak, cleaned it up & we were going to watch it.
700 interstate miles later, undercarriage coated. Took it to dealer garage. They say:
Blowing xmsn fluid out the vent tube. Did a xmsn flush; during flush they said they kept
having trouble, as if they were running into pockets of air. Got it flushed & filled. They ran
it & said: still blowing out vent tube & it showed over- full. They drained a qt out & same
thing - fluid level showing overfill & blowing out vent tube. (No loss of radiator fluid
level)What would cause this?

4 Answers

James Ramond

You don't believe the mechanic ? well cared for 200k miles, that don't stop parts wearing out .Sorry.


LOL, Jimmy! Yes, 207,000 good miles. I did believe there was a problem; just trying to understand what, exactly, would cause that particular issue. But your answer did make me feel better about buying a new tranny, cuz I plan on getting another 100,000 (and if its not failing now, it probably will before I am done with it!).


But, if anyone knows of something else that could be the cause that a new tranny won't solve, please clue me in! Oh, also having all the seals in the transfer case replaced, while they are at it, just in case. Anyone know of anything else?

James Ramond

seals should correct the oil loss

Your Answer

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