: Differential fill plug under pressure upon loosening..

06-14-07, 06:29 PM
I drove my "V" for about 20-minutes, then i let it sit for about 30-minutes. When i loosened the differential fill plug, all i could hear was hissing from built up pressure. I have not seen this before, so i need to know if this is normal behavior or not with these new vent setups. :bigroll:

06-17-07, 02:38 PM
Unfortunately, it's normal, and for two reasons. One, the factory vent for the CTS/-V differential isn't big enough. Two, there's a spring and a valve in the vent that will only let pressure out if it overcomes spring pressure.

IMHO, it's a design flaw, and most likely the cause of pinion and axle seal leaks. There's a bulletin out right now that has us removing the vent cap/valve, and installing a hose and new valve onto the old vent. We've only recently starting putting them on, so no long-term tests to determine if this fixes the condition.

06-17-07, 03:17 PM
Thank you... You just gave me "peace of mind". My differential is brand new, and so is the vent. I was wondering if i got a bad vent.