Re: [VACList] Tow vehicle rear axle venting?

["Dash7 (Michigan)" <dash7_@xxxxxxxxxxx>]

In November of 1973 we purchased a new 73 Suburban 454 with a 3.73 to tow our 68 
Overlander.  They made a great couple.   However, when the weather got warm, 
driving at highway speeds for any distance  would cause the transmission to lose 
fluid out of the vent on top of the case in sufficient quantity to cover the 
front of the AS and the lower half of the tail gate.  No other indication of 
trouble, just a well oiled trailer.

The chevy dealer could find nothing wrong except the oil was coming out of a 
vent on top of the tranny.  He suggested I run it a quart low to see if that 
would solve the problem.  I was not too keen on that but since he noted it on 
the work order I agreed to try it.

While waiting at the dealership I picked up a brochure on towing with various 
Chevy vehicles.  That night,  I was reading about towing with a Suburban when I 
came across a note near the bottom of the page that said when towing heavy 
trailers it was necessary to run the tranny a quart low so that fluid expansion 
due to the additional heat wouldnât cause the fluid to flow out of the tranny 
vent!  There was no mention of this in the ownerâs manual.

Don (MI)