Originally Posted by 9296D21B14

92 D21 2.4 w/auto. Had rear differential fluid changed a few days ago, level was a little low, and it was slightly milky in appearance. Mechanic said possible water contamination. No performance issues in the drive train. I have used this truck to trailer and launch a small flatboat and the diff does go under water at the boat ramp at times. I noticed a small fitting to the top left of the diff housing. Is this the vent? Can water enter the diff housing through the vent? Is there a way to fit a short tube to it and run the tube higher than the vent position on the diff itself? Will doing so interfere with proper venting? I've heard this is something that offroaders do at times for this problem. Or is there another way to temporarily seal the vent during ramp use? Any help is appreciated!