Pumpkin low on oil

[TominMO]

Removed my T4's pumpkin fill plug and felt around as far down as my little finger would reach. No oil. Uh-oh, I says, bad juju. Drained the oil and refilled with a quart of Lucas, to the point it started coming out the fill hole. I had assumed the growliness I was hearing was rear bearings (which it still might be), but maybe the rear end being low on oil (about 1/3 quart low) was what I was really hearing. Hopefully this will stop or at least lessen the noise; will check tmw when I go meet the other Tom M.

[dlb]

iirc the rear diff takes 1 liter of oil but i don't think missing 1/3 of that would damage it. what i would consider is why it was low on oil at all. are there leaks at the axle shafts or where the rear driveshaft connects to the diff? if you take the axle shafts out to inspect the bearings, you should replace the seals while you're in there anyway. a tip for installing them: check the FSM regarding the depth of seal installation but if in doubt when measuring, leave it slightly further out than in. too far in and the there's not enough contact between the seal and the bearing retainer. too far out will wear the seal out faster so try to be precise but i'd rather have a seal last years than have to do it again the next day.

[TominMO]

Yeah, I think the diff is OK too. Why it was low is anyone's guess. Might not have been filled to capacity the last time. That oil is so thick that I don't think much would get by the axle oil seals. But I will be pulling the axles soon anyway, and expect I will need to replace the bearings, clean out the drain channels, and replace the oil seals. Seal drive-in depth is 5.6mm(!), or 0.22 inches. I plan to install them slowly, checking depth with something that I have previously miked the thickness of.

[Petros]

watch for slow leaks, I recently change my diff oil and likely it still had the factory oil at about 340k miles. I figured it was about time it got changed.

If it is a minor leak you can add a seal conditioner and likely that would solve it, or just check it twice a year until you know how fast it drops.

I do not think I would bother pulling a diff apart for replace the input seal for a slow leak. the axles seals are fairly easy however, so you should check that those are not leaking (just pull the drum off and inspect inside the center retaining for gear oil).

[TominMO]

Yeah, I don't know that the diff is leaking at all, but will check the usual suspects, and will keep an eye on the oil level. Next Ineed to check the tranny oil....

[dlb]

regarding the axle bearings, i found the best way to determine which side is making the noise is to put the rear seats down and lay in the rear cargo area while someone else drives. by just putting my ear near each side, i could easily tell which one was making the growl. sometimes it's clearer than others but that's the method i used when i really couldn't tell.

when replacing the trans oil, there are a few different approaches but a few crucial things. first, make sure to crack open a fill plug before draining any oil so that you don't wind up with a dry trans you can't refill. second, when refilling the trans, keep the rear drain plug undone 7-8 turns and only tighten it back up afterward.

since the t4 was the first car i started doing my own maintenance on, i thought all cars had trans magnets conveniently located on the drain plugs, and that all rear diffs had drain plugs. i've since learned that neither of these are the norm, and it only makes me appreciate the t4's maintenance-minded design even more.

[TominMO]

Thanks David. BTW my rear diff is dry as a bone at the input, so the seal there is probably good (enough).