Help! Level the Car or Diff. for fluid refill??

[slipnfall]

Hi there, This should have been such a simple task... 120k on my '92 S13 M/T, and so I decided to change my open diff fluid(99% likely it's original) just for peace of mind. Well I drained out about 1qt+ with the front end on ramps. Drain plug had minimal sludge, so there didn't seem to be excessive wear.

Anyways, I bought two quarts of Valvoline SynBlend 80W90 to refill. I called a local transmission shop and my dad to ask about refilling. I wasn't sure because the diff isn't level when the car is(it tilts towards the rear). Both my dad and the shop told me that the car should be level, *not* the diff. I fill it up, letting it stop dripping out the drain plug, so it should be level with the hole. This is the way the FSM illustrates. I also noted I could not refill with nearly as much fluid as I drained out.

I take it for a test drive filling it this way, and about 2miles down the road get the most gawd awfull screeching from my rear end. I knew immediately that it must be low. Drove another 1/2mile gingerly and called for some help(gotta love women... ).

Jack the rear way up, squirt some more fluid in, and plug it back up. The 2+ mile drive back home was better.

So WTF... Should I put a bubble level on the bottom of the diff, then refill(this was my original assumtion, but this is what I get for trusting the 'professionals'. The FSM wasn't very verbose about the leveling.

Also when I pulled the drain plug originally, I heard a 'hiss', like air entering or escaping. The transmission shop told me that the fluid will foam, so re-check the level later. Is this what the vents are for, to vent air outwards? How can I check that my vents are clear? He also said that over-filling will force fluid out the vents.

Thanks for reading folks...-Jamie

[slipnfall]

OMG I hope I didn't just do what I think I did... I didn't *see* a fill plug- I thought the fill plug was the same as the drain, like the M/T. Is there a seperate fill plug??

Sheesh, I'm gonna go look again...

I'm such a 'tard if this is the case...

[slipnfall]

Ok... it's official: I shouldn't work on cars...

If anyone stumbles across this, yes there is a seperate fill plug. Driver's side, near the rear. It's a PITA to get to, you'll need a 1-2" 1/2" extension, no longer, no shorter.

If you don't feel like putting the entire car on jack stands, raise the rear, fill with 2liters, and slowly lower. Let excess drain out, raise again, and plug the fill hole.

What a mess...

-Jamie

[NISTECH]

DUDE I am sorry but you literally brought me to tears on this thread.

Thank you!

[slipnfall]

haha... well I'm glad someone got something outta this thread.

I'm going to recheck the level later this week, but my rear end is noticably noisier, esp at cruise in 3rd... trade-off from a syn-blend?

[NISTECH]

it shouldnt be noisey at all. usually when I fill them they are on a hoist, the car is pretty much level at that point. If you got nois you may have done some damage to the bearings running them dry.

[slipnfall]

mmm, great. The noise isn't horribly loud, I only notice it between 35-45mph. Just a whirring sound when I'm on the gas... goes right away when I let off and coast.

Well I was planning on upgrading from an open diff eventually, so I suppose as long as it lasts me untill then I'll be OK. I might as well swap it when I get the time/money to rebuild my m/t.

Thanks.