C3 Diff Fluid Removal

enkeivette

enkeivette

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Mar 30, 2008
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Theyre repaving my street tomorrow so I thought it was a good time to change the fluid again.



I couldnt find my hand pump and it was getting dark... so I said fuck it, and I duct taped a hose to the end of my mini shop vac. Sucked that puppy dry in under a min. Then I just washed the vacuum out. The foam filter kept the oil out of the motor... winning.
 
Curiosity question....why does diffy fluid STINK so damn bad?? smell that shit 4 blocks away.....

and another related question....I put synthetic 30W engine oil in my Muncie years ago and it was fine, shifter SO much easier and ran for a couple years including a couple trips from DC to Jax on I 95 no sweat.....

SO, if I added the same fluid and some posi additive.....why not for the diffy also??? modern stick shifts use ATF, is what I hear....so why not???

shit, ATF has friction additives....would it work in a diffy?? why NOT???


:shocking:
 
Wayyy to light for a diff, if anything Id run 75w 140 over 75winter 90. But youd have to be crazy to run straight 30 in a diff.

TT, I didnt want to risk making the case any weaker. Im expecting it to grenade any min as it is.
 
The HD cover is beefier than the stocker, it should handle a drain plug just fine.... I drilled mine and use a NPT plug. Well, I had it off the car at the time I did that so i thought 'why not?'
 
MYBAD79 said:
The HD cover is beefier than the stocker, it should handle a drain plug just fine.... I drilled mine and use a NPT plug. Well, I had it off the car at the time I did that so i thought 'why not?'
Click to expand...

Did you drill it with everything put together? I don't see a good spot to get a drill in there to get a hole at the very bottom to flush all the metal pieces.

There has to be a ton of metal in there, being that the stubs wear 1/8" or more after a lot of miles.

As far as using motor oil in there, i think hypoid gear oil is just loaded with extreme pressure additives. That's why it stinks. It's a sulfur EP additive.
 
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I drilled when the cover was off, there are pics in my rear susp thread .... I even installed new stub axles (yokes) , it's better than new ;)
 
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drain/temp sender combo. This small 1/8 npt hole is more than enough to drain the fluid if you pull the fill plug. It takes a littel longer but being a small hole it should not compromise the setup. It's drilled so it's @ or very near the lowest point.
 
Twin_Turbo said:
drain/temp sender combo. This small 1/8 npt hole is more than enough to drain the fluid if you pull the fill plug. It takes a littel longer but being a small hole it should not compromise the setup. It's drilled so it's @ or very near the lowest point.
Click to expand...

My spring is in the way to do it there. That looks clean enough to eat off it.
 
IF you drill it with a small bit first and coat the bit with grease just before it goes thru, then drill to the final size, 99% of the chips get caught in the grease. Not enough of the chips get inside to cause any problem. IF you're really worried about 1 or 2 chips, a wire coathanger bent at a 90* and a magnet up thru the hole will catch anything that might have been left in there..
 
If you drill with the diff installed the draining fluid will flush all the drilling chips out ....

Use lots of grease when you tap the hole ...

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