A523 leaking somewhere over differential case area

[pauly_no_van]

Been driving my 89 van with a 5 speed conversion since august now with no issues until...
I passed somebody going up a hill in 3rd gear at ~18 psi and noticed a small puddle beneath the diff housing in my drive the next morning.
My combo is stock with garrett t2 light porting of intake and exhaust IC and Shelgame flashable ecu.
I have not installed a 4th engine mount yet, I do have a stiffened front engine stabilizer.
I did some searching here and nobody seems to have a documented breakage of a trans case/diff housing at my power level with an a523.
I removed the top cover of the transmission and noticed that the top shift lever pinion shaft seal has been leaking probably the whole time and spilling oil into the empty spaces above where the diff housing is bolted.

The question to you manual breaking experts is, did my going up a hill more quickly under power for the first time simply cause the collected oil to spill down the sides of the diff housing, or did I crack something?
The drive shaft seals are dry, everywhere I can look on the outside of the transmission seems to be intact.
There is no indication in it's operation that it is broken in some way besides the freakishly instant oil spillage.

[pauly_no_van]

Found the leak.
I broke the diff cover its cracked right in the middle from one of the middle two bolts and a bit toward the pass side axle.
Further inspection suggests the case is cracked
I checked and re-checked the torque on all the bolts when I had it out of the vehicle.
So, in my case, full weight minivan with an a523 - 155k miles mfd 1992 blue plate 6 puck tu clutch - might break if you spike 20PSI with a garrett.
Is this common with vans?
Not sure what my next move should be. I am not about to get another diff cover only to likely break that too, I am not done turning up the boost even....
:/

[cordes]

I would inspect the bearings before moving on. They seem to be what ultimately causes the case failures. As they allow for more movement between the shafts it puts more load on the case than it can bear. Really, a 3.77FD 523 is the 2nd strongest trans you can use.

[135sohc]

The lack of a bobble strut to keep the transmission from flopping up/down during clutch operation with a heavy vehicle and lots of power probably shifted/shocked everything and it let go.

[Vigo]

I would not presume to be able to lay blame on power. Sheer power doesnt even break these cases at 500whp. It had to be an 'abnormal' load from something else. Shock load from wheelhop or a clutch dump or the cover being tightened down over some little piece of something that shouldnt be there, etc.

[pauly_no_van]

I would not presume to be able to lay blame on power. Sheer power doesnt even break these cases at 500whp. It had to be an 'abnormal' load from something else. Shock load from wheelhop or a clutch dump or the cover being tightened down over some little piece of something that shouldnt be there, etc.

I am sorry if anybody feels hurt by me sharing my experience with this thing. Just trying to help.
I don't presume or brag
Somebody else here mentioned 200 foot pounds being the input limit on this trans, so power would be a reason for this failure if that is true.
No clutch dump Ever, i babied it
The clutch IS quite grabby though, over stock. It was hard to keep the releases totally smooth all the time.
It wheel-hopped only once a few weeks ago since I put it in.
On assembly The parts were all clean, I am very particular about that.

Maybe it was fatigue from not enough support, too much movement?
I can see that.
it is still too delicate IMO, if it breaks because there is no shock absorber at the back,
and I put 20psi to it once or twice.. It could have been near to failure from before I got it too... Boneyard...
When the incident happened i was in third gear a while - just keeping up, then I hit the gas and passed.
I waited for the hill to start before passing because I wanted to see what would happen.

[wallace]

The lack of a bobble strut to keep the transmission from flopping up/down during clutch operation with a heavy vehicle and lots of power probably shifted/shocked everything and it let go.

I agree. Think about how a rwd engine is mounted it has one on each side of the engine to limit the movement under accel and decel. It's a similar situation on the fwd and with a stick and aggresive driving the engine probably moved so far that the CV shaft alignment bound and with that long lever of the shafts against the diff it broke the diff. I would add a bobble strut.

[5DIGITS]

I would inspect the bearings before moving on.
They seem to be what ultimately causes the case failures.
As they allow for more movement between the shafts it puts more load on the case than it can bear.
Really, a 3.77FD 523 is the 2nd strongest trans you can use.

I agree.
Worn bearings and/or improper bearing pre-load allow the gear-train to separate which loads the gears and the case abnormally.

BTW:
There was a TSB (technical service bulletin) long ago for the 523 and the 568 that installs an extension tube between the case and the vent.
In extended third gear operation and especially at higher speed the oil sling from the gear set would 'burp' from the vent and leak, down the top/back of the transmission case.
The nearly two inch extension raises the vent upward and provided a enough distance for the oil to run back into the trans, before coming out of the vent.

[Vigo]

Somebody else here mentioned 200 foot pounds being the input limit on this trans, so power would be a reason for this failure if that is true.

Non sequitur. I've had my 523 2.5 van to 20 psi once or twice as well, why hasn't it broken?

If this one failure was really any evidence of the 523 case being subject to a repeatable failure at that power level, it would already be old news because 100s of other people would have posted about the same thing happening to them over the years.

I would just put another diff cover on it and keep going. Most likely, whatever caused that crack will not happen again.

[Ondonti]

People who make claims of small amounts of power being the limit of something drivetrain related 100% of the time don't even make that much HP. Even a 525 will handle more then that and I have seen it for years and that same car recently sold still functional.

[pauly_no_van]

People who make claims of small amounts of power being the limit of something drivetrain related 100% of the time don't even make that much HP. Even a 525 will handle more then that and I have seen it for years and that same car recently sold still functional.

These are all things to think about.
I will cover exactly what got broken with pictures as well as pictures of any part someone might want to see in this thread once I take it apart.
Apropos, the diff preload is what it was when I got it from the yard. Good or Ill TBD.

[Vigo]

Cool. Good info is always appreciated.

[wallace]

Your van weighs almost double what a l-body does that has a big impact on the durability of the parts. Interested to see what you find is wrong/broken.

[135sohc]

diff cover is machine matched to the case, like main bearing caps on an engine block.

[shackwrrr]

After reading this thread I had to test the durability of my 523 in my van. 18 psi, 4k drop and no lift shifting, still works lol. Sucks that you broke it, sometimes this crap happens, I had a 568 in my old shadow and I killed it, a ring gear bolt backed out and destroyed the case, the diff pin had also broken loose but somehow stayed in the diff. I all depends on how it was was put together that day and how it was treated for the 100k+ before you got it.

[pauly_no_van]

BTW:
There was a TSB (technical service bulletin) long ago for the 523 and the 568 that installs an extension tube between the case and the vent.
In extended third gear operation and especially at higher speed the oil sling from the gear set would 'burp' from the vent and leak, down the top/back of the transmission case.
The nearly two inch extension raises the vent upward and provided a enough distance for the oil to run back into the trans, before coming out of the vent.

This post has been bothering me for a while, so I just looked this up:
http://www.turbododge.com/forums/f4/...-question.html

I put 2 quarts in this thing when I put it together in August. I had not added a drop thus far, it appears to have enough if the hole in side cover is any indication.
At the time of the incident, There was quite a lot of oil spilling from the vent-which is also called the crossover shaft.
It had pooled in the casting over the diff and spilled over and down the back of the diff.
At that point I shrugged it off as a vent leak.
Then I looked underneath just to be sure. I wiped the case clean, but it appeared to be coming out of the diff cover.
That is the reason for post 2.

Now, that was a while ago, there had been no more on the driveway since then, so I drove it the last two days.
Now there is no leak. No abnormality of any sort.
I am losing my mind . .