Crack, a big social problem....worse in a 915

[sus911]

I was going great guns on my first valve adjustment (backside method thanks to 2.7 Racer).

I adjusted, rechecked and buttonned up the LH side happy with my progress.

Gave it a good clean then jacked up the RH side and started cleaning, feeling pretty confident I'd knock this side over quite quickly without exhaust in the way.

In my mindless preoccupation of cleaning, I wandered across to the transaxle where I spotted a few little grease splutters. Track day next Friday and Sunday so I thought ooohhhh..problem. Then in the corner of my eye, I could hardly believe what I saw:



and it doesn't stop there......check this out




This crack must be 6" long starting from the bottom of the diff. housing right up to adjacent to the drive shaft flange.

I guess I won't be racing next weekend, just dropping the motor a few weeks earlier than planned with a few more jobs to do.

I wonder how long it's been like this and should I risk driving it? The car runs beautifully and shifting is great. No oil leaks yet so I presume there is oil in there. I'll check that tomorrow. I also wonder if the small grease splatters are from the case opening at the drive shaft flange under load as I have not yet found any torn boots.

I am baffled how this happenned. The car is basically a mechanically stock '84 Carrera with 94k klms (55k miles in US language), owned by me for 20 years and well cared for.

Whats the casual prognosis from the Pelicanites? Will I be able to TIG it, JB weld or new casing? Our host doesn't list one so where from and cost? Australian dealers will quote me prices well into orbit I'm sure.

I'll heed advice but I'm thinking... give it a good going over- synchros, bearings and slip in a Modena LSD while I'm in there.

The WIIT for the engine may be a marriage breaker.....

[MBAtarga]

That may just be casting marks.

[Gogar]

+1 casting marks can look like cracks sometimes. Did it have any fluids coming from it?

Don't stop driving IMO. If indeed it is a crack, it's not like you're gonna do any lasting repair to it anyway. Drive it till it breaks, then get another.

Of course, it's easy to say that about someone else's car.

[IROC]

If nothing else, it looks like it's been there for awhile and not a recent development. I would keep an eye on it and "don't fix it if it ain't broke"...

[sus911]

Mark if these are casting marks, they are pretty serious ones. They travel completely around several reinforcement ribs.
You can really "feel" the crack at it widest part around the base of the housing.
Gogar, no oils leaks or any sign of them.
I am tempted to keep driving it and even track it next weekend.
What is the worst that could happen given that I would half expect something anyway?

[Mo_Gearhead]

If those are 'casting marks' Porsche needs to fire their tool and die maker.

Drive it till it breaks or you are ready to take it apart anyway.

Good luck with that.

[GaryR]

Originally Posted by sus911

no oils leaks or any sign of them

Did you drain and refill it? Last I read you were unsure there was any oil in there... Swepco will leak like crazy if given any opportunity.

[sus911]

Not yet, its late here but I'm sure there's oil in there. It's working beautifully and without oil I don't think it would, nor would I be able to hear the engine, for a little while at least until it seized.

[Porsche-O-Phile]

Those don't look like casting marks to me.

JB Weld time!

J/K. Sorry. Don't know what else to tell you.

[Quicksilver]

Look at the circled area.

There is really no way that a crack could come up through the middle of a rib and then follow it. The other part may be a crack but I would clean it very well and see if it weeps.

[TerryH]

From those pictures it could be anything from a crack to dried sealer. Use sandpaper or a file and get it shiney. If it were cracked as far as it appears, how could it hold together this long?

[shbop]

That sure looks like it's cracked to me. I'd replace it, asap.

[Zef]

Mine got the same pattern...and it was a casting mark...
Is it a crack ?

[RonDent]

I'd have to agree with Wayne. A crack wouldn't follow a rib like that. It would form at the base. Not run the length

[RetroSC]

Check out Zef's link. His is the exact same pattern as yours and is a casting mark.

If that thing was cracked like that you'd have fluid gushing out. Bill

[Superman]

Interesting. It sure looks like a crack but I can verify that transmission oil will go EVERYWHERE it gets a chance. It flows like MAD.

[cgarr]

If its a raised mark then its just a casting mark, this one does not look raised, is it leaking gear lube?

[rallyracer]

don't forget to reattach that spring.

[john walker's workshop]

kind of hard to split a rib lengthwise with a crack.

[Rich Lambert]

Hit that rib gently with a grinder and see if the crack disappears.