915 Gearbox Leak

[Crow911]

Bought a rebuilt grarbox for my 1986 911. New box 915/68 74F replaced 1986 915/73. swapped axle flanges from old box to new because I needed the 10mm bolt flange from old box to mate new box to 10mm axles. Took it out for drive around block to fine tune shifting set up and when returned to garage had a massive oil leak on floor and all over drivers side of box aft of the axle. Thinking it is the input shaft seal leaking, but the more I look at the pic, I am thinking it is the diff plate side output flange seal. During the drive there was zero slipping of clutch so no oil in the bell housing. thoughts? as you can expect the output flange seal does not require pulling motor and trans to address.

[john walker's workshop]

Missing mainshaft seal? The vent fitting on top of the diff housing needs to have its vent hole facing forward or lots of oil will blow out. Reach up and feel with your finger. You got swepco in there, too.

[Crow911]

Vent hole correct orientation (I wish is was that!). I think what I am going to do to hopefully minimize the work (removal of engine and trans) is to replace the diff side output flange seal and take it out for a drive. If no leak, success. If leaking, then it must be the input shaft seal so......engine and trans drop. I was just thinking that since I swapped the output flanges from by old box to the new, there might be a sealing issue on the diff side (other output flange dry as bone). Just can't imagine a rebuilder of the reputation where I got the new box from forgetting (or damaging) the input shaft seal.

[proporsche]

As John W. said..............btw is it me that the trans.look too low..axles seems to go up and the throttle linkage also .I do no know those mounts-blue-there seems to be too much space between the bar and body..am i wrong?Also the pace between the clutch cable ned and the throttle link is unusual big the cable is always just a little above it...how it the transmission shift rod in the tunnel Is it in the middle?

Ivan

[proporsche]

crow911...way too much oil to be the side seals,really

Ivan

[gled49]

It’s too dry around the drive seal at the side cover to be leaking there, that’s a massive leak, I vote for MS seal. Any chance it’s overfilled?

[Crow911]

not over filled. Shift shaft perfect in tunnel. I think my iphone and angle of pic distorted the view a little. The car is lowered.

[proporsche]

Originally Posted by Crow911

Bought a rebuilt grarbox for my 1986 911. New box 915/68 74F replaced 1986 915/73. swapped axle flanges from old box to new because I needed the 10mm bolt flange from old box to mate new box to 10mm axles. Took it out for drive around block to fine tune shifting set up and when returned to garage had a massive oil leak on floor and all over drivers side of box aft of the axle. Thinking it is the input shaft seal leaking, but the more I look at the pic, I am thinking it is the diff plate side output flange seal. During the drive there was zero slipping of clutch so no oil in the bell housing. thoughts? as you can expect the output flange seal does not require pulling motor and trans to address.

I do not know those mounts..are you sure you have them installed correctly ..??Looking at the net it seems like you do not....

Ivan

[Crow911]

better pic of axle. Those are Stomski solid trans mounts. They are exact same height as stock with bush installed.

[Ian Comerford]

It’s probably too big a leak to have come from this but the fill plug doesn’t quite look square in its hole and has a weep. Or have you just topped up?

[Crow911]

I had just topped off oil and installed fill plug not to full torque yet.

[proporsche]

if you drive it like this ,the oil will get to your clutch assembly ruining the dics
Ivan

[Crow911]

Ivan, agree with that if its an inpurt shaft seal issue.

[porschedude996]

You could set it up on jack stands and run it through the gears. Be very careful.

[yelcab1]

Got a cheap endoscope camera?

[Crow911]

yes, doing the scope this weekend to verify oil inside bellhousing.

[john walker's workshop]

Later ms seals are set deeper in the guide tube than early seals. The early installation tool is too short.

[proporsche]

i do have a feeling the spring on the seal is off...
Ivan

[BwshGulbleSheep]

Which brand gear oil is blue like that ?

[dannobee]

Swepco 201 is blue.

Could be that the garter spring fell off of the input shaft seal. Or that it was omitted altogether by accident.