Where is the gearbox leak?

[Lars S]

Every time I lift my 412 in the rear it slowly starts dripping from the front end of the manual gearbox.
The input shaft from the shifter is dry aswell as inside the big rubber boot.

So Im wondering which gasket or seal can be leaking?

Three oil drops circled

Nothing obvius can be seen through under the backseat inspection hole, the big plug is tightened well.


/Lars S
_________________
Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold

[raygreenwood]

Good detective work so far!

But, on your 2nd picture of the plug, notice that there is some oil and grit in the lower recess area of the big screw plug at about 6 o'clock position. There is also an odd little bit to the left of the nut at 12 o'clock and underneath the bracket that supports the clutch slave hose.

Under that flat bracket .....is the vent hole for the transmission. If you had the car on a slight left hand incline when last filling up the transmission with oil, it can have a small amount too much and when outside temps are high and/or when also driving down hill roads quite a bit at speed,l....it can push small amounts of oil out of that vent hole.

If you can reach it, you can remove the nuts at 9 and 12 o'clock and get a better view of whether there is wet oil in the vent hole.

The only other thing I can think of that can and does happen ....is if the last time you had the transmission out for one reason or another, if it got in a bind while you were moving it or got bumped hard enough, the long tail cone with the shift rod that protruded through the rubber bumper can get cracked right where it joins the housing and will have a very slow seep or drip.

Ray

[Lars S]

Thanks for your input Ray!
Yes, when filling gearbox oil, I like to jack up the same side of the car as where the fill plug is so a slight overfill may be possible.

Also when you mention the vent hole...never knev where it was....it might be so that my "poor mans lift" gives the car a to steep angle so the oil reaches the vent hole even at correct oil level...it must be a very high oil level in the cone at this angle Im afraid...


/Lars S

_________________
Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold

[raygreenwood]

[Lars S]

Got rid of the bracket in front of the vent hole and, yes, oil is seeping out there!
Since I often use my "poor mans lift" at the rear Im planning to insert a short 90degree tube or pipe pointing upwards a couple of inches (poosibly going through the sheet metal) so that the oil level never reaches the top of the tube.

Thanks again Ray for helping me finding out this leak!

Also note the black sealant, applied at factory 50 years ago around the sheet metal screw holes to make it water tight, still present!


/Lars S
_________________
Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold

[raygreenwood]

Nice lift!

Yes, doing something similar with my very first manual trans 412 (using a high lift floor jqck and high jack stands) are how I first discovered there was a vent hole! It leaked all over my floor.

Ray

[Lars S]

Goodbye oil puddles!

(I will route the transparent hose up a bit under the backrest).


/Lars S
_________________
Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold

[Pepperbilly]

Nice investigative work here! I love figuring out these problems. Your tubing solution looks interesting but I have to ask why is it leaking in the first place? Was it overfill or something else? The factory never intended it to leak so much.

Bill

[Lars S]

[Pepperbilly]

Got it. You need to consider a full lift. I like my BendPak scissors lift. Very portable and lifts level. I hate crawling on the floor anymore.

Bill

[Lars S]

[Pepperbilly]

Lars S,

When fully up about 5 feet. I can sit upright on a regular chair under a car and I am 6’3” tall. I love it. By the way, that photo is 2 years old while restoring Goldie. She looks a whole lot better now as I am sure you know from reading my threads. Goldie is almost just as much fun as driving my ‘95 993! Certainly not as fast but the smile per mile factor is the same.

Bill

[Lars S]

Bill, 5 feet, thats a lot!!! Unfortunaly my workshop suffers from a low celing (old stable) cant lift a car more than 3-4 feet...
Yes, I have the same experience with my 914...I rather drive my 412 ( thats part of why I just donated the 2056cc from my 914 to the 412 he he).

Goldie looks great!!

Lars S
_________________
Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold