Technical Transmission leaks only in reverse

[unfacedman]

Hi everyone!
I have a small leak of oil from my gearbox (manual. C514), likely from the main shaft bearing seal.
But the strange thing i've noticed - the leak appears, allegedly, only when I drive in reverse.
Only then I do smell a slight odor of the oil, and afterwards can find some drops on beneath.
Does it makes any sense?

 

[koalar]

Any other symptoms

What part of the engine is the oil dipping from

If it's from the imput shaft the inside of the bellhousing will be wet on the inside

There's an inspection hole it may or may not still have a cover

There are other places it can leak from if it the gearbox

Selector and drive shaft are common

There's a couple on that side of the engine that are also common


If it's not wet inside the bellhousing it's best to degrease and then inspect to find the source

 

[unfacedman]

Thank you for your reply.
I can find the drops on the lowest point, the forky 2 bolted mount of the bellhousing to the lower gearbox mount.

 

[koalar]

Engine off

Put your finger in the inspection hole in the photos above

If there's oil on the inside, then you need a new input seal and possibly bearing

Otherwise we need to be looking elsewhere

 

[Yolanda]

Hi everyone!
I have a small leak of oil from my gearbox (manual. C514), likely from the main shaft bearing seal.
But the strange thing i've noticed - the leak appears, allegedly, only when I drive in reverse.
Only then I do smell a slight odor of the oil, and afterwards can find some drops on beneath.
Does it makes any sense?

No it doesn't make any sense to me. The gearbox oil is not under pressure the same as the engine oil. So I'm baffled as to how you can only smell it when in reverse. You may well have an oil leak but unless you clean everything off then go for a bit of a run you won't find the source.

 

[jackwhoo]

I think the vent fan only sucks the smell in when moving backward

 

[Yolanda]

I think the vent fan only sucks the smell in when moving backward

How do you mean?

 

[jackwhoo]

How do you mean?

When moving forward air flow over the vehicle is front to rear. The airflow blows gearbox smells beneath car away from air intake for cabin

 

[Yolanda]

So therefor when the car is moving backwards the air flow is rear to front blowing any smells forward away from the cabin.
Anyway, let's not get to involved with the movement of air and see with the help of the op where the oil is leaking from.
Hopefully he'll get back to us soon with an update.

 

[jackwhoo]

When car is moving in reverse smells from engine bay (and exhaust) are much more likely to enter the air intake for the cabin due to turbulant air flow toward the cabin air intake.
The original post mentions gear oil odour in cabin when vehicle reversing.

Many vw Audi group vehicles automatically switch cabin air vent system to re-circulate cabin airWhen reverse gear is selected to stop vehicle smells entering the cabin.