T6.1 Manual 6-Speed Gearbox Casing Seep / Loose Bolts?

[EdH]

Hi all, looking for some feedback/experience from the group.

I’ve got a 2020 T6.1 Transporter (CXHA 150 Engine, 6-speed manual) with low mileage (15,000 miles) campervan. We had it from brand new. It's not a daily driver just for the camping trips, hence low mileage.

Before April, I noticed a bit of a greasy oil-dirt sweat on the lowest section of the gearbox casing split-line flange, and stain mark on the undertray. Cleaned it with a degreaser to monitor. However, after a long run this weekend from Bala back to Newtown (Mid Wales), it started again with a slight drip onto the plastic undertray from the lowest casing bolt. I run my fingers over it and it was a slight clear oil residue, no smell just clear oil, not much at all. I have read somewhere on the forum that apparently gearbox oil smells.

I’ve had the van up on ramps immediately and checked thoroughly, the entire gearbox casing as far I could see is dry, oil filter housing, completely bone dry, can't see anything that it would drip. The issue is strictly isolated to the bottom of the casing seam when I touch it earlier.

Interestingly, when checking the casing bolts around that lower flange, I managed to get 1 or 2 notches of movement on the ratchet to tighten them up (they weren't spinning loose, but they definitely weren't fully tight anymore). I’ve now blasted the whole area clean with brake cleaner to monitor it.

Has anyone else experienced torque relaxation/loose casing bolts on a low-mileage T6.1 causing a seam weep? If it keeps seeping despite tightening the bolts, has anyone successfully sealed it externally with RTV silicone, or did it require dropping the fluid and splitting/resealing the case?

I am at loss what it could be to be honest for a such a low mileage campervan?

Any advice or shared experiences appreciated before I book it into my local garage. Cheers!

 

[PhillH]

Hi there, have you checked your brake fluid reservoir level? Looks like the slave cylinder inside the gearbox is leaking. Or rear crank oil seal. It would be a suprise with such low mileage.

 

[EdH]

Hi there, have you checked your brake fluid reservoir level? Looks like the slave cylinder inside the gearbox is leaking. Or rear crank oil seal. It would be a suprise with such low mileage.

Yes, brake fluid fine, no losses there at all.

 

[EdH]

Some more photos of underneath. I just can't find any leaking from anywhere else, bone dry

 

[Dellmassive]

gearbox oil stinks - its very distinctive once you have smelt it.

engine oil will be black in appearance. (has it has its first service from new 10-12k miles? - is the dipstick oil black?)

brake oil is normally clear - and also has a distinct smell.

you will need to clean and monitor again.

i also used leak detector spray to try and locate a DSG leak - that ultimatly just dried up itself.

++

could it be overspill from the last fill up?

its going to be tricky to find. . . you will have to just keep cleaning, documenting with pics and re checking.

++



.

 

[EdH]

gearbox oil stinks - its very distinctive once you have smelt it.

engine oil will be black in appearance. (has it has its first service from new 10-12k miles? - is the dipstick oil black?)

brake oil is normally clear - and also has a distinct smell.

you will need to clean and monitor again.

i also used leak detector spray to try and locate a DSG leak - that ultimatly just dried up itself.

++

could it be overspill from the last fill up?

its going to be tricky to find. . . you will have to just keep cleaning, documenting with pics and re checking.

++



.
View attachment 327556

Definitely not engine oil leak as its clear almost yellowish oil (like brand new engine oil), no smell either. I checked brake oil level, all fine but it doesn't smell either (I really couldn't smell it).

The campervan had 4 services with the VW, and I carried out oil/filter change this April and that's when I noticed the large oil stain on the undertray and kind of oil misting along the bottom of the gearbox seam. Cleaned it with a brake cleaner and dried it off. Yesterday coming home from Bala (2h drive or so), I noticed this little drip on the bottom of the gearbox seam where that black silicone is, it was tiny drip still hanging out on the seam.

When I was changing oil I was super careful not to spill any new oil and used a proper oil filling jug, so definitely it's not that.

I was really surprised that I was able to tighten the bolts along the seam bit more, hence I thought that it could be dripping the oil from the gearbox.

If it's brake oil where it could be coming from (brake oil was changed last October during the MOT).

I am at loss to be honest, I I felt it with a soft paper tissue all around and to the top to see if it dripping down from somewhere else and then down over the gearbox casing, absolutely nothing.

 

[Dellmassive]

Just time and monitoring will tell....