| Leak point | Typical engines | How it presents | Usual fix |
|---|---|---|---|
| Sump joint sealant | EA888 TSI, 2.0 TDI | Weep along the sump flange | Sump reseal |
| Drain plug washer | All engines | Drip from the plug centre | New plug and washer |
| Stripped drain plug threads | Alloy sumps | Leak soon after a service | Thread insert or new sump |
| Rear main crank seal | Higher mileage EA888 | Oil at the bellhousing join | Crank seal, not the sump |
| Oil level sensor seal | Sump-mounted sensors | Wet around the sensor plug | New sensor seal |
| Oil filter housing or cooler | 2.0 TDI, EA888 | Oil running down the block | Housing gaskets |
| Cam cover gasket | 1.8T, EA888 | Oil trail down to the sump lip | Cam cover reseal |
| Grounded or dented sump | Lowered cars | Sudden leak after an impact | Sump replacement |
Often you cannot tell from underneath, because oil runs back along the engine and drips from the lowest point, which is usually the sump. Leaks from the cam cover, oil filter housing, crank seals or the oil level sensor all end up looking like a sump leak. We degrease the engine, run it, and use UV dye where needed, so the part we reseal is the part that is actually leaking.
A light weep is not an emergency, provided you check the level weekly and top up with the correct oil. It will not fix itself though, and leaks get worse. A significant leak risks oil starvation, which damages camshaft adjusters, turbochargers and bearings, and a visibly dripping leak can also be picked up at MOT time. Booking a reseal early keeps it a small job.
On many VAG cars the subframe is lowered or supports are placed near the sump during clutch, gearbox and driveshaft jobs. Levering against the sump, or simply disturbing a joint that was already ageing, is enough to break the sealant bond. It is a pattern we see regularly. The fix is a proper reseal with full face preparation, not a smear of sealant along the outside of the joint.
Because that is how many VAG engines are built at the factory. Engines such as the EA888 TSI and common rail 2.0 TDI use an anaerobic or silicone sealant between machined faces instead of a solid gasket. Done correctly, with clean faces, the specified bead and the right cure time before refilling, it seals reliably for years. Done badly, it leaks within months, which is why preparation matters more than product.
Not always. Alloy sump threads strip easily when a plug is overtightened, and in most cases a quality thread insert restores a permanent, oil-tight thread for far less than a new sump. We assess the damage first. If the boss is cracked or the threads are beyond saving, we will tell you honestly and quote for a replacement sump instead.
Yes. The oil has to be drained to remove the sump and we never reuse drained oil. The engine is refilled with the correct VW specification oil for your engine, such as 504 00 or 507 00, along with a new drain plug washer. If your service is nearly due it often makes sense to combine the two, and we can fit a new oil filter at the same time.
Yes, if it is ignored. The leak itself does no harm, but the falling oil level eventually does. VAG engines rely on oil pressure for camshaft adjusters, chain tensioners and turbo lubrication, and these suffer first when the level drops. By the time an oil warning light appears, damage may already be underway. A reseal is cheap insurance against a very expensive failure.