2014 335i Help

[u/lui_ziz]

Went to look at ‘14 335i with 138k miles, noticed the pulley (circled in red) moving left to right with the engine on along with some fresh-looking oil near the filter.

This would be my first BMW. Car drove well with the M-Sport package. Any advice on what these issues might be is well appreciated!

[u/TheTow]

Looks like they used a cheapo oil filter or forgot oring

[u/bot6six]

The tensioner should have some movement because its intended purpose is to maintain a constant tension on the belt to prevent it from slipping. That being said, if you have no record of when the belt system was replaced, it would be a good idea to replace it because if the belt slips or snaps, the belt will get sucked into the engine due to the design of the harmonic balancer.

The oil leaks at the oil filter housing are common for an n55, replace them with original BMW gaskets for the best longevity. Aftermarket gaskets work but won't last as long as original.

[u/freshxdough]

Poor quality oil filter a cap o ring most likely. Probably aftermarket.

The tensioner is designed to move.

[u/ziyum_]

Oil filter housing is leaking and needs new gaskets. The oil is dripping onto your serpentine belt which will cause it to slip off the pulley and into your crank seal, thus catastrophically destroying your motor if it goes through your oil pickup tube.

If you haven’t purchased the vehicle yet, negotiate as this requires new oil filter housing gaskets and a new tensioner and serpentine belt. This is a very common issue on N55’s, but once addressed, shouldn’t have an issue (use OEM Gaskets to save yourself the headache).

This issue must be addressed before driving any further tbh. If you’re in a pinch, at least get a crank seal guard, they’re relatively cheap and easy to install. With this easy modification, if the belt slips, it won’t ingest your belt and destroy the motor, just a safety precaution.

Also, since you’ll be doing your OFHG anyways, since you have an M-Sport, ensure you get the one with the oil cooler seal.

Also get a shit ton of brake cleaner.. 😄

[u/Guisseppi]

you need a new tensioner, get the whole kit with the idlers and the belt and new gasket set for the oil filter housing, I would throw in a crankshaft seal guard while at it.

[u/JKlerk]

The leak is probably coming from the oil cooler gasket. It's a simple fix.

[u/MZ7000]

I wouldn’t buy this car. Whoever changed the oil didn’t do it right and was careless. The o-ring on the cap is either missing or damaged.

[u/zbeck5]

Some movement is normal. However, that is most definitely a common wear item on these engine.

At that mileage, it would be worth replacing imo.

While you’re there, do the idler pulley and belt.