An oil filter housing gasket leak on an N55 BMW can take out the serpentine belt. What to watch for, what the repair involves and real owner prices.
This is the one we tell BMW owners not to sit on. The oil filter housing gasket (OFHG) is a cheap gasket. The trouble is where the oil goes when it leaks.
The housing sits on the side of the block, right above the serpentine belt and pulleys. When the gasket hardens, oil runs down onto the belt. A soaked belt swells and frays, and on some BMW engines a shredded belt can get pulled behind the crank pulley and into the front main seal. That turns a few-hundred-dollar gasket into a much bigger job.
What to look for
- Oil on the belt or splashed on the underside of the engine
- Burning oil smell, sometimes mixed with the valve cover leak (they love to happen together)
- Oil level dropping between changes
- A squealing or slipping belt
Why it takes hours
On paper it's one gasket. In real life, the intake side and a pile of stuff above the housing have to come out to reach the bolts on most N55 cars. One of our reports says five shops quoted 5.5 hours of labor at $100 to $130 an hour, which tells you most of this bill is labor, not parts. The other report included belts, which makes a lot of sense since you're right there.
Things worth doing at the same time
- Serpentine belt (if it's had oil on it at all, replace it)
- Oil cooler seals, which share the housing
- Belt tensioner and idler, if they're noisy or original
Data note
Two reports so far, both from 2018 and 2019. Labor rates have gone up since. If you had this done recently, tell us what you paid.