
I bit the bullet, now it's time to restore it! M52B28 – cold idle/hesitation and strange noise
Hi everyone,
I recently bought a 1996 E36 328i Coupé with the M52B28 and around 103k km (theoretical mileage, haha).
I’m trying to diagnose a couple of engine-related issues and would love to hear from other M52 owners who have experienced something similar.
When the engine is cold, it has some hesitation/bucking at low RPM. The idle is also not completely smooth, and the RPM seems to jump rather than increase smoothly. This gets progressively better as the engine warms up and is basically gone once it reaches around 90°C.
The car was scanned during the pre-purchase inspection, both before and after the road test, and no relevant fault codes were found.
There is also a noise when starting the engine that sounds somewhat like a bearing or a belt squealing/rattling. It gets louder as RPM increases, especially when accelerating under load. I’m wondering whether this could be related to the accessory belt system, tensioner, idler pulley, alternator, water pump, etc.
The inspection also found some oil seepage around the upper part of the engine, apparently around the VANOS hose area. I haven’t done any repairs related to the cold-running issue yet.
Has anyone experienced this combination of symptoms on an M52B28?
Any advice on where to start diagnosing would be greatly appreciated. Thanks!