Help! 318I making horrible high pitch sound!

[jroberts312]

ghead
My 318I started making a very loud sound coming from engine. Had my mechanic take a look and thought it was the alternator or tension roller. I had the tension roller replaced before and it was not half as loud as this. Here are the symptoms: When you accelerate it tends to go away. When you release the gas and just coast is when it gets really loud. Also, you can hear a loud hissing sound as if there is a vacuum leak of some sort. One last thing, when you cut off the engine, you hear one last squeal. This is after the rollers have stopped completely. It is also idling rough. I don't think it is a pulley or roller. Could this be the pcv valve (or crankcase vent valve)?

[PhunkDJti]

i had a very similar problem on my 318ti. the engine was loud as hell and idled extremely rough. my idle would fluctuate between 300-900k. my breather hose was shot with a big rip in it (connects at a corner at the top of the valve cover). which helped, but not completely. ..... then i replaced the pcv valve and presto - problem solved.

so in short, yes the pcv valve is possibly/probably the problem

[Autotechnica]

Sounds like either the clutch fan bearing or the clutch fan belt. Check the tension on the belts and make sure there are no rips along the teeth. Also, make sure you use only original BMW V-Belts, aftermarket ones sometimes will make horrible noises. Do not spray anything like "belt dressing" onto the belts, it only makes it louder and more brittle. If you get water or oil onto the belts, it will also makes really loud noises until it dries up.

Bry

[jroberts312]

It did turn out to be the crankcase vent valve or pcv. When I removed the old one it had a piece fall out. It was completely broken internally. Put new one in and it fixed it fine. This part looks awfully cheap and brittle. After looking at my maintenance receipts, this is the second one replaced within two years. Damn part costs $50+ dollars. A lot of money for a cheap plastic part.