Author Topic: New thermostat, rough start and humming (Read 5518 times)

DesktopDave · « **Reply #15 on:** February 12, 2011, 10:13:23 PM »

I didn't mean drain all the motor oil. The tensioner might weep a bit but it's way above the oil level. The tensioner has three parts, a piston, a spring, and a case. Pull them apart & drain the oil out of the tensioner body, then slide them back together. What you're trying to do is make it shorter than it was...or needs to be. It might have a bit of air trapped inside it that's making the tension too high.

If you have any trouble with it, think about replacing it. The part is pretty cheap at a BMW dealer and the original M42 part was replaced by the slightly longer M44 part by BMW. It's $39+shipping at Pelican Parts.

It will readjust automatically and refill itself with oil when you have it back in the engine.

Sarstan · « **Reply #16 on:** February 12, 2011, 10:20:42 PM »

Oh, that sounds a lot more reasonable to do. Is it really that simple to take care of? Drain it, push 'em together, stick it back in and after a few minutes running everything will be just fine?

DesktopDave · « **Reply #17 on:** February 12, 2011, 10:25:29 PM »

Yep, that should do it. Chances of permanent damage to the guide are minimal, you likely just stripped a little plastic off. Should be OK. If the noise doesn't go away let us know. Maybe make a short video & post it here.

Sarstan · « **Reply #18 on:** February 12, 2011, 10:29:56 PM »

Righto. I'll be doing this first thing in the morning. Funny how something I didn't think much of after I got it back in can really make all the difference. Also glad I (hopefully) don't need to replace it. My local Autozone says they simply don't carry it and I bet the stealership wouldn't be making any bargains.

Sarstan · « **Reply #19 on:** February 13, 2011, 12:42:43 AM »

Well, I lied about waiting until the morning. Went and pulled it out, drained it, and stuck it back in. Started it up and sure enough the whining is gone, replaced by a clanking for a bit. Now it runs great (although it still had a small idling issue which may have just been the cold).

I'll have to check out that green sauce. It sounds pretty good.

DesktopDave · « **Reply #20 on:** February 13, 2011, 08:19:13 AM »

I'm glad you mentioned it. Replacing a worn timing chain the right way goes for about $500-$700 around here.

Don't let that put you off working on the motor, though. The M42 will last a long time with a few little repairs here and there. Mine has nearly 280,000 miles on the original engine. Granted, it leaks oil from almost every gasket, but it'll last if well maintained.