Author Topic: strange sound from engine (transmission) (Read 2415 times)

marlin · « **on:** May 07, 2011, 03:21:35 PM »

Hello all. I have little question. I created swap engine from M40b16 to M42b18. Everthing is ok, but. Today a get to first test run and after cca. 20 km i began to hear crazy engine sound...
Doing it at idle, but, when i have the engine about 1500 - 2500 RPM, can not hear anything. At 2500 rpm and higher is terrible sound from engine. Next one, while driving, when the engine is in the grip is ok. Engine is silent, but, when i change the gear and pres the clutch sound is back. When engine slowing down, sound is back.
So, where is problem?
Engine working normaly, transmission working normaly, clutch working normaly. I think, problem is in the clutch... But i�m not sure. And i need to make sure that engine is not dead.
Here is video with sound.

http://www.youtube.com/watch?v=9OwG7suhHIU

Thank you to help me.

DesktopDave · « **Reply #1 on:** May 07, 2011, 03:54:59 PM »

Hard to tell what that might be.

Is the noise still there when you press the clutch pedal in? I had a bad release bearing (throw-out bearing) that sounded a bit like that, only quieter. Only made the noise in neutral with the clutch pedal out. Car shifted OK, drove great, but clattered in neutral all the time.

If it isn't that I'd have a quick look at the cam chain; make sure the tensioner is good and the cams are still timed properly.

marlin · « **Reply #2 on:** May 07, 2011, 04:16:52 PM »

when i press the clutch pedal, sound remain, but is little bit less.
Timing chain i checked before the swap, and he is ok. Tomorrow i take of valve cover and check the camshaft...

DesktopDave · « **Reply #3 on:** May 07, 2011, 04:58:34 PM »

Sounds like transmission or clutch to me. Let us know what you find.

marlin · « **Reply #4 on:** May 08, 2011, 06:36:57 AM »

so, i get down valve cover and tried to turn the engine. And it seems to me that the sound comes from the tension bar. It is strange.

DesktopDave · « **Reply #5 on:** May 08, 2011, 07:27:39 AM »

If that's not holding oil, the guide might have been damaged. I hate to say it, but I'd recommend pulling the front covers and inspecting all the guides. Especially if they haven't been replaced with BMW's updated M44 parts.

Better that than jumping time & bending valves, top-end overhauls aren't cheap. Where'd you get the engine from, a salvage yard? Maybe they'll help out.