BMW M5 Forum and M6 Forums banner

1 - 7 of 7 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter #1 (Edited)
Hey, I have a 90 M5 with 230k miles and in the 6 days of owning it I've had my second full-on breakdown. The situation leading up to the failure has been similar both times. Both times the car had been running strong and for 50+ miles that day, hard acceleration in second gear on an on-ramp to 5k an 6.5k respectively followed by sudden power loss and a loud knocking. The first time it turned out being a sheared woodruff key on the crank/hub. In diagnosing the problem I drained my oil (which had no metal in it), checked my compression all but one were above 190 and one was at 160. After fixing the key the car ran strong and hard (pulls dead even against my friend's 91 through all gears). I'm confused as I lost power in gear again, have new belts, coils, oil, woodruff key, and tightened down the crank hub again tonight with a large breaker bar. I'm really confused because the car is REALLY strong when running and goes from hard charging to broken suddenly. The engine seems to be pretty mechanically strong and I haven't overrevved it since it happened in gear both times so I'm honestly not sure of my issue. I have a quick video, hopefully someone can help me so I can get on the road without any unnecessary time or monetary expense (though obviously some will be necessary). Any help is greatly appreciated
+ https://www.youtube.com/watch?v=TU7XwcZ-MuQ" title="View this video at YouTube in a new window or tab" target="_blank">YouTube Video
https://www.youtube.com/watch?v=TU7XwcZ-MuQ"> https://www.youtube.com/watch?v=TU7XwcZ-MuQ" /> ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
 

·
Registered
Joined
·
188 Posts
Maybe a stupid question:
Is your woodruf key still OK at the moment and have you tightened the crankhub bolt to spec? IIRC it's 150Nm then loosen, tighten to 60Nm, 60 degree angle, 60 degree angle, 30 degree angle (so total 150 degrees after torquing the bolt to 60 Nm ).
 

·
Registered
Joined
·
13 Posts
Discussion Starter #4
Maybe a stupid question:
Is your woodruf key still OK at the moment and have you tightened the crankhub bolt to spec? IIRC it's 150Nm then loosen, tighten to 60Nm, 60 degree angle, 60 degree angle, 30 degree angle (so total 150 degrees after torquing the bolt to 60 Nm ).
I retorqued it last night but honestly I haven't ruled out the possibility of it having resheared due to a weak key, bad hub, or warped crank.
 

·
Registered
Joined
·
3,725 Posts
That sounds like a valve or something , sounds nasty

Get a screwdriver and use it like a stethoscope to try and pinpoint where that noise is coming from, from under the cam cover or in front of the engine ?
 

·
Registered
Joined
·
24 Posts
That sounds like a valve or something , sounds nasty

Get a screwdriver and use it like a stethoscope to try and pinpoint where that noise is coming from, from under the cam cover or in front of the engine ?

Last night on the highway I tried to stethoscope the engine to point out where the noise was coming from, and it sounds to me like is coming from around the starter area, specifically below the intake manifold somewhere between cyl 4-6

Towed to the shop, my dad believes it sounds like a rod knock.


Sent from AutoGuide.com Free App
 
1 - 7 of 7 Posts
Top