Potential Premature Rod Bearing Failures on Early 3.8 Engines due to Oil pump issues - The Unofficial BMW M5 Messageboard (m5board.com)

Euro-M5 · 1st May 2004, 08:42

Hi,

Has anyone heard of premature Rod bearing failures on the Early 3.8 Motors due to oil pump issues? This apparently was corrected with a revised oil pump. Cause for the issue was identified as the Extra Cylinder oil squirters that were added to the 3.8 motors causing oil starvation at the Rod bearings..

This issue was related to me by a M635csi owner. I just want to check the validity of such an issue if it exists.

Chewbacca · 1st May 2004, 16:08

Hi,

never heard of these problems. Oil pump issues sound much more like the early M3 E46 problems.

Top three reasons for a failing e34 m5 engine are still:
- broken / old chain tensioner // old chain
- leak air (correct term?) at the throttles
- old / leaking injection valves

Quote:

Originally Posted by Euro-M5

Hi,

Has anyone heard of premature Rod bearing failures on the Early 3.8 Motors due to oil pump issues? This apparently was corrected with a revised oil pump. Cause for the issue was identified as the Extra Cylinder oil squirters that were added to the 3.8 motors causing oil starvation at the Rod bearings..

This issue was related to me by a M635csi owner. I just want to check the validity of such an issue if it exists.

rcalvin · 2nd May 2004, 10:13

Just passing along some info that was discussed a while back on the
http://autos.groups.yahoo.com/group/bmwe34m5/

"The crank journel is 1mm larger on the S38B38 crank
then on the S38B36. The big end of the rod is the same
size on both engines so the actual bearing shell is
0.5mm thinner on the S38B38. This coupled with the
shorter rod length, longer stroke, higher compression
(of the S38B38)increases the bearing loads alot.
Thinner bearings are not going to hold up as well in
the long run. Detonation takes its toll faster."

Hope this helps.

Thanks
Rick