Quote:
Originally Posted by BYprodriver
In My Informed Opinion IMIO there are 3 different categories of watercooled 911's & engines.
98-01 996 3.4 these engines are the most problematic because of the thin cylinders & thus should include leakdown & compression tests as part of the PPI.
02-04 996 3.6 this is the sweet spot of 911s IMO do the PPI then LN IMSB & you are 
05-08 997 3.6 & 3.8 these engines have several upgrades BUTT require complete engine disassembly to replace the "somewhat improved" IMSB with the LN upgrade!
Any engine remanufactured by Porsche & installed by a authorized dealer incorporates all the latest upgraded parts & has a 2 year warranty, so if it was rebuilt 2005 or later it has the bigger IMSB & 997 RMS, any engine rebuilt prior to 2004 has the easily replaceable IMSB & leaky RMS. |
Exactly the kind of info I was looking for. Thanks!
Tell me if I have this correct...
Years & IMS/RMS Issues:
- 1999-2001. 3.4L engine. Potential issues with RMS (rear main seal), IMS (intermediate main shaft) bearing, AND thin cylinder walls. IMSB can be upgraded to LN (ln engineering) version if you get to it before it fails.
- 2002-2004. 3.6L engine. Same issues with RMS and IMSB as earlier models. Cylinder wall issue resolved. Also upgradable IMSB
- 2005-2008. Both 3.6L and 3.8L engines. Improved RMS, improved IMSB, BUT IMSB no longer replaceable without an engine teardown.
Factory replacements & upgrades:
- Engines replaced after 2005 will have improved RMS and improved (but non-replaceable) IMSB.
- Engines replaced after 2002 will have original 3.4L thinwall engine, or improved 3.6L engine?
What about single row vs. double row IMS bearings? Are both replaceable without teardown? Is there a cutoff date when they switched? Is one notably better than the other?