Post by
philipa_240sx »
https://forums.nicoclub.com/philipa-240sx-u68765.html
Tue Mar 17, 2009 3:54 pm
The issues with the Altima were mostly confined to the '02-03 models (pre-cat failure) and late model '06 (improper spec piston rings which caused high oil consumption). There were also issues with intake manifold butterfly valve retaining screws coming loose on some motors. The Sentra SE-R suffered the same issues as the Altima since it shared the same QR25DE motor.
I owned an '03 Altima that suffered a pre-cat failure. Nissan did replace the entire motor (long block) under warranty. The replacement motor and updated ECU programming fixed the pre-cat failure issue. When I sold the car it had over 100,000mi on the replacement motor with no issues.
Thankfully Nissan throughly revised the QR25DE for the '07 Altima and the Rogue. Now in it's 2nd generation, the QR is far quieter, smoother, and so far has none of the issues that afflicted it's 1st generation cousin. The butterfly valves are now gone (the intake is now a single runner design made of composite material), the motor uses different mounts, and the balance shafts have moved location slightly and revised in design. No one here has reported pre-cat failure issues with the new motor either.