Welcome to Ultimate Subaru Message Board, my lurker friend!
|Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.
We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!
Serving the Subaru Community since May 18th, 1998!
2.5L 96 Legacy Outback Engine Vibration
Posted 27 September 2004 - 06:22 AM
While stopped making a left turn in her 98 Outback Wagon, my wife got rear ended by a dump truck going about 45 mph. Car totalled, wife not a scratch. Needless to say we are looking for another Outback!!
Posted 27 September 2004 - 11:34 AM
Engine vibration can be attributed to several causes, some external to the engine, some internal. Since it happens at only one RPM, it sounds like you're hitting a resonance mode of some kind. The vibration you feel in the steering wheel suggests an engine/chassis interaction of some kind.
My suspicions would first be directed to the engine (and tranny) mounts. They may be worn, and therefore not damping out the engine modes as well. If I recall correctly, a flat-4 engine is perfectly balanced, with all primary and secondary modes cancelling each other.
The next set of possibilities are internal problems, with something out of balance. That's unlikely unless the engine was worked on or the flywhel changed for an unbalanced one. An incorrectly aligned timing belt?
Glad to hear your wife's okay. My wife rolled her '96 on the freeway (hit & run, never found the guy) and walked away unscathed. We now have a 2002 OBW, naturally.
Posted 27 September 2004 - 12:09 PM
True to a point. The 180 degree "V" (flat, horizontal) does provide a cancellation of certain vibrations, since they oppose each other. (I couldn't tell you which mode or harmonic, since I'm not that up on it.) But, the 2 banks of cylinders are offset. The pistons are not directly across from each other. So there is still a vibration mode. (I believe it would be one that would want to 'twist' the engine about a vertical axis, as oppose to 'rocking' it.)
If I recall correctly, a flat-4 engine is perfectly balanced, with all primary and secondary modes cancelling each other.
My guess would be engine mounts as well. They are probably worn / hardened / aged. When I had the engine work done on my 97 OB over 2 years ago, I had them put in the newer liquid filled mounts. It helped to dampen a slight vibration that I got after putting a lightweight crank pulley on.
There's another thought for you. Crank pulley. But I can't say I've ever heard of one going bad (in this sense).
0 user(s) are reading this topic
0 members, 0 guests, 0 anonymous users