Jump to content


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*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* 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!

Guest Message by DevFuse
 

Photo
- - - - -

Knocking Legacy Turbo


  • Please log in to reply
5 replies to this topic

#1 dave.marchment

dave.marchment

    New User

  • Members
  • Pip
  • 2 posts
  • Victoria BC Canada

Posted 25 October 2004 - 12:49 AM

1992 Legacy Turbo makes very loud knocking noise that fluctuates with engine RPM'S but ONLY when defroster set to defrost or heat/defrost.
Started about 50 miles after dealer did head gasket.
NOT going back- they did plug wires and coil in response to my ?'s about low idle induced vibration that was NEVER an issue before gaskets et al and is still a problem.
Where to start??
Could it be vaccuum related??
What could they have missed (or misconnected) in the re. and re.?
Heater, fan and all controls work fine. No problem on vent or heat setting.
Car seems fine except for this dreadfully frightening knock
I searched but could find no reference to anything similar anywhere.
ANY advise greatly appreciated.

#2 P K

P K

    Devil Dog Liaison

  • Members
  • 1,171 posts
  • Omicron Persei Diego

Posted 25 October 2004 - 01:31 AM

Sounds maybe like an Air Cond compressor problem... it's usually on for AC and defrost on most cars. AC compressor will knock with too much freon in it too. Others opinions?

1992 Legacy Turbo makes very loud knocking noise that fluctuates with engine RPM'S but ONLY when defroster set to defrost or heat/defrost.
Started about 50 miles after dealer did head gasket.
NOT going back- they did plug wires and coil in response to my ?'s about low idle induced vibration that was NEVER an issue before gaskets et al and is still a problem.
Where to start??
Could it be vaccuum related??
What could they have missed (or misconnected) in the re. and re.?
Heater, fan and all controls work fine. No problem on vent or heat setting.
Car seems fine except for this dreadfully frightening knock
I searched but could find no reference to anything similar anywhere.
ANY advise greatly appreciated.



#3 rallyruss

rallyruss

    Subaru Master

  • Members
  • 1,653 posts
  • San Jose CA

Posted 25 October 2004 - 01:46 AM

Sounds maybe like an Air Cond compressor problem... it's usually on for AC and defrost on most cars. AC compressor will knock with too much freon in it too. Others opinions?


I second that

#4 dave.marchment

dave.marchment

    New User

  • Members
  • Pip
  • 2 posts
  • Victoria BC Canada

Posted 25 October 2004 - 06:58 PM

Sounds maybe like an Air Cond compressor problem... it's usually on for AC and defrost on most cars. AC compressor will knock with too much freon in it too. Others opinions?

Thanks - you nailed it - disconnected compressor and all better
-probably still hurtin' from the service?? and forgot to think
-easier to blame dealer
thanks again

#5 WJM

WJM

    SUBARU

  • Members
  • 7,828 posts

Posted 25 October 2004 - 08:06 PM

there is a handy pressure guage for AC systems to see if the system is overcharged or not...me thinks its over by alot or way under...

#6 Legacy777

Legacy777

    Moderator

  • Moderator
  • 12,602 posts
  • Houston, Tx

Posted 25 October 2004 - 09:23 PM

Dave I moved your first thread here, and replied to it.

The knocking noise is the ac compressor. The ac system turns on when the defrost mode is selected to remove excess moisture from the air.

You can try shooting some more refrigerant/oil in there to see if it quiets down. If not, you'll need a new compressor. You can probably just keep running it.....I ran mine that way for a while.




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users