'90 240 now runs better than ever... Could this be why?

Discussion in 'Volvo 240' started by Randy G., Apr 28, 2008.

  1. Randy G.

    Randy G. Guest

    I have been driving this car for three years, and have put about
    30,000 miles on it in that time. it was a bit carboned up when I got
    it, and I think the previous owner drive it gently- too gently. It
    uses very little oil and is a dream to drive.

    I recently did two jobs on my 1990 245 with just over 200,000 miles.
    First I replaced the timing belt and cam seal. The leak was barely a
    dribble, but it was nice to get it done. The idler pulley was also
    replaced.

    The other job was to stop the annoying exhaust header pipe rattle. At
    about 2,000 RPM the inner and outer layers of the exhaust header pipes
    would rattle annoyingly, very much noticeable inside the car. I
    drilled two holes in each pipe, about 25-30% from each end, and
    inserted short sheet metal, self-tapping screws. Once the holes were
    tapped, I removed them and cut them off so that they would protrude as
    little as possible into the exhaust flow. Rattle completely gone.

    Since that time the car is running noticeably better- smoother, with
    more power, and better low-end torque. This is not just a matter of
    some psychosomatic reaction to the work I did

    Here's my theory: I do not believe that it was the timing belt. The
    rattling of the pipes, even at times when inaudible, created some
    frequencies that were picked up by the anti-knock sensor which was
    retarding the timing a bit. Is that possible?
     
    Randy G., Apr 28, 2008
    #1
  2. Randy writes ;
    My ol'mind and memory is beginning to fade. I can't recall the proper
    wording however I know a similar phenomenon did occur on mid-eighty's
    Oldsmobiles with 5.0 L (307) V-8's. The KS's were picking up ambient
    _signal_ noise (not sound in itself) and retarding the timing. Product
    Engineering's fix was to increase the "buffer period" (wrong term)
    between the KS's "hearing & reaction" time.
    Regardless Randy, I like your willingness to explore the not so
    obvious alternatives.

    Best Regards - Mike Baldwin
     
    Michael Baldwin, May 1, 2008
    #2
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