[xj-s] PCV valve revelations (longish)

After following recent threads and browsing the archives about PCV
valves, I surmised from some of the entries that it might be possible to use
any PCV valve that was designed to handle a motor of like displacement as
the Jaguar V12. For the Jaguar XJ-S valve I found three different prices on
the web: $35.90, $36.57,
and $46.36. Not enamored of these prices I picked up a bubble-wrap PCV
valve for $3.00 that was identical in physical size rated for 5.0 up to 5.7
liter and popped in into PURR (vanity plate). Oops, the rpm at idle dropped
by 100. Now the question was . . . was the valve I removed functioning
properly or is it gummed up or some such thing. Some time was spent washing
it out with solvent and brake cleaner, and when re-installed brought the
engine back to 750 rpm. Another question occurred to me, is it an original
and correct OEM part? Only one mention of a possible part number was on a
thread from back in March of 2000 by Chris Carley who said his PVC valve was
an AC # but didn’t include the number. The original from PURR does have an
AC #, in fact it reads AC 3848.
The difference between the two appears to be the spring tension, and I
surmise that the generic was being closed by the high vacuum at idle thereby
causing the loss in rpm. Further information on the valve action was found
at http://www.filtercouncil.org/techdata/tsbs/94-2R.html which convinced me
that the valves are engine-specific, and Jaguar being Jaguar, just
installing a valve that is for an engine of like capacity is not going to
By the way, the URL above said PCV valves should be changed every 10,000
miles or one year, and should not be cleaned and reused. Of course if I
were the manufacturer, I would say the same thing for at least two reasons:

  1. profits, and 2) liability. Corporate America lives in constant fear of
    liability . . . a personal experience during the 80’s that comes to mind is
    when a vice president and a member of the board of directors of Dow Chemical
    visited my company in Palm Springs to investigate the efficacy of our
    product called Silvoxx which was a combination of hydrogen peroxide and
    colloidal silver, and which the medical University at Linda Loma had found
    to be particularly effective in destroying staphylococcus urea, the cause of
    toxic shock syndrome. They were interested in perhaps incorporating Silvoxx
    with tampons.
    Unfortunately, I had to point out that hydrogen peroxide is an oxidizer
    that if combined with a flammable tampon might spontaneously ignite.
    Evidently they found the image this presented less than attractive. Their
    faces froze up like I had offered them a glass of Thalidomide. Liability . .
    . but I digress.
    Biting the $35.90 bullet I ordered the PCV Jaguar part #C 44231 and sure
    enough it had the #AC stamped in it. Actually the entire number is E7 AC
  1. I can see no difference in operation from the one I cleaned since
    they both idle the engine at 750 rpm, but who knows, maybe there might be a
    difference at cruising rpm.
    Anyway, tomorrow they’re in the mail to Kirby for his edification,
    amusement or whatever.

Dave Osborne
88 H&E (PURR)
Carson City, Nevada