Anybody have experience with a failed Suburu Head gasket.
      Milo was on the way from Washington to Texas and made it as
      far as SZP. Then the Soob engine had a mysterious over heating
      problem towing a trailer.

      Paul Lamar

      No experience with Soob and blown head gasket, but with a Dodge
     Minivan, I
      had an overheating problem that seemed 'mysterious'.

      It would overheat, and when you checked the coolant reservoir
it     would be      full. When the engine cooled, the reservoir
would go down as expected.

      The problem was a small leak in the head gasket, which would
put     combustion      gas into the cylinder space, driving the
coolant out of the  engine and   into    the overflow reservoir.

      Bill Schertz
      KIS Cruiser #4045
      N343BS

      Bill, did you try any chemical sealants such as duraseal or
  steel seal?

      Paul Lamar

      Yes I have as that is my business and I rebuild 3 to 4 engines
a     week, no     none of those sealants will work as the problem
is the combustion     pressure     is pushing past the gaskets into
the water system and pushing the     water out     the burp tank and
so there is no way to plug the leak unless you could     get     the
sealant into the combustion chamber to shove it into the hole  thats
  leaking, hate to say it but you are best to go for a whole  engine
as   you can   mill the heads when you replace a head gasket  but
you cannot mill the   block   and the block warps as much or  more
than the heads so if you put a new   gasket on a straight head  and
a warped block it wont last long, I can   do a   compete long  block
for $1500 to $1600 depending on which engine it is   and I  fix all
the problems that Subaru had to make it better than new.  Give me a
call if you need more info.   Ken

      360-834-4089

     I don't know which engine is in that Subaru, but my sister has
  one and it   had a bad head gasket and this is a known problem.
  They have an improved   replacement gasket that fixes it but they
  didn't do a recall and   replace it   on their dime.

     Steve Brazil

     The good news is as far as Milo and family are concerned is
they were     able to plug     the leak with goo. After the engine
cooled off it sucked all the     coolant back     out of the over
flow can. That would not have happened if the leak     still
existed.     That is part of the process. If the exhaust valve and intake
  valve is   closed   hot air in the cylinder cools off causing a low
  pressure in the   cylinder drawing   the sealant into the leak.
This  is somewhat of a crap shoot as the   leak must   occur around the
  cylinder that happens to stop in that sealed condition.   Also of
  course the coolant itself also contracts drawing coolant in   from
  the   over flow can.

     There has been several recent breakthroughs in these stop leak
  type   fluids.   Prior to these breakthroughs most stop leak type
  products required you   to purge   the engine of antifreeze
coolant.  This is no longer true of the better   products.   The
other  breakthrough is a chemical reaction that is triggered by the
 high   400 to 500 F metal temperatures that causes the goo to
solidify in the     area     of the leak but not in the radiator.

     Here is the web site that claims to be the best.
     It is called Steel Seal. It is a clear liquid with no
particulate  matter   at all. It is rather expensive at $70 and they
claim to  have an iron clad   patent. "The product is drawn into the
damaged  area and seals the crack   with a thermo-chemical bonding process."

     I have not tried it on a leaking rotary yet but
     it sounds promising to fix the shrunk rotor housing problem due
to     extreme over     heating of the rotary. Milo has some on
order to test it on the soob     if the     stuff we actually used fails.

     https://secure.steelseal.com/index.php/t2b

     Paul Lamar

      Re  Overheating Soob.   Most Subaru's only have electric fans and
    sometimes the switch in the radiator fails to switch on and
causes  a  overheating porblem, can happen if people turn off the
air/con, because    the air/con turns the fans on even if the engine
is not hot, then    without the air/con turned on the fans  you have
NO fans at all!!      Can also have a overheating problem only when
towing because the    radiator tubes are partly blocked internally,
 and so not enough reserve    cooling available, so the engine
overheats, will also happen if the    radiator cap is not holding at
least 14/15 psi.       John Burey

    It was definitely a head gasket. IMHO here is why head gasket problems
    on the Soob are common. Not enough head bolts. Too much distance
    between bolts allows the aluminum head to deflect between bolts.

    Paul Lamar

    Here is the Chevy LS1 V8 head bolt spacing with about the same bore
    and center to center spacing. Also with an aluminum head.
    LS1 head gasket failures are less common.

    The Soob engine needs to be redesigned.

    Paul Lamar

     I use ARP head studs on my race engines and offer them to
people with    grocery getters for extra insurance, with these studs
they will  handle 45  lbs of boost at 700 plus hp, for more boost
you can tap  out the case and run  oversize studs as the next thing
that will  happen to the threads will pull  out if your replacing
the head  gaskets get the original OEM multi layer  steel gaskets
from Subaru  and if its a 2.5  ask for the gaskets for a 97  outback
regardless  of what year it is, that is the gasket that I put on all
 my engines  including the turbo engine, also spray the head gasket with
  permatex copper spray, with that it should get you home but it
will probably    give problems latter as chances are that the case,
 heads and  cylinders are  warped if it has overheated and that is
why I mill  the case and heads and  bore the cylinders 20 over on
all the  engines I rebuild.

    Ken

    In the case of the Soob, unlike the rotary, the strength or stiffness
    of the studs does not help much.

    Consider the cylinder head a simply supported beam. Deflection is
    proportional to the cube of the distance (l) between the bolts.


http://www.codecogs.com/reference/engineering/materials/beams/simply_supported_beams.php

    A reduction in stud spacing from 4 inches to 3 inches will halve
  the head deflection. 4 cubed is 64 while 3 cubed is only 27.

    Paul Lamar
    -
    Sounds good on paper but I am not a paper person I am telling
you what  works from experience, I have rebuilt over 400 engines and
never had  a head gasket problem on a single one of them, if it will
work at 45  lbs of boost it will work just find on a non turbo
engine, also what  year is it??? if its 2001 or later put a 12mm oil
pump in it as they  went to smaller 7mm pump and they have rod
bearing problems, call me  before you put this back together as
there is too much info for email.

    Ken

  I don't think Milo is going to rebuild it. The car is not worth it.
  He will probably junk it. I don't know what year it is. Too bad it
  did not break down in your neck of the woods.

  Have you tried 6 studs per bore? That is basically what the Chev has.
  What works in drag racing or on the street does not work in
aircraft  engines or trailer towing applications that are generating
 significant power hour after hour. IMHO the Soob engine is a
defective design for aircraft use. The horizontal opposed feature is
 a good point as it reduces the weight.

  I will say one thing about the soob crank. The rod bearings are so
narrow  oil pressure would leak out the sides so they very cleverly reduced
  the side clearance to trap the oil in the bearing. This allowed
them  to use a closer bore spacing and keep the over all length of
the  engine down.

  Too bad they did not go to six head studs while they were at it :)

  Next time you get a chance weigh an SVX for me. I can't seem to
find  the weight anywhere on the Internet.

  Paul Lamar

  Paul,

  You have to admit the GM LS series engines are a good design.
Power and reasonable fuel economy. Simple to work on. More so than
the equivalent Ford or Chrysler engines. One of the hot rod
magazines asked readers what they wanted and it came back- hang a
turbo on an LS and beat it to death. They got the boost up and it
put out 1200HP. Then they found out it was a 4.8L. They then took
mercy on it and relented. Not bad for stock rods and pistons.

Dale Davies

It is OK for street engine. The question is how long will it last
at 75% peak power?

Paul Lamar


A few hundred hours. More with the expensive internals; forged rods, pistons.
I do not think reliability will compete with a rotor motor. For a vehicle they
are great but in AC use any short comings will show up soon. Cheaper than
certified. But what is your families lives worth?!

Dale Davies