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


Paul Lamar