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