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

 The reason the water is pulled back out of the burp tank is that the
coolant system is full of air and it contracts and I still say there is no
stop leak that will plug the leak it is combustion pressure going going into
the water not the water going into the combustion chamber so you would have
to pour the stop leak into the spark plug hole to get it where you want it,
there is no way no how that stop leak will fix the problem.

Well while we are on the Subaru subject I may as well make a confession and
I know that is probably a capital sin and I will probably go to hell for it
but I have a 6 cylinder Subaru SVX 3.3 engine sitting on the floor that is
going to find its way onto the engine pylon of my coot.

Ken

Life is sometimes like that. One takes one step forward and has doubts and then
takes 2 steps back :) What PSRU ratio will you use with the Soob?
You are currently using a 3:1 PSRU ratio with the Rotary.
My guess is you  have about 480 foot pounds at the prop at 6000 RPM with the rotary.

231 HP at 5400 RPM  Max torque  228 at 4400 RPM.

Torque times rpm divided by 5252 = HP

So HP times 5252 = torque times RPM

So torque = HP times 52542 divided by RPM

So max soob engine torque is 228foot pounds.

But the max PSRU ratio you can use to keep the prop under
2700 is 2 to one. So torque at the prop is 456 foot pounds.

Running a piston engine at full load max HP RPM is like
standing next to a hand grenade. You need to try it sometime.
A real experience to say the least.
My guess is the life expectancy will be about 300 hours
unless the head gasket goes first or a valve burns :)

Since the last flat six they made was in 1997 you may have problems
finding parts.

The final question is what is the weight. Search as I might but
many say it is heavy. My guess is 3 to 4 hundred pounds while
the rotary weighs 200. The double over head cams and four valves
per cylinder do little for the weight.

IMHO you would be better off with a p-port.

So you save 1 gallon an hour with the Soob for awhile.

Interesting experiment Ken. Keep us informed on how it goes.

Paul Lamar

I plan on using the redrive I have and changing the ratio to 2.1 to 1 and
cruising it at 4000 rpm and at that rpm I know that these engines will live
a long life, as for parts these engines are basically the 2.2 engine with 2
more cylinders added onto it so parts will be around forever plus all the
after market parts like ACL race bearings ARP head studs and Scat race rods
for the WRX engines  will drop right in as Subaru and there are also many
types of forged pistons available, also I have core engines stacked up like
cord wood here and shelfs full of new parts so parts will never be a
problem.

Ken

Race car parts always helps automotive piston engines for aircraft use but ups the cost.
The Chev race LS7 has titanium rods, SS valves  and a forged crank
but cost $15,000 when they were selling it. A regular LS1 has cast crank
and rods.

What is the weight of the SVX?

Paul Lamar