Yes it was leaking on the non JB Weld side. Big mistake
    using that high temp epoxy I bought. I should have asked
    Mazdatrix what they used for p-ports and they would have
    told me JB Weld as they did later.

    OK it worked great. It is like working on someones teeth however.
    You need a small inspection mirror and a small pencil flash light
    that will lie in the bottom of the tube. I glued a small
    section of 1/4 inch  dowel about 3/16 long to a small wood tongue
    depressor to apply the small gob of JB Weld to the leaking
    area. The vac pump pulled in the JB Weld.


    If you want belt and suspenders on
    this Burns stainless has 321 SS 1.875" OD tubing with
    a .035" wall. Cut the SS tubing just long enough to go
    up to  where trochoid wear surface starts but not beyond.
    Coat it with a very thin layer of JB Weld and insert it into the
    aluminum tube. I have some inquires out for even thinner
    wall SS tube. On the order of .015" to .020". I think I will
    do this with Marks engine.

    Best to just pressurize these tubes to 50 psi before you assemble
    the engine to check for pin hole leaks.


    BTW one advantage of the P-port is you can visually inspect
    the trochoid wear surface with a flashlight and a small  inspection
    mirror in the compression chamber area.

Paul Lamar


Well, one of my concerns over this approach is definitely  longevity of
the repair.  I have no doubt that the current leak is fixed by the
JBWeld sucked into the crack(s).  I have more concern over what will
happen given future heating / cooling cycles.

One of the assumptions we've been operating under is that the first
failure was caused by residual water in the water jacket freezing  over
winter, expanding the tension bolts, & failing one of the combustion
o-rings.  Yet, on tear down we saw no evidence of this -- in fact  I still
have all the original combustion o-rings & they are pristine.  I  submit
what actually happened is that the "bad" epoxy was coolant-soaked  during
the dyno runs.  This then froze, failing the epoxy in a big way such
that when I went to refill the engine with coolant, splish-splash it
ended up in a puddle on the floor.

So - given this scenario I worry about both the heat/cool cycles from
running the engine, as well as freeze/thaw cycles from the upcoming
winter.  Because the existing repair technique can only fix fully  failed
cracks (such that the vacuum can draw in JBWeld) there still seems  to be
a big risk for future failures -- areas where the old epoxy has not
*yet* failed.  The scenario above is still very much in play, and  thus I
would expect future failures due to heating / cooling.

I suppose a sleeve inside the existing P Port could in some ways  address
this.  But this scenario counts on a very small (and perfect) ring of
JBWeld holding regardless of the leaks which may or may not develop
behind it.  It also counts on the JBWeld to prevent the sleeve from
being ingested into the rotor - not a pretty thought!

Mark

That is a possible scenario.

Not to worry about the sleeve moving Mark. The sleeve is so long the
epoxy will keep it in place. Also there is no force applied
to the sleeve.

The next thing to do to ease every bodies mind on this subject
it to make a sample. Boil it in anti freeze solution and place it
in the freezer and do it repeatedly.

Many P-port engines have been built over the past 30 years with
different epoxies and different methods of installing the tubes.
I have never heard of a seal failure but then most people don't store
them in an unheated place with pure water in them either. I think
the guys at Mazdatrix would have mentioned it as well.

Jim and Dave have you ever heard of a leaking or failed P-port?

What ever you want to do Mark. We will take the engine apart and
replace the white epoxy with JB Weld if you wish. I think
the thin SS sleeve is still a good idea as it is easy to do
unlike a press fit.

Paul Lamar ...No rotor no motor.

Here is where it was leaking. Gap in the aluminum filled
with the white epoxy. Right where Jerry said it would.

That is why the thin SS sleeve will help greatly.
I can cut it off at an angle to rougly match the
throchoid wear surface contour. It will then be a rather
wide bond area.

Paul Lamar ...No rotor no motor.

Has anyone tried tig welding the tube at both ends to the housing ? By
pulling the trimed tube out from the housing about 2 or 3 mm and  laying
a very small stitch weld there - only 5 mm or so at a time so the
housing does not get hot beyond the local area. the outside weld would
not need as much care, maybe 10 mm at a time, Any thoughts ?
-dave

Real risky as the trochoid end is a mix of steel and aluminum.
I think everybody agrees. It is not a strength issue. They
seem to be concerned with the hot coolant effects on the JB Weld
as far as leaks are concerned.

Paul Lamar ...No rotor no motor.

I like the sleeve as a fix.  However, I don't think its a model for
future  construction.   What is objection to just installing the
insert all the way through?   Its clean and  simple. And, I think,
eliminates all the insert leaking problems.  If the slide throttle
flanges could be round, we could build the entire insert at the
lathe, no welding at all.  There would be a low stop collar so that
the insert butts up  the same depth each time during the fitting,
trimming and gluing phase and a wide collar at the outboard end that
would be the slide throttle flange.  That would be a fun project.
Sure there would be $30.00 + worth of chips per insert needing to be
swept  but who cares.  It would be such a strong, neat looking,
functional part.    Jerry

------------------------------------------------------
The sleeve is an additional labyrinth seal. The water has to
turn a couple of corners. If you bore all the way through
you still have a simple leakage path.
Hard to fix too. The thin SS sleeve cost less
than $10 and there is no precision about it. Also there is no
question about epoxy sticking to stainless steel. Way back
in the early 1960's we made composite chassis race cars
with SS reinforcements for bolt holes. We used SS
because epoxy stuck to it better than aluminum.
We also built some bonded aluminum chassis and we either
anodized the parts first or etched them with some sort
of solution I forget which. We were looking for maximum
strength in the bond. I'll research that etching fluid shortly.
This was long before Burt Rutan.

Starting with four inch round and cutting most of the
material off on the lathe leaving a flange is not practical.
You need to weld a flange on the tube. You need the flange
so you can take the engine apart. The original Teflon
slide throttle design can be made by anybody with just hand
tools and a modern saber saw. No lathe required. The hole in
the rotor housing must be done on a mill however I have heard
of people doing it with a hole saw.