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I am probably way off on a tangent with
what follows, but here is my two cents. After installing my '88, 13B
(non turbo) in the '86 RX-7 car for testing, I decided to tear apart the '86,
13B engine that was originally in the car. The owner of the '86, 13B
told me he had ran it out of coolant and severely over heated the
engine. When I originally brought the car home, I started it,
and it ran but the exhaust created a white smoke screen behind the
car. I examined the oil, and it was mixed with water from the
radiator. I only paid $100.00 for the car, so I wasn't
concerned. As I began tearing the '86, 13B engine apart (last
summer), I notice the paint in the oil pan was all bubbled up and flaking off
from being over heating. After removing the outside rear side housing, I
found one inch of the outside( near the bottom of the end housing
- by the hot oil) O-ring wall and O-ring were broken. In
this case (probably a classic example), it was obvious where the coolant was
leaking from. However, when I was examining the intermediate housing
I came across what looked like a loose piece of cast, inside the cavity of the
end housing, (looking inside the housing on an angle from a top view). I
am still not sure if it is cast plug that is put in during manufacturing
or it is a piece of cast that worked its way out after being
subjected to moisture, cold/hot temperatures etc. The purpose
of this cast wall appears to separate coolant from the oil (oil that
works its way into the intermediate end housing cavity when the
engine is running ) and then drains back into the oil pan. As I was
cleaning the intermediate housing , I put some pressure on the loose piece of
cast, and it popped out, destroying the intermediate housing; I ended up
purchasing another intermediate housing. The point I am trying to
make is you may want to examine the cavity inside the intermediate housing for
any obvious signs of cracks etc in the cast. Probably not the same
problem, if you didn't have coolant in the oil??
Later, last summer, I purchased ($250.00)
another '88, 13B engine that had lost an apex seal from the rear
rotor. The previous owner had haywired the rear barrel valve
actuator in the open position (in his '88, RX-7). I was surprised to
find very little damage to the rear rotor housing/rotor from the
expelled apex seal. This engine had no problems with coolant
leakage; however, when I examined the front side housing, one (half inch)
section of the outside O-ring wall was broken, but the O-ring was still intact,
and, therefore, the engine never developed a coolant leak. I intend
to use acceptable parts from both the '88 and '86 13B engines to
build another engine for the '86 RX-7 car, later this
year.
Tom
----- Original Message -----
Sent: Thursday, March 13, 2008 9:45
PM
Subject: [FlyRotary] Various Possible
solutions to coolant in housing
I have been inspecting and re-inspecting the
plates (front, center and rear) and the housing over the last few days...over
and over with trusted second set of eyes helping with the process. I
have taken a straight edge to the plates and with a .0015 feeler
gage (the smallest I could find...the spec is 0016 IIRC ) could
not get it to even think about going under the straight edge. The plates
seem solid, straight and in damn good shape.
I have taken a dental pick and "ticked" it around
the oil seal grooves and it seems solid all around. However, after
viewing the Mazdatrix website, it shows where the side of the O-ring groves
may give way. They state it is hard to diagnose but can be a way coolant
gets into the combustion chamber (http://www.mazdatrix.com/faq/sidehsgs.htm photo's
4 and 5). They had to use very high pressure over an extended period to make
the bad area actually VISIBLY fail. IS THERE A WAY to determine if
these groove side walls are solid without the high pressure, long term
pressure test process....which is beyond my ability? I hate the
idea of putting these back together and continue to have a problem......I also
hate the idea of the about $400.00 ish each for new plates :-( I
really thing the side plates are ok IF these grooves are good. Any
ideas?
Next, when we have meticulously inspected the
housings, we seem to see a couple of EXTREMELY slight irregularities around
the edge where the water seal would lay between it and the side seals.
My buddy...a VERY trusted resource, feels this could be enough to cause a
problem. Also, when I broke out the digital calipers I measured several places
around the housings and it seems the thickness around the diameter I am
getting is reading slightly out of spec for differences in thickness around
the housings.
Is it proper or even possible to take these to a
machine shop and have them machined smooth and flat? Or is it better to
just suck it up and buy new housings? I am about a "wild hair" away from
just giving in and buying two new housing just to get going again and end all
question of them being a future problem....at least for the current
reasons. I hate the idea of throwing money at something that may be
perfectly fine (after all I am not the government) What are y'all's
thoughts?
As to the O-rings that came out of the engine for
the inner rings there does seem to be some roughness along a couple of areas
on the O-rings. The areas are about 1.5 inches long, give are take, and
seem to be on a couple of the rings and in about the same area on the various
plates. This would seem to be indicative to over heating......Yes,
No....?????
Also, the price for new housings from
Pineapple Racing (558.00) does not seem too bad (Mazdatrix are 571.78 w/
cash discount). One of the "features" Pineapple
Racing promotes on their site is that they have "machined spark plug
holes" so as to accept alternative plugs. What the heck is this? I
hope to get a chance to call them on the morrow but what say Ye?
I tend to kick around the various ideas before I
decide, but as a rule do not knee jerk react to things even though it may seem
this way. I do not want to drop a grand+ for new housings, but that may
be inevitable. More so, I don't want to toss an additional $1400 on new
side plates......however, I also want some piece of mind that at least these
issues are addressed.
Will love to get your opinions.
TIA.
All the best,
Chris
Velocity SE
Houston
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