Date: Sun, 01 Feb 1998 17:54:42 -0600 The following is my experience with installing a competition radiator in
my 93 RX7. It is simply my experience and is not intended as a step by
step procedure. I am not encouraging anyone to do this. Should you do
it, please follow safe work practices, especially regarding supporting
the raised vehicle - you'll be underneath it a good bit. If you screw
it up or hurt yourself, it's not my fault! And please, cut me a little
slack - I'm neither a mechanic nor an engineer; I'm not exceptionally
bright, and I'm a little mechanically challenged, so you may find ways
to do things that are much easier (I sincerely hope you do). A few
vendors are mentioned by name; I have no connection with any of them (or
any other vendor for that matter) and listing them specifically is not
meant to be a recommendation. I did all the work alone in my garage; a
friend to lend a hand would be a great benefit.
Now, on to the good stuff. While installing new radiator hose clamps, I
over tightened the clamp on the upper radiator hose, cracking the
plastic hose inlet (or whatever it's called). There seemed no secure
repair possibility, so a replacement radiator was in order. I contacted
Mazda Competition Parts and was told of a competition radiator that was
a direct bolt in replacement (see below). The competition radiator sold
by Pettit Racing _looks_ to be the same piece; Pettit claims "some
fitting required."
The radiator is all aluminum (well, it looks to be all aluminum; there
are no plastic parts) and is thicker than the stock radiator. Also,
there is no foam border at the sides of the radiator like the stock unit
has (more on this later).
I removed the stock radiator as per the instructions in the workshop
manual. It goes pretty much as shown there with the exception that the
shop manual fails to mention the two nuts on the upper corners of the
radiator that must be removed; this omission is pretty evident once you
do it, and access to the nut on the left is the reason the battery and
battery carrier must be removed.
Once the old radiator is out, the various pieces must be transferred
from the old to the new. There are a few brackets that are pretty
straightforward. The fan assembly must also the transferred. The fan
assembly has 3 rubber feet that fit in holes in brackets attached to the
bottom of the radiator. On mine, the holes didn't line up with the
feet; I solved this by slightly enlarging the holes with a Dremel tool.
This was a really minor annoyance.
The radiator with fans attached is returned to the car from below, just
like the stock unit came out. Getting the radiator positioned so the
upper left side nut could be reinstalled was a bit of a pain. The bolt
the nut attaches to is actually a post on a rubber insulator (for lack
of a better term) and the radiator tends to push the post forward so the
post does not line up with opening on the radiator that you hope to get
over the post. There was one additional line in the area that I hadn't
removed (you'll either see it or have already removed it); removing it
(well, removing the mounting bracket; you don't remove the line) allowed
room to fit my hand in the area and hold the rubber insulator as the
radiator is pushed into position.
Now comes the real fun. The air conditioning condenser is attached via
4 brackets. One of these (the lower right) cannot clear the aluminum
"piece" on the side of the radiator (this "piece" was foam on the stock
unit, so this sort of thing wasn't a problem). I made a rectangular
"notch" in the aluminum piece that allowed the bracket to be installed.
This can be done pretty easily with the radiator in the car. I used
the Dremel (if you don't have one, get one; I can't imagine doing this
job without it) to cut two sides of the rectangle and clamped a small
pair of vice grips on the aluminum "border." Be working the vice grips
up and down, I was able to break the aluminum, leaving a rectangular
opening for the a/c condenser bracket. The right upper a/c condenser
bracket was also a problem. It attaches to a gold colored bracket that
is held on by a bolt; I simply could not get the hole on the a/c
condenser bracket to line up with the threaded hole in the "gold"
bracket. I finally had to grind down the gold bracket to move the
threaded hole into position so the bolt from the a/c condenser bracket
could meet it. Your fitting problems may be different, so YMMV. Also,
I tried all the possible combinations of installing the brackets in
different orders to see if that would help, but it didn't.
At this point your troubles aren't over. There are a couple of a/c
lines that travel from the condenser to the receiver-drier and, maybe,
the compressor (didn't really trace these down, so I'm not sure exactly
which ones they are, but you'll see them), passing around the left side
of the radiator. These lines rub on the aluminum border on the side of
the radiator (again, this was foam on the stock radiator). I used a
file to shave away enough of the aluminum to allow the lines to pass
without rubbing; as the tolerances are pretty tight, I stuffed a piece
of bicycle inner tube in the space between the radiator and the aluminum
lines for a little extra protection. This was a real pain and would be
_much_ easier if done while the radiator is still on the bench and not
in the car. You could probably measure and get it right; if you decide
to do this project, I'd be happy to measure what I did some time when
the undertray is off. As I was using a hand file mostly (not enough
room to safely use the Dremel - those small, thin aluminum lines are
mighty close by), I was left with a concave "defect" in the aluminum
border to provide room for the a/c lines.
At this point, I thought I was home free. However, there was one more
problem. My radiator came without a drain plug. The drain plug from
the stock radiator does not fit. A call to Mazda Comp provided the
information that this required a plug with =BC inch NPT. These are pretty
readily available, and Randy at Mazda Comp supplied a part number for an
Earle's plug, which I ordered from Summit Racing. Well, I still don't
know what thread size the bung (that's the piece welded to the radiator
that has the threads for the drain plug - one of the many things I
learned during this project) had, but it wasn't =BC inch NPT. I got a tap
and retreaded the bung, and the plug seems to fit. However, had I
realized this problem was going to arise, I could have easily solved it
by getting a plug before the radiator went back in the car. Should you
do this, make sure you have a drain plug _before_ you put the radiator
back in the car.
Well, there you have it. The hoses and electrical connectors are now
reinstalled, and everything seems to be working. Was this a beneficial
upgrade? Beats me. I've never had overheating problems, but I only
have the stock coolant temp gauge. Since heat is such a problem with
these cars, it seems like a reasonable thing to do to me.
If you try this and have specific questions, let me know; I'll try to
answer them. I hope you found the above information useful, or at least
mildly entertaining. Good luck!
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From: "Steven F. O'Sheal" 