Radiator Installation

Last updated: February 17, 1998

Date: Sun, 01 Feb 1998 17:54:42 -0600
From: "Steven F. O'Sheal"

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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