dasupacat

I need a new rad. for my 84' 12a. Will a 79-82' fit? I would like to fit a under rad oil cooler sometime from a 79-82' also. Is this rad. much diff. from my 84' rad? Will the under rad oil cooler fit under the 83-85' rad?

Mikeydred

The 79-82 rads are shorter. The oil cooler mounts to the bottom of the rad. The 83-85 rads are taller. I don't think it'll mount to the bottom.

dasupacat

So I take it the 83-85' cool better? Other than that is there any other diff? Wouldn't I benefit from the older style oil cooler?

Mikeydred

I wouldn't say that the 83-85 cool better....I think the 79-82 rads are better for mounting the oil cooler up front. I'm trying to decide which rad to get too.

Aviator 902S

The 83 to 85 units don't cool any better. They're taller but not as thick as the older rads. In fact, with the 83 to 85 bee hive oil cooler your engine does not get cooled as well as with the under-rad oil cooler. This has a direct impact on how long your engine lasts, especially if you drive the car harder than most.

The larger oil cooler will not fit UNDER the taller rad, but it will fit IN FRONT OF it. This is the arrangement used on the GSL-SE. If you go this route you will also need to pick up the longer oil hoses used on the SE that go from the engine to the cooler--- the hoses that come from the older (pre-1983) RX7s and go to the under-rad cooler are too short to reach to a point in front of the rad.

Get rid of the beehive and replace it with a oil filter mounting plate from a pre-'83 engine. Getting the bee hive off is a bitch (three 10 or 12mm nuts, accessible only from up top by feel and using an open end wrench), but the plate goes on very easily and makes other components (ex: clutch slave cylinder and rear plugs) way easier to service.

dasupacat

So the 79-82' will be a direct fit? i'm thinking going this route, will everything hookup? or will i need new hoses and stuff?

Aviator 902S

The '79 to '82 rad will bolt right up, and you can then use the stock hoses and under-rad oil cooler. What ever you do, replace the copper crush washers at the ends of each hose with new ones, no matter how good they may appear to be. If you don't, it will take more torque to tighten the fittings enough to prevent leaks, which will cause the oil cooler to crack and leak oil where the hoses attach. This will cost upwards of $60 to have a specialty welding shop fix, and this assumes you (not them) do the re and re.

BTW, be very sure these cracks aren't already there before you buy the cooler second hand. Often, this is why these coolers are for sale in the first place. If it's still in the car before you buy it you may see oil on the outside of the hoses and surrounding area, but these cracks seep oil so slowly that they won't spray out oil or be readily visible. If the cooler is not in the car the cracks may not be visible without a magnifying glass. The place to look for them is inside the fitting where the hoses attach on the cooler itself.

These crush washers are also available in aluminum (which works just as well) from Mazda for around $1 each. You'll need four of them.

When you remove the bee hive, splice the two coolant hoses that went to it together using a short (3") piece of copper tubing and hose clamps. (a few cents from hardware store). The longer oil hose from the oil cooler goes into the bottom left side of the engine. You'll need to remove a plug that's there in order to screw in the hose fitting. The shorter hose runs from the cooler to the front cover where the metal oil tube from the beehive used to go.