Hello All!
It's my first post and you should probably know that I don't even own an RX7. I admire them a ton and I'm using some FB oil coolers for a custom project on my Audi. They are simply awesome, I really couldn't ask for a better cooler

I got 2 coolers at a junkyard for $6.50 each. I just got them back from the cold-tanker and they sound like they both sound like they have rocks in them. I took all the thermostatic parts out as well as the small male-male fittings out for max flow, and from what I can see the inside of the core is spotless.

What's going on? Is this normal for this cooler? I REALLY want to run them because they are perfect for what I am doing and the built-in thermostat is awesome. Second question: anyone know what temp that thermostat is? I presume around 180F (pretty standard)

Thanks for you help! I hope the RX7 Community is receptive of outsiders like me

 

tared up oil most likely

 

Take it to get Ultrasonically cleaned. Probablly just metal debris from former motor, which you don't want in your motor. Not uncommon. Thermostat is around 160/180. I'd have to check my shop manual.

If you take the thermostat out, you MUST plug the bypass hole with a 1/4" NPT plug from the plumbing section of Home Depot. Otherwise you'll always be bypassing the fins and oil will not cool down. BAM!!

 

I don't think its coked oil because the coolers sat in the cold tank for about 2 weeks. That tank is basically a giant vat of industrial solvent at around 200 degrees.

I am putting the thermostatic controls back in. They were just out for the cleaning process. I did notice the bypass hole.

Other than cutting the tanks off, and blowing it out with compressed air, I can't think of a way to get that junk out of there. Would ultrasonic cleaning actually get the metal chunks out? I don't think it would but I've never had it done before.

Thanks for the tips! If anyone else has any thoughts please feel free to chime in!

 

What leads you to believe there foreign material in it? Does it sound like something is in there? Like when you shake it side to side you hear something? Thats normal. Mazda put metal louvers (for lack of a better word) in the coolers, and they arent welded or connected in any way to the cooler, hence they can be heard moving around in the cooler. Mazda added these to disrupt and boundary layer from forming on the oil passin along the tube walls, effectively increasing the capacity/efficiency of the coolers dramatically. Thats why for their size they will out cool anything else out there. It's also why any knoweldgeable builder/racer will tell you to never use anything but the stock Mazda coolers on a rotary. They are that good.

 

Thats exactly what I mean. When I shake it, it sounds like there are loose pieces inside and it sounds more like metal-on-metal than anything else.

I thought it was odd that both coolers made the exact same noise, thats why I asked you guys.

So from what you say, there is nothing wrong with the coolers and I should run them as-is.

The more and more I read about these coolers, the gladder (if thats a word) I am that I am using them.

Thanks for the input, I owe ya a