[NB] Little Red Sports Car Redux - Page 5 (2024)

MN MX-5

Join Date: Jun 2017

Location: Lakeville, MN

Posts: 948

Now that I'm retired I have time to catch up on a few items I wanted to do on the car. After posting the picture of my engine bay above I noticed the color of the radiator was the dreaded green-brown shade. Though it had done a great job for the last 20 years and was still functional, it was time to change it out to prevent any problems. And while I was at it, I figured I would change out all the cooling hoses and replace the thermostat as well as maintenance items.

After a bit of research I bought the Koyorad VH060650 aluminum radiator. I did consider putting an OEM radiator back in, but liked the idea of having a bit more cooling capacity. Also I wanted to add a bit of bling to the engine bay. I considered the Mishimoto and CSF aluminum radiators – both of which had favorable reviews and I like the polished mirror finish of the CSF, but at 67mm and 39mm I wanted something thinner and closer the OEM size of 32mm that would fit easily without impeding any other engine components or require any modifications to anything. At 36mm the Koyo fit the bill.

I bought the full cooling hose replacement kit, thermostat, thermostat and oil cooler gaskets and a set of cooling hose clamps – all OEM - from the Priority Mazda. I probably could have reused the existing clamps but new ones were cheap enough and new is always good.

After removing the intake tube to give me more working space, I disconnected the fan connectors and removed the radiator brackets. The radiator and fan lifted out easily. I removed than fans from the radiator, and removed the fans from the shrouds and cleaned everything. I had purchased some black plastic paint to dress up the shrouds, but after hitting them and the fan blades with some Simple Green and a bit of scrubbing both units look brand new. I also took the opportunity to clean the rubber isolator bumpers being transferred over as well as the under tray while it was off the car and 303’d the lot.

Hose removal was straight forward enough. I was glad I had invested in 11” 45° and 90° needle nose pliers as it made much easier to remove the clamps. Two were particularly difficult because the clamps were installed in awkward orientations – the lower radiator hose had the clamp facing the block, and the right heater hose had the clamp facing the firewall. I couldn’t access this one without removing the left hose first. Also of note is the white plastic clip that holds the hose in place. It opens by prying on the lip of the clip on the top and hinges open on the bottom.

The other opportunity installing was one of the small hoses coming off the thermostat going to the block (mixing manifold?) is a bit thicker than the original. It went on the nipple fine, but the new OEM clamp gave a good fight trying to get all the way on. The clamp got a bit bent, but it holds without leaking.

The thermostat replacement took longer than anticipated with trying to clean the old gasket off of the two surfaces. I started scraping it with a razor blade but noted I was still getting some aluminum shavings no matter how careful I was. I tried a plastic scraper but it was ineffective. I found Permatex Gasket Remover online and after a couple of applications it did the trick and I was able to clean all of the old material off with a plastic scraper and some rubbing with some emery paper. Reassembly was straightforward after inserting the new thermostat. I did use a little bit of Permatex Waterpump and Thermostat Housing gasket sealant on the OEM gasket as recommended to hold it in place and ensure no leaks.

Before putting the new radiator in I hit the top of it a couple of times with Mothers Mag and Aluminum Polish. I did use a polishing ball on a drill. I could have done it few more times to really get it glowing but it was going to take more effort with wet sanding and more polishing to get all the scratches and swirls out. I was happy with it being shinier. Since it seemed to work so well I also polished up the aluminum bumper support in front of the radiator, the cam gear cover and the header heat shield.

Installation was a breeze. I added the rubber isolators to the top and the bottom. The fans lined up bolted right on to the points on the radiator. The whole unit slid right in leaving about a ½” gap between the radiator and the AC condenser in front of it. The condenser line bracket on the bottom was touching the bottom of the radiator, I bent it easily by hand slightly to ensure there’d be no rubbing on the bottom.

I did purchase this no-spill funnel from Amazon as I had read this was the best, no mess and easy burping way to fill the car with coolant. Unfortunately I didn’t seem to use it properly as it spilled coolant all over when it filled up and I started the car up to burp it. Checking closer, I saw that I had used the wrong cap adapter. It worked well after I cleaned up the mess and tried it a second time.

The original radiator cap leaked a touch and let some steam out when I fired the car up and I could see the rubber gaskets had lines in them. A new OEM cap from Priority Mazda took car of it.

This was the most extensive job I’ve done on the car so far. I’m looking forward to doing more now I have the time to do so.