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The K24Z3 has a different thermostat and housing from the K24a2. The K24Z3 thermostat is designed to be used with a quick release, so without the quick release it has no lip to make a seal with the lower radiator hose (see pic). With the quick release attached it sends the coolant hose in the completely wrong direction (see pic). You cannot just get the K24A2 thermostat, you have to also get the housing/case that attaches to the block because the bolt pattern from thermostat to housing is different. So you have to get part numbers 19301-RAF-004 (K24A2 thermostat), 19320-RAA-A02 (K24A2 thermostat Case/housing), and 19322-PNA-003 (Thermostat case housing gasket). The gasket and the bolts are the same between K24a2 and Z3.
David at kmiata warned me way from that Ktuned piece because of reliability issues. And with the suggested lower rad hose the stock k24a2 parts work pretty well. The hose doesn't rub on the subframe at all. I'll be doing a whole post about coolant hoses later once I get them all sorted.
Took a break from updating this for a while. Just wanted to focus on working on the car.
The car is running and driving now, but I'm going to pick up where I left off and walk you through everything I did.
Coolant hoses For the lower radiator hose, I used the one that Kmiata suggests Dayco 71718. It clears the stock subframe by about 1/4in. At first, I hadn't tightened down the thermostat side enough and it was leaking. Because of the severe angle and not perfect fitment you'll want to crank down on your clamp to get it to seal.
For the upper hose I used these two ACDelco 26623X and Dayco 72816, and then a 13in long piece of 1.25in aluminum pipe that I had bead rolled edges and a bracket welded on so I could secure it to a threaded hole already on the car by the strut tower. My windshield washer fluid bottle did not fit.
For the heater core to the back of the head I found this Dayco 87675, with trimming it fits perfectly. Heater core diameter is a metric size slightly larger than 5/8ths, I used a little shin etsu grease to help them slip on
For the heater core to thermostat case, I used regular 5/8ths coolant hose. It only barely touches the manifold, I don't think there will be any issues there. I used the Tractuff K series thermostat port adapter to get rid of the metal pipe that comes out of there from stock. I also used a little grease on that boring to help it slide in and seal. So far no leaks.
And finally, I used the stock honda k24z3 hose that goes from the thermostat case to the intake manifold. Fits great with the 90-degree hose port Kmiata provides with the manifold.
Worth noting is I use Breeze worm gear clamps for everything (CT9412 x6, CT9424 x6). I got a few of these included with the silicone lower rad hose that FM makes and they weathered 4 years of year-round driving in the North East and looked brand new. They hold a lot more torque than other cheap worm gear clamps and they use a built-in spring to maintain constant clamping pressure despite heat fluctuation and materials expanding at different rates. Overkill, but hey you only live once.
First I tried to use both the k24 (BSPT Thread) and VDO (NPT Thread) Senders with a Ktuned oil pressure adapter. I wasn't a fan of the adapter, stripped an aluminum port block, and overall expected it to leak. Also, I realized the Honda sender is just an on-off switch so there was no point in keeping it and having to run an extra wire for the VDO sender (The Kmiata adapter harness has a lead to wire the oil pressure sender into the Miata's wiring harness).
Then, I got a Mishimoto sandwich plate to mount the VDO Sender. I hated it. no matter what it would unthread itself every time I took off the oil filter, which would make for a very messy oil filter change. I even tried thread tape for the adapter threads and that didn't work.
Eventually, I got wise and realized the stock Miata sender is BSPT thread and threw out the sandwich plate. I got a used sender (new is like $160) from a 90-94 and used gauge from a 90-94 and I was in business. Super clean install, no extra wires. The only downside is the gauge/sender tops out at 90 PSI and the K24 goes is usually higher than that whenever the RPMs are up. Semi warm idle I was at 60PSI. But this way the gauge works, looks totally stock, and you will now if the oil pressure ever starts to dip down below normal operating range.
Ah Good to know the 90-94 OPG sender fits on the K24. I was gonna use a sandwich plate and a NPT -> BSPT adapter. I'd also like to implement an oil temp gauge and have Hondata have oil pressure data for failsafes.
What wiring harness is that?
Also is there a spot further down on the downpipe to mount an O2 sensor?
Have you considered wrapping the exhaust or adding a heat shield to keep the rad hoses and oil filter protected?
I cut and terminated my fuel hard lines. I used Earls AT165056ERL, 5/16 hard line to an6 fittings. They were a right pain to get on. I had to use a wire wheel on a dremel to take all the paint off the hard lines so I could get thefitting to slip on. And even then I had to heat up the fittings to make it happen. I also reused the hardline bracket to secure them to the body.
How are these compression connectors holding up? Any regrets? I'm about to do the same thing but opted to go with a Parker A Lok fitting which used a "double" ferrule seal instead of a single.
How are these compression connectors holding up? Any regrets? I'm about to do the same thing but opted to go with a Parker A Lok fitting which used a "double" ferrule seal instead of a single.
They held up great! Not a single leak, really happy with them.
How are these compression connectors holding up? Any regrets? I'm about to do the same thing but opted to go with a Parker A Lok fitting which used a "double" ferrule seal instead of a single.
They held up great! Not a single leak, really happy with them.
05-02-2020, 10:39 AM
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