sobe_death Dork
3/8/22 11:12 a.m.

Another question is do you have the temp sensors swapped?  It doesn't make sense for the fans to be running if the radiator isn't hot (or the AC output is switched on).

captainawesome Dork
3/8/22 11:14 a.m.

In reply to sobe_death :

Temp sensor is WAY back on the back of the head by the firewall. It's so far from the thermostat that the disparity in temps is quite staggering.

captainawesome Dork
3/8/22 11:34 a.m.

So here's how it's been modified.

Blue line goes to upper rad hose.

Yellow line goes to the heater core intake line.

Orange line is the return from the heater core which has technically seen a heater matrix so slightly reduced in temp from that.

Green line is to the lower rad hose.

What's been changed? The throttle body heater line is deleted. No biggie. BUT there's also one less line to the thermostat housing. You can see it's now blocked off next to the orange line. This line would normally go to where the yellow line comes out of the intake side of the head. The heater core line would have normally come from the neck on the back of the head.


What I'm suggesting is to add the fuscia line below and add a port on the rear neck for the heater core line. This is what the stock configuration was using essentially just snaked around in a different manner.

Or this which I think is more correct:

¯\_(ツ)_/¯ PowerDork
3/8/22 4:38 p.m.

Depends how hard it is to switch them around, but assuming the lines are all a standard size this seems like a relatively simple experiment to conduct.  I would agree that adding one line back to the thermostat housing seems like it should improve things in this situation.

captainawesome Dork
3/8/22 4:46 p.m.

In reply to ¯\_(ツ)_/¯ :

That's the path I think I'll take, just gotta figure out the logistics of shutting the car down for a couple days while I sort that out. Since it's been upgraded to my daily driver I can't kick it out of rotation. The DSG flywheel on my TDI A3 decided to take a dump at the most convenient of times.....

I did some more digging on the low temp thermostats. It looks like they have updated the Mishimoto and other branded low temp thermostats to begin it's opening around 154.4 then fully open at 173.

Stock would be 172.4 opening and then fully at 194.

So roughly an 18-20 degree drop in opening.

Sonic UberDork
3/8/22 5:43 p.m.

Hondas have always seemed to run better if you leave all the coolant lines, they seem to be there for a reason.  This similar thing used to happen with B and D series too when people would try to simplify the cooling systems for swaps.  

Great progress on this, I'm a K fan, currently putting our k24a2 into a new chassis after the old one was retired.  It works so well and hasn't given us an bit of trouble.  

captainawesome Dork
3/8/22 5:49 p.m.

In reply to Sonic :

It seems that's a pattern I've found as well from my forum searches. Folks try to reduce future problems but end up creating them to chase instead.

This engine has North of 264k miles, still kicking, and doesn't seem to be in any state of duress. I think that's pretty neat.

captainawesome Dork
3/8/22 8:38 p.m.

So I tested some stuff when I got back to the house.

My previous settings for fan 1 to kick on was 198 and it should shut off at 190.

Fan 2 was set to kick on at 204 and should shut off at 195.

I started the car in the garage and let it idle. I revved it up a little to get the temp up and fans kicked on as intended. The thermostat housing got warm enough to start to warm the lower hose. Not much though, so it didn't seem to be fully open. Either way that's what I expected to happen.

So I adjusted the temp on fan 1 to kick on at 200 then shut off at 195. Then fan 2 was set at 202 and same shutoff at 195.

This allowed the lower hose to get warmer when idling in the garage.

I took the car out for a spin and under load with RPM above 3k I can keep the car below 200 easily. If I putter around at 2k however the temp started to climb. In fact it managed to get to 212 under light load. I quickly sped up RPM and it would drop pretty quick. When I pulled the car back in the garage it was hovering at 207 and couldn't drop enough with both fans on. The hose on the passenger side was hot but again now the lower hose is cold. Not ice cold but actually cool enough it's shocking.

I don't have a way to really check the temp on the thermostat housing but it's warm. Clearly still not enough to open the thermostat.

At this point I'm either ordering a low temp thermostat to get a quick cheap fix OR I'm going to order Kpowers Miata coolant neck and barbed fitting so I can add the second heated line to the thermostat housing. Realistically I'll probably do both but swap the thermostat back to the stock one when I add the second line?

daytonaer HalfDork
3/8/22 9:30 p.m.
captainawesome said:

So I tested some stuff when I got back to the house.


I took the car out for a spin and under load with RPM above 3k I can keep the car below 200 easily. If I putter around at 2k however the temp started to climb. In fact it managed to get to 212 under light load. I quickly sped up RPM and it would drop pretty quick. When I pulled the car back in the garage it was hovering at 207 and couldn't drop enough with both fans on. The hose on the passenger side was hot but again now the lower hose is cold. Not ice cold but actually cool enough it's shocking....

I have a scan gauge on my k24 in my stock TSX (k24z3), it generally hangs at 190when up to temp, I have only got it up near 200 beating on it during the summer.


I vote  "fuscia" mod before thermostat mod just to try to get as near stock as possible first.


Either way, I'm enjoying following along at home and appreciate the updates. 

captainawesome Dork
3/8/22 9:57 p.m.

In reply to daytonaer :

Agreed. The thermostat is a temp fix since I need to limit my downtime. Once I have my backup transportation sorted I'll go straight to the fuchsia plan.

AWSX1686 (Forum Supporter)
AWSX1686 (Forum Supporter) UltraDork
3/9/22 8:57 a.m.

In reply to captainawesome :

Just out of curiosity, when you swap thermostats I'd test the old one just to see if it was opening at the correct temperatures. Maybe even test alongside your new one. If you have a digital thermometer and a pot of water you can boil it's a pretty easy test. 

captainawesome Dork
3/9/22 9:06 a.m.
AWSX1686 (Forum Supporter) said:

In reply to captainawesome :

Just out of curiosity, when you swap thermostats I'd test the old one just to see if it was opening at the correct temperatures. Maybe even test alongside your new one. If you have a digital thermometer and a pot of water you can boil it's a pretty easy test. 

That's a good idea. At least I can confirm that I'm not crazy. When comes to the thermostat at least.

I also finally found a good diagram of the actual k24a2 coolant system. I think it really confirms the secondary hose is needed. I wonder if I was able to have the current hose going into the blocked off port that it would activate the thermostat quicker. It would dump directly onto the thermostat versus the other kinda being only closer to the tip of it and easily sucked into the water pump bypass.

captainawesome Dork
3/14/22 5:20 p.m.

This weekend I dove into the coolant system issue. First my low temp thermostat came in and that's all I planned to do. Then I realized swapping the gasket on the rear water neck would get me a good idea of whether I can tap or if I need to weld. Tons of meat to do the tapping so I checked to see when my new barbed fitting will arrive. I could have sworn it said Sunday so I started running around town gathering a 5/8" barbed fitting, a new passenger side rad hose(I feel like the one I had before was cut too short), and another splice for the 5/8" lines added.

While I was waiting on this fitting....

I decided to set valve lash. For some dumb reason I never did that with all of the k24 refresh so it seemed like a good time as they were a bit noisy. As expected they were out of spec. After a few minutes of adjusting they were good to go and all that's left is waiting on the fitting. That fitting apparently wasn't actually showing up until today. Frick! So tonight I should wrap up this coolant hose experiment and know for certain if it helps any with my issues.

It's now hooked up to the smaller port that the heater core was using before. The outgoing heater core line will now connect to the larger port once the fitting arrives and the coolant line fed by the intake manifold will now connect to the inward flow of the heater core. Whew! I'll still be using the stock temp thermostat to confirm it all functions like it should have to begin with.

Almost forgot. This friggin plastic piece on one of the injectors decided to commit Harakiri. I ran over to the local U Pull It and snagged four injectors in hopes I can swap over at least one of them. It worked out great but amongst all of this I then realized the RDX injectors I purchased for e85 use are fake copies. The flow pattern will be all wrong so I'll be getting some ID1050x or similar at some point when my wallet catches it's breath. Then I'll install right before doing my remote tune with Tuned By Shawn.

captainawesome Dork
3/15/22 8:51 a.m.

The new barbed adapter came in yesterday but for whatever reason they didn't send the safety wire normally included with the kit. I didn't have any in the garage so for now I used two loops of guitar string until I can do it properly.

I also bought a fancy vacuum coolant kit to try out and I like it. A lot. While it didn't completely eliminate the need to burp the system it made checking for leaks and filling quicker with way less mess.

Burping went well and before you know it the lower hose was getting warm. I didn't want to get my hopes up much until I went for a spin, so after letting it cool I topped it off and went for a ride.

Temps stayed steady at 179-181 at low RPM and would drop to 176-177 with higher RPM. At a stop light the temp would slowly rise to 185ish if there for a short minute. If I have to sit longer it would get to 190. Best of all when I ran it up and down the highway it stayed steady at 180-182 regardless of whether a car was in front of me or not.

So, my conclusion is that the added coolant line made a HUGE difference. When I got back from my trip last night and to work this morning the lower coolant hose was warm. Before it would be dead cold with the fans just going to town. Now the fans barely kick on. I changed Fan #1 to kick on at 195 then off at 190, Fan #2 kicks on at 198 then off at 192. Both are timed flawlessly and get it back to 186 or lower just from that quick cycle, and I do mean quick.

sobe_death Dork
3/15/22 10:56 a.m.

Awesome news!  Maybe I didn't catch it, but are those new temps with the OE thermostat or the lower-temp?

captainawesome Dork
3/15/22 11:41 a.m.

In reply to sobe_death :

OE thermostat is in it now. So I basically wasted $80 on the low temp one but oh well. I also forgot to mention that I boiled both and they were activating as described.

Slippery UberDork
3/15/22 12:31 p.m.

Glad you got the temps sorted. 

CAinCA HalfDork
3/15/22 12:39 p.m.

Awesome! That's great news.

captainawesome Dork
3/25/22 2:24 p.m.

Started the car this morning and could hear a bearing whine in the belt assembly. Ugggh. I waited until lunch time to pull the belt and check bearings for each pulley. Best I could tell is the alternator that I got back in December was already failing in the bearing department. So I took it over to Autozone to swap it out and now the noise is gone. Pretty sure I'll be finding a genuine Denso soon to eliminate the trash I've bought. The good news is that with all the engine bay space it takes less than 5 minutes to swap an alternator.

First autocross of the season is this Sunday. I'm really excited to see how the car does when I can finally open it up. It feels great. Going to adjust dampers for the first time past street settings so hopefully that helps tighten things up a bit.

I've also began looking into more power.......

Because why not?

If I want to keep things NA I can still build a streetable 300hp setup. While this isn't a cheap endeavor, it's also not crazy expensive compared to modding an Fa20. Heck I paid $1300 for headers alone on my last FRS so getting a CNC ported head for the same cost seems like a dang good deal.

So here's what's rolling around in my head. I find another k24a2 engine and tear it down. Then add the following recipe:


4Piston TSX head

4Piston RR3 or RR4 cams

12.5:1 pistons

K1 H beam rods

Supertech valve spring kit

74mm Bosch throttle body

ID1050x injectors


If I decided to go with the future Jackson Racing supercharger kit it would probably cost about the same or a smidge less than the NA build. It would give me more considerably more power with less effort. However it does add extra complexity with belt setup, added weight, piping, and also the chance of a Rotrex failure. I had one seize up on my previous FRS and the wound on that one is still pretty deep. Either way I'll be on the lookout for a spare engine. Whatever I do with the NA build head wise will still benefit the supercharger so no loss if I did both right?

captainawesome Dork
3/28/22 9:36 a.m.

What a great weekend! So much to unpack here.

Saturday I finally got a chance to slap new rotors and Carbotech 1521 street pads on. I'm really happy with the change as the previous pads were just terrible. No feel and didn't seem to really like stopping all too well. These have a good initial bite that isn't too grabby with plenty of room for pressure modulation. On the street.

I may upgrade to AX6 at some point but for now these will do the trick. I still have some XP10s ready for a track day. Trying to stick with Carbotech since I can just change pads and not worry about having to bed them after swapping.

Sunday was our first local autocross of the season with OMR SCCA. A good buddy of mine is now Solo Chair and was asking for some help this season. I said heck yes cause that's what friends do, and for whatever reason he asked me to do course design. Uh wut?

I've never designed a course. Ever.

I can honestly say at first I wasn't jazzed about the idea, but sometimes you gotta do stuff that's challenging. So I sketched out 8 total, 4 without any fancy crossovers and 4 with. I was told it's good to start the season with something everyone can ease into, so I picked one that would be a good fit.

The morning of the event I was nervous as hell. I've helped setup courses before but it's different when they point and tell you where to place a cone vs doing the pointing. Luckily I had a really experienced helper to make my sketch a reality. We got it all set up with minor changes from the sketch and then it was showtime.

IT WAS AWESOME! Of course I liked it but what about the other fellers? I really hate to toot my own horn but all of the guys I look up to and respect in our club were super pleased. So I guess I get to try out a few more sketches and see if it was a fluke.

Anyway, enough about me. The car. The FRS. Oh great white wonder. How did it do?

We had sun but it was windy and chilly so tire temps weren't great. Either way it just did everything awesome. I love this car. It's the best version I've driven of one yet with just a tiny couple tweaks needed to make it just about perfect. Power delivery and extra revs were so much better. The PS4S tires did awesome considering they are only 300tw. In fact I ended up 6th overall out of 70+ cars. I have some footage to load up but forgot to do so last night. For now just a couple pics I snapped while in grid.

So what's next? I sold some stuff over the weekend to start my quest for more power. Whatever I go with I want to make sure I don't just move the powerband up as the low end torque was rad for keeping momentum or just digging out of low speed situations without much throttle input. The CSG Tein Flex A's did great in "race" settings with 5 clicks up front and 7 in the rear. I could tell the car what to do with throttle or steering with ease. Under heavy cornering load however they were bottoming. I think. Pretty sure I just need to raise the car up a little but I had the same issue with my KW v3s on the previous FRS. I don't want to increase spring rate. Before I go too crazy I need to get the car up in the air, pull a wheel and see where it's touching. I never rolled the front fenders, so that's a possible reason? I'm also considering a second set of wheels with some 200tw tires for autocross and track work. That's probably a better place to spend money instead of power but it's nice not switching wheels for an event. Enough chat for now I'm sure I forgot stuff. More to ponder. 

captainawesome Dork
3/28/22 9:34 p.m.

No I didn't join the Blue Man Group. Also the audio sucks but hey it's still a video of me doing hood rat stuff with my friends.


Here's a few pics a local hot shoe took during my heat. I'm sure there will be others soon. Judging by the visible body roll I think it's fair to say the theory of bottoming out is fairly accurate. I don't want stiffer bars or springs for ride quality so I may just have to see how I can mitigate it another way.

ae86andkp61 (Forum Supporter)
ae86andkp61 (Forum Supporter) Dork
3/29/22 12:14 a.m.

In reply to captainawesome :

Sounds like a successful weekend! The car looks great, and looks like it was fun to drive.

 As someone who just ordered KW V3 for my own FR-S, how was your experience with them on your previous car? I was hoping they might be the ticket for a street car also used for autocross and trackday now and again.

captainawesome Dork
3/29/22 8:45 a.m.

In reply to ae86andkp61 (Forum Supporter) :

I think they are a well rounded coilover for what you need. I was really happy with mine until I wanted to go full race and swapped for RCE Tarmac 2s with 500lb springs all around. My only real gripe was with rear droop being limited, and that was for both sets since they are KW based. I can't say for sure if it was the Eibach sway bars causing the issue or not but I don't believe that to be the case. I also had bottoming out issues up front on autocross and heavy loaded corners. A big reason for that I think is my wheel and tire package being 18x9.5 with a 245 40 18 and too low of a ride height. I think a 17x9 would take care of that issue real quick like since the tire diameter is a little less. The Tarmacs didn't seem to have the issue since I raised it up a little and possibly the 500lb springs.

Anyway, I recall something about folks switching the front springs to the rear for the v3? Something to look into. There are a couple different spring rates they released over the years, and I think the earlier versions had slightly stiffer rates. Some folks preferred the stiffer if I remember correctly.

With all that said I really like these CSG spec Teins. Having only one adjustment knob is so nice, and they ride phenomenally in the street/race recommended clicks. If these start to degrade, I'll send them back to be rebuilt for sure. The biggest downside to these is waiting for a set as they are always on order. So if the KW doesn't tickle your pickle the CSG just might.


docwyte PowerDork
3/29/22 9:28 a.m.

Lord help you if you need to warranty the KW's.  They won't just send you another shock/strut, charge your card and then refund you when you send in the bad one.  They require you to send in the bad strut/shock for them to rebuild, which in my case, took 6 weeks.  On my DD, so I bought a completely different suspension and when KW finally sent me back my stuff, I immediately sold it.

captainawesome Dork
3/29/22 10:12 a.m.

In reply to docwyte :

Honest question, but does anyone else send you a new part without seeing the "failed" one yet? I get what you are saying but that sounds like a tough situation in both directions via company and consumer.

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