So after about five hours of doing this without a lift, I managed to get the new undertray from Mazda installed. Started the car up with no ac fan on, nothing. After about ten minutes the temps got up to 224, the fan kicked on, and brought them down to about 214~ when it went off. The cycle would repeat, I noticed coolant on the ground again.

So i turned the AC fan on and the park lights, the temp lowered and held at 189. Aren't those temps a bit high for just idling? Are they normal? They seem way high. (idle is bumped up to 1500, but still.)

Also, Idk if this matters, but i stuck my hand through the bumper and touched the AC condensor in front of the rad. Certain areas were very warm, other areas, not warm at all. Granted that's not touching the rad directly, but could that be symptomatic of a plugged radiator?

 

224F (107C) is HOT... 214F (101C) is getting hot... 189F (87C) is where my car lives. anywhere from 84-89C. very rare i get to 90. on an all stock set up with everything in the bay with the FD thermoswitch, i think your actually about normal lol. the issue with high coolant temps is that they run away and continue rising. if yours stabilize then i wouldnt worry too much but that is pretty hot. if you still have a stock radiator then i would replace it as a preventive measure while also deleting the AST.

 

That just seems way too hot to be normal, I think the OEM gauge had begun to move at 224 if memory serves, though I don't think it was much past 1/2. The fan seemed like it kicked on way late..224. This is just the car sitting. Why would it be puking some coolant on the ground? Expansion? I'm looking at replacing the radiator.

 

im sure its connected. youre going to want to find out where the leak is. you can rent a pressure tester from an auto parts store and find it. it might be a little difficult to spot with all the stock stuff in the way

 

https://www.rx7club.com/3rd-generati...system-906142/

If you haven’t, check out Dale’s thread about fan control. ECU should turn the fans on low at 105°C, OEM fan switch should kick the speed up to medium at 107°C, not sure if AT ECU does anything different. If they don’t and your fans don’t come on till 107°C then somethings not right with your ECU input, check relay or temp sender. IMHO, you should give the whole system a full overhaul before looking any further. Replace every hose and gasket, good time to change the wp and radiator since you have the system drained, and swap the fan switch etc.

 

So I took the car out, AC fan was on, but this was the first drive with the undertrey on. Cruising at 70-75 the highest temps I saw on my gauge were 197. RPM's were 2.6k~ I want to say. 60mph, they were in the 180's for the most part. Probably took it on a fifteen mile one way trip, with most of the speeds being between 70-75. Of course it will probably be well over 200 degrees during the day in the heat.

I need to install the FC thermoswitch as well, in addition to checking the temp sender. I just got insanely frustrated last time when I pulled the alt off just to find out I couldn't get the switch off. Idk how people say they got a wrench back there. Maybe I'm just missing something. I feel like I'd need deep offset box end wrench, my regular ones were not fitting.

 

I have change the thermoswitch with everything still on the car and have done it with the wp housing off the car, much rather do it with it off, as you can make sure that super thin o-ring seal properly and both sender torque down properly.

 

I'll try it tomorrow with some offset wrenches, maybe that will give enough room to pull it off.

 

Is there a reason you replaced the undertray?

 

It wasn't there previously.

 

Could you maybe have pinched a line, and/or verified that both fans are actually blowing? Seems unlikely it would suddenly not work after an undertray install, unless you affected something else... temps should be better not worse.

P

 

So after picking up the offset wrenches, I managed to get the old thermoswitch out. What concerned me is the new one that was supposedly from Atkins (was given to me by the previous owner) Just had the part number written on the clear tiny bag it came in, with black sharpie. The part number matched the FC thermoswitch, however, it had no markings or identifying information on it whatsoever. This one had minor size differences in the height of the bolt head on the thermoswitch compared to the one that came off the car, and the connector was black, just like the one that came off the car. I was wondering if I got an exact FD replacement, even though it was in the bag with the part number written on it that matched the FC thermoswitch.

I called Atkins today, and I'm not sure who I spoke with, but they said they have seen the FC thermoswitches come in that had black coloring on the piece that connects to the wiring harness.

So I put the new one in, put everything back together, replace the few ounces of coolant that leaked out, and start the car. No AC fan on, nothing. When the AEM water temp gauge read 195, a fan kicked on, then it dropped down to 186~, and would repeat. Temp never got above this, and the car sat idling for awhile.

I feel like this is different than before, but maybe I'm wrong and it's just a placebo effect, sine the FC thermoswitch isn't supposed to kick the fan on until 205~, correct?

 

I have the FC switch and my coolant temps are steady around 85C on the street and at auto-x.

I'd say you never really had a problem and the stock 110C switch was just doing it's thing, which is to say letting the engine get hot as f. The 85C FC switch lowers the temp to a more reasonable range and is doing it's job now.

Read that classic Dale thread linked by ZE Power... it has all this info in it.

 

Tonight it has been generally in the low 190's while driving+stop and go with nothing on. Though on the way back I did turn the headlights on due to it getting dark, the temps never got above the mid 190's. I'm curious as to if that switch that came out of the car was broken, the car seems to be behaving much differently now. Even the idle is lower now. I have no idea. I just hope it holds and doesn't overheat at sustained highway speeds.

 

The FC thermoswitch really won't do much. Your temps are pretty normal for a stock car. The temps will always rise at idle until the fan kicks on around 224.

 

You may be chasing two things. First the fan control. All the switch does is turn on the fans. You should be able to test the switch placed in water heated to the switching temp. If the fans don't come on, you've got a problem with either your switch or a relay.

Now if the fans come on (blowing in the correct direction) and you experience high temps, you have a cooling issue not related to the fans*. Correspondingly, if you are driving at speed, say over 40, and you experience high temps, you have a cooling issue.

*Fans can only do so much if you idle for extended periods of time in hot temps

What's your percentage of coolant. Coolant helps reduce boiling temps, but reduces heat transfer ability. If you are running 50/50, try 20/80 (with water wetter). You may need a higher pressure cap to keep your system from boiling.

FWIW, I'm running a Ron Davis (i.e. Mazdaspeed) radiator, twin 19 row Setrab oil coolers (oil cooling improves engine temps), 99 spec bumper (better flow than USDM), Mazmart water pump, and deleted A/C (no condenser in front of the radiator). At speed, it's rock solid at 180F. At the track, it gets up to 200 (210 max) which i think i can get that down by better ducting the undertray