MazdaManiac

iTrader: (3)

'Twas a joke.
Obviously, fans on the oil coolers is a bad idea.

9krpmrx8

iTrader: (46)

I agree, I wish I had the oil temp gauge installed when I modded the vents behind the coolers. If you are planning on keeping the stock coolers definitely get screens (mine were destroyed) and open up the backs of the liners. I think ideally two aftermarket coolers (Long, Fluidyne, or Setrab) and 5/8" hose with a Mocal thermostat is the way to go.

For coolant I think the Pettit setup is the best I have seen.

ASH8

Terrible Idea!

longpath

iTrader: (1)

I'm looking for a way to keep oil temperatures under control under a very specific worst case scenario - After at least an hour (and sometimes more than 3) of highway driving in 98F/37C or greater ambient temperatures, needing to be able to idle the car with the air conditioner running for ten to twenty minutes or more. For that reason, I'd considered installing oil cooler fans; but the Fluid kit isn't available any longer and I haven't been able to find out what diameter those fans were. I do think I will try opening up the fender vents; but I'd like to know what other options exist to keep temperatures under control under this particular scenario. I've switched to Evan waterless coolant, which was helpful when the coolant temperature spiked to 243F/117C; but, I am concerned that oil temperatures must be dangerously high. Popping the bonnet seems to help once the car is parked. Does anyone have any other recommendations?

mdw1000

Do you have an MT or an AT? A second oil cooler helps oil temps on an AT.

Rote8

You suggested you had tried running without a thermostat; is it possible that the RX8 has too much coolant speed without a thermostat?


A test for you over in "The Phoenix":
Take a stock thermostat, gut it where you only have the flat, "washer" part left, using that "restricter plate" in place of a thermostat will limit the speed of the coolant and hopefully give the radiator more time to cool the flow.

Possibly try even smaller holes in the washer, if the "washer" in place of the thermostat improves the temps.


429 Fords needed this trick many years ago, they would overheat without a thermostat.

longpath

iTrader: (1)

I have a 2004 MT. I am planning on making Ash8's suggested modification to incrase air flow through the oil coolers. I'm already using Evans waterless coolant, which I am convinced was helpful in not breaking the engine when the temperature spiked to 243F.

longpath

iTrader: (1)

I did some more testing this morning. The first thing I checked was to see if my coolant levels were low. They were actually a bit high; but I haven't figured out how to get the excess out.

I then checked to see if increasing the revs to 3000 rpm might improve the situation (I was thinking that the coolant pump might not flow adequately at idle). That made the situation worse even though I had the hood up, causing a spike to 245F (air temperature was 79F). I turned on the heater full blast to get the temps down (the vent temperature hit 136F before the digital thermometer I have stuffed in the AC vent became unreadable). The in-dash gauge was definitely moving; but I was mainly paying attention to the numbers from my ScanGauge II. When I let the revs drop to idle with the heater on, the temperature dropped to 210, so I was able to close the hood, and then take the car around the block, further dropping the temperature.

I'm wondering if the 2004 vintage thermostat might not be fully opening. It's an elusive problem. I don't know if the problem has been there all along that I just didn't happen to trigger or is something new.

The radiator, overflow bottle, coolant pump, and thermostat are all original. I am not sure if the hoses are all original or not, though none show signs of leakage. My only cooling system modification is Evans NPG+ coolant.

Razz1

Have you tried grabbing the fan and trying to spin it?

If you can move it easily the fan is hot.

Even though you see the fan working doesn't mean it is spinng fast enough.

longpath

iTrader: (1)

I think you've probably hit the nail on the head. I'll be inspecting the fans as soon as I can because I think they showing their age. They don't seem as loud as I remember them being when the car was new.

ASH8

Razz, I think you Definitely Hit the Nail on the head with your advice...

Many of these Overheating or Hot engines, or poor Air Cons are due to the fan motors themselves..not sure if they are "wearing out", but they appear to be slowing down.

Ask oneself WHY did Mazda change the Fan Motors in the Series 2 RX-8's, the two Fan Blades are the same, the fan shroud has changed to accommodate the 2 new motors...??

So, You could upgrade with 2 new motors and shroud.??

N3R1-15-150 Motor (2) $59.00 each.
N3R1-15-210A Shroud (1) $92.00
D201-15-T52 Nuts (6) $1.18 each
Or
N3R1-15-025A Fan Set Complete with Blades, Nuts, Motors and Shroud. $366.00

nycgps

iTrader: (1)

I replaced Motor #2 once. not because its dead or anything. cuz I turn it with my hand once and it felt like something is "clicking" inside.

hmm, new fan shroud? it might seal a bit better? did an of the cooling passage changed for S2? I never looked at it (like tube goes to ECU, battery box)

nycgps

iTrader: (1)

wait a minute, you said you're using NPG+ coolant ?

if so, your temperature will usually be higher than using EG coolant. thats because PG based coolant like NPG+ absorbs more heat than usual.

longpath

iTrader: (1)

NPG+ does run warmer; but only about 5F warmer. It's enough that the heater is a little more inviting in Winter; but not enough to cause coolant temperature spikes of 243F-245F.

Thank you! If the fan motors, electrical circuits, fuses, and air pathway all seem good, then I will probably go with that upgrade to the S2 fan motor and shroud.

lflood

Can you guys tell me the easiest way to change the fan shroud. maybe not the easiest but just how to?

THanks!

DarkBrew

Thread resurrection! I often wonder what happens to these guys... was this ever resolved?

Iflood,
Have not done it but understand from WCS who has done it... there is no easy way...
Must drain and pull radiator.

Must do this myself soon as I end up running the fans a lot with the lower turn-on temperatures I have programmed into the ECU

BTW, in 37C weather, stop-and-go traffic, AC on the coolant temps (50% standard antifreeze) never got over 95C

nycgps

iTrader: (1)

easiest way is to drop your radiator from the bottom.

sad but true.

Afterall, <----------- this dude is the dude who created the original Radiator DIY thread Yeah, he knows how to swap a rad. lol

Dennis Woo

Stock coolant temperature gauge

Let me start off by telling you that our stock coolant temperature gauge(meter) on our dashboard is a dummy gauge.
It is not accurate and it only moves once your engine starts to overheat and by that time it maybe too late.


So how do we then get an accurate reading?

Well, you have 2 options:


1) Install aftermarket coolant or water temperature gauge

or


2) Run an app on your Android Smartphone paired with a ELM327 OBD-II Bluetooth Dongle.
- For those using iPhone, you cannot use the Bluetooth dongle but instead get the Wi-Fi version.
- For more info please see this posting - Bluetooth ELM327 OBD2 Diagnostic Scanner


At what temperature range would be considered as normal and what would be considered as overheating?



At idle, the range that is considered normal is anywhere between 90 to 98 Celsius (+- 2 depending on ambient air temperature and air flow).

When the car is moving or cruising at highway speed, the in coming air flow will help cool the radiator down further and you should see your coolant temperature hover between the 88 to 94 Celsius range.

What constitutes as overheating is when you see your coolant temperature go past the 100 Celsius mark and starts to climb higher and higher. You should start to panic when it hits the 110 Celsius mark as you are heading toward the danger zone.

When would overheating normally occur?

Typically, there are 2 (or more) situations where you might encounter some overheating issues.

They are:
1) During slow speed or caught in a bumper to bumper traffic jam on a super hot day (34 Celsius and above).
2) After 1 or 2 hot laps at the race track (track days)

Dennis Woo

Overheating Scenario 1: Happens only during traffic jam or long period of remaining idle on a hot day

This condition is common with old or high mileage cars. The overheating only occurs during traffic jam on a hot day.

Symptoms:
- The car's air conditioning suddenly no longer blowing cold air.

Possible cause(s):
- Faulty radiator fan motor(s) that could have stopped working completely or is still spinning but at a much slower speed that before.
- Faulty wiring to the fan motors
- Faulty thermostat
- Leakage somewhere in the cooling system (radiator, water pump)

Solution(s):
There is a high chance that the main cause of overheating in this scenario is a faulty radiator fan motor or the wiring issue of the fan motor(s). So get it replaced as soon as possible.


Overheating Scenario 2: After prolonged or sustained high RPM driving (Driving the car hard)

This scenario happens typically when you are driving your car hard especially after a couple of hot laps at the race track during track days. Then when you back off the accelerator or slow down during the cool down lap, the coolant temperature starts to drops back down.

Symptoms:
- The aftermarket water/coolant temperature gauge indicates a sudden spike in temperature every time you gun the throttle to shift at high RPM

Possible cause(s):
The stock RX-8 water pump impeller fins were not designed for prolonged or sustained high RPM driving. What happens during high RPM driving is that the stock water pump impeller fins is turning so fast until it starts to churn the water and caused bubbles (the term is called Cavitation) and this causes havoc to the cooling system as we do not want air bubbles (air pockets) on the surface of the metal as this will cause hot spots in the engine as well.

Solution
Replace the stock water pump with Mazmart Water Pump and also replace the stock thermostat with Mazmart's lower temperature thermostat which opens up sooner at 76 Celsius.

Dennis Woo

DEI Radiator Relief + Distilled Water + Coolant



DEI Radiator Relief is an additive and not a coolant(anti-freeze). It is an add-on that will help make your coolant more efficient in drawing away heat as much as possible from the engine block.

The best combination so far is 3 bottles of DEI Radiator Relief + Distilled Water + 3 bottles of coolant (best to use red or blue color type).



Read my review about DEI Radiator Relief at the following posting.
DEI Radiator Relief really works

9krpmrx8

iTrader: (46)

If you put that crap in and it worked it was only because you needed a coolant change anyway. And adding the Mazmart pump MAY only help at high RPM and that it is, I have seen no benefit from my Mazmart pump or Thermostat.

The best cooling mods you can buy are a good radiator and good high cfm fans. But for 99% of owners a PROPERLY WORKING oem setup is ideal.

longpath

iTrader: (1)

Which fans would you suggest for high cfm? I am not convinced that my original OEM fans are, in fact, in good working order; but I only see issues when the AC is running on hot days (indeed, I verified this Summer that just turning off the AC and sweating it out was enough to bring down temperatures when idling or trundling along in slow traffic).

I am considering swapping the OEM radiator as well; but have't made up my mind yet. I need to run something past Charles at BHR first.

9krpmrx8

iTrader: (46)

I have this setup. This is just an example, I got mine for much cheaper.

Flex-A-Lite FAL-220 Dual 12 inch Puller Auto Electric Fans 2500CFM


They also make a 420 that flows even more, Hoss-05 has that setup

http://www.flex-a-lite.com/auto/html...ro-puller.html

FLCL

So someone said if you have overheating to post cause he/she would like to know, so here goes:

OEM Radiator broke - Replaced with all aluminum (BHR) radiator
Went ahead and replaced the water pump, thermostat, thermostat housing, & any gaskets associated, since I was right there anyway.

Ambient temperatures of 40°F up to 80°F I will start to overheat ONLY when:
A) Bumper to bumper traffic for 7+ mins
B) Sitting idle (after normal temp reached) for 13+ mins

No other time have I yet to see the dash temp gauge go higher than normal (normal being slightly left of the middle).

I live in GA so it does not get into the triple digits like whoever from New Mexico or the Texas person.

I am 90% sure if I replace the following items my problem will go away:
1) Replace water pump with the Mazsport one i suppose (the new one was OEM from like autozone lol)
2) Replace the thermostat with the one that opens at 180°
3) use something other than 50/50 radiator fluid, or with it
4) driver side oil cooler (many of the fins are clogged with concrete.....wtf...ya concrete, I drove through powder concrete that was coating the road, looked like road until I drove through it......)

Anyone's thoughts would be beneficial.

Thanks!

71K miles, original engine...that I know of (4th owner)

Fan fuse was blown, changed it out and now no overheating issues.

9krpmrx8

iTrader: (46)

Mazsport is out of business, I think you mean Mazmart and if your pump is new I doubt that is the issue. You do you know you have cooling fans right? have you checked them to make sure they are working properly? Did you properly bleed the cooling systems as per the FSM?

http://foxed.ca/rx7manual/2003mazdar..._S01_0165.html