I'm concerned about my water temps in my s4 gxl. I know the stock guage is not very accurate but know how it reads and the temps do climb when I drive the bag off the car or climb a long hill. I put in some Purple Ice (Royal Purple stuff) with no visible change but I wasn't expecting a miracle. Would a Koyo radiator be overkill in my situation? Are there little tricks you can do to improve the cooling capabilities? My current setup has an e-fan with a good condition turbo rad and I recently had the system pressure tested. Please enlighten me fellow rotorites

 

1: Fan Shroud
2: 1.3 bar Radiator Cap
3: Undertray installed correctly
4: Clean (external) radiator
5: Proper ratio Antifreeze/Water (Minimal anti-freeze)
6: 160degree thermostat
7: Correct timing/fuel ratio
8: ensuring the cat converter is not blocked/plugged

 

If you still have the original radiator getting it flushed (rodded) would be a good idea, although just replacing it would be cheap insurance.
Mine looked like this when I pulled it...

A previous owner had globbed a bunch of epoxy along the bottom seam (lower left corner) but it was starting to leak again anyway.
Any new rad would be fine, Koyos included.

While you're at it you may as well replace the hoses as well.
My upper looked relatively new (figures, it's easy to get to) but the lower was very soft and squishy and appeared partially collapsed where it makes the tight turn.

Also, confirm proper operation of your fan clutch- it should almost freewheel when cold and get increasingly lockedup as it gets hot.
Mine failed this test as well, so I searched for junkyard replacements which is how I discovered that a S5 cannot use a S4 hub (but a S4 should be able to use either).
This lead me the efan conversion.

Oddly, even with the clogged rad, bad fan clutch and dubious hoses, my car didn't overheat and I consider myself very lucky given that the stock temp gauge would have provided no warning.

 

damn thats ugly.

To the OP. Make sure everything works correctly in the cooling system. You shouldn't have to go with a Koyo but it does help from what I hear.

 

If your cooling system is in good repair and is working correctly, it is NORMAL for the temp gauge to show a rise when you flog the car or when it works hard uphill. NORMAL. The car is working harder, it has more heat to reject, the temp should go up.

When you climb 6 flights of stairs, you sweat. If you do 100 pushups, you sweat. Same thing; it is NORMAL.

Too many threads with posters worrying about temps that are NORMAL.

Don't worry about things that are NORMAL. There are plenty of things in life to worry about.

So check the system, verify it is clean and in good repair. Then worry about world peace or maybe your apex seals.

 

This isn't a suggestion, just an observation. So, take it what it's worth.

Before swapping out my motor i had the ac condensor in front of the radiator and it blocked a lot of air from hitting it. After taking it out my temp gauge never goes over 1/8th the scale while previously it would mostly hover around 1/4. And that's with me beating on it.

 

160deg thermostat will only keep the car from warming up to normal operating temp as quick - meaning increased fuel consumption. If the rad/cooling system can't maintain the temp with the regular 180deg thermostat, a lower opening point won't fix that - the temp will still climb to the same point, it just may take slightly longer if the cooling system/engine start from the lower temp when you start putting load on it.

FWIW, the indicated temp on my 7 never moves beyond the slightly past half-way point on the gauge, where it sits once the car is warmed up, even in doing 20 minute lapping sessions at the local track, which has an extremely long front straight (so lots of WOT), and fast speeds elsewhere that see lots of high rpm, heavy throttle in 2nd and 3rd on the rest of the course, or accelerating to pass at speeds of 150-160kph on grades in the mountains, or idling in traffic in hot weather with the a/c on. So I would expect a healthy cooling system on an NA to be able to maintain the thermostat-regulated set point - it seems to have plenty of extra capacity.

Remove the undertray and see if your rad is clogged with debris like in clokker's pic - around here, there are a lot of poplar trees, and they drop a lot of "fluff"; I've used a vacuum cleaner to clean mine on a couple occasions when it got looking similar to clokker's.

 

can your car be overcooled????? It happened to me while driving through a snowstorm.

I honestly don't consider radiator upgrades unnecessary (kinda like the sweat analogy. My body knows I'm hot but I don't sweat like a normal person, i sweat A LOT. DO I like it? no. Do I need it? Probably not. Does it cool me down? fo'shizzle!). I mean yeah, it might be expensive and you don't need it but I'd pay just to KNOW the cooling system will never need to be upgraded. Look into some AFCO radiators if you want a cheaper alternative to Koyos and such. You might not find an exact replacement but the price is nice AND you can make it fit with some effort.

 

put the mechanical fan and shround back on and see what happens. does the temp gauge read lower?

 

+10. I've seen quite a few FC's in the junkyard with electric fans and no shrouds (although the shrouds could have been pulled).

Another thing, did you completely bleed all the air out of the system? Search for it 'cause until I did it the right way I was running a bit warmer than usual.

 

turn your heater on thats what i do. brings the girl right down in temp!! LOL

 

Thanks for all the replies...

1: Fan Shroud - no fan shroud as i run an e-fan
2: 1.3 bar Radiator Cap - stock rad caps for now but something to consider
3: Undertray installed correctly- check
4: Clean (external) radiator - check
5: Proper ratio Antifreeze/Water (Minimal anti-freeze) - check
6: 160degree thermostat - new oem thermostat
7: Correct timing/fuel ratio - runs pig rich when booting it probably of oversized injectors when motor was built so thats not a problem
8: ensuring the cat converter is not blocked/plugged - have no emissions whatsoever

 

REPLACE THE THERMOSTAT FIRST.

If you've already done that, than continue with the other suggestions.

Old thermostats will get sticky - they'll work, but will stick partway open, so when things heat up, they can't open the rest of the way to get you full coolant flow to the radiator. Partial bypass around radiator + high heat output = rising temperatures.

Based on your sig, you have a NA. Unless you've done some incredible things to it, the stock NA radiator should be more than enough to keep it cool.

Replace the thermostat, and see if it fixes it. My 88SE was doing similar things - it'd get warmer when I was beating on it, or on long highway hill climbs, etc. Replaced the thermostat, and now the only time the temperature rises is sitting in traffic with the AC on, or coming off the autocross course after a 1st gear run (and I think that's just from cavitating the water pump so it's not circulating as well).

-=Russ=-

 

The same thing can happen when you go on an off-road excursion at a race track... just not quite as badly.

 

If the coolant seals, hoses or housings are weak because of using insufficient anti-freeze or age, a 1.3 bar radiator cap is a good way to blow a motor

Yes and no... no more than 70% water to 30% coolant, but I would highly recommend 60% water to 40% anti-freeze in all but race track conditions.

NO NO NO NO NO bad bad bad. The stock 180F thermostat is the only thing you should ever run. If the aftermarket 160F thermostat even works in the rotary and has the weep and proper bypass (which most don't) 160F is too cold.

If you need to drop the temp using a OEM Mazda thermostat, there are serious other problems with the cooling system that should be fixed first.

This is not some FWD piston car where bolting on a cold thermostat keeps the temp too low and makes the engine run rich. Running rich on a non turbo (such as the one the thread originator has) will rob you of power.

 

listen to icemark... HE'S the MAN!

 

I have a new Mazda thermostat for all the dudes saying to replace it (as it states in every post I've made lol). I'm just wondering what else you can do to lower temps if your cooling system is in proper working order. If you, Icemark, have anymore advice I'd love to hear it.

 

well what do you consider high temp that you have to lower it.

A S4 typically runs at about 2/5ths up on the stock temp gauge, while a S5 typically runs slightly over middle.

If you have High temps at idle and below 35 MPH, you probably don't have a working fan or fan clutch
If you have High temps above 35/40 MPH then you probably are missing the fan shroud, or under body shroud, or top radiator shrouds, or have a poor condition radiator.

If you have high temps all the time, you probably have a bad thermostat, or bad radiator or failing water pump.

If you have high temps only when driving hard and with high RPMs you probably have a bad mix of coolant (see my above comments on mixture levels- too much water or too much anti-freeze- will lead to cavitation at high RPM) or a failing water pump.

 

I have almost identical symptoms and its usually running there, but after driving it...

My car is completely stock, so all the shrouds are in tact. You are suggesting a new radiator?

I bought the 50/50 premix. Is this bad?

 

check the weep hole on your water pump guys, see if theres any residue from coolant, good chance it needs to be replaced

 

Another thing to check is the water pump impeller. If the cooling system was rarely serviced and people did stupid things like running pure water, then the impeller may be rusted away...

 

50/50 is just fine.

If you properly bleed the system, and it still runs poorly, check your thermostat to see if it's a stant piece of trash, if it is, get a new OE mazda one. Alot of people buy the cheap stant crap that dont know any better.

I'd check the radiator and see if it is dirty on the front, if you have AC, check to see if the condensor is dirty.



Also, personally, one thing i must ask, is why there is they metal panel behind the oil cooler? At least on AC equipped cars, is it safe to remove it? I'd imagine it would hurt oil temps.

 

wait wait, NO fan shroud at all??? you just have an efan bolted to the radiator...please tell me you at least mean there's a shroud around the efan itself that seals around the rad

 

vented hood

 

OMG WHERE DID YOU GET YOUR HOOD!!!!????????











just ******* with ya.

For the record a replica can be found at www.aerokits.net

I am partial to the knightsports copy that aerokits offers

venting all that hot air is one of the best ways to decrease under-the-hood temperatures.

The REAL D-max hood * showed a 10degree celcius difference on a Nissan Silvia (tested in Japanese magazine).

*VIS sells a copy of the D-MAX hood as a DRIFT HOOD without the rear vent by the wipers [based on the pics they show]