Overheating...GAHHH!!

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07-20-2011, 05:04 PM
Jiggerachi

Overheating...GAHHH!!

So it's summer, and that means my car is overheating. The damn thing is basically doing what it always has(after I fixed the radiator), driving fine untill over 100* then every stoplight the AC gets lukewarm and in traffic the temp needle starts to move.

Today while picking up my son from daycare I left the car running for about 2 minutes. Got back to the car smelling coolant, looked in and the needle was pegged on H. I got it down with the heater on the way home, poor kid. When I got home about 5 minutes later, the needle was at in it's normal spot. Ran out to pop the hood and about 30 secs of being stopped(ac off) the needle was on it's way back.

The fans are blowing and moving air, but I can't help but think it's gotta be the fans blowing slow. The car never overheated in under 100*, never overheated while moving over 20mph. I had a slow pair a few years ago, but I replaced them with some I had that blew stronger, unfortunately they are out of a 90, so they might not be in their prime. Hey I was broke at the time and the were free.

Finally, my question: I've searched but couldn't really find an answer. Would it be worth it to get one of these Mishimoto Fan Shroud kits for an NA car? I know the FM Spal kit is king, but i'd rather not spend that kind of cash at the moment. But I'd like my AC back so I am willing to buy what I need.

http://www.miatamania.com/Shop/ViewP...IndexID=101797

http://1xracing.com/mizu/mizu_radiat.../i-305809.aspx (don't know anything about these, but I included them anyway)

I figure they'd have to be better than OEM
07-20-2011, 05:08 PM
Jiggerachi

Forgot to mention, The radiator is a Koyo OE replacement, only a few years old. I'm going to try to flush the radiator this weekend with a 70/30 mix, and probably replace the thermostat if I have time.

However, I really doubt either of these will help, as I topped off the radiator a few months ago(the correct way), and it's got a good about 70/30 mix at the moment. The problem only occurs in traffic so it doesn't seem like the thermostat.

Edit: I just realized I put this in Bull...can somebody move it?
07-20-2011, 05:24 PM
SirHustlerEsq

Did you fill the radiator with distilled water?
Is the thermostat opening all the way?
I think you can test resistance on the fan motor and compare it to a working fan. (I have a spare in the garage we can compare with)
How much resistance on the CLT sensor at cold 100*f and 210*f?
Where is your belly pan?
What are the chances of a leaky hose?
Did you possibly warp the head with it pegged hot? Its time for a leak-down test after what you've done.
How much pressure is the water pump making?

It could still be the thermostat because it's much easier to cool the car when it's moving, making traffic require more flow through the thermostat.
07-20-2011, 05:52 PM
sammm

Mine got hot today (maybe 5/8 up) when I was stopped in traffic. Came back down once I started moving again.
07-20-2011, 05:58 PM
cone-cerned

When I was having overheating problems a couple of years ago, I replaced the coolant with just distilled water and water wetter. That worked well in the summer. Before winter I replaced the radiator with an OEM from Mazdaspeed.

First, I would try distilled water, water wetter and a new thermostat.
07-20-2011, 06:17 PM
Jiggerachi

Quote:

Originally Posted by mr brg

Did you fill the radiator with distilled water?
Yes, always distilled.

Is the thermostat opening all the way?
Not sure, but I think so. Car runs normal 80% of the time, even in this brutal heat.

I think you can test resistance on the fan motor and compare it to a working fan. (I have a spare in the garage we can compare with)
Can I use a volt/ohm meter for this one? I'm a n00b in this dept.

How much resistance on the CLT sensor at cold 100*f and 210*f?
???

Where is your belly pan?
Stock belly pan is on the car, it's seen better days, but structurally it's sound.

What are the chances of a leaky hose?
Hoses are not very old, pretty sure all the water is still in the car.

Did you possibly warp the head with it pegged hot? Its time for a leak-down test after what you've done.
I don't think it got that bad, I think I saved it in time. It wasn't pegged, I exaggerated. It was maybe 90%. I'll keep an eye out for oil in the coolant of the other way around.

How much pressure is the water pump making?
No idea, but I have a TB kit in the garage with a new water pump. Maybe it's time for the dreaded TB job.

It could still be the thermostat because it's much easier to cool the car when it's moving, making traffic require more flow through the thermostat.
The car stays cool 80% of the time, only when it gets below 20mph for an extended amount of time.

....
07-20-2011, 06:36 PM
POS Racing

Another way to see if the fans are good is to run an amperage check on them Mazda has a spec. 4.5 to 6.5 amps.
07-20-2011, 07:23 PM
OZMDD

+1 on water wetter. Even helps when added to 50/50 antifreeze mix.
07-20-2011, 07:47 PM
slowchildmiata

I just use urine in mine. The natural distiller.TM
07-20-2011, 08:03 PM
cone-cerned

I would use urine in mine also, but the radiator opening is too small for the dispenser.::Banana::
07-20-2011, 09:16 PM
black roadster

I'm guessing slow fan. You could also try wiring them so they both run all the time. We also trim the sides of the belly pans to allow air to flow better. What temp thermostat are you using? We have 160 degree thermostats at the shop but you will want to swap it come winter if you like your heater to work well. Don't waste your money on aftermarket fans. Good stock fans should keep you cool.
07-20-2011, 09:53 PM
SirHustlerEsq

Quote:

Originally Posted by black roadster

I'm guessing slow fan.

My money is on the thermostat not opening all the way, I'll take the slow fan as option 2. I'd take it out, boil it, and see how far it opens.

Quote:

Originally Posted by black roadster

We also trim the sides of the belly pans to allow air to flow better.

Air is turbulent under there, I wouldn't do it. I took the time to box-mine on the sides and my car stays under 200*f in 103* heat on the track. His car is stock, it should work on the stock parts.

Quote:

Originally Posted by black roadster

You could also try wiring them so they both run all the time.

It's summer, the AC is on all the time, so both fans are already running all the time.

Quote:

Originally Posted by black roadster

We have 160 degree thermostats at the shop but you will want to swap it come winter if you like your heater to work well.

It will also run ASE below 180*f so it will run super-fat.

Quote:

Originally Posted by black roadster

Don't waste your money on aftermarket fans. Good stock fans should keep you cool.

Agreed, stock fans work for me and my shitty stock, non-aluminum radiator in my daily.

Which radiator cap do you have? I run a 16psi cap, I'm not sure what stock should be.
07-21-2011, 07:35 AM
Jiggerachi

I do know the AC fan is slower than the radiator fan, doesn't move near as much air. From what i've been reading the AC fan is supposed to be much stronger.

The thermostat, I can't remember what temp it is, it's a few years old. Same thing with the cap. I might make a trip to the dealer this weekend and get both new OEM, I think I have aftermarket on there now.

So aftermarket fans are not worth the trouble, for a mostly stock motor? I'm sure quality isn't as good, but I was thinking the mishimotos would move more air, plus with the shroud, for the same price. I might look into just replacing the AC fan since it's at least the weaker of the two.
07-21-2011, 09:08 AM
motorollow

I like my aftermarket Spal fans, but they came with car (thanks HudsonHawk). I bought a new fan motor a few years ago for my 1990. The oem motor had a flat spot, it would not turn without some help. New fan motors are not cheap though.
07-21-2011, 09:37 AM
jakepkoe

If the a/c gets warmer than you're used to experiencing below 20mph, it's gotta be airflow. Unless your compressor happens to be going out at the same time as your thermostat or water pump.
07-21-2011, 12:35 PM
SirHustlerEsq

Ok, now I think its the fans, lol. Mine turn at the same speeds.
07-21-2011, 01:46 PM
Rob®

Yeah, my 90 turns both fans at the same speed, so there's definitely something going on there.

As a tip, if you're going to pull the fans, take a hose to the backside of the radiator, and ideally the AC condenser, and spray all the road crap that gets collected in both. I know you said the radiator is fairly new, but I'm willing to bet the condenser fins are jam-packed full of goodness. Not saying that will solve your problem, but it certainly won't hurt. And you'll be right there if you're swapping fans.
07-21-2011, 02:50 PM
CosmosMpower

Quote:

Originally Posted by slowchildmiata

I just use urine in mine. The natural distiller.TM

LOL, ok ken o
07-21-2011, 05:14 PM
gabkwong

Do you have both fans wired to be'ON' all the time? This may help. From my real world under the hood data, when the A/C is running, it increase the under-the-hood temp by at least 30 degrees even at highway speed. You can imagine at idle. If I were you I would try wiring the fans to run all the time and cut the A/C when the car is not moving. I have a TCB temp prob under the hood and they is why I know the temp differences. The under-hood temp can be more than 40-50 degrees more than ambient temp when the car is at idle w A/C on. It is worse on 1st gear grinding your way through slow traffic!