overheating question

[Billy Blaze]

Hey guys, I have found the need to use the air conditioning recently as everyone else has I'm sure.
I am noticing that the temp gauge is running higher than ever before, its not maxing out but it moves toward the H quite a bit more than it used to.
Since I have never owned one of these cars I am curious is this somethihng that happens to all the 99's or am I special...lol
I am sure it will rise some I just don't know whats normal and don't wanna fry my motor.
I can live with the top down if its just that way or is there anything I can do to determine if this is normal operating conditions.
If it is running hot, where should I start to determine what to fix, the wife won't drive it til I fix it or she knows it's safe.
Thanks for any help.
I usually drive between 70 and 85 mph.

[POS Racing]

Heating up with the A/C on is not normal on either of mine, plus this is just a precursor of hot.

Do you have the undertray under the motor? It helps move air thought the engine compartment at speed.

When was the last time you flushed the radiator? And put in new coolant?

[Majik]

is this somethihng that happens to all the 99's or am I special

Well we all know your "special" billy,
but your car apparently is too, because mine does not overheat really under any condition. First thing to check, do both fans come on with the ac? If not there are a few threads rolling around right now solving that problem. Even if they do work, I would recommend flushing the radiator. Use distilled water, and go ahead and change the thermostat at the same time, who knows when the last owner did it. And like POS said the undertray will make a huge difference as well.

[Billy Blaze]

Thanks for the tips!!
The undertray is on the car, I dont know when it was flushed and filled with new coolant it does look green though.
Where is the thermostat on the 99?
I will check tomorrow about the fans, and plan on doing a flush and fill and replacing the Thermostat for good measure and also getting an AC charge just to do a complete job (soon).
One other thing does the Redline Water Wetter work to make it run cooler as advertised? anyone have any experience with this product?
Thanks again for the advise and tips.
I also noticed a small increase in temp as I reach over 83MPH.

[channelmaniac]

Follow your upper radiator hose and you'll find the thermostat housing.

DO NOT OVERTIGHTEN THE BOLTS or you will snap one off in the housing.

RJ

[black roadster]

I've heard Water Wetter tends to sludge up. I've also heard a drop of dish soap will help.

Seems like you're on the right track. Check the condition of all your hoses and replace the bad ones before summer gets here. Don't forget the often over looked small bypass hose on the fron't of the engine. A coolant flush and maybe a cooling system back flush might help.

I've only seen overheating on REALLY sweltering 100+ degree days while stuck in traffic with the A/C on and attribute it to limitations of the cooling system. This has happened on every Miata I've owned. I've learned to give some space in traffic to provide cooler air instead of the guys hot exhaust air.

Another thing to look at is do you have a grill? Grills can often restrict airflow.

[TurboDuane]

I've noticed my '97 is running up to 108c with the a/c on, but if i keep the rpms low and am easy on the throttle, so far I'm not having any problems. However even at 108c my temp gage isn't moving. On my last car though I was always fighting high temps in the summer with the a/c on. I think that's just part of having a boosted car, especially when the turbo is water cooled.

Once you've done the above mentioned recommendatons, try driving easier when running with the a/c on and see if it runs a little cooler.

[Majik]

I second the NO water wetter. I have heard it is good in a racing engine that is torn apart after every event, but not good for a street engine.

[rjosey8385]

Kinda amusing story...it gives me a chuckle once in a while, anyway. When I bought my '86 Scirocco at auction with the idea of getting into autocross, I came up with endless new and inventive ways to keep the car cool, as the temp gauge was always hot....got an electric fan with more blades, different thermostat, had the radiator cleaned, left the hood up and fan going between runs...still the same thing...the gauge just flirted with H all of the time, never overheating, though. At some point I changed over to REAL gauges....guess what....my car was barely running warm

[Billy Blaze]

I checked the fans both are running.
Was headed down the highway today, top down, just to give her a try...doing about 60 turned on the air and I watched as the themostat started rising,...I was actually watching it move, I turned the ac off it took a good while for it to drop back down to about half way on the gauge display.
I will start next with the flush and recharge of the AC system, and changing the thermostat.
I will report my findings afterwords.
Hope everyone enjoyed the AutoX today, real sorry i missed yet another one.
I will do this,..its just gonna take a while I guess, I want the car to be in tip top shape. Also need to rework the brakes (new pads) flush and fill fluid.
I did however find the brace thanks to Majik that holds in that pesky oil plug..lol so that's fixed at least.

[altiain]

Sounds like the t-stat is toasted. In these cars they tend to die on a pretty regular basis. Fortunately, they're only a $5 part, so I make it a habit to change mine every summer, along with the coolant and the radiator cap. Try those three things first, and that *should* take care of any overheating problem.

That said, some of the '99s seem to run hotter than others. Mine will run a little hot in the summer, especially when running the a/c between runs at an event (with no airflow over the radiator), or when towing the tire trailer in traffic with the a/c on high, especially on a day like today. But even mine (which seems to be more prone to running hot than most) won't budge the needle when running unobstructed at 60mph with the a/c on and no trailer.

[POS Racing]

I will start next with the flush and recharge of the AC system, and changing the thermostat.

You mean the radiator don't ya? ??: Don't use tap water in the radiator!

Never heard of needing to flush and recharge and A/C system unless it's been taken apart.

BTW. I'm another one who doesn't like water wetter!

[Billy Blaze]

Yup thats what I meant flush and fill the radiator and recharge (if needed) the A/C.
And replace the Thermostat.
Thanks for the tips and the heads up about the Water Wetter.
Also I forgot to mention the guy who had the car before me put the license plate in the air Dam there is quite a bit of room on either side and a little below it but even still I am sure this might not be helping things I am thinking of taking it off and putting it in the windshield for a day to see if that helps some too, and if so will invest in an offset license plate bracket even though I like what I have now better.
I don't think this is the case as I used the A/C before and didnt have this problem.
one another note, I bought a cheap 120psi air tank today for $20. at Wally World, can someone recomend a real good and accurate tire pressure gauge?
I am slowly getting all the stuff I want to Auto X may be next season at this rate...lol
I am looking forward to the fun.
Majik, I may also request your assistance in building a CAI like yours in the near future when you can spare some time,...I could meet you where ever so you don't have to drive out here. Yours looked pretty kewl and I think it would help since mine is right over that Hot A** Header..lol
Thanks again guys, hope everyone had a great time and some great runs today.

[jolberry]

Don't use tap water in the radiator!

Why not? I flushed mine a while back with tap water and have not had a problem. Of couse I used the appropriate mix with Prestone.

[sammm]

Why not?

Too many minerals and contaminants in most tap water. It will lead to clogging and ruining the radiator internals.

[jolberry]

hmmm..so should I re-flush or just wait til next summer?

[sammm]

hmmm..so should I re-flush or just wait til next summer?

Since you can get a gallon of pre-mix (50-50 water/antifreeze) at Vatzone for around $6-7, I wouldn't wait.

[Screamin'Screw]

Don't Wait!

Tap Water is Terrible for your radiator. Get it out of there and be sure to use DISTILLED Water only.

[altiain]

You need to use distilled (pure) water in a radiator. As Sammm mentioned, all of the added minerals in tap water or bottled drinking waters will let deposits form in your radiator, which will eventually lead to blockage and failure.

You can use tap water to flush the system, but the final fill should be distilled water and antifreeze only. If you've got tap water in there now, I'd drain it, flush it out, and refill it with distilled water ASAP. If you wait until next summer the damage will already be done.

[Titus]

Don't Wait!

Tap Water is Terrible for your radiator. Get it out of there and be sure to use DISTILLED Water only.

Some people say it is fine to use a garden hose to flush the raidiator, but they still recomend running several gallons of distilled water through the radiator after the garden hose and before the final 50/50 mix. Others say it is not worth the risk at all...