Quik_RX7

Howdy gents. I've searched the forums for the past couple days looking for anything relating to the problem I'm having but haven't found much of anything informative. So, the problem I'm having is an overheating problem. Or I think it is....

Anyway, what is happening is my water/coolant overtemp light is coming on. It starts shortly after I start the car, but before it reaches normal operating temperature. When it reaches normal op temperature, it stays on. I was going to burp my system, but my coolant was full and stayed that way until it got warm enough to expand and spill out the tube. So I topped it off, waited for my car to cool down, and did the burping again. Same thing happened. I topped it off and decided to look at my air filter. It was disgusting. I have pics on my phone, but I am too ashamed to put them on here. The filter was manufactured in March of 1997. I bought the car in September of 2011. Never thought to look at the filter because of how well the car was taken care of. Then I had the engine rebuilt in November of 2012 and haven't had a problem with her since. Until now...

So if anyone has any idea what it could be, please let me know. Or give me a hint. Or point me in the right direction. Something haha. I also observed that my fans are not coming on when the temp is normal, and the buzzer is on. So I think the buzzer is getting a warning from somewhere else that isn't cooling.

misterstyx69

iTrader: (142)

In the future,Post your car and any mods,or your tech question will not appear.

1994 RX7 FD

Quik_RX7

Sorry about that. I have a 1994 RX-7, like you said.

Natey

iTrader: (19)

Your AST (air separation tank) may be leaking or need a new cap. Is it stock?

EDIT: Here's a link with a pic.

https://www.rx7club.com/3rd-generati...estion-945019/

Sgtblue

iTrader: (16)

I think the buzzer and light will be from the low coolant level sensor. That's the black hex-head sensor that's screwed into the front of the filler neck housing with a single wire lead.

You apparently have air in the system. I'm way no guru but this is what I would do.....
Fill the AST, replace cap and leave it alone. Open the filler neck cap, fill, replace cap, squeeze upper radiator hose several times, open cap fill again and repeat until it absolutely won't take anymore fluid. This is called burping the system. Once you're absolutely sure it won't take any more, fill the overflow to the half-way mark on the dipstick. THEN check the length of the small hose leading from the nipple on the AST to the overflow. Make sure it's sealed on both ends and has no kinks or anything pinching it. If you don't know how old your caps are, consider replacing both.
If after all this you STILL have the issue with low coolant/air in the system, then have it pressure tested.

Quik_RX7

Natey. Yes, I have an AST. It is an after-market cap I believe. It doesn't have a pull-tab, which is how I am making my assumption that it is after-market. Maybe I have those backwards....

SgtBlue. The hex-head sensor with the black wire lead is fine. The line is still attached and didn't look like it was in bad shape.

EDIT: Well, I just went out to see if I was low since I haven't run the car in over 24 hours. It was a bit low, but that may be from me never filling it after the coolant spilled over the side from getting hot with the cap off. But I have no leaks from the AST or the filler neck. Tomorrow, I am going to go out and see if the level has dropped any since I just filled it, and then proceed to do your suggestion. Btw, my overflow dipstick is almost always over the full mark. Maybe there is just residual liquid in the tube that drips on the stick higher, but I'm pretty sure it is always over the full mark.

Thanks for the help so far. I am missing a job interview because I'm afraid to drive my baby

Quik_RX7

So I went out to check my levels this morning. Everything was about the same as where I left it last night. But I went ahead and filled the filler neck as high as I could, squeezed the radiator line a few times, let it sit for a couple minutes, squeezed again, and then let it sit for a few more minutes. The level was a little low, but I think due to the overflow line at the top of the filler neck. So I repeated the process 3 more times and the same outcome happened. It didn't appear that any extra fluid was necessary. So I went ahead and checked the line from the AST to the overflow tank. There were no kinks and it was sealed on both sides.

Shortly afterwards, I ran the car until it was at normal running temps. About 20 seconds after starting, the buzzer and light for the overtemp came on. I let her get all the way to normal temps and ran her for about 10 more minutes and the light and buzzer stayed on the entire time. I am now waiting for her to cool down before I go check the levels at the filler neck and AST again. About 5 more hours.



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Sgtblue

iTrader: (16)

And after filling you replaced the cap before squeezing the hose?

I'd have the system pressure tested. If it holds pressure, then I might try replacing that sensor...that's why I told you where it was earlier. IIRC, the sensors aren't all that expensive and although you'll loose a little coolant, the whole system doesn't need to be drained. It's not common but they have been known to go bad. IMO, it's worth a shot.
BTW...I forgot to ask earlier....do you have an aftermarket temp gauge? If not get one ASAP. That stock gauge isn't linear and worse than worthless. If it ever gets higher than what's shown in your picture above...it's overheated. If your interested and need it, I can give you a link to a helpful thread on the subject.

Quik_RX7

Yes I did replace the cap before squeezing the hose.

Can any ol' garage or shop pressure test the coolant system?

My needle has never gone higher than that. Not even a little. But the buzzer and light make me very wary.

I do not have an aftermarket temp gauge. I was going to get gauges (oil pres, oil temp, water temp, boost/vacuum), but I recently got off of active duty and have been trying to save money till I find a new job. And sure, I would much appreciate that link.

Sgtblue

iTrader: (16)

For a near-stock to mildly modded car, you don't need alot of guages. Oil or water temp and boost will do IMO. Water temp is an easier install (see link below). As for pressure testing...IIRC the chain parts stores will rent you a tester with the proper adaptor for your particular car or take it to a trusted mechanic and have them pressure test it.
The stock oil pressure gauge has some issues with the connector getting dirty and occasionally the sender, but I don't think that needs to be aftermarket...especially on a tight budget.
LINK----> https://www.rx7club.com/3rd-generati...d-idea-392910/
It's a great place for a sensor, accessible and reversible. I think post #36 has a list of what you need and pictures.

This is a picture of mine installed years ago per that link. Even though I've since deleted AWS and removed the line from the throttle-body, I'm still using the line to this day for the sensor....

evo8u2

New to the forum and car good info to know

Natey

iTrader: (19)

A good way to make sure it's completely full is:
Make sure the car is cold...do this in the morning. Pop off the cap of the AST and start the car. Stand there and keep topping off the AST as the car warms up.
Once it stops draining and begins to overflow, put the cap back on. The babbling brook behind your dash should be gone now.

I use 75% water, 25% coolant (don't use the orange stuff), and a little water wetter for good measure.


Also, if your AST is stock, it's made out of 20 year old plastic that's held pressurized hot stuff it's whole life. They're infamous for failing. Get an aluminum one, stat!

Quik_RX7

Nasty: I do this almost every morning bro. Go down, pop the hood, pop the caps, check the fluid. If low, I fill it up and then get her running. If there is no change in level, until it is about to overflow, I usually kill it and let it cool down.

I was going to go with 65% water and 35% coolant, but since it just hit 120 today, I think I may dilute it more with water. And of course I don't use the orange stuff! Isn't that dextron? I use Peak. Trusted that stuff for years

And oh yeah, my AST is the aluminum one. But I have a newer cap. Probably wouldn't hurt to buy a new AST cap and filler neck cap, though.

Sgtblue: Thanks for all the links and advice. Needless to say, I have bookmarked every link you have given me.

I think I may go borrow one from Autozone. There is a store not 5 minutes down the road, just gotta get my funds situation figured out. California is taking forever with my unemployment money.

Natey

iTrader: (19)

Just covering bases, Quirk.

Quik_RX7

Alright gents, got another question. The gears in my head got turning today and I realized that if the engine coolant isn't up to optimal running temperature, then why does my buzzer and light go off within the first 15 seconds of starting the car? Because before, when I guess things were normal with the car, the buzzer and light never went off so it just seems odd that it does come on and stay on before the car even has a chance to over-heat. Which leads me to believe that it isn't over-heating at all. But I'm not exactly sure what causes the buzzer and light to come on. I assumed it was just coolant over-heat but I have since come to believe that it isn't just that.

So the questions are:
1. What causes the buzzer/light combo to come on?
2. Why would the buzzer/light combo come on within the first 15 seconds of starting, and then stay on even after the car reaches optimal running temperature?

misterstyx69

iTrader: (142)

That buzzer indicates low coolant.The funny thing is that once the car heats up it can go away because the coolant expands.
you need to find the source of either a leak or an entry point for air getting into your system.
On an FD it is usually the AST that is the culprit.OR a Cap...I'd go as far as checking all hoses and clamps too.

Sgtblue

iTrader: (16)

^Agree. It's the coolant level, not temperature.

Quik_RX7

Well then I am thinking the sensor is going bad or maybe is dirty, even though it was changed 7k miles ago. Everytime I check the level when the car hasn't been ran in 24 hours, it is fine. Not low at the filler neck or the AST.

The buzzer is such a headache lol

Angelo Erik Baluca

low coolant level

Quik_RX7

Well, I finally got the funds to order a new sensor, which got here probably about 2 weeks ago. Once it got here, I got it out of the package and went down to my car to get the old one off and the new one on.

So I proceeded to try to remove the old one without having to take any of my hoses off. You know, the lazy way. That ended up not working because EVERYTHING was in the way so I just went ahead and took off the hoses.

I eventually had to tie the lower radiator line to my strut bar with a t-shirt cause I was too lazy to come back inside haha...Anyway, it took me like 10 minutes to get the old one removed because I didn't want to strip the sensor head (it is plastic ). On it's way out, the electrical lead ended up snapping off because it was worn the hell out.

But I got it out, and began trying to get the new one in. It took me about 30 minutes because it felt like everytime I'd try to thread it in, it would almost cross-thread. So I took it out, cleaned the threads, and tried again. Did it about 5 more times till I eventually said f-it. I threaded it till it felt like it was going to cross-thread then slowly threaded it some more and eventually, it felt like it was threading normally. So I tightened it, gingerly. And I attached the electrical lead. And then wala! No more light or buzzer!

So thanks guys for helping with the information. I really wasn't aware that it was just a level sensor, and not a temperature sensor. But now I know where the thermostat is also located.

Sgtblue

iTrader: (16)

Now get that temperature gauge installed. Don't rely on the stock one.

Quik_RX7

Definitely man. Just gotta play the waiting game again till I can muster up the funds.