So recently I've been having a problem with temps and coolant recovery. I would start the car, get it all warmed up and drive without an issue. After shut down, once the fans came off their 10 minute cycle, if I started the car I would get the low coolant buzzer until the thermostat opened up. For the past few days I just added coolant and hoped it wasn't a seal or anything, and eventually my overflow filled back up and spat coolant on the ground.

I tried everything, replaced the AST cap (I have some aftermarket alum. one) with a Stant lever type, did some searching and found that those have been known to not seal well out of the package, then settled on a Stant one without the lever. Knew it had to be something with the overflow line as others have had issues with this, so I check it and nothing was torn/kinked or abused. None of this made a difference.

So I tested the thermostat. It opened fine, lift was fine, however it wasn't OEM Mazda and didn't have a jiggle pin dealy. Did some more reading, and decided to drill a small hole to help air pass through. Found that this also helped my t-stat housing mounted W/T gauge read as the car warmed up.

Finally, I pulled the whole overflow line and found 2 couplers in it. Took a pack of zip ties, and put two on either side of the coupler, putting the ends 180 deg. from each other. Also did the same on the connection to the AST. And it's fixed! Now I don't have to add coolant on every semi-cold start, car recovers coolant on it's own, and no more low coolant buzzer.

Try this out if you were ready to torch the car like I was, hopefully this can save a headache or two...

 

thanks for the tip

 

I'm sorry I dont understand what exactly you did to fix the problem, would you mind explaining with a little more details and pics.

thanks,
Dave

 

Putting zip ties on the overflow line would only help to correct leaks at the splices. It has nothing to do with the overflow tank overflowing. It sounds like you had air in your system from in improperly bled cooling system, and it has finally worked its way out. Glad its fixed now.

 

I think you are incorrect. If your coolant return line from the overflow is sucking air back into the coolant system instead of coolant then he would be filling up the area in the coolant system with air instead of water which is jsut sitting in the overflow. If he is adding water every time to take the place of the air he has already sucked in instead of water he could be overflowing the overflow. Basically his overflow is stayinf full since his coolant system is never emptying any water from it, but then he is still adding more water.....hence overflow. Now that he fixed the return line he is sucking water back into the system not air so it won't overflow.


I know that was a crappy way to explain it, but it makes sense in my head. hahaha

-josh

 

Sounds like you guys are saying the same thing in different ways

 

adam c, recon fd: YES!

I guess what I mean overall is that the overflow line can leak at the couplers, if you are getting frustrated with your coolant recovery system try the zip tie method and it should clear up. I searched for a while, this problem usually drove people to run Evans so they had a 0psi system. I figure a few zip ties and fixing the problem is better.

 

And zip ties are cheaper than couplers too. LOL Thanks for the tip.

 

I can update with pics later tonight, but here goes for the explanation. There is a rubber line that is attached to the top of the AST, it runs down underneath the stock intercooler and stock airbox then into the overflow tank in front of the passenger's front tire. This is actually three pieces, joined by two plastic barbed couplers. I figured that these could leak, so I zip tied them on the coupler, two on each side, placing the head of the zip ties opposite of each other so there was a better chance of them sealing. That way, when the coolant in the engine cools down and takes up less space, the AST cap will draw fluid back through the overflow tank, instead of drawing air through one of the leaky couplers. Hope that helps a little more.

 

Nice. I may try this as well, since I was having a problem with my overflow tank overflowing...However, I think mine was just overfilled and when the coolant expanded it pushed out the weep hole in the top. Either way, wouldn't hurt to do, since I'd bet those couplers leak over time.

 

The original poster never mentioned that the joints in the overflow coolant line were leaking, therefore I assume they were not. Even if they were leaking, the system would still suck in water, since the overflow tank was not empty. The only way that air would be sucked in was if the overflow tank was empty, which it was not, since it was overflowing.

I don't think that's a crappy explanation

 

thats a question i have do the 93's have the fans come on after u turn off your car or was that 94 and up?? because anytime i drive my car hard or just normal.. when i turn off the car (after proper cooldown) the fans never ever come on.. not unless the key is turn to acc is it just my car or all 93's?

 

If you were sharp enough to cut the wind, you would know that this thread has nothing to do with your fan question. It doesn't belong here. Please "sharpen up"

 

adam c: from what I've found, even though my overflow line was not leaking, and my overflow tank was full, the joints still didn't seal well enough to pull coolant back through. It seems that under vacuum the line was more apt to pull in air through the couplers, rather than drag fluid up through the line. Does that make sense? I also think my lack of a jiggle pin didn't help create vacuum in the proper spots for the recovery to work right.

Jason

 

It has everything to do with the recovery tank over flowing. If the system pulls air back in at the couplers then it will allow air to take the place of the coolant. Keep adding coolant and the recovery tank becomes full....eventually it over flows. I did away with the couplers and ran a single piece line from the AST to the recovery tank. Sometimes you surprise me Adam.

 

Since the couplers are not leaking, air cannot be pulled thru them. If they were leaking, they would pull air only when the overflow tank was empty, which it was not. If the lines have coolant in them, how can air be pulled thru?

I don't want to be too predictable

 

Not to be an ***, but is that what you meant?

This is how it works out in my head (which, well, you know...): What has less resistance when drawn through a tube under vacuum, coolant or air? I would go with air. One of the couplers is placed almost directly below the stock intercooler, the other right below the middle of the stock air box. This line isn't under any real pressure when expelling coolant, other than that to overcome whatever pressure caused by the coolant in the vented overflow tank. So somehow it makes sense to me that coolant can flow easily to the overflow without leaking out the couplings because of the lack of pressure in the overflow tank, but air is more likely to be drawn in under vacuum at the couplings if they aren't sealed. The line is all uphill from the tank to the ast, maybe 14" or so vertical.

I don't have any other explenation as to how securing the couplings (or replacing the line with a continuous one in cantgostraight's case) allowed the coolant recovery to start working again.

Maybe the lever type stant cap that I used really did fail out of the package. Or maybe somehow returning the thermostat to the OEM functionality fixed the problem. Out of the three possibilities, only one makes real sense to me.

Jason

 

Dont have to be an ******* about it and he did say that "After shut down, once the fans came off their 10 minute cycle," so while he said that i figured to ask alright.. all you had to do was mind your business or just post wrong thread.. so how about you sharpen up

 

I don't know what fixed your problem. I can 100% guarantee that zip tieing your coolant overflow line couplers didn't do it. Even if they were leaking coolant, they would not draw in air unless the overflow tank was empty.

The coolant overflow line is lower than the overflow tank, and lower than the ast. If there were any air in that line, water would displace it, as the air would rise to a higher point (overflow tank or ast). There will never be air sitting in the lower part of that line unless the overflow tank is empty.

 

If I wanted to be an *******, I would have said something a lot ruder than that. The fact is that his post didn't belong, and with over 1200 posts on this forum, he should have known better.

You figured wrong.

 

ok thanks that was rude

 

sorry i ment to say thanks that time you werent rude but for some reason i guess to much time passed and i couldnt edit it

 

Again I think you are wrong.

IF there was a pin hole leak where the couplers connect the lines it will draw in air from that pin hole instead of drawing water from the overflow. The coolant system will def draw in air over water if it can since air is easier to return then water. The zip ties may have sealed the gaps between the couplers and the hose where air was seeping in.

So no, the overflow does not need to be empty to draw in air if there is a leak in the overflow return line. A leak in the line doesnt mean he would leak cooant, but it could allow air to get into the system. The zip ties are just sealing where air was getting in at the coupler joints.

SO I think that zip tieing your coolant return line could have 100% fixed your problem.

I was having the same problem (had a pin hole in the line) and replaced the hose....blammo it was fixed.

-josh

 

No, I am not wrong. Don't they teach you kids to think any more???

First, lets talk about your pin hole leak. How did you know it was there? Since I can think, I will tell you. It was leaking coolant. You didn't find it because it was leaking air!! If there is a hole in a coolant line, it leaks coolant. It can't somehow magically suck in air, and not leak coolant. In the case of the original poster, he didn't have a leak in the line. No coolant out means no air in.

Even if there was a leak in the line, air would still not get in. Water displaces the air. The water in the line will leak out. It is under more pressure from the gravity of the water in the overflow tank. Air can't get in unless the overflow tank is empty.

When engine coolant gets hot, it expands into the overflow tank. Lets say that it expands enough that 12 ounces more coolant is in the overflow tank after the engine heats up. Upon shutdown, the engine begins to cool, and the coolant is sucked back into the cooling system. It seems that many of you youngsters think that there is some huge amount of pressure pulling the coolant back in. This is where you are wrong. An FD engine will take several hours to cool down to ambient temperature. So, if 12 ounces of fluid is to return to the system, and it takes 3 hours, there is almost no pressure on the coolant return line. That coolant is being returned at a very slow rate. You also need to consider that there is a small amount of pressure (gravity) from the coolant in the overflow tank pushing the coolant in the coolant overflow line.

I hope that wasn't too difficult to understand

 

Not difficult to understand.....it is just not entirely correct. It has happened to more then one person. Sorry, but even though you think it can't happen.....it can, it has, and it will.

As stated before it has happened to me.

-josh