FD Seeker

Ok, so there's a lot of coolant leak posts, but none seemed to apply to me specifically.

Here's the details of what's happened:
After a car wash, my car smoked/steamed from the front for a couple minutes. It smelled a little like coolant - and seemed like more than just steaming excess water off the radiator (I didn't even open the hood for the car wash). For the 10 miles back to my house, the car ran fine with a normal temp. Some others said they noticed this kind of thing after a car wash, so I didn't worry too much.
Next time I started the car up (two days later) the low coolant light came on. I took a look underneath to find a good amount of coolant dripping from a few places. I removed the plastic radiator cover underneath to see if there was an obvious source. The stuff was everywhere - so I couldn't tell anything. I began adding water... and after I put in a gallon or so it started spilling out onto the garage floor! An overflow or something? WEIRD? I started the car again to see if a leak in the system would be obvious - but it wasn't. NOW there's a huge plume of white smoke coming from the exhaust. I revved the engine a tad and it went away (probably smoked for about 20 seconds total). Temp still fine, low coolant light still on.

The car has 125K miles, but has been recently inspected by Tripoint with a good bill of health (excellent engine compression).

Does this sound familiar to anyone?
Should coolant be able to leak right out of the system when being added?
What in the hell is an AST exactly?

Toadman

The AST (Air Separation Tank) is behind your intercooler and to the right of the center black duct and has a red/black filler cap on it(Left of the battery). Mazda went cheap on it and it can seam-split due to hot coolant and basically puke all over the place. You can either eliminate it or get a metal one from Pettit for about 140 bucks. Check the side hose and hard-to-find bottom hose on the AST for coolant leak(feel around the clamp).

Was it cold-air start-up steam? Did it smell like coolant? You put a gallon of water in it? You were runing very low. The temp guage is not to be trusted. Did the guage go above 1/2 way before you shut it down? Sounds to me like you split a hose somewhere. Was it peeing or gushing out? Right or left side of engine looking from the front? Back by the turbos or coming around the underneath splash shield on the drivers side?

Toadman

*double post*

FD Seeker

I think it was more than just cold air steam... I didn't notice it smelling like anything. I'd say it was more than I have ever seen before (but this car does do that a little on cold start up). The temp guage NEVER rose above half - in fact it looked the same as always. Even after adding the water and running the engine, I didn't notice any obvious source for a leak (no spraying etc.). I can't say I've noticed a particular place that the coolant is coming from. When I took off the plastic shield underneath, it had A LOT of coolant pooled up on it and the front/smaller radiator seemed to be completely covered in it. If I had to guess (and I DO have to guess) something like the AST you mentioned broke and spilled it onto everything below???

I guess I'll try to look at the AST - like you said.

What about the overflow I noticed? Is that normal?

Toadman

Overflow goes into the white plastic coolant reservoir near the right fender. You should add coolant and not just DISTILLED water. It really sounds like your AST puked. Feel around under the tank for coolant/water, or unbolt it and inspect for cracks. Cmon guys, help the guy out with advice before he pops the motor and has an unpleasant Xmas.

Rotaree

What are the benefits and drawbacks of eliminating the AST tank?

FD Seeker

But don't worry toad, I'm not driving the car at all until I get this resolved. There will be no engine popping around here.

And... thanks very much for your advice so far!

Toadman

Cant really help you, being up by Magic Mountain and all.

CantGoStraight

Just guessing from what you've said....were you filling the engine at the water pump filler neck ???? If so then the water would go over to the AST and should reach a full level at the water pump neck if the AST is not split. If this this is leaking out water with no pressure on it then you should be able to find it. Do you have access to an pressure tester for coolant systems???? This will help if the problem (or leake) only happens after the system builds pressure. I agree with Toadman that you have probably had your AST let go at the seam. Hope this is of some help, you don't want to drive the car with air in the coolant system. Localized boiling within the motor (not good)

FD Seeker

I was filling at the coolant resevoir (behind the passenger headlight). After I put in about a gallon, it started flowing freely from somewhere down near the tank (I couldn't see) onto the garage floor. It was not overflowing at the cap.

IS THIS NORMAL??

BTW I'm only using water at the moment because I know the whole system is going to have to be drained and replaced anyway.

DamonB

You cannot fill from the reservoir. The neck just snaps into the reservoir and will overflow from underneath if you try; it's normal. Fill from the cap on the waterpump.

If the radiator was covered in coolant I bet you have a radiator leak. They start leaking from the seam between the tank and the core, usually at the top near the intercooler scoop. Do a search for "coolant leak"; there was a good thread recently with pics that clearly show where the leak comes from. I just replaced my radiator recently when it started leaking from the same area as well.

CantGoStraight

DamonB is correct you can't get water into you coolant system filling it at the overflow resivor. The two places water has to be topped off at are the water pump filler neck and the AST. In the top of the overflow tank is a breather hole (vent) once the tank is full this is where the excess is pushed out and you will see it puddle on the passenger side just in front of tire. So if this is where you were putting water in then this is normal.

FD Seeker

That definitely makes sense about not being able to fill the coolant system via the resevoir. I even looked in the manual for instruction on how to place coolant into the system, but it wasn't very clear, and I guess I wasn't very thorough??

Anyway, thanks guys.

I'm going to try to look at my AST tomorrow... maybe I'll get lucky and that will be the problem instead of the radiator.

FD Seeker

After reading more 'coolant leak' posts, I'm seeing more and more relating the white exhaust smoke to bad O rings, which means engine rebuild! I'm going to try and smell the smoke again to make sure it has no coolant smell to it (hopefully).

FD Seeker

After reading more 'coolant leak' posts, I'm seeing more and more relating the white exhaust smoke to bad O rings, which means engine rebuild! I'm going to try and smell the smoke again to make sure it has no coolant smell to it (hopefully).

CantGoStraight

FDseeker,
Your jumping the gun on this one. Have you gotten the right caps in the right place and topped off your coolant system, gotten all the air out of it and looked for a leak ????? Unless you overheated the motor there shouldn't be a bad o-ring just yet. You will also find carbon or oil on the level stick in the overflow resivoir if you have a bad o-ring.

FD Seeker

Last night: I got no sleep just thinking about how bad this could be.

This morning: I filled the coolant system with water from the correct neck (not the overflow resevoir, and not the AST tank). I started the car up with the intention of double checking the smell of the exhaust smoke. The car barely smoked at all. Of what little it did smoke, it a little gray and it DID NOT smell like coolant. I would consider this normal smoke for me that goes away in about a minute. Obviously, no 'low coolant' light this time. I'm starting to think that the white SMOKE that happened the ONE time I mentioned above had something to do with the fact that the car was jacked up in the front at the time (???).

I let it warm up (and revved it a little to make sure). When the car got up to normal temperature (just under half on the guage), it began leaking about a drop a second from the driver-side of the plastic shield underneath. Through the air dam, I could see the same drip rate coming from the bottom driver-side corner of the front radiator. That whole front radiator is still wet. The AST tank looks completely clean.

I can't really take everything apart to locate the leak, so I guess I'll have to have Tri Point look at it.

FD Seeker

I ended up putting in about a half a gallon of water.

FD Seeker

The drip I saw was coming from the AC Condensor (which looks like a radiator to me). But, I'm sure it was leaking onto the condensor from something above.

Tri Point thinks it's the radiator. I'm taking the car in today. But they say a fluidine radiator is $540!!! Shouldn't it be less than that?

Toadman

That's about the going rate for the Fluidyne. You sure it's not the AST or a hose clamp? If you remove the battery you can inspect it easier from up top. Tri-Point should let you inspect underneath when the car is lifted.

FD Seeker

I just drove the car 30+ miles to Tri-Point with no overheating problems at all. Right after I shut down the engine, a lot of coolant started flowing from beneath the car. Mark (TriPoint) and I looked through the air dam to see coolant bubbling out of the radiator and a good rate. Apparently, shutting the car down stops the cooling process, which temporarily made the source of my problem (leak) very obvious.

I'm going with the Fluidyne aluminum radiator - which I can at least consider an upgrade from this whole mess.

CantGoStraight

Glad to hear you located your problem. The reason the coolant overflows when you shut the car off it the coolant is no longer moving through the system and temperature climbs in the motor. With the radiator being bad there's lower pressure so the boiling point is lower and you probably pushed alot of coolant out. Don't forget to replace one of your caps (the one on the water pump filler neck) with the proper one, get a metal AST, or eliminate the AST and your problems should be gone.

FD Seeker

Well, the deed is done. $850 later, the Fluidye is installed and the car seems to run great. I guess I'm ready to handle some more serious driving now!

Thanks everyone for your troubleshooting help. At least I can say I've learned a bit about the cooling system. By the way, I don't think I'm going to try to remove or replace the AST until I have a problem with it.

Toadman

Good job seeker on the "radidiator". Unfortunately during the cool-down heatsoak pressurized period after shutdown the plastic AST doesn't normally seep, and tends to split in a cloud of steaming coolant in some parking lot far from home(don't ask how I know). You have AAA for a flatbed truck I hope, because there's no advanced warning when the cheap plastic seam-splits and you're suddenly standing in neon-green liquid with a pissed-off woman tapping her foot giving you the stink-eye and legs-crossed indefinitely.

Ok that was over-dramatic.. sorry.

FD Seeker

Dramatic... maybe.

I'll move the AST up on my list. It's just so 'not sexy' compared to intake or exhaust mods that I would like.