Ive got a little problem. A couple of days ago, I drove my 93 about 2 miles, let it sit for about 10 min, and came back out to find a bunch of coolant under my car, right under the overflow bottle. I fill it back up, no problem, didnt get hot, buzzer didnt go off, nothing. Ok, whatever, I dont know what happned but it seemed OK now. So a couple of days later, Im driving for about an hour on the highway, pull over to get some beverage, and my damn coolant level buzzer starts going off. ****. I look under the car, and theres a little bit of coolant under there, not a lot. Theres nothing I could do right there, I had to drive a couple of blocks to get somewhere I could pull over and get some water. Well, in thosse 2 blocks, the temp needle climbs right to the top, and I overheated for about 50 sec before I could **** it down and coast in. I got a big towelle, and used it to pop both the caps, getting all the hot air and little amount of water out. I wait a while, and fill it back up. I drove it the rest of that day and yesterday, and no problems, stays cool, no buzzer. When I got to the overflow bottle, I noticed that where the stem meets the bootle, theres a little crack, and its leaking a little when fill it. So. Is the coolant getting hot, expanding in the overflow, and leaking out that crack at the top of the bottle? Does that make sense? I hope thats the issue. Any help would be appreciated.

Thanks
Tanner

 

Definitely time to get an aluminum AST.

Btw, my dad was stationed at Kadena when I was a little kit. Okinawa kicks ***

 

If you have a crack in the bottle, the engine won't recover the coolant when the temperature comes down and will probably suck in a lot air into the system, hence the low coolant light buzzing and overheating issue.

I lived at Kadena for 9 years when my dad was stationed there (Washington Heights and Terrace Heights) - good times.

 

A new AST? why is that, it seems to me that the overflow is the culprit. Although a koyo and aluminum AST is on the list. And the above post makes sense, but why am I losing all the coolant?

 

whoops, sorry, I saw overflow and thought AST.

A crack in the neck of the overflow won't matter really, it isnt pressurized. there are vents at the top of the overflow anyway to allow excess coolant to drain out.

Have you overheated the car lately? I am not saying this is the case with your car, but the only time my FD puked coolant out of the overflow is when my original motor **** the bed due to bad coolant seals.....

 

Replace your AST cap. The cap is leaking so when the engine cools it cannot pull the coolant back out of the overflow and into the engine. As you keep topping up the coolant the engine keeps pushing it into the overflow and never recovering it since the cap is leaking. A slight leak in the hose from the AST neck to the overflow would cause the same problem as well.

 

Agreed!!! This happend to me. I replaced the cap to my Aluminum AST and all was well. Mine was leaking around the locking part of the cap. I did not have over heating issues. I just went to advance auto parts and picked up a new 16PSI cap and all was well. No more problems at all.

Simple fix costing you $3 MAX.

 

That's some good info, much better news than a potentially bad motor. I've been lucky, have never seen an AST cap go bad before.

 

Cool, Ill go pick one up. I might as well pick up the other one too. Both at 16psi?

 

I had similiar issue, could drive all day but when I stopped had coolant under the overflow tank. At that time I had aluminum AST <1 year old. Figured bad coolant seals but was incorrect. Had cracked rotor housing. IMHO you will be very lucky if it is not a major issue. I had tried the Blockweld fix prior also. Did not help. Hope it is an easy fix.

 

No they are not both 16 psi. one of them 9the one next to the air pump) is just a cap with no spring or secondary seal. In the coolant system service bullitan recal Mazda dropped the 16psi (1.1 bar) cap in favor of the 13 psi cap (.9 bar) or AST cap. When you over heated your car the first time (needle went to the top) it pushed a bunch of coolant into and then over filled the recovery tank. When you added water and it cooled down there was air introduced into your system, later when you drove it again with air in the system, it then pushed more coolant out and then when it cooled it brought what coolant it could back into the system but it retained air in the system from the first overheating session. With any luck you didn't damage anything when the temperature gauge went to the top, highly doubtfull, but possible. Once you change your caps and get all the air out of the system you may find that it will stabilize and no longer push or use coolant. All I can say is good luck.

 

It was only at the top a max of 1 1/2 min before I popped th caps. I think (hope) it sould be fine.

 

Put hose clmaps on the line that goes from the AST to the overflow, also. You can lose pressure that way and you might as well while you're doing all this. I miss Okinawa in a way. Ahhhhhhhh Gate 2 street.

 

hmm... I guess they dropped the 16PSI system in '94+ mine is a march of '92 and my owners manual says 16PSI. hmm... not sure then. But I have had no more problems with my 16PSI cap. Mine used to drain like I was doing a coolant flush it seemed like. No more problems now after I put on my new cap.

Give it a shot. This forum will make you paranoid it seems. Thats why I do my own diagnosis. People tell me your turbo's, engine's shot in alot of cases I've had. All it was was a simple $50 part or replace this hose and put on some electronics to control turbo spool and stuff. I often wonder if people on here just repeat what others say without first hand experiance. It also seems people like to over diagnose issues on here. Just me and my opinion and experiance.

Give it a shot it couldn't harm anything by the way. All it can do is help you.

 

Hmmm. Ill get the cap and everything. Its been 4 days since it happened, and I just checked my coolant, and its still completely full. Hasnt dropped a bit. I dont get it. Some kind of damn fluke.

 

Sounds exactly like what happened to me when my coolant seal went bad inside my engine. When the seal goes bad it can allow exhaust gases to enter your cooling system which in turns forces the coolant out of your overflow.