ok i got a 1992 3rd gen from japan. drove it 2 years ran great. recently i had to keep adding coolant to the system cuz it had slow leak, i discovered after a week and a half of topping up, it was the rad. got new rad , generic aluminum rad from china, made it work and removed ast, ran the overflow off of the stock filler neck ( i added a nipple to attach the line. ok so i had trouble getting the air out of the system and then i ran it with the cap off to fill it as the air worked itself out, well it appeared too but i was getting a slow steady stream of bubblesabout maybe 3-4 ever 2 seconds... but the level stayed high, so then i let it get warm then i drove it for 10 mins near my house... then i parked and let the coolant cool before checking again, came back 2 hours later and it was down about 1-2 cups of coolant, so i put it in, (car still reading warm) and i strarted it again, cap off, check for bubbles, and it slowed down alot... it was like 1-2 bubbles every 10 seconds, and the bubbles were smaller this time... so what do you guys think??? do i have a bubble in my system or good chance at coolant failure, havnt cvhecked compression yet... car has 138,000 kms so like what.... 86,000miles. the guy didnt know if the engine was new or not as it was from japan.. but compression when i got it in the moutain air was 115psi times 3 and about 112 times three. and if its a air pocket whats a good way to get it out or test for it, keeping in mind i have no AST anymore... thanks guys i did a search and found limited similar information... anyways i appriciate all your inputs guys

 

wat seems to be the problem though?

 

ok so the problem is coolant is dissappearing, not on the grounf and i cant see or smell it in the smoke. but the overflow tank is full, ... ok before i go anyfurther i drove the car again after my last post, deove bout 1/2 hour then let it cool completely overnight, i just started and checked fluid with the cap off... no bubbles at all !!!!!! so thats good but im still having to add about 2 cups of coolant every time she cools, im thinking its going into the overflow but not coming back in... i had a decently new cap on... what could be the cause of coolant not going back into the system??

 

Did you burp the cooling system after the radiator install?

https://www.rx7club.com/showpost.php...21&postcount=4

 

he said he did on two separate occasions

maybe you should try running it a few more times to see if you still need to add coolant. are you using the right pressure cap on your filler neck? i think its suppose to be a 0 psi cap. idk if that would cause your coolant to rise and drain into the reservoir though..

 

0 psi? Uh...thats for Evans NGP. With normal coolant a 0 psi would cause catastrophic overheating/boiling of the coolant as soon as the car hit 213f operating temps. Maybe you meant 10psi.


For the OP, pull the spark plugs? Are they wet with coolant at all? Put a big funnel or plastic cola bottle on the filler neck and let the water rise until it settles above the neck...then check for a fast stream of bubbles coming up in a tempo. Better yet, buy a block test kit for 50 dollars from you local auto parts store and test the coolant for hydrocarbons.

 

Check your coolant level sensor for any leakages around the edges of where it screws into the filler neck. I had a similar problem and discovered that mine was tear-dropping them out very slowly (not really obvious until the car is WARMED up by driving hard, not just idling in the garage).

New O-ring gasket for that sensor is $1-ish from Ray @ Malloy Mazda.

 

I would check the the thermostat.I have the same problem that coolant go in to the over flow and not coming back out so i think the thermostat is not working right so i whenahead and change it and the problem is gone.

 

What are you using to keep your coolant pressurized? Without an AST or proper AST-deletion kit, you need to make something that will retain system pressure, and you will see your coolant get pushed out the coolant reservoir with each time you run the car.

 

pressurized? well i didnt do anything like that just took out the ast... how do i pressurize this system??? you may be onto something there... and all you guys had good points thank you for your comments i appriciate that alot

 

All standard cooling systems have a cap that relieves at a certain pressure. On the RX-7, this cap is in the AST, and there is a line in the AST that runs off toward the reservoir to catch overflow. If you just simply removed the AST you will no longer have the cap and all expansion of the heating coolant will dump straight to the reservoir with no restriction.

Install an AST delete kit and things should improve.

Dave

 

ya i bet thats whats happening i took it to the car wash to spray the engine bay to i could tell forsure where coolant was loeaking and what was possible spill from constant filling.... anyways when i got back i parked it in garage and let it run while i checked for leaks... i found a small leak on the plastic filler neck i installed, when it cools ill fix that.. then all of a sudden.... it just started pissing coolant out the right full overflow tank... so what is this ast delete kit and where do i get it? im about to do a search on it but still let me know where u recommend... and is it possible to fabricate one of these kits? i am a welder so i can handle the welding and materials if needed.. thanks again man..

 

This is what you need, it replaces the stock one which is on top of the T-stat housing

http://www.mazdatrix.com/getprice.as...m=15-17YA-N326

You can find used ones on the forum too, I just bought one.

 

ok problem has been solved... hopefully for good... there was a problem with the neck i was using... i got a new neck off of a 88 and shes good to go... i had a neck before but i thought the "ast removal kit" was more then just a cap... thats where i got a little confused but i thought i could beat the system cuz at canadian tire i found a "help" brand 'overflow nipple repair kit" ... which consisted of a sleeve that slides in from the inside then a screw slides over and threads onto the sleeve but from the outside... so i drilled a hole in the stock filler neck and put the cap on (but i didnt blow through to verify the seal) and i assumed it worked cuz it looked like it fit... anywyas the thing i put on was affecting the seal of the cap, i put the new filler neck piece from the 88 and its good as new.. so im a bit of an idiot and i should have mentioned that but hopefully some other new memeber will come along and learn from my silly mistake.. anyways thanks alot you guys for all your help u led me to the problem area which allowed me to find the problem... thank you all