RX7 allnight

i have been searching for weeks about this cooling problem i am having. replaced AST cap, the filler cap looks great but will soon replace that also. i loose coolant every now and than. my buzzer will go off and the temp will rise, it seems that my coolant was not returning into the system..i thought it was a air leak somewhere.. turns out the main tube going from the over flow tank back to the engine is has came off or devolvped a hole/leak.. i pur water into the over flow tank and it just goes to the floor just as fast... so questions? how do you get to the tank? behind the passenger front side wheel well? any write ups or links would be awesome as i have been searching forever and since iam on 56k =( i cannot d/l the FSM

Bad_Karma7

To get to the overflow tank, you have to go through the wheel well.

audiobot7

How far does the coolant temp. needle go up? Is all your cooling system working properly?

DaleClark

iTrader: (55)

Two possibilities here.

First off, check the level in the overflow tank. You check it like an oil dipstick. If it's where it should be (between empty and full) and not leaking, it's fine. If you overfill it, it will leak out.

If the hose between the overflow tank and the AST is popped off, hole in it, whatever, that's bad. Fix it.

As coolant expands with heat, you have to have somewhere for the expanding coolant to go - the overflow tank. When the car cools off, it should suck it back in from the overflow tank so you always have a full cooling system. If that line is bad or popped off, coolant will push out, not be sucked back in, you have air in the system and overheating problems.

Now, if all that system works well but it still is constantly pushing into the overflow tank and not recovering, you may have a bad coolant seal in the motor. If so, you can use the block weld fix to buy you quite a bit of time. It's time consuming to do it RIGHT, but it does work.

If your overflow tank is truly broken and leaking, fix it NOW. A good used one should be reasonably priced. And, yes, you do pull the passenger wheel off and the wheel well liner off to get to the tank.

Dale

RX7 allnight

coolant system has been replaced 40-70k ago with new engine.. the temp gauge stays almost half way all the time... than the car will spit the coolant into the over flow...leak out and not come back in...mostly...when cooling down from driving i.e idling than the temp gauge will rise and buzzer will sound by the time the hood is open and engine is soon shut off... the temp gauge doesnt go past 75% at anytime if that i know i shouldnt trust the stock gauge do i have to remove the wheel to get to the over flow tank or can i just turn it?

RX7 allnight

i just checked the over flow thank.. and it is full and so is the AST but the filler neck is not.. the car idles fine no smoke on start up and has no problem's on cold starts even in the winter..can it have a bad or worn seal and still act this way?? so now i need to check for all air leaks? i need to go replace the AST cap for the hell of it.. could the over flow tank have a hole in it somewhere to the engine where it would stay full but leak out when returning to the engine?

RX7 allnight

btw i already replaced the AST cap i meant to say i need to replace the filler neck cap for the hell of it ;]

RX7 allnight

<img src="www.http://i38.photobucket.com/albums/e149/cbm7/e8cbcf75.jpg.com" alt="93 r-1" height="250" width="250"></img>

RX7 allnight

<img src="www.http://i38.photobucket.com/albums/e149/cbm7/e8cbcf75.jpg" alt="93 r-1" height="250" width="250"></img>damn typo

twisted7

iTrader: (3)

jpandes

Your coolant overflow problem may be a tell-tale sign of a bad coolant seal. Do you have any white sweet smelling smoke at start-up?

Do a search for the "Champagne Bubble Test" and do it. That will tell you if you are getting exhaust gasses into to your cooling system. These exhaust gasses will displace your coolant in your system and cause it end up in your overflow bottle and not in the engine.

Bad coolant seals = the need for a rebuilt motor. You can't fix or replace the coolant seals w/o removing and opening up the motor. $5000. Give or take some $$$

Look up "block weld", many people on the forum have done this to "fix" a leakiy O-ring. Many say its only a band aid and doesn't really worko and some guys have had great luck with it. Where the "fix" worked for 1-2 years. It's definitly worth a try.

Good luck.

RX7 allnight

car idles fine great cold start ups no smoke.. oil looks clean ( clean as any rotary could ) boost great hot starts fine..could there be bad seals or worn seals enough to leak but still act normal? passed smog test CA smog test i might add... months ago

RX7 allnight

btw engine codes reading. = ait temp sensor and egr vavle

Mahjik

iTrader: (1)

If you are getting the air temp sensor code, that's not a good thing but it won't cause this problem.

Have you checked your thermostat yet?

Fix the air temp sensor problem (bad sensor, disconnected plug, or wiring problem) and then check your thermostat to make sure it's working properly.

RX7 allnight

i havent checked my thermostat..- could it be the item behind my coolant problem? i would not think so.. and when the ecu gets the error from the air intake sensor.. it just goes to a defult setting ( i.e runs richer ) thinks the air is always at ( )º ??

RX7 allnight

ok so today i went to work on the car removed intake box.. removed intercooler and other parts.. removed pass. side wheel well cover to expose the over fill tank.. everything looked good.. i than started the engine let it run and build pressure topped off filler neck before i started it.. same with over fill tank watched filler neck when started.. capped it.. built pressure i could see no leaks i ran it for 20 mins temps were fine shut her off for good and let her cool down.. opened filler neck and it was an inch from the top 1/2 an inch to an inch... where did the coolant go? i than topped her off...(filler neck) waited 10 mins and it was down 1 inch again... topped her off ( now it looks fine ) iall check in the morning... now could the system build pressure and still have an air leak with no coolant leaks?? i replaced my AST cap next will be the filler neck cap.. if i replace the filler neck cap AST cap and still have problems with the coolant returning from the over fill tank to the engine what would it be??
i checked all lines going to and coming from AST checked all RAD hoses looked by the turbo coolant lines and so fourth..iam really stuck here summer is coming and my third gen needs the love!!( so do i...)
could a coolant hose somewhere in the engine have a small air leak? to cause this and how would one find such a thing? btw my car does not smoke on start ups.. pass's smog CA smog, runs great all the time everytime besides this coolant thing =/ i will replace the filler cap tomorrow..put everything back together take for a run and hope for the best! please help anything would be great thank you

Bad_Karma7

What type of cap do you have on the AST? If it's the "safety" type with the red pressure release lever, I just had to replace one of those and it was new. I guess those are prone to leak. It was not sucking the coolant from overflow tank back into engine.

RX7 allnight

a have the one with the safty lever (red) 16 lbs cap on the AST
one the filler neck is just a normal cap no spring

any advice if i replace both caps and still no coolant going back to engine from over fill tank?

Bad_Karma7

I had that issue not too long ago, I replaced the AST cap and problem went away. I think the no pressure cap on the filler neck should be ok. Sometimes the AST neck is warped and won't get good seal on pressure cap. It kept filling the overflow tank, not sucking any back. Pretty soon it started do flow out of the over flow tank.

RX7 allnight

that is my exact problem! after awhile it will flow out of the over fill tank... wont suck any back in so iall replace the AST cap again for ***** and giggles and than replace the filler neck cap iall check the AST neck for warpage thanks for the info..

Bad_Karma7

Good luck! And don't get the cap with the saftey lever!

RX7 allnight

question? is there a cap on the RAD on the third gen? or just on the AST and filler neck.. if there is one on the RAD.. i couldnt see it btw i have stock RAD so is there three or two CAPS for the third gen

Bad_Karma7

Only 2.

Retserof

iTrader: (1)

There are only 2 caps on the stock system - a pressure relief cap on the AST and a simple sealing cap on the filler neck.

Before you do anything drastic like block weld, make sure that the AST cap is good and that the hose running from the AST to the reservoir tank is air tight. It is not a pressurized hose, so it is possible for it to not leak coolant but still have a small air leak that defeats the vacuum needed to draw coolant back into the AST from the res tank as the system cools. (On the factory AST, no clamp was used on this line -- it was just a wedge fit that works loose with time.) Sometimes all you need to do is install a hose clamp on this line at the AST nipple.

Also make sure that the line's couplers are sealed and that the line is connected properly to the pickup inside the res tank.

riptor

what color is your coolant...green i would assume or i feel u would have changed it already. umm...i did actually have same kinda problem and mine ended up being the thermostat...still looking for the AIR INTAKE THERMOSENSOR tho....lol. good luck.