Bad_Karma7

Are you trying to find where it is, or are you looking for the part? It's located right under the UIM it is blue and sits vertically. If you're looking for part, the used for sale section or call Ray at Malloy mazda.

jpandes

Have you checked to see if you have a leak in your O-rings yet? Check to see if you are getting exhaust gasses in you cooling system. Do the Bubble test. At lkeat you can eliminate that as a cause for air getting to your system.

Can you smell coolant from the engine bay? I had a the water pump housing leak where it meets the engine block. It was a bitch to find.

RX7 allnight

if one (me) took the tube from the AST leading to the over flow tank.. created a vacuum (sucked from the hose) and got coolant (taste's so good) would that test ok? if there was an air leak.. i would be sucking in mostly air... with little or no coolant right? i got coolant from the hose no problem..so feed backs on that..

also would/could a T-STAT be causing this problem?

Mahjik

iTrader: (1)

That is something else you should check:

https://www.rx7club.com/showpost.php...7&postcount=14

RX7 allnight

is the T-STAT in the same (area) as the second gen...
i have not yet to remove it on the third. i just searched all of my fav sites.. and none give write ups on the termostat removal.. would it be the same as "water pump removal" i have my intercooler + intake box + pass side wheel well cover off/out anyone know of a good T-STAT removal + install page? thanks

btw. after wokring on my third gen it make's my second look like a cake walk

Bad_Karma7

If you take the coolant filler neck off, it's right there, not too bad to get to.

RX7 allnight

1.)well any info on how to do so? 2.)could i do it just as easy with the intercooler + intake box back on?? because i would like to put it back on asap..

Mahjik

iTrader: (1)

The T-stat housing is circled above. Remove that (the unit, not just the neck) and the T-Stat is right there.

Montego

iTrader: (1)

I had the same problem. Replaced the AST and filler neck caps, problem would go away and then come back a few months later.

As of a month ago it started to do it again. I was at my mechanic's getting a PFC installed and tuned. I told him that I was having an overflow issue and he set the fans to come on at 85 deg C (which he does anyway). Without changing the caps the problem disappeared.

As it turns out my coolant was getting a little too hot and thus overflow... I should really look into it (as in why), but at this point no more problems. Before I had to refill my AST every two days, now I haven't done it once since I got the PFC. Since nothing was changed other than at what temp the fans turn on I consider the problem solved.

Retserof

iTrader: (1)

[QUOTE=RX7 allnight]if one (me) took the tube from the AST leading to the over flow tank.. created a vacuum (sucked from the hose) and got coolant (taste's so good) would that test ok? if there was an air leak.. i would be sucking in mostly air... with little or no coolant right? i got coolant from the hose no problem..so feed backs on that..QUOTE]

You might want to use a MityVac Plus instead of your mouth, but the test would be ok if you do this test once from each end of the hose, with the other end connected or in place as normal. The problem with this hose is usually that it draws air where it slips over the AST nipple on the stock setup. Installing a hose clamp there is the simple fix.

sevensix

iTrader: (1)

i installed hose clamps along that ast to overfill tank hose and it has since stopped the overfill leaking problem i've had for the past 2 months.

RX7 allnight

my thermostat was shot..replaced it
checked all coolant lines to/from AST
replaced both caps AST/FILLER
installed hose clamps on AST to/from
now.. with car shut off i cant seem to keep the filler neck topped off..
topped it off started the car let the t-stat open.. capped it went for a drive.. checked filler neck and it was low.. topped it off with engine (off) checked it next day it was a little low.. is there enough air in the system to cause this? slowly leaking out top cause a low coolant level in the filler neck? any info thanks

dgeesaman

iTrader: (7)

The system can absorb quite a bit of air unless you're very specific with the filling. When filling, it helps to 'burp' the upper radiator hose right in front of the water pump housing, and to do the fill with the coolant hose disconnected from the throttle body near the firewall.

Or, just run it and top off as the level goes down. It will eventually purge all the air.

Dave

fdeeznutz

I had the same thing happen to me when I changed my T-stat a few years ago. It took me almost a month to get all of the air out, even though I only drove it about 30 miles that month.

RX7 allnight

so today i went out and did the champange bubble test.
my car was dead cold.. started it with filler cap off. it started to rise with no bubbles for a good long while i give it a bit of throttle maybe 2-3k revs to get up to temps. than all of a sudden ( untill T-stat opened i think ) i saw many fizzy tiny bubbles =/. it was very consistant and didnt stop. it was new years all over again.
is this my O- rings? or could it be a air leak? i have read and heard many things about the block weld method what do you guys think? did i do the test right?

dgeesaman

iTrader: (7)

That sounds like you did the test correctly.

I would take it to a shop that can test the coolant for exhaust gases, or to a rotary shop that can confirm the problem. Might as well put an extra $100 into diagnosis before putting 1000s into a rebuild.

That sounds like a pretty hefty coolant seal leak. I would research the block weld idea to see if it will have a chance of working at all in your case. One thing is clear: there is a very specific procedure for the block weld thing, follow it precisely. Half-*** it and you'll have gunk in your cooling system and no improvement in the engine.

Dave

RX7 allnight

so i got a pressure tester and i tested the system. to my shock i noticed coolant coming from bottom of rad, and near the fire wall i have never seen coolant on the ground. now question is. i did the champange bubble test. could these tiny fizzy bubbles be from air leaks? through out the system? i ran the system to about 20-25 psi

RX7 allnight

went to my local smog shop and put the sniffer down the filler neck, with the engine at normal op. temps turned the car on and the sniffer dectected nothing! yay.. put a rag around the hole of the filler neck with the nozzle inserted just to make sure and still nothing. so a small air leak could cause this many bubbles with no visual coolant on the ground (leaking) but still be enough of a gap to make the over flow bottle not return the coolant?

RX7 allnight

??

sevensix

iTrader: (1)

^

it might be worthwhile to just replace the coolant lines. im having coolant problems myself at the moment frustrating isn't it

sk8world

iTrader: (5)

Sounds just like me.. I know this thread is old but any new news??

RX7 allnight

what are the proper methods used to refill the 3rd gens cooling system?
my system still boils i dont think i have enough coolant to water ratio. my system holds pressure i used the pressure tester for like 12-18 hrs and it maybe dropped a few hairs maybe 1/8 of a psi i was told to only test it for 10 mins to see if coolant seals were bad but i thought i should just leave it as i heard of other people trying to find leaks does this mean my seals are ok? so why is my system still boiling and overflowing out the overflow? with my system pressurized via pump i have turned the motor over and pulled the plugs and their dry as a bone i removed my ast a bit ago due to it cracking inside maybe some of the pastic is blocking my RAD or anorhter passage? thanks for your help iam going to drian my system and make sure proper coolant/water ratio is used

DaveW

Boiling out the overflow is a sign of temperature at some point in the cooling system exceeding the boiling point of the coolant. It could also be a sign of trapped air.

Possible causes are:
1) bad AST cap not holding pressure (not likely, you did a pressure test)
2) not enough A-F to raise the boiling point enough to prevent boiling, especially critical with the OE thermoswitch
3) coolant seals allowing exhaust gasses into the coolant, but the seals don't leak coolant into the combustion chambers

Solutions:
o Higher A-F to water ratio (50/50 is normal, up to 70% A-F can be used, but reduces cooling efficiency)
o Higher pressure AST cap (puts more stress on the system)
o Install FC thermoswitch to reduce coolant temperatures
o Hydrocarbon coolant analysis to rule out coolant seal problem
o "burp" the system to remove air pockets - many threads on this

Dave

RX7 allnight

i did the sniffer test at my local shop and no signs of HC's iam burping the system as we speak. so it is possible to have exhaust gasses pass the seals but when pressure testing not have coolant go the other way. thanks iall post when new results come

RX7 allnight

so i took my engine out removed everything now iam done with tear down of the block the seals were intact. but didnt look that great.