NINjaX7

So i have a 1993 AUTO, with 82000 miles. It's really weird sometimes it'll leak sometimes it won't ,so here are the symptoms and what has happened on a couple of the drives in the last 2 weeks.

-On average I lose about the same amount of coolant every single drive, probably about 12 oz's to the point where it lets air touch the sensor at the bottom of the t-stat housing.

-One time i let the car sit there and filled it up to the top when i burped it before i let the car sit there for three days. After 3 days i started up the car and the coolant buzzer went off. I had to fill up probably 6 cups. The weird thing is... it holds pressure when I drive, once in a while the coolant buzzer will go off for like 10 seconds and stop until the of the drive. I guess a bubble hits the sensor

-Another time it starts overflowing from the overflow bottle when i shut it down, but this was after i filled up the overflow.

-I'm really praying that it's not a coolant seal, but all the hoses except the lower and upper radiator hose have 82000 miles on em, so there's a high chance that it's the stock hoses.

The first day of owning it I swapped the radiator out because it leaked out of the endtank, the last owner never told me about it....

so, someone was telling me about silver seal, i don't know if it's be a good idea in the FD, has this happened to anyone before?

the car runs great, starts right up, both turbos boost fine, but i do get boost creep on a rare instances, i'm just trying to find the easiest cheapest fix before i sell it, i don't want the next owner to have to do what i had to do

DaveW

Could be a lot of things (that you've already seen, since you said you searched). You already saw this, too, but the only way to find the cause for sure is to do a pressure test.

1QWIK7

iTrader: (33)

agreed on the pressure test

btw, i thought you sold your FD already?

TwinTurbo93

Start by checking, actualy replacing the most simple thing, the cap on the AST, which goes bad often, and as a result you'll lose little coolant and it will not happen all the time, just as you discribed, than look for leaks, if you don't have any at all, than you might consider a pressure test, which will reveal a possible internal loss of coolant.


Good luck.

KevinW

iTrader: (1)

i had the same problem and it turned out to be a hose but inever really saw any coolant because it wouldnt leak out of the hose it would evaporate so no leak. i did a pressure test and found that it was comming from that little hose behind the filler neck. just my .02 but i wouldnt worry too much yet

quicksilver_rx7

Look to see if there is coolant residue (i.e. rust spots) on the side of the housings above the spark plugs (i.e. where the "13B" is stamped) If there is evidence of coolant there, it's probably the TB coolant hose. Mine had the same symptoms, that's the only reason I suggested this. A pressure test IS the best method to diagnose with, though

NINjaX7

hmm, i think it's evaporating, i'll get it pressure tested since i see no leaks coming from anywhere, and coolant smell coming from the engine bay

bdennis

Are you losing any coolant at the overflow tank? If so, start your car and check for bubbles at the filler neck. If you dont have bubbles it's not a coolant seal.

NINjaX7

damn..... i have bubbles at the filler neck, it's a coolant seal, this totally sucks!!!!!!!!!!!!!!!!!!!!!!!!!! grrrr.... i guess i'm going to have to lower the price of the car

DaveW

I would still do a pressure test to confirm that there is no other place it could be leaking. You COULD have bubbles due to air trapped in the engine... You did say you smelled coolant in the engine bay.

quicksilver_rx7

Hyperite

Bubbles can be a false-positive for coolant seals gone. I'd suggest searching again.

series6bat

Mine had bubbles and it proved to be both radiator caps where worn and letting air in.
Changed those and sweet as

eric e

i hope i've fixed my coolant loss problem but getting the -ve pressure valve on my ast cap opening again, have attached a photo of what it should look like. the little silver circle should open easily with just a light fingernail pull eric e

eric e

find out where the coolant is going by doing this test

pull off the overflow hose from the ast body, replace it with a short bit of clear hose leading to an empty coke bottle

fill the ast, then after testing the -ve pressure valve on the ast cap, put the cap on

then fill the final coolant at the filler and cap

start car and let idle. when engine gets hot watch as +ve pressure valve in ast cap opens and sends coolant to the bottle.
some small bubbles are ok, it's called the ast because it's an Air Separation Tank. when fans cut in shut down engine.
you should have less than half a bottle of coolant in bottle.
just after shut down you will see more coolant and some bubble come out of the ast as the heat soak raises temps now the fans are off.
some boiling sounds may be heard from the filler area.

about 2 hours after shut down the coolant should have contracted enough that the ast -ve pressure valve opens and sucks almost all the coolant back from the bottle

this is what your test rig should look like, you can drive around with it like this and record exactly what happens with your car

eric e

in that last photo you may notice that the ast cap looks like the filler cap with it's "ears". that's because it is actually a same sized nissan radiator cap and not the stock mazda ast cap. just something i'm trying out as i had it lying around the garage and it fits and is rated the same. should have changed it for the photo

eric e

NINjaX7

hmm ok i'll definitely do that this weekend, i guess the coolant smell in the engine bay is kind of a questionable dilemma

seven samurai

After time and money I realized its just easier to get a pressure check. I was haunted by the same thing and this is freshly after a rebuild. checked all lines everything fine. buzzer go off for a couple of minutes till i was at running temp. only about a cup to fill up but then reservoir would be spitting out when car was stopped and cooling down. got greddy cap and new ast and it helped for about a month . till it came back again finally got pissed and tore the car apart. stock radiator had a crack which wasnt visible because it was where metal and plastic meet. metal was just detaching from plastic I guess. No drip or steam line it was just damp like when you put a drop of water on a napkin. got a fluidyne all problems gone