fc3sguy

I know there are many threads on overheating but somehow i can't find one that relates to mine. When I start my car and start driving everything seems to be fine. Add coolant buzzer doesn't come on and car's temp stays at about 1/4 gauge. But as soon as I park the car for few minutes and turn of the engine I can see the coolant being thrown out from the reservoir. It's like something is causing the coolant to come out and leting the air. And as soon as I get air in the system more and more coolant is being spit out. Usually the car looses like a gallon on coolant.
Basically here's whats up.

I can drive it hard and it wont overheat, but as soon as I park it or let it idle at a stop light for few minutes it starts spitting out the coolant , getting air into the system, overheating like hell, spitting more coolant out.

Now I checked the thermostat and it's working. Radiator is flushed. Water pump is supposively new.
I don't know exactly about water seals in rotary, but I suppose if it was bad then maybe that's where the air could be coming from? That's the worst scenario thought.

What should I check next? Please, any advice will speed up the process for me.

Rxmfn7

iTrader: (4)

My car was doing the exact same thing, and I too, was afraid it was a blown coolant seal, letting the compression bleed into the coolant system, pressurizing it and making it overflow. I then replaced my thermostat and rad cap ( Use only OEM mazda ones, I ordered mine through mazdatrix) and it fixed the problem.

1987RX7guy

iTrader: (3)

Have you cheked your fan at all? Heating problems at a light could be from a broken fan clutch causing little or no air to go through the radiator. At high speeds you don't need a fan so thats why it may not over heat in that situation.


Santiago

Aaron Cake

iTrader: (1)

http://www.aaroncake.net/rx-7/cooling.htm

fc3sguy

Ima go get a new cap now and see if it helps. Thanks so far

fc3sguy

Aaron Cake. How does the removal of thermostat will cause the car to overheat? Can you explain?

fc3sguy

Just got new radiator cap. $16 !
Also, If I had bad colant seals wouldn't my car throw white smoke all the time? It only smokes a little when I first start it, warm or cold but after few seconds it stops so I'm assuming my water seals are fine. Or at least I hope so.

Rxmfn7

iTrader: (4)

With the thermostat removed, the coolant is moving through the cooling system unrestricted. This constant flow of coolant does not provide enough time for proper heat transfer from the engine to the coolant. You need to have time for the coolant to slow down, to let it absorb heat, and then be moved out to the radiator to be cooled. Even race cars use a restrictor plate of some kind to slow the coolant flow.

With the thermostat removed, you will see lower coolant temps (because of the lack of heat transfer, as I explained above), but you will see a distinct rise in oil temp.

Rxmfn7

iTrader: (4)

Not necessarily. If it is just a small coolant leak through the seal, then when the engine is running, there is no coolant being pushed into the combustion chamber, because the pressure is much higher in there as compared to the coolant system. Any pressure transfer would be the other way, compression being blown into the coolant system. What would happen, is that after the car is shut down, and compression pressure is lost, then the coolant will seep into the rotor housings. This is where people get flooding issues, and white smoke on startups.

fc3sguy

Ok, so the only way to test that without taking engine apart is to do a radiator pressure test right?

fc3sguy

One more thing,
In case I did have a tiny leak on my water seal , could I pour something into the cooling system to seal it up (I heard autoparts stores carry some kind of a product that can seal leaks on radiators or something) or would that be pointless to try?

RETed

I basically don't have a thermostat (cored stock thermostat), and my car does not overheat in street driving.

Wow, half a million posts in just this section!!!


-Ted

Rxmfn7

iTrader: (4)

There is stuff calles K&W block seal. Follow the instructions EXACTLY, and I have heard of many people having alot of success with this product. I would only use it as a extreme last resort, and plan on a rebuild as soon as possible if that turns out to be the problem.

fc3sguy

thanks for all the help guys.

Aaron Cake

iTrader: (1)

Yeah, but that's quite different from just pulling it out...

SureShot

I assume the cored stat still has the disc that covers the bypass port.

RETed

People have argued otherwise, but I don't see how much different it can be.  I've been warned that if I put my car on the track, it'll overheat (due to the bypass hole not being blocked).



-Ted

RETed

Uh, dunno what you mean exactly, but the bypass hole is still there.

Basically you clip the legs off the thermostat, so the center drops out, and you're left with the flange.



-Ted

KNONFS

iTrader: (14)

I ran my NA F for years without a thermostat down in PR, and NEVER had a temp issue either.

h20scorpio

do a geyser test for the coolant seals. There are many posts describing the precedure.
Shin

fc3sguy

I read about the geyser test and I have question. What is that bypass port people are talking about? Does it let small amount of coolant circulate thru the radiator all the time even when thermostat is closed? That would radicate the geyser test. Cause otherwise if there is no coolant running thru radiator at all times, then then the geyser test would not work.

fc3sguy

Ok I did the geyser test. Turned the engine with egi fuse out and with the radiator cap off. The coolant was slowly being pushed out but not shot out with high pressure. Does this mean my seals are OK?

fc3sguy

does anyone know what is the purpose of the radiator switch located on the bottom left side of the radiator? Mine's broken and was wondering if it's important? It's # 8 thing

Digi7ech

iTrader: (1)

Save for a rebuild.....

OK this exact scenario happened to me.

In the summer my car would drive fine but I would park and come out later to find a puddle in my drive way.

I got a new Rad cap and it "fixed" it. Around 3 months later the "cap" went bad again. I got a new one and then a month later I was driving home from work and at a light the coolant gushed out. My idle then went funk for a second.

The cap stayed open and pushed everything out. My car then over heated on the spot and blew a coolant seal so bad that it never started.

My theory is that I had a small coolant seal hole on the intake/compression side of the engine and it was pressurizing the cooling system.

Never before the catastrophic night did my car idle funny/blow smoke/ anything! Hell it passed emissions about 3 weeks prior!

The capos might be signalling a bad seal. I tried the gyser test and it didn't spew or bubble so I'm thinking it took a while to build up pressure.

I can't confirm this though since the engine totally over heated and blew a seal in the end.

J-Rats got my block now so when ever he pulls it apart we can get a better idea.

My other 88 (Se) blew it's seals over a period of 2 days.
One morning it was a little hard to start and a puff of smoke came out for a second. Then it progressivley went bad. Then by the next mornging I couldn;t start it.(I could if I pushed it but that's a pita nd worthless.)

fc3sguy

Damn, I might do a rebuild myself then. Might learn a thing or two. . anyway, I have two nipples on the filler neck unplugged after removing rats nest and I notice some white smoke coming out of there right as soon as my temp starter rising past 1/2 . I took oil cap off and saw a white mist + white condesation on the neck wall. Water in the oil? Could it come from bad.water seal or could this condensation result from something else?