what makes the coolant deplete on these cars? seems like once a week im adding 1/4-3/4 cup of water to the car....car doesnt smoke at all so i dont think its a coolant seal....is it just something that is regular? I dont seem to have any leaks anywhere. is it just the nature of the beast? or something to look into?

 

I chased down small coolant leaks for a few months. Its a freakin pita. Mine were coming from a couple of places. A few reasons for leaking coolant:

1. using worm type hose clamps instead of factory ones and tightening them too much causes the rubber to pinch and eventually start leaking in small quantities.
2. old hardened hoses that no longer seal properly
3. leak from radiator from when the FMIC piping was mounted too closely to the radiator and actually caused the radiator welding seam to separate very slightly.

Took me months of screwing around to find everything... Would have been easier to just buy a complete hose set and factory clamps from Ray and do them all.

 

i do have new rad hoses and coolent lines for the turbo.....guess ill have to check around......

 

What is the pressure cap psi on your AST? In early 1994 the guys at my Mazda dealer switched up my caps on my engine with my stock ast cap. I lost like a cup a week. I can send you the darn service record if you do not believe me. I have learned that depending on mods and pressure balance between the AST and the stock engine cap a bit of coolant will blow past the cap on the AST to the overflow line- with nothing to be seen. What radiator is in the car, are all lines stock, do not cut off the heat etc. I can not tell you what your cap should be on the AST or what the engine cap pressure is/should be but this can happen if the differential betweeen the caps is not correct. I would suggest a pressure test on the system to find the culprit.

 

i have the same problem...every time i start my car up cold, i get a lot of smoke coming out the tailpipe, i don't see any coolant leaks under my car, but every time i check my coolant filler neck its not at the top...i also did the bubble test and no bubbles were spotted at all

 

I had a similar problem. No smoking on start up. I tried replacing my thermostat, radiator,waterpump, water hoses and fill cap with no luck. A year later the coolant started to go faster and sure enough it was a bad seal on the water jacket. So just because it doesn't smoke and the volume is small doesn't mean you are not possbily due for a rebuild.

 

My coolent is at the same level after months of driving. If you need to refill coolent that regular, sounds like the coolent seal is heading south

 

Takr your car to a radiator shop and get them to presurize the coolant system and check for leaks.

I had this same problem and mine turned out to be the pressure cap. Take the tube of the header tank that goes to the overflow canister and presurize the system, check if any coolant trickles out the headertank pipe.

Good luck.

 

It could be an engine o-ring. 1-3 quarter cup a week of water would not necessarily cause engine smoke. How many miles are on the motor?

 

It IS one of two things: A leak in the coolant system that is allowing air to negate the thermo-siphon effect so that once the coolant expands into the expansion tank, it doesn't get drawn back into the system, and then you add coolant, and more pukes into the expansion tank, and this cycle repeats itself.
The other thing is a small leak of a coolant 'O' ring inside the engine. Not enough to cause coolant smoke, yet enough that combustion pressure is forcing coolant into the expansion tank and out the overflow. My car did this when it had a bad 'O' ring. I was always adding about a half cup of coolant, and when I'd shut the car off, it would leave a small puddle under the overflow.

 

I notice that you said that you add water instead of coolant. do you have any coolant in? Because if you have nothing but water and you have a leaky water seal, it won't come out the back becuase it will evaporate inside the engine.

 

It may be the start of O ring failure. I have the same thing. My mechanic did a pressure test and told me this which surprised me because the motor runs so well and starts easy in the AM. However, since that time I switched to Evans MPG Coolant. I haven't lost any coolant since. Evans is a higher temp, no water, racing coolant. It has very low expansion properties and is anti-electrolysis too which can be a big problem with rotaries. For some reason it really seems to solve my problem in the short term. However, if my rotary specialist is right, I will need to deal with the O ring problem eventually. I only put about 1000 miles per year on this car so I may get by a long time with this situation. So, I'd at least get it checked out by a rotary specialist just so you know what you're dealing with. BTW, don't take it to the dealer. As far as RX7s go, they are all about as dumb as a bag of hammers

 

ummmm.....motor has 3k miles on it...its brand new.

 

bajaman has give you the best advice. Just to aggrandize on his post, a leak in the cooling system includes the AST cap, filler cap and the line running from the AST to the expansion tank. The leak can be very small.

 

Did you do the rebuild yourself or have a shop do it? If you had a shop do it (not the dealer I hope), then take it back to them to investigate. It is not uncommon to have o-ring problems after a rebuild if it was not done properly. It is a very touchy thing to sandwich one of these things back together. Any imperceptible warp in anything can cause the seals not to "seal" properly. Of course you would want to rule out anything minor such as leak from a hose fitting or bad cap. The shop who did the rebuild should get to the bottom of this and not charge you anything extra.

 

yes there is coolant in there.....and it was a mazda reman...not a rebuild.

 

I would pressure test thet system. It can be hard to pinpoint expansion leaks. I doubt it is a coolant seal.

 

so any updates dude?

 

not yet, been working alot have not had a chance to work on anything.

 

What happened with this? Did you need rebuild? Did you find the leak?