God damn motherfucking son of a bitch. I swear this car does really HATE ME !!!!!

(I know the above will be edited, but I needed to vent)

Car overheated again last night. Buzzer came on, I didnt have any place to stop so I tried to cruise slowly to the next exit or sideroad. Needle in temp gauge was dancing up and down towards the H mark Turned on heater full blast, but didnt help much...

When I finally got to stop (about 6-7 minutes later), I pop the hood, and yep all coolant was in the overflow up to the brim. No wonder car overheated. It didnt have any coolant in the radiator, just plain air I tried to relieve the pressure by slowly opening the rad cap, and when I finally managed to open the radiator in order to put the coolant back in, the coolant had turned a very nice grey Poured the coolant back in the radiator (didnt have any fresh coolant with me ) and NO, the car didnt burn one drop of coolant. All the coolant was there, it had just moved to the overflow tank.

I tried to go back to my house slowly, and just minutes before arriving, the buzzer came on again I have left the car in my house, and I'll try to figure this out in the evening.

FACTS:

I have meticulously maintained the car (full service/tune-up every 5K km ), I have replaced thermostat (twice), rad cap (twice), thermostat housing, belts (3 times), flushed radiator, changed coolant (9-10 times ), and the system seems to hold pressure just fine (no -apparent- leaks). Also the fan works (thermo-modulated works only when car is turned on, cannt really hear the electric fan), but last night I tested the fan and it really didnt have much of a resistance.

The only thing I have been able to deduce is that this happens when I turn on and off the car 3 or 4 times in a day. If I leave my house, go to my gf house, turn car off, then on, go to a cafe, turn car off, return, turn car on, drive her back, turn car off, turn car on, leave, then on the way back I will hear the dreaded buzzer AGAIN.
If I turn on the car in the morning, drive to the office, turn it off, then turn it on in the evening, drive back to my house, turn it off, then next day everything will be just fine.

It seems that the car (cooling system) starts to "leak" or take in air when it has reached a certain temperature, or has been turned on/off more than 2-3 times per day. I really dont know what the **** is going on here. I have taken the car to two different official Mazda shops, where the head honchos have also RX7s as personal cars (I checked that BEFORE going to them ), and they both said that everything is fine.

Guys, if this keeps up, I may have no choice... I have paid 15K EUR to have a nice, fast, daily driven car, and I have waited to get this PARTICULAR RX7 for more than a year, but I still have no car. And all because of some stupid ****, which I'm sure is just a hose or little thermo-switch....

Any ideas guys ? ANY at all would help...

 

possibly water pump? get an electric one instead of pully driven

 

Check all your hoses, make sure none are collapsed, how many miles are on the engine? Do you have troubles starting sometime, where it sounds like it's only running on one rotor? How long has this problem existed? Any air/bubbles in the overflow tank when it's running? Sure your water pump is working?

 

an electric one probably isn't the best of ideas, especially if it's just a daily driven car.

 

I have replaced heater hose which split and poured coolant all over the driveway, and a couple of others that had very small cracks. Now cooling system seems to hold pressure just fine

Car has just passed 100K km, and engine is VERY strong. Last compression check showed 8,1/8/8 bar Front, and 7,8/8/7,9 Rear. No coolant is burned (every time I pour the coolant back into the radiator from the overflow tank, it is just the exact same quantity).

I dont know if the pump is to blame. The car is revved high once or twice (yesterday just once, when I pulled a 7,1" for 0-60mph and measured 188RWHP on my AC22 meter). Water pump is working because there is pressure in the system, and the coolant does circulate, it just pours over to the overflow tank. No bubbles (car does not burn coolant), just vacuum hiss when I remove the rad cap. I know that this means problem somewhere along the coolant lines, but HOW CAN I FIND THE LEAK IF THERE IS NO LEAK ?

Rad cap and thermostat are brand new stock Mazda equipment. I really am running out of ideas, and the car has overheated three times in the last month, when both Mazda shops told me that everything is just fine....

EDIT: oh, and "8,1/8/8 bar Front, and 7,8/8/7,9 Rear" equals "117/116/116 psi F, 113/116/114 psi R"

 

Intresting, have you tried to run without a thermostat at all and see what that does for you?

 

I'll give it a shot, but I dont think the thermostat is the problem. The thermostat (actually all of my last three thermostats ) opens and closes just fine (I can see that in the temp gauge), it's just the fact that the coolant goes to the overflow tank AND ******* STAYS there, does not return, system takes in air, so engine overheats. The whole process is very logical, except for the fact that I DONT ******* KNOW WHY THE SYSTEM TAKES IN AIR ........


......OK, more calm now.......

I've read the FSM back and forth, I've read everything I could find on overheating for 2nd AND 3rd gens and I have tried/replaced everything. Guess it'll take an act of God for this car to run right......

 

Well ****, I don't know what would be causing it to back up so much, and you say your water pump is working. Short of bad seals I have no ideas left. Have you checked the hose coming from the engine block to the throttle body? and from the throttle body to the BAC? and from the BAC to the water pump?

 

Well, it seems I'm not alone in this "overheating" pile of ****...

Anyway, the throttle body hoses have been replaced a long time ago, because they had hair-like fracture lines. Since then (and after I replaced the heater hose as well), the cooling system holds pressure when testing with the standard procedure, so...

I think I'll just go ahead and replace every hose there is (again ), just to eliminate the "hose" factor. I have eliminated "thermostat" and "rad cap" factors, so...what's left ? Fan (not really relative) and water pump (which works and does not leak)

 

Perhaps the pump inside is just worn/broken/who knows. It seems odd if you replaced EVERYTHING that it would still spew it all out like that, seem sort of odd to me. Has it always done this? And since there aren't any bubbles coming in the overflow tank, it doesn't sound like seals/or a rusted rotor housing. I'm clueless, good luck!

 

Thanks man

I thought it was a simple thing to check a system that has a metal box (radiator), a small cap, a thermostat, some hoses, and just one mechanical pump...I guess I was wrong

I have also never seen this happen, at least not for so long...it has been 4 months now, and I am still at square one and minus 500EUR

Guess I'll.....I dont even know what to guess

 

That's how I feel, sort of like, well try this... oh yeah you tried that already. I'd just try changing the pump, it's like the only thing left!

 

Used pump: couldnt find one even if God himself came down and searched for it in Greece
New pump: before I ask for a new pump at the dealer, I should really apply huge amounts of vaseline all over my bottom end....if you know what I mean

 

I have the same problem u do. Coolant goes into the overflow and doesnt return. I think my coolant seals have a little hole in them. When coolant seals are going, white smoke is supposed to come out of the exhaust. My car doesnt shoot white smoke. Not even a little. The car just shoots flames I changed the radiator, radiator cap, thermostat, fan and clutch fan and a heater hose that blew up causing my car to overheat. I was thinking about changing the water pump but I dont see any water coming out of the weep hole. Maybe the pump's internals are busted. I still think its a small hole/crack in the coolant seals. I hope your seals are still good

 

So, if the coolant seals have such small holes that exhaust gases can enter the coolant passages, but coolant cannt get into the engine (so it burns and you get the white smoke), shouldnt you -and I- be able to see little bubbles in the neck of the radiator ? (i.e exhaust fumes)

No it must be something else...somewhere there is a tiny ******* leak, that is allowing air into the system at high temps (when everything is expanded), but does not allow coolant to leak (and thus its impossible to locate the leak)...

I think I'll go back to Hondas now.....j/k (mostly )

 

have u warmed up the car, taken the filler cap off and checked for small bubbles?? I did and I saw very small bubbles coming out. Something to look into.

 

I have never seen any bubbles. Might as well do the test again...

Hey wan, does your Rex eat up any coolant ? Or the only indication that you have is the overflowing and the overheating ?

 

I dont know if it eats any. I've seen it go into the reservoir and out onto the pavement My car is weird. Does your car overheat if its sitting there idling for a while??

 

As for your last questions, NO. The guys at the Mazda shops left it idling for 3 hours (ate up all my gas, but who cares ?), and didnt even overflow a tiny drop (or eat any coolant).
I got it Monday evening, no problem, Thursday no problem, I went for a coffee last night, on the way home, overflows and overheats....

I swear this car is possesed

 

I dont know what to say then. As long as the car runs good is cool with me. My car sees hard canyon driving atleast 2 times a week and its still running pretty good. I wonder how much more abuse this engine can handle before it blows.

 

But how can you drive a car when you know that it will overheat in the end ? And I cannt really make any trips either. Wherever I go, I have to let car sit for a while, and then take out the overflow tank and pour the coolant back in the radiator

Dont know about you guys, but I really dont feel like doing this for the rest of my life with the Rex....

Hey wan, does your car overheat as well ? (it should, just asking) What do you do then ?

 

Mazdaformance has new pumps at a reasonable price, also consider switching to Evans NPG+.

 

It starts to overheat if i leave it idling for a while. It does that when it spits the coolant out. Every morning I top off the coolant. I do this 2-3 times a day. At first it sucked ***. Now I'm used to it.

Do you have an air pump hooked up?? Just asking because my cars water pump was running on just the alternator belt. I installed the "yoohoo belt" (do a search for that term) and my car dint over heat when I ran it really really hard anymore.

 

Nope, air-pump is still on, so I dont need the belt (or the pulley).

As for ordering a new water pump, cannt really afford to order something from US without knowing that this is what's to blame for my agony

And my car doesnt spill out coolant...I can drive it for days and it will be just fine. Then I will take it for a spin, turn it off/on a couple of times, and the coolant will overflow and I will get the buzzer

 

My car has the same problem.. and yees, coolent comes out of filler neck, so its parked untill i find a doner