lfd75

exactly, but it was the coolant in the overflow reservoir that was boiling (and it was exposed to the atmospheric, mind you I could be wrong but it would be the easiest thing to troubleshoot

FBsliderseven

iTrader: (2)

hmmm..well ill have to troubleshoot this weekend stuck at school and work during the week days.
hopefully i didnt pop a coolant seal.
i think im gonna give up on the supercharger and go with my drawthrough setup that i have sitting on my shelf.
btw anyone know how much boost a 12a cartech turbo produces?

FBsliderseven

iTrader: (2)

it could be so because the tape was off when i opened up the panel to access the reservoir.
but not sure if that would cause the coolant to boil

djessence

dude, that stuff is at like 180 degrees @14 ish PSI, I dont wanna explain but its a pressure/temperature relation kinda thing. It will steam if it comes out of your rad. If it was properly boiling and bubbling and stuff this means it was above 200F which is bad which means you have overheating issues......... or coolant seal. You can tell if you have a coolant seal blown by previously listed methods.

Look in the FSM for troubleshooting techniques as well as in liek a haynes manual

DivinDriver

iTrader: (15)

Properly mixed 50/50 coolant doesn't boil until around 260 degrees F @ sea level. Our cooling systems work above atmo pressure, which raises the boiling point further, to around 310F or so.

A bad water pump will stop coolant circulation, resulting in overheat, overpressure of the radiator cap, and overflow of hot fluid into the reservoir. Likewise a failed thermostat. This type of boiling-over won't start until the engine comes up to operating temp.

I had a water pump fail once where the impeller broke off the shaft. Never leaked a drop from the weep hole, but pumped no flow. Symptoms were as discribed. Took about 15 20 minutes to heat to the point it would overpressure the rad cap and flood the reservior.

Blown water seal on the combustion-to-exhaust portion of the rotor path will cause rapid overpressure throughout the system, which can cause an overflow even before the coolant is hot enough to boil. (blown seal on the intake side will cause exhaust steam)

There's also a small chance that this is an intake-manifold gasket problem; he's running boosted, so if there's a leak between the intake runners and the water jacket circuit that normally goes thru the intake manifold, seems like that could also cause an overpressure in the cooling system - - but only when on boost.

Way to check this, IMHO, is to let the car cool completely, and start it with the rad-cap off. If revving the engine while the car is cold (t-stat closed) makes large quantities of AF surge out of the rad cap hole, it's most likely a seal problem. If it boils over only after heating up, but before flow is observed in the coolant, t-stat or water pump could be the culprit... or it could be a water seal leak that only shows after heating up.

I'd work thru it in order of least-difficult fixes, after diagnosing. T-stat, then pump, then intake, then rebuild if needful.

Kentetsu

DivinDriver, you have explained it very well.

A blown coolant seal can result in one of two things, depending on where the problem is. It will either cause coolant to enter the motor, or exhaust gasses to enter the cooling system.

Dave Meyers

Is your radiator cap new or at least in good shape? I know, it may be overly simple, but I am just a Joe Sixpack, dontcha know!

FBsliderseven

iTrader: (2)

i had one cap leaking...would that cause my problem?

trochoid

iTrader: (6)

Possibly, a leaking rad cap doesn't allow the system to seal and build up pressure. When the cap leaks, it often, but not always, goes to the overflow tank.

FBsliderseven

iTrader: (2)

heres a picture to clarify the cap.

trochoid

iTrader: (6)

Take that circled cap off, start and warm up the engine, look for Don Ho 'tiny bubbles' in the coolant stream once the thermostat opens. If you have bubbles, you blew a coolant seal. If not, replace the cap with the highest rated psi release pressure you can find, keep the rad cap at the stock psi rating.

FBsliderseven

iTrader: (2)

do i really need the thermostat?
it rarely gets below 65 here.

GavinJuice

I dunno about anyone else, but in that picture your top radiator hose looks like it's very swelled up right where it curves. Unless it's just the picture, i would replace that ASAP.

FBsliderseven

iTrader: (2)

figured out why it overheated.
the efans werent on someone turned it off #^#@$!!!
anyone know what the possible results of overheating?
this is probably the first time...

trochoid

iTrader: (6)

Overheating is the #1 rotary engine killer. Do the bubble test I mentioned earlier and a compression test. If neither show a problem, keep an eye on your coolant level for any loss. If you shut the engine down soon enough, you may have avoided any short term damage. Might be a good idea to replace that upper radiator hose too, that was a good catch Gavin.

Do you need a thermostat, most definitely and it needs to be a Mazda oem one. There's a long explanation why, but just trust me on this one.

FBsliderseven

iTrader: (2)

ok, i will replace both hose and cap.
hopefully theres no bubbles i didnt see them in my earlier test so it should be fine.

DivinDriver

iTrader: (15)

Very clean bay, BTW

FBsliderseven

iTrader: (2)

thanks!
didnt have time to work on it today but will get to it tomorrow.