ok guys i put a huge aluminum radiator in my car with an efan. i messed up and got a thermostat from advanced auto parts, the brand is unknown. the car ran great for about 2 days. well, first i blew my upper radiator hose off sp i got another and put 2 hose clamps on it, then the next day a tiny crack appeared in the thermostat housing. i jb welded the crack and on my way to work this morning....POP, white smoke everywhere!!! my Tstat housing exploded...what can cause this? i am running a radiator cap rated at 25psi, is that too much? my friend said that my thermostat might be sticking and building up pressure, could this be true? i am running a very long upper hose because the hole on the radiator is on the opposite side and my heater core is not connected....please help. thanks

 

i would just replace it with mazda thermostat and housing. they tend to crack over time.

 

Crack might have been from overtightening, or simply age.

Pressure cannot be built up by a sticking t-stat. The waterpump is a volume pump - not a pressure pump. The only reason the system becomes pressuized is because of the cap. And 25psi is FAR too much.

A "race" version rad cap is 1.2bar or about 17-18psi as opposed to the stock 0.9bar or 13ish psi. 25 pounds is WAY too much.

Replace it with another housing - if your car is an S5, Mazdatrix sells an aluminum neck to replace that plastic heap - or is you have an S4, you already have an aluminum one and just grab another from a yard/forum member.

And run an OEM t-stat as stated.

 

thanks classic.....so it should be the cap only? so do you think i should find one around 13psi....btw i have a TII swap if that makes a difference.

 

which rad cap is the one rated to 25 psi? The one on the thermostat housing shouldnt really matter as long as the one on the radiator (thats connected to the overflow) is correct.

 

25 PSI is way to much like the other guys was saying.

That is correct IF your overflow is connected to the radiator. Some rx7s have the overflow connected to the thermostat housing.

You should have a 15- PSI pressure cap on the radiator or thermostat housing, which ever one is connected to the overflow.

More pressure is not always a good thing. Yes it raises the boiling point, but if the cooling system is not designed for it, leave it.

To explain further, when the fluid heats up, it expands and will onle create pressure if its in a sealed system. This is where the pressure cap comes into play.

 

oh ok, thanks. i put all the stock radiator back in it with the e fan hooked up.

 

I would never put a higher than 16PSI cap on a car.

 

yeah you know what to do already just put back the oem parts. they're really designed well and you shouldn't have any problems after that

 

The Haynes manual states that is should be a 15psi cap.

 

also, by JB welding a crack in metal you really should have expected it to blow...

 

yeah seriously. Bad call on trusting your cooling system to JB weld.

 

It might have held if he didn't use the wrong pressure cap. 25 psi? He should consider himself lucky that is the only thing that failed.

James

 

I've actually had good success with JB weld on my 323's radiator (on the plastic part, mind you), but I slapped it on thick for a VERY small crack (seriously, the crack isn't even visible) and after a year of that I had to redo it. I've also never had the wrong rated rad cap on it.

 

My FC's one had the same kind of crack... JB Weld seemed to work pretty good. "Like New" hehe

 

this is what happens when you dont know crap about a cooling system and decide to put a radiator cap on that evidently is made for a jumbo jet.

 

HAHA, maybe i can just put some duct tape on this and put it back on......i got an oem tstat and put the stock radiator back in with the efan attached to the radiator.

 

this thread delivers!

wrong part + rx7=

 

I took a look at the pic. The fact that it cracked lengthwise suggests failure from too much pressure inside.

 

right, so long story short an rx7 needs an rx7 radiator cap, i had my friend go to his shop and weld me a metal tstat housing.....im bout to go pick it up, he assured me this will not blow. with the stock radiator back in i dont have to worry, but i do have another idea about a radiator setup, which i guarantee will be the cheapest cooling mod ever. only time will tell. i will make that thread when i start the project in a few days.....later.

 

Sweet Jesus. Now THAT'S a part failure.

 

I'm sure as long as you use the right cap you should have no problem with the aftermarket radiator and e-fan. 25 PSI is WAY too high for the FC. Stock cap is rated to 14ish PSI. When you build up 10ish extra pounds of pressure that is way too much. But hey, at least you're learning from your mistakes.

 

yeah im just lucky that i didnt learn at the expense of my coolant seals or engine in whole. here is my new housing, it's a shady tree mechanic special......this one is bulletproof though. i made it a little shorter because i always buy the universal flex hoses for the radiator that every parts store has. its better than hearing, "sir we'll have to special order that part." my friend made the housing for me, i'm gonna paint it and slap it on tomorrow. this is my first step in making a great intake and cooling system for under $200. everything will be brand new as well. i will post no details as of now because i know i'll hear some crazy comments so ill take pics and keep track of the totals and see how it goes before i report to you guys.

 

my suggestion is to put the aftermarket rad back in and use the stock rad cap. the rotory need to be *** cool as possible. you spent the money on you might as well use it.

 

well my friend used to run dirt track cars and has a ton of parts he doesnt use so i got the radiator for free.....he does all my welding/fabrication for free.....so it really didnt cost me anything. im up right now waiting on my new radiator to come in so we can start our budget build for a true CAI and aluminum radiator. were trying to keep the cost around $200 but ill post pics and info as it comes. then ill drive on this for a week or so and let you guys know every detail of where i got parts and stuff afterwards......like i said ill leave it at this for now.