Hey guys I have a really weird cooling system issue. My temps are reaching 95-109 deg celsius when cruising which is too hot. the weird thing is that when I idle the temps drop constantly back to within the 70's . Also the coolant is being forced to the overflow bottle untill it is full. i have no leaks. some body help me please.

 

do you have a stock fan?

 

no im using an e fan, have an aftermaket rad 3 inch core

 

is this a new set up or has it just recently started doing this

 

new setup, im considering a bad rad cap

 

do you have the stock under tray? the under tray helps push air through the radiator and not allow the air to flow down and around. also, the radiator fan shroud (i hope ts shrouded) might not allot enough air to flow through it at speed.

 

the fan is shrouded but your saying the shrouding may be preventing the air from flowing through freely? i dont have the undertray on at the moment

 

It ain't the undertray (or lack thereof).

 

when the engine is cool and rad. cap off, try squezing the rad. hoses by hand and see if you get a "burp" from the rad. maybe air could be blocking coolant flow.

 

what is the set up on this car, need more info

 

the setup is a 87 TII with
- aftermarket 3 core aluminum rad
- electric fan from a mercury villager https://www.rx7club.com/forum/showthread.php?t=895916
-BNR stage 4 turbo
-aftermarket intercooler
-megasquirt ecu


need to know anything else?

 

aftermarket FMIC and a 3" radiator?
do you still have ac condenser in the car?
my opinion is you either need a water pump because its not pumping properly, or I really think the radiator is too thick when combined with the FMIC and even worse if there is a AC condenser still in the car

also- what kind of shroud do you have around the radiator? does it cover the entire radiator?

 

Did it have this problem before you put the radiator and e-fan in?

 

ok So I was driving it today and I really think it is a blown seal because when im driving after it warms up the temps climb steadily but once i get off the throttle and coast or sit at a light the temps drop. I think when on the gas I have a bad seal and that the exhaust gasses are entering the coolant and heating it up. only thing is that i dont have any white smoke coming out the back. ....

I dont have an ac condenser im running rad in stock location with stock intercooler to figure this issue out.

 

its hard to get air through a 3" thick radiator and a FMIC

are you saying you will run the stock IC to figure it out?

 

no i had a v-mount setup with the stock rad, but when i got a new rad i put the stock intercooler on and put the new rad in the OEM location to figure out what was causing the cooling problems.


Thinking it might be a bad coolant seal, but i don't have any white smoke??

 

how old is the water pump?

I have never been a fan of a 3" radiator, also have not mentioned shrouding on your fan set up
full shrouds close to the radiator do not work well

 

this is what my fan looks like on my rad.

my waterpump is a used one, but has no leaks from weep holes.

 

waterpumps can still have the impeller corrode , it wont leak.
I had this happen to me with another car, no leaks but at speed it would not circulate enough coolant.
But I assume you noticed the condition of the pump when you installed it

 

hook up the fan to HI Speed.
I have the same fan on my car with a FMIC and the car would get up to 190's and up on LOW.
I switched it to HI and I sit at 176 degrees.

 

i've got it hooked up on high speed. If i'm correct it's the BLUE/RED wire on the fan.

The condition of the pump seemed to be fine, came off a spare engine a couple of days ago because my pump started to leak from the weep holes.

 

this is the EXACT same thing that happened to me. i would get into the 200's while cruising and then suddenly lower when i would stop the car. it puzzled me. but for hsits and giggles, i got an undertray. BLAMO, problem went away.

btw, corksport rad, fanshroud, and using the stock fan.

 

hmmm i guess i'll try the undertray, i'll try anything at this point lol

 

Ya,I got a undertray on my car,so it would help with that fan setup!

 

put the undertray on, will test it out tomorrow morning.