ok ive read a bunch of threads, read http://aaroncake.net/RX-7/cooling.htm , plus many other peoples ideas.

ive had coolant leaks = replaced 95% of stock water hoses
bad t-stats (stant units) = replaced with oem
failed water pump = replaced with oem all new seals as well
cracked radiator = replaced with koyo
failed fan clutch = replaced with efan (2500 cfm)
passed the coolant pressure test

no ps, no ac, no airpump running dual alt pulley

the problem i am having is i overheat when cruising at highway speeds 80mph 4k in 5th gear. the temp gauges will slowley rise from 1/2 to 3/4 in about 15-20 mins worth of driving at those speeds. now if i turn on my heater the temp gauge will drop back down to 1/2 and stay their.

the only thing i can think of is that im cavitating the water pump. because i can do normal stop and go street driving and not have a single problem.

PLEASE SOMEBODY HELP! ILL SEND YOU A PAYPAL DOLLAR!

 

do you have a belly pan?
when you deleted the A/C, did you leave the condensor in front of the rad?
are your belts tight?
how is your efan wired and does it have a full shroud?

S4 or S5? n/a or turbo?

 

do you have a belly pan?
YES
when you deleted the A/C, did you leave the condensor in front of the rad?
NO, but i do have a front mount intercooler
are your belts tight?
YES
how is your efan wired?
relayed with my microtech
and does it have a full shroud?
NO i know this one is probably hurting me. but why would this affect only at a constant high way speed, than at stop and go traffic? (not being a smartass just very curious)

s5 turbo

 

well, the FMIC might be whats hurting you actually. The rad is getting choked at speed because of the large blockage.

The shroud wouldn't effect the cooling at speed that much, but I just always think its the best idea. I don't like air to make the desicion of where to go. Im pretty dominant that way, I like to make it go where I want....


Do you have your upper rad panel? (either the stock black plastic panels around the hood latch or an aftermarket aluminum one)

 

Do you have your upper rad panel?
i have the stock plastic one

 

Yes, I managed to fit it back in over the FMIC (I put mine under the hood latch in that space to save chopping my rebar) and from what I can tell it makes a difference.

I even noticed a difference on my DD N/A with them removed. (purely experimentation)

Where is your front mount plumbed? Im asking because if there is some large holes for air to escape where the piping goes through, that might be something to look at. But if its a greddy kit - then Its probably not the problem.

Edit: Also, is your oil cooler in good shape?

 

Im asking because if there is some large holes for air to escape where the piping goes through, that might be something to look at. ?

yeah their are some large holes on boths sides of the engine bay

Also, is your oil cooler in good shape?
yes it not leaking, no bent fins that ive noticed, and just installed new lines not to long ago.

 

but where....in the path the air would be travelling between the I/C and rad? or behind the headlights?

 

behind the headlights

 

shouldn't be an issue then...

I call front mount starving the rad of air........perhaps look into opening the mounth up a little with either another bumper, a slit in the bumper at the moulding, or some thing along those lines.

 

yeah i want to duct it and run a reverse hood, but i didnt think i would end up needing it this bad.

 

There's so little you haven't replaced, I'd just replace everything else :P. Hehe, sorry. That probably doesn't help.

Oh wait, how about blown coolant seals? Probably not, but I thought I'd give another possibility. A search will tell you how to test.

 

Yeah, I hate to say it, but I went through a similar frustration, replacing everything I could imagine, and it all came down to the fact that the problem was INSIDE the engine. My 88 had bad coolant seals at 68k!!! So yeah, it's definitely a possibility. In this situation, it seems like all you have done would solve any cooling issue. Unless your intercooler is putting to much work on your radiator.

 

mmmm i was afraid of getting that answer.
but could a blown coolant seal be possible if ive done the gyser test. and my exhaust doesnt smell sweet and no smoke(not even on startup)?


also what about the fact that if i turn my heater on the temp stays normal (look at my 1st post again)?

 

Fan rotating the correct way?


-Ted

 

yep its pulling air through the radiator

 

And the fan is mounted behind the rad?


-Ted

 

what would be behind? its mount in the engine bay pulling air through the radiator blowing towards the engine.

 

I think what he was getting at was whether the fan was actually a pusher or not (therefore mounted infront of the rad).

Someone mentioned coolant seals....you could do a test, but you'd be having more issues then a raise in temp during sustained highway speeds. But do the test anyway......

It sounds like simple starvation of airflow to the rad to me.....

 

read the previous posts ive already done the test for coolant seals.


im either leaning towards cavation the pump, or starving the rad for air.

 

Is the intercooler in front of the radiator or behind it? Is this normal?

Couldn't hot air from the intercooler make the radiator hard to cool?

 

Is the intercooler in front of the radiator or behind it?
front of the radiator
Is this normal?
maybe
Couldn't hot air from the intercooler make the radiator hard to cool?
yes thats why people go with either v-mount and use some sort of reverse scoop hood.

but i didnt think with my application i needed it

 

the only other thing that I never brought up is what ACTUAL temp it is....

what does the microtech tell you the real temp is when its at its hottest on the highway? it may be somethign actually safe like around 200 degrees....

 

well i havent plugged into the microtech since the ive been having these problems with leaking and failing tstats. but i think i will plug it in a go on the highway for and see what it does.

when the tuner was pushing it hard on the dyno i think i remember it getting up to 93 C about 200 F

 

i have the same issues....temp creep at 4k plus....i also have a FMIC. I turn on the heater to get the temp back down. ..you can upgrade the radiator or live with it. I do....