New radiator and thermostat, higher operating temp now. wtf??
 

I recently replaced the stock radiator with a koyo. I then flushed the system with distilled water, put the radiator plug back on, and started mixing 50 50 water and coolant. after i couldnt fill anymore, i would start the car for a few minutes, turn it off, then fill it some more. i let it sit overnight, came back the next day to do it more, and i let the stock gauge go past the top hot line, because my power fc only read 75 celsius, so i thought i was fine. just to be sure i turned off the car, checked the engine, and it was popping and cracking very loudly, and coolant was bubbling from the resivoir, but not from the top, i couldnt see where. i left it over night. i drained it again, researched for a week, called friends, called my shop, and went back to work a few days ago. i replaced the t stat with a new duralast ( i know oem is best but i cant go buy a new one if i dont have a car to drive). i used about 60 40 water to coolant this time, made sure to take off the tb coolant line on the manifold until fluid came out, pumped the radiator hose, filled it all the way, then turned on the car. it was fine for a while, the fans kicked on at 94 celsius, then temp went back down, from the power fc readings. before the koyo, my normal temp was 82, now its 87 or 88. i took it for a ride, and right away the stock gauge started rising, so i turned it off, let it sit for the night, and came back the next day. i filled it with more coolant, about 1/8th gallon. ive been going easy on it, but now the temp is higher then what it used to be. i thought i blew a seal inside the engine cause i let the stock gauge get so high, but i havent driven it hard yet. any ideas on cheap tricks to keep it cool? i plan on doing the fan switch mod soon.

Was your fan disabled when you did this? From what I can tell, the FD gauge is similar to the one found in S5s, which is basically a warning light. If you ever peg the gauge in an S5, the coolant seals are done. According to these threads, if the needle is in the middle, you're around normal operating temp. If the needle is all the way up, you're somewhere around 250+F (121+C)!

https://www.rx7club.com/showthread.p...ock+temp+gauge
https://www.rx7club.com/showthread.p...ock+temp+gauge

What year is your car?

no the fans were always connected. the needle did go all the way up, but now its fine and i drove it a little last night, up to 4500 rpm, and the power fc read 86. im going to huntington beach today to neptune speed to get a check on it, make sure everythings all right, its the trip there im worried about lol, im gonna buy a dp as soon as i find one on the listings that hasnt been sold

93

also, my water temp rises to 103 when i turn the car off from 88 deg C. then it slowwwwwly lowers back down, i know cause the waters not being cycled, but the temp has never been that high after i shut down

Sounds like you have an air pocket somewhere. You need to pressure test it to make sure you do not have a leak even a small one can cause this. But first try burping the rest of the cooling system to get the remaining air out.

Yes, pressure test the system. If it holds pressure, remove the filler neck cap, fill it with coolant/water, replace the cap and squeeze the radiator hose 4 or 5 times. Remove the cap, re-fill and repeat the other steps until it won't take anymore. This is burping the system. Then fill your overflow tank to the proper level indicated by the "dip-stick".
If it doesn't hold pressure, closely check ALL hoses...including the turbo coolant lines for any signs of leaking.
Consider replacing the t-stat with OEM. That aftermarket version may be hotter and personally I don't like going cheap with ANYTHING related to cooling on this car.
Then check to make sure you have all the fan speeds.
The rise in temp on your PFC commander right after shut down is normal heat-soak. When you turn the car off, the coolant stops circulating and it will rise in temperature initially.
Sounds like you got it pretty hot. From what I've read from the big-brains, coolant seals start to degrade around 240 F. and you probably went beyond that if you pegged the stock gauge.

i drove it 100 miles today, boosted to 5k multiple times, temp stayed around 82 C. im pretty proud of how it ran, i think the cars fine now, its just a pain in the ass. thanks for the tips guys, i will keep that in mind if i ever have a problem again. i made sure to burp the system as much as i could, 1 week to be exact, i would fill it, start the car, shut down, come back the next day when everything was cold and settled, repeat.

Just because you got it to 5000 RPMs a couple of times and went 100 or so miles does not mean the problem "fixed itself" or has gone away. Double check all clamps tightness. When you get time follow these steps:

1. Remove rad. cap
2. Top off cooling system
3. Start car and let idle out side or a well ventilated area to operating temp
4. grab a beer (or favorite beverage) While car is warming up
5. Watch the top of the rad for proper operation of the thermostat (coolant should go up and down a little)
6. Once the thermostat has opened fully squeeze the upper hose.(lowest point is prefered) watch for bubbles and gulps repeat until bubbles and gulps have stopped if they continue after 30 minutes proceed to step 11.
7. Top off as needed
8. shut down car
9. Top off fluid including res. to the full COLD mark
10. Reinstall cap and monitor over the next couple of days and check weekly or on a reular basis :nod:
11. Get a pressure tester they are inexpensive and good to have on hand.
12. Pump it up to 14PSI (I go 16-17 PSI) and check for leaks.
13. Fix leaks and repeat steps 1-10
That should conclude this burping lesson

sounds good, i will do that tomorrow morning. tonight the coolant buzzer went off, i shut down, restarted, and it didnt come back on. not sure what my coolant/water mixture is, i would say around 60 water 40 coolant, more close to water higher.

What is the coolant level in your overflow tank?

I did not read every post but it sounds like you have some air in the coolant

so my power fc read 118 c today, then i drove it a few more miles, then the rpm started jumping when i idle, and coolant is coming out of overflow hole, not the neck but tiny hole on the top.
conclusion, coolant mixing in the engine, andddd its dead. ready for a rebuild!

any tips on that? I KNOW I WILL READ THE FORUM

but any tips you guys would that you wish you wouldve known during a rebuild?

Most of the time when your coolant seals are blown there will be white smoke pouring out of your exhaust and you will smell in the air that it is coolant by the sweet or kind of fishy smell.

its weird cause im not getting that, but the car keeps idling badly trying to shut itself off, and when you take off the oil cap, theres yellowish whitish fluid, creamy looking, which i heard is coolant mixing with the oil. i use castrol gtx and only have a few 100 miles on the changed oil

I guess that is a different way your coolant seals can go too but I havent heard of it. I blew the coolant seals in my first Rx-7 because I didnt flush the cooling system when I bought the car. I was too stupid to think of it since it was basically my first "real" car and I was pretty young. When it happened there was white smoke pouring out of my exhaust and it was really hard to start. I dumped some radiator sealant in and it temporarily fixed the problem but my car ran like shit.

that stuff on your oil cap is called "lung mustard",which is condensation from heat when the housings cool down,it mixes with heat from oil and you get SPLUCK!
In an FC engine(anyways) they get that shit all the time and consider it kind of normal.

what about the coolant overflowing from the coolant tank at the top of the nipple? i took off the coolant stick to release air pressure but that didnt help. i already started disconnecting everything to start the rebuild, will be pulling the motor tomorrow. trying to find a build thread for a good single turbo on stock internals, you guys have any recommendations?

We had an similar problem with air pocket in cooling system. We got rid of it like this: We filled the system full, then revd the engine and as the coolant level dropped we filled it at the same time. Then we let it idle some time, rev it again and as the coolant level dropped we filled again. We repeated this untill the coolant level didnt drop any more. We noticed that normal coolant system airing didnt work on FD's cooling system. Btw, are you sure that you engine is ruined? The over leaking problem may result from an coolant circulation problem... If there is no color canhge in coolant i wouldnt be so worried yet, unless you just want to rebuild your engine.

I know one thing with the FC is that a lot of people who changed thermostats with aftermarket ones had higher operation temperature and weird cooling problems. Im not sure if that goes for the FD but if you didnt use an OEM thermostat try that out?

i let the temp get past the H on the stock gauge, even though the power fc only read 75 C. i know they both have sensors in different spots but i think that started the initial downfall of the engine. what would explain the horrible idle then? my buddy said its the engine overheating and trying to shut itself off cause of bad cooling. i filled the coolant to full many times and it keeps going down, i already took off the dp, drained fluids, took out intakes and intercooler, i dont wanna chance trying to drive it again. it kept randomly overheating, after driving for an hour on the highway, or some stop and go traffic. im leaning more towards bad coolant seal cause of all this, i think its safer to just rebuild it and not have something else go wrong

Well if you can afford the rebuild then go for it, sh!t might as well port it too.

Overheating probably caused a coolant seal failure. That may be allowing coolant/water into the combustion chamber. Since it doesn't burn and probably only one rotor is affected (for now), that could cause a lumpy idle.
In cooler weather, a small amount of baby poop under your oil cap is typical. Water condenses in the engine and isn't able to evaporate completely. It forms a little emulsion. But in your case, with the bad seals, I suspect that small amounts of coolant/water may also be getting past the side-seals and into your crank case...resulting in more of that same baby-poop emulsion.

Did you fix the problem I'm thinking about doing mine.