I've had cooling issues ever since I purchased used a few months ago.
Replaced all the cooling relays, new temp sensor, new thermostat, tested the fans to make sure they work. -- replaced pretty much everything that controls cooling except the pcm because , I mean, it *couldn't be the pcm, right?* -- or so I thought.

Well, what seems to have finally solved it was purchasing a cooling fan control kit from rx8performance.com to bypass the pcm.

Now, no issues. It seems to hover betw 62 and 65 celsius.

So, for anyone that has similar cooling issues-where you know the fans/relays/temp sensor is in good working condition and it still runs hot--this is a good fix.

 

62-65 huh?

That's not going to happen ..............

 

....... Yes, is it has happened.

62-65 celsius.

I live in Boston, it's February.

The point is, no more cooling issues.

 

I live in Montreal, it should still be able to get to operating temperature. 65c = 149f. Operating is ~180f/82c. You're overcooling now :/ In fact at 65c the thermostat is closed so coolant isn't going through the rad... which negates any of the fan mods. Think you might want to check that reading.

However, if that reading is from the stock ECT sensor, and it has always been reading low, it explains why the fans might not have been coming on and all of the cooling issues to begin with.

 

This isn't adding up Freq . What were the symptoms you were having in the first place ?
EG : was oem guage reading hot ? Was aftermarket gauge reading hot ?

Where did you get the 65C reading from ?

 

Like everyone has said....


Unless the thermostat is stuck open and it is really cold outside you have something funny going on

 

Um, most of what they said, unless you are running the heater flat out because it is horribly cold. Heater will suck heat out, oil coolers will also dump some. But, that does seem a little low. The only radiator flow at that time will be the tiny little hole.

Then again, -4 C air through the heater core can suck up a lot of heat.

Will be cooler, just that seems really cool.

 

Rofl, your car has other problems genius. and it's not ur PCM/ECU rofl

and i hope u know its "normal" for cooling temp to go over 100 Celsius with stock PCM

 

Like others have said, 65C is way too low. The fan kit is not supposed to turn on the fans until 180F. That's 82C. Either your temp sensor is off, or there's something else going on.

I just don't get how a fan kit that turns on the fans at a lower temp, fixes overheating. When you're overheating, the fans are already on full speed! If when the stock fans turn on full speed at 213F, and can't stop the temp from getting to 230F, if doesn't matter if the fans turn on at 180F with the kit. It's not gonna work. So how can this FIX the issue?

Unless the fan kit is giving more power to the fans, making them spin faster. In that case, yeah.

 

I'm using the Torque software to read the obd. Possibly that is reading too low incorrectly?
Previous to the cooling mods, the stock gauge would run at ~40% and stay there.
Now, the stock gauge runs at around 30-35% and I actually see *some* movement after the fans kick on.
I bought the car used a few months back and have totally redone the cooling system -- including the water seals(ie engine rebuild). So, the thermo senso, fan relays, reservoir, are all new. Last week I noticed that the cap that was on it, tho looked to be in good shape was of the wrong pressure, so I replaced that.
So far, so good-no more overheat issues.

 

For the short time I drove the car before rebuilding, I don't remember hearing the fans running(even the single low speed fan) outside of my testing the relays.
So, I would assume that the overheating was caused by the fact that the fans were not coming on at all.
So, the fix was simple.. the fans actually comes on now.

 

Understood-I've gotta assume then, that the software I've got is reading low, though that seems like a stretch since the software probably just pulls the numbers directly out of the pcm thru the obd. I seriously doubt that the software does any real processing when it comes to temp.

But regardless, as it stands now anyways, no cooling issues. I'm keeping an eye on it as the weather starts to get warmer, but so far, so good.

 

My guess is that your thermostat is stuck open and that you never had an overheating problem in the first place .

 

I dont think so. I replaced the thermostat when I rebuilt it. First start, I let it idle to start the break-in process. During that idle I was watching it like a hawk, the fans never came on--same symptoms, new thermostat.

It's possible,tho, that the cap could be the culprit. The cap that was on there was a 12 or 13 psi cap (and who knows how old or if even working correctly). I replaced that cap last week after I took a drive and noticed some bubbling and overflow.

So, say months, maybe years of normal driving with a bad cap--constantly losing coolant from a bad cap, causes alot of mild overheating--not enough to move the useless stock gauge, but enough to eventually blow the coolant seals and force a rebuild.
Tho, that doesn't really explain the fact that the fans didn't come on.

Who knows--bad gremlins?

 

I'm really puzzled how the car could be running cooler than operating. That shouldn't be possible unless you're forcing the fans to run full time or something silly like that.
The stock rad cap spec is 0.9bar ~ 13psi. What have you got on there now?

While its obviously better than overheating, overcooling isn't necessarily great either - the oil isn't at the temperature range it's designed for, so may not have the shear properties it should; and if you beat on the car you could end up with more temperature differential between the exhaust port area and the "cold" parts of the engine, which risks distortion. It's why we don't beat on cars before they're fully warmed up, especially rotaries.

 

Both fans come on low speed at the same time, and then both fans go on high speed at the same time. It's not just one fan.

The OBD2 is accurate. How high did the temps get when you were overheating? Do you recall hearing the fans? They're fairly loud on high.

For how long did you idle at 65C? It didn't go over that at all? Were your fans spinning at 65C?

Like others said, it seems like you have a thermostat stuck open.

 

Freq ..... the cap is not something that helps cooling . All it does is allow the system to get hotter without boiling.
Still interested to know what temps were at the beginning .....

 

oh man this is funny ...

I sorta have a feeling that he build his engine wrong (flip the inner coolant seal so the white side was facing the chamber) and the combustion gas is blowing all over and he gets boil coolant (which is really just over pressure) all the time.

 

But that doesn't explain his coolant temps sitting at 65C.

 

true, but now he probably did something funny like fan on all the time and it's overcooling left and right.

 

Re: operating temperature--the only explanation is that the it's actually operating at a higher temperature than indicated. The gauge reads as I mentioned, but the controller is supposed to turn the fans on at 180. I hear the fans come on at an *indicated* 156.
So, doing the math that's at ~24 degs off farenheit.
But you tell me.. according to the stock gauge, before using the controller, it wld stay pegged at 45%. Now, I've actually got movement and it hovers no higher than 40%.

 

A bad radiator cap can cause the engine to overheat at lower temperatures. This will cause the coolant to boil over to the expansion tank.
When pulling the engine, there was evidence of coolant overflow all over the left side of the bay. This is also what I saw the first time I started breaking in the engine--bubbling in the coolant tank and spitting overflow into the engine bay.

 

If you got the temps from the OBD2 port, chances are it's pretty accurate. The stock temp gauge is supposed to stay pegged at 45 degrees. Your fans are not supposed to come on at 160F. I think the fan kit turns them on around 180F.

 

Sounds like the ECT sensor calibration table on your PCM could be out. You can get a rough indication of whether it's out by looking at the temp value in the Torque app and compare against your IAT (also in Torque) and the temp sensor displayed on your dash.

 

Exactly my point, it's supposed to come on at 180. I'm assuming it does-no reason to assume the new controller is faulty as it's independant from thee pcm, yet the obd reads much lower than 180 when it does come on.
--leads me to believe the reading off the obd is off.
..but I'll look into it further.