FC Rotory Help

[SecondGenPAt]

Only after the hard test drive did it seem to heat up. When the engined shut down it pushed a quart or so of coolant into the overflow (gurgling sound) and later (30 minutes) it had pulled the coolant back into the radiator. No coolant on ground.

I had the same issue. a brand new oem cap from Mazda solved it.
I'll be there Saturday with my S4 FSM and Mazda Rotary compression tester (and a few other diag tools)
Question, what hand tools do you have available? I'm assuming a good selection due to the work performed already?

-Pat

[D Walker]

Not to argue, but I had the same heard the same as you just stated, and me myself have never really gotten concerned with 200-220 deg temps although most of the time we shoot for 180deg temps if possible. However, I literally just spoke to Jim Mederer from RB (we use his ECU in the world challenge cars) and he was very unhappy to hear we were running over 200deg, ever. He gave me an entire speach about how I was killing the motor and to NEVER let it get over 195 if I could help it. I know the RX8's run hotter from the factory, but I have to believe that is an emissions driven temp, and that no good comes of it. On track at 9k rpm for extended periods we see 170-180deg's unless we are nose to tail for any length of time, then the temp climbs to over 200 quickly and we have to stick the nose out in clear air on the straights.

Now what I have seen is that any overheating of a rotary is bad. They usually dont stop running, but they will never be the same and the best thing is to just stop and fix the issues.

200* is just past the optimal operating temperature for a rotary...hell, Mazda doesn't even have the fans kick on in an FD until 221*F and the RX-8 doesn't kick on it's first fan until 202*F and the second at 212! While I agree these are high temperatures (when I tune I set the fans on the FD to kick on at 84*C) 200*F is not overheating.

Every rotary from the factory runs at 200*F plus with the way Mazda has set it up. Not to mention I was told by Jim Mederer himself, in person at SevenStock, that overheating a rotary isn't until about 235* when you do real damage. Now is it good or even advisible to run 225* then? Hell no, but I don't sweat 105*C coolant temps.

[chickenwafer]

I'm not saying I aim to run 200*F, the ideal operating temperature is around 185-195* for a street driven rotary. Obviously on the race track it's a different story.

Of course it's an emissions related thing to keep the cars running warmer, but my point is every FD from the factory ran around 210-225* and while they do blow coolant seals it's not as common as other issues, so cars running these temps for years and years aren't blowing coolant seals left and right, or warping plates.

I agree it's not ideal, and in a race environment you want to control temperatures as much as possible. I just want to make sure someone doesn't come in here thinking 200* is overheating and freak out because their car hit that temperature every now and then. I don't worry about shutting the car down until about 220* on the street.

[christi]

Good info, the only things that make me think there is a heat issue, is that Christi says the car shuts down when it gets too hot. The gurgle past the radiator cap (and not violent) may be just a weak cap.

it does.. I even told my father that, and he said it's not suppose to happen. Before it gets excessive (It's NEVER reached "H") it'll shut down maybe 2/3 (is that the right fraction?) before "H".

Would Eric's thought on the subject of it overheating and reading the wrong temp may be accurate if the sensor is not reading proper or the gauge?

[D Walker]

I never trust the factory gauges. I also dont trust "tuner" gauges like Greddy etc. A simple Autometer mechanical or electrical gauge works perfectly and doesnt cost too much.

[ecam8000]

Drained to coolant last night and pulled the T-stat, only to find the one I picked up is a larger version (had the same secondary seat on the bottom, but a larger diameter). I retested the original (Christi told me it was newer) in a water bath. It started to open around 185 and was fully open before the water started to boil - 210). I reassembled and filled with 50/50. Used a small phillips between the upper radiator hose and t-stat neck to aid in filling (burping). Pressure tested to 14 PSI and it held for several minutes. Started engine and went to tail pipe to look for signs of coolant in combustion - nothing. Idled for a half hour, temp came up, t-stat opened, radiator got warm and fan started. Temps held stable but fan never "cycled" just stayed running. Drove it around the neighborhood for about 30 minutes watching temp gauge. Brought back into shop still running opened hood and inspected. Everything seemed normal. Raced engine a bit with no load and had a fuse do a melt down (electric fan circuit I think) so I shut the engine down. Did not "gurgle" past new radiator cap.

I my opinion, if this overheats when driven hard or climbing big hills (Lookout Mtn) then the radiator/fan is unable to remove the heat that is being generated with the higher loads.

[chickenwafer]

^That sounds like a good evaluation, Eric.

Christi, I would recommend you get a good aftermarket water temperature gauge in you car to keep a good eye on coolant temps so you know when to shut it down. The factory gauge is not a true "linear" gauge meaning it has a dead spot in the middle of it's range.

So the needle will be reading "all is good" from roughly 150*F to 220*F or so. You obviously want want to monitor those a little better so a coolant gauge is a good idea.

[RX-7 Chris]

I thought the FC gauge is a true linear gauge. The FB gauges are true linear. I thought it was only the FD that didn't have a true linear gauge.

[ecam8000]

Car gauge moved up to warm and then never waivered. Idle and test drive, it stayed right in the middle of the "norm" range.

It was the smoke and fire afterwards that made things interesting! I was trying to decide gas or water, but then it occured to me it was in my garage....

[RX-7 Chris]

sounds about right for a rotary that isn't tuned right.

[ecam8000]

sounds about right for a rotary that isn't tuned right.

What? Throwing gas on the fire?

[RX-7 Chris]

I set my black car on fire once....by mistake.

[christi]

Whoa! Fire?!
I had the e-fan on for a long while though before the overheat happen. Unless it's truly the e-fan and rad together ?
Edit:
Also with the aftermarket reader...would that be accurate? I only ask because soon as the stick temp gauge specifies it's about to
Overheat it auto shuts down...would this remedy it or am I just confused?

Sent from my iphone

[iani1.1]

ive set the silver one and the one i have now on fire on more than once occasion

[ecam8000]

Whoa! Fire?!
I had the e-fan on for a long while though before the overheat happen. Unless it's truly the e-fan and rad together ?
Edit:
Also with the aftermarket reader...would that be accurate? I only ask because soon as the stick temp gauge specifies it's about to
Overheat it auto shuts down...would this remedy it or am I just confused?

Sent from my iphone

Relax, the fire is out. There was a melt down at a fuse holder attached to the battery surround. You can see it tomorrow. I have the parts to repair it too. It looks like the main fuse for your electric fan.

We are not discounting your fan. If the overheat issues are long past when the e-fan was installed then the problem is something else. It could be engine tune, it could be old/dirty/plugged radiator. The more heat we make with our engines, the more the cooling system needs to git rid of. The car seems to be fine at low engine loads, but if it still happens at high loads, more work is needed.