by everything i mean:
Thermostat
hoses
radiator cleaned
water neck + gaskets
water pump + gaskets


could it be my sending unit? the car is getting SUPER hot and i cant figure out why.
im running w/o a hood and when the sun is out, she tends to overheat and leaves me on the side of the road for a while until she cools off then takes me home. i wouldnt imagine direct sunlight would do that... but then again with a hood it must be like an oven in there w/no where for the hot air to go?
does anyone have a picture of how the thermostat is suppose to sit? the nipple piece is right around 1 O'clock if you were looking straight at it.

idk what else to do

 

Is the fan working properly? Maybe a bad fan clutch, unless you are running an electric?

http://www.aaroncake.net/rx-7/cooling.htm

 

I will second the fan clutch. If it overheats while idling or very low speed, it's fan related. If its overheating while at 35mph or faster, it's radiator or thermostat related. Or worse, a clogged line in the engine. Is the thermostat the proper temp? I think 185 is stock. And it isn't in backwards, right?

 

If it overheats at speed it is the water pump usually. Are you using AC? Try cleaning out the condenser, or move it slightly out of the way of the radiator as to not obstruct air flow. Check your timing. Check your idle mixture. Check for clogged cat.

First off, put the hood back on. It is required for the fan to pull proper air flow through the radiator.

Second, is there coolant boiling out of the overflow tank? Could spell bad coolant seal.

Third, the easiest fix could be the sending unit. I've had a couple crap out and be stuck on like the 10% mark.

 

radiator cleaned? do you mean rodded out?

on the thermostat, the little nipple thing is supposed to let out the air so that coolant will hit the thermostat, heat it up so the thermostat opens. The nipple thing needs to be at the highest point. Punching a hole in a regular thermostat will do the same thing, allow the air to escape so that the coolant can contact the thermostat so that the thermostat knows to open.

I've run without the thermostat without a problem. Lots of mechanics will swear that this is just aweful.

 

Rx-7's have a bypass in the water pump hosuing. When the thermostat opens, it closes the bypass. Running without a thermostat is not suggested. The RX-7 race car guys that run without a thermostat have to plug the bypass.

 

First off - running without a hood shouldn't hurt things, but it won't help things, either. In front of the radiator there's a header panel which MUST be present so that the air coming in the front doesn't divert around the radiator at speed, so I'd recommend that the header panel be in place at all times. It won't affect anything at idle speeds (car not moving), as the mechanical fan clutch will pull air through the radiator as needed.

On that, the fan shroud on the backside of the radiator MUST be in place for the mechanical fan and clutch to operate correctly at idle speeds. If you're running without a fan shroud - there's your problem The Fan Clutch mechanism uses a bi-metal strip to increase or decrease friction on a metal clutch mechanism to either allow the fan blades to slip a bit or lock tightly to the water pump shaft - which is what makes the fan speed variable, and based on engine temperature. Sure, you could bolt the fan directly to the water pump with no slip at all, but it would sound like an airplane running at freeway speeds. In those conditions, the clutch allows the fan blades to slip, as most of the cooling air is being forced into the front - not pulled from the back side.

Also, the question above regarding 'rodding-out' your radiator means an internal cleaning. This is done by unsoldering the top tank from the radiator and then physically running a brass rod through every water passage port to shove all the crap out the bottom. This removes debris, scale, and any dents which would impede water flow. If you have a hand-held laser temperature gauge, you can point it at various locations on the front of the radiator and see if you have any hot-spots, which would indicate flow constrictions in the core. If you only cleaned the dead bugs off the outside - you didn't do everything to be sure it flows air and coolant as efficiently as possible.

New things to check:
1) Belt tension - the water pump is driven by belt from the eccentric shaft, and a slipping belt from spilled coolant or a leaky oil metering pump will cause the belt to slip which will kill water pump velocity and fan clutch speed - leading to overheating. Check the tension of the belts running over the water pump pulley and be sure they're uniform and tight. You should not be able to rotate the water pump pulley by hand.

2) Fan Clutch - sometimes the mechanical fan clutch will go out, resulting in a fan which slips all the time, instead of only when not needed. To test this, the next time your gauge is showing an 'overheat' condition, turn off the engine, open the hood and give the fan blades a spin - they should NOT spin easily by hand. In other words, when the engine is hot - the fan clutch should not slip, allowing maximum air to flow due to the fan blades pulling air through the radiator. If it spins freely - that's bad. Alternately, when the engine is dead cold - first thing in the morning - grab the fan blade assembly and give it a spin, it should spin freely, because it's freewheeling as the radiator isn't hot enough to need the fan sucking air, yet.

3) Coolant Mix - these being aluminum and iron engine cores, don't run straight water! You should be running a 50/50 mix of distilled water and antifreeze coolant. Even if you live in a desert like I do, you'll need antifreeze added because it raises the boiling point of water, along with providing a lubricant for the water pump assembly as it runs. Additionally, the coolant mixture ensures you won't have a galvanic reaction inside the engine assembly which can cause internal corrosion.

4) Don't rule out the Oil Cooler as a culprit - The rotary engine derives 1/3 cooling from the radiator and associated stuff, 1/3 from adiabatic cooling (aka thermal heat transfer to the air surrounding it, or radiant heat being transferred to other parts nearby), and the remaining 1/3 due to oil system circulation and cooling. Depending on the year and engine, 12a's have a Beehive cooler with the oil filter at the top, and if the oil system isn't flowing well through the cooler, it will overheat - because you've removed 1/3 of the cooling capacity. Once you get 2 of these systems malfunctioning (adiabatic cooling happens no matter what!), then you're in trouble and the car will overheat quickly.

In the end, get it sorted out, as troubleshooting overheat problems is still far easier than paying for a new engine! Take care, and good luck,

 

alright running an e fan w/o the fan shroud. I'll check the bolt tensions and put the shroud back on. Does anyone know what the heat things in front of the radiator look like so I can make sure I have it? Lastly, been considering switching to an external oil cooler. Anyway to acquire the platform that sits on the 3rd iron that the oil filter screws into? I.e. To delete the oil cooler? I took these pics from an sa22 I'm looking at with my gf as a project for her, these in/out ports look correct?

Also no AC,
-heater core is still in and works(:

 

dont know about the oil cooler but it sounds like you may have air trapped in the lines somewhere........is there a correct way to bleed the cooling system? sorry Im a noob too.

 

maybe this...

https://www.rx7club.com/1st-generati...ating-1046358/

 

Have we tested the radiator cap. I have had many vehicles come through the shop with over heating problems and it ends up the cap isn't holding pressure. Check it since it's a $5 fix.

 

+1 on the cap. I had the same problem with my old se and it was the cap. Also, I run a tiny efan with no shroud and my car runs cool. I wouldnt worry about the shroud.

 

I'll try to grab another cap today if I can, I can't find the cfm the fan moves.... Like it doesn't say it in any stats on the web. It's a pretty good size and pulls a lot through.
I'll also look into getting air out of the oil lines I guess, I'll report back if I find anything. The help is much appreciated (:

 

What tread type are those oil lines I have to replace mine but I can't find any already made. Local parts store was going to make some but we don't what tread and size they are?

 

I bought the an fittings from racing beat and 10an nylon line. The nylon is easy to assemble. I also have a nice digital fan control for sale $55 pm me your number ill send pics.

 

Well started it up today after getting RB's Holley red on and it immediately jumped to 6k, tapped the carb (float stuck) and nothing. Do I need a fpr for this?

 

Get a laser thermometer and check the actual temps. It could very easily be a gauge or sensor problem.

 

Yes, and a gauge to set it with. You need that for any non stock set-up IMO.

 

playing with idle screws, cant get it to start :/
if it's not one thing its another. mikuni 44phh

 

rwatson touched on this. is it really over heating? a redneck check would be to flick a couple of water droplets on the engine with your hand. if it is really over heating, the droplets will immediately evaporate.

one other thing to check is run the engine with the radiator cap off. when it comes up to temperature, the radiator water should rapidly flow. do this in the parking lot, and not while going 120 mph.

 

after replacing EVERYTHING lol i drilled two small holes in my thermostat. still warms up within the same time, but when driving stays noticeably cooler. still getting a little hotter than it should but much cooler than what it was. oh well, runs great now with that and a weber45.

just thought i would update, figure i didnt have anything to loose if i just took a chance and drilled some holes haha

 

Sounds like your T-stat is stuck closed. Drilling holes in it would allow some additional flow which may allow just enough cooling to get you buy. A cheap fix may be to put a new T-stat in the car which you know is working properly. Good luck,

 

if you're using an aftermarket thermostat it is likely that it doesn't fit right, and its probably also bad out of the box, stant is a name brand, but they have no quality

 

Double check your timing for the hell of it.

If its retarded it could be running hotter in general.

 

I'll give this a shot as well.

I suppose I could take mine out, throw in a pot of water on the stove and see if it opens at the correct temp