2004 6 speed 149k miles. engine was supposedly replaced 30k ago with a rebuilt street ported engine by a "rotary specialist". I get like 11 mpg. new coils wires and plugs. Thermostat works and right passenger fan works for certain.

It will overheat when idling at a red light or stopped. I have a ob2 plugin so i watch the temps. The temp will go back down instantly the moment I start moving again. It will also overheat when im coasting even at highway speeds but when i put it back in gear still be moving at the same speed it will immediately cool down again from like 105c to 95c. So is my water pump fins broken? or do i have a blockage somewhere or are my fans broken? I did block test it but the liquid only turned green not yellow.

Also i think my coolant seals may be going out. hard cold starts and sometimes misfire + white smoke but not all the time. hot starts are fine. starter spins at 300ish. in the morning i might have to crank(not constantly cranking it) it for 10 seconds to min or so before it starts sputtering and then itll start. Air pump deleted and will be putting a ebay mid pipe on cause im premixing.

I already wrote a post but i guess it didnt post?

 

Are the foam around the radiator and the undertray still there?
105c is hot, but not too bad.
And 11mpg is really bad, you might have a problem with that.
as for coolant seal, do a exhaust gas test and send a sample of your oil to black stone lab to be sure.

 

That last point about hard cold starts and smoke definitely point to seals. Have you had a compression test?

What about the other rad fan? You said one works, need both.

 

Street port on this engine makes the car more difficult to run at low RPM. It's generally a mod only used for RX8's that are exclusively track cars because they will always be run at high RPM. This alone would explain your poor gas milage. The overheating though? 95-105C is not overheating in this car. Anything past 110C I would worry. If it passed the block test your coolant seals should be fine. I'd wager its either an issue with the radiator or cooling fans. You'll definitely need a compression test done as it shouldn't have to crank more than a second or two to start up.

 

300rpms is pretty damn good for the starter. I wonder if that is masking a hot start issue. If it passed the block test, that is good news. Do a comp test next.

I am dealing with cooling issues as well both stationary and moving. I found my rt side fan not working plus all the foam is gone and condenser is really dirty. In your case it could be a combination of factors, but I would rule out water performance because you are good moving. You have an air issue. The fans when working on high are pretty loud. Make sure they are both working at all speeds. Then check the condenser and radiator are clear and clean. After that the radiator needs to be sealed to the plastic panels on the sides and bottom. Sticky foam can be used.

 

It does go past 110c sometimes. I just watch the temp at red lights and turn it off once it goes past 108

 

I havent done a compression test yet and what does the foam look like.

 

I have seen people use couch foam. Door sealing weather strip type foam may work. You want something that is higher density, can be glued, thick enough to fill in the gaps but soft enough to conform to the surfaces.

My car seems to be missing the foam, so I have no idea what the original looked like.

 

I have gap filler the spray can stuff. maybe that will work?
So i checked and there is no foam. Also just now i let my temp rise and at red light the temp sits around 114c but when i got home at let it idle in my drive way for 10 mins the temp was around 106 - 107.
Both the fans do work i did the relay jumper test and they both came on. Idk whats up with it.
Also since trailing plugs start the car do you think that may be a reason for hard start if they were messed up? cause right after cold start for a min there is no power when you press the gas but after it runs for a bit it is all good.

 

First of all please stop making your car overheat by not going over 104c.
Secondly, gap filler works, anything that rigid and blocks air flow will work. I used gap filler + swimming pool sticks (the toy).
the fan will slow down over age, and also consider vent your hood.

 

Leading plugs start the car.
It still sounds like leaking seals. Was there evidence of coolant on the plugs? Is the coolant level going down at all?

 

Are you sure?

I had thought it was the trailing but TBH wasn't positive.

 

I am loosing coolant cause it’s flowing out thru the overflow and making a mess in my engine bay. Painted my engine green. I will check my plugs tomorrow and update y’all. Exhaust is Smokey but mostly smells like gas not sweet. Smells acrid? Acidic? Idk harsh smell. But mostly unburnt gas. Also got a mid pipe now so maybe why it smells terrible 😂 smoke not thick white more thin

 

I’ve driven enough piston engines with a blown head gasket to never forgot that sweet smell of antifreeze passing thru the combustion chamber 😂

When I took off my catalytic I noticed the exhaust was smokey.

Not like a James Bond smoke screen but you could notice it.

 

Is the rad cap actually holding pressure? Does the coolant bubble and boil when at operating temp ( don't touch the cap while it's hot, remove while the car is cold and warm it up to operating from there if you have to).

Everything you're saying so far fits bad seals, except block test not detecting exhaust gas.

 

Blowing coolant out of the overflow is not a good sign. It’s possible it’s as simple as a radiator cap. But it is a sign combustion is being pushed into the coolant system. Piston cars the likley source is a head gasket. Rotary it is coolant seals.

Another good test is a coolant pressure test. Make sure the system is still sealed.

 

Yea new radiator cap and thermostat. Coolant tank is newish no cracks or holes. Its probably my coolant seals are going out. is it possible to only replace seals and not everything else?
When its at operating temp the coolant doesn't bubble or boil. But when its heated it starts boiling and spitting out of the overflow hose

Tonight I was driving back home. 78 degrees out. I was going a constant 55 mph. The temp would go from bounce between 212 - 230f. Like the moment it reached 230 it would start cooling down to 212 and when it reaches 212 it would start climbing again until 230 and this would repeat. At a red light it climbs to 235 and stops there but when i got home and idled in my drive way it started to slowly cool down to around 220f

I will do a coolant pressure test soonish.
Also my heater core is either clogged or not getting coolant cause its not hot again. I flushed it out previously. I also need to bleed the system I think.

 

This right here

 

It's possible in the past someone used a radiator repair fluid which always clogs the heater core. You can use radiator sealer liquid like Blue Devil but you must ensure the heater core is blocked from the cycle.

I believe your radiator will need to be replaced at the least. If you can do a block test and make sure there is no exhaust gasses in the cooling system this would be helpful to know. The stock radiator is complete garbage. I've replaced it in every RX8 I've had.

There is unfortunately nothing else that can solve the issue but a rebuild or engine replacement if the issue is a coolant seal leak. Hopefully you have about $5000?? WELCOME TO THE WONDEFUL WORLD OF ROTARIES!!!

 

I see. I think I can bypass the heater core with some hosing and run some radiator sealer and see if that fixes the seals from leaking. I will check tomorrow morning for coolant on plugs.

Did a block test already and it only turned green and not yellow and I looked around online and some people said it turning green meant there are traces of exhaust gas but none current leaking. Radiator was replaced back in 2014? with a koyo one. Thats what the dude told me and there was a sticker on the radiator with x/xx/2014.

I got the car for 1.5k. is it worth getting a new engine or rebuilding it is a better option? Cause it was street ported and i only get 10-11 mpg cause of that lmao.

 

That's still 7 years old and the Koyorad isn't held in particularly high regard around here. This engine does run hot and 100C shouldn't be concerning. I run these cars here 100-105C regularly where I live (hot climate btw) and it's why I run 10W-40 conventional.

This is a very busy little engine and it deserves a solid cooling system to work properly. Between this and the ignition system, these are the critical areas to worry about. Overheating this engine, even once could require a rebuild. That's just the reality.

Do the block test first. Make sure you ensure that there is a coolant seal leak. If this is the case it is catastrophic.

 

Yea I think its been over heated a few times already now maybe? The highest ive seen it was 117c. But on a hot day and idling at a red light it stays around 113-114 which I know is still too hot.

 

Should I add some pusher fans and see if that helps cool it?

 

Do the block test first. That's your main objective right now. If it passes you likely just have a radiator or fan fault or both. If the coolant seals have failed you'll need a new engine. Your best bet at this point would be to sell this car and buy a new RX8 honestly.

 

I did it turned green. Or do you mean to pressure test it.