frastydragon

2004 6 speed 149k miles currently. Previous owner said he replaced the engine with a built street ported one 30k ago by a "rotary specialist". It gets like 11 mpg. I replaced all the hoses and replaced the thermostat(170 degrees F one). Both fans do work now but previously one of the connectors was broken before and i had to tape and glue it in place.

So my current problem is that it over heats at idle or coasting. If I'm coasting at whatever mph the temp will climb and it will over heat but when I revve or go past 4k rpm the engine immediately starts cooling down. The temp drops from lets say 108 degrees C to 95 degrees C in less than a minute. I have obd2 thing to watch my temps. If I'm suck at a red idling and the temp starts climbing I turn my car off and the fans would still run cooling the coolant in the radiator. Then I would have to start the car when the light turns green and the temp would also rapidly drop a few degrees(3-8) depending on how long the light was. Driving is fine but the moment I come to a stop the temp would start rising.


Has the stock water pump fin broke before? I will be getting one of those mazmart water pumps tomorrow currently doing a coolant flush with distilled water.
I think the oem fins got broken and/or something is blocking the passage or theres a blockage somewhere in the radiator?
I also think my coolant seals may be compromised. I used a block tester and the liquid turned green but not yellow. Which means there was traces exhaust gases but not alot.
Should I get aftermarket rad and fans? I think the current one are the plastic koyo radiator and there was a sticker with 2014 on it. coolant tank is new looking no cracks and new pressure cap.

Cold start is hard sometimes I would have to crank it for a few mins. It would sputter kinda and I figured if I lightly press the pedal it would help start it but if I push too much it would just go back to turning over and no sputters. Starter cranks at 300-350. New plugs coils and wires. Sometimes there is also some white smoke(coolant seal?) at cold startup(Hot starts are fine) I only smell gas and no coolant. I still have stock cat and will be getting a cat delete soon cause premixing. No air pump. The car had sat for a few months before hand. There was oil in the airbox and accordion tube when I inspected it and cleaned it. Ess is clean af and did the 20 pedal thing.

Danhig

a previous owner could tell me felix wankel rebuilt the engine himself, without receipts or paperwork I wouldn't trust a thing someone says about a car that I couldn't see with my own eyes and feel with my own hands.

if your temp gauge has gone even a LITTLE off center, your engine is most likely damaged. continuing to run it in this state is just making things worse, most likely cooking the coolant seals even further and degrading usable parts in a rebuild which is most likely required. I don't know anything about the stock water pump having issues, but if you're getting the remedy pump it seems like they **** out after about a year of use. personally I'd rather have the cavitation issues of the stock pump than having a water pump that kills itself so quickly, especially in a car that is so reliant on cooling.

the only way there would be an issue with the radiator is if it were damaged by debris (majority of fins bent), cracked, or had been sitting for years and electrolysis got it and ate away at the inner core.