Hello all! I was wondering if anyone had any idea or suggestions for my cooling system. I have a problem with overheating. Heater doesn't get hot sometimes, the radiator fan doesn't turn on sometimes when the car temp raises. Once the fans turn on the temps go down. Bottom coolant hose is cold. Also, one time I parked after driving, coolant came out of the reservoir and was a little high past full. After a day of not driving, it went back down to normal fill line in the reservoir.

I thought there was just air bubbles in the system or a bad thermostat. So yesterday, I had my mechanic replace my thermostat and flush the coolant. I also had them do a leak down test, and they found nothing. When they started filling the coolant back, no bubbles was coming up. After awhile of the car being on and waiting to see if bubbles come up, bubbles started coming up in the coolant. It would just be small air bubbles though every once in a blue moon or few minutes. Long intervals in between the small bubbles (No huge bubbles would ever come up). The fans also started working normally again and coming on consistently. My heater also started working normally. The cars temp also never went past normal during this process as well, so no overheating. However, I was worried about how no matter how long we waited, small air bubbles would still come up every few minutes. Would this be a sign of a small head gasket leak? If anyone has any ideas or suggestions, please let me know.

Thank you!

 

I took almost 20 minutes of idling to remove all the bubbles using the Lisle spill-free funnel system. My son's CR-V took over 30 minutes to bleed all the bubbles. You'll know, the car's heater will work quickly once the air is out of the system.

These car's cooling systems must have all kinds of nooks and crannies for bubbles to hide.

 

Were you using a coolant bleeding funnel?

Hopefully you used a Honda genuine thermostat?

 

Yeah, the heater started working again when we were burping the system. Very small bubbles would come up every few minutes or so. We had the car idling for about 20-30 minutes. I can buy the funnel system and try again. Maybe it just needed more time.

 

Yeah we used a coolant bleeding funnel.

I also used a Honda genuine thermostat. Got it straight from the dealership lol.

 

If heater isn't burn your fingers hot, there is still air. Air is ticking time bomb, bc it will overheat, typically all at once without warning. Often without even driving it hard. Can easily destroy engine.

It does take a looooong time to bleed this system. You also need to crack open front bleeder till it spouts like a fountain. Kinda looks like an overgrown brake bleeder, near front corner of valve cover, drivers side (on LHD cars).

At first it'll whistle air, then be ready to close it as soon as coolant spews.

The Lisle funnel, with front of car elevated, occasional revs, heater on, and time idling, along w bleeder, should get any remaining air.

 

Wear a heat protection glove (I like the Makita workshop ones) and squeeze the upper return hose while at idle. It helps to free up trapped bubbles at the top of the system.


The long hose is on the right of the photo.

 

It did overheat when I drove on the highway one time, but I pulled over right away. It also goes up like 2-3 bars at idle but goes down right away once it gets driven. Ever since we did the thermostat and bleed, it hasn't overheated at idle and the heater is hot again. Just worried about those small bubbles that kept coming up every few minutes. I feel like it would over heat again in time like you said.

I will definitely try again and do what you suggested.

 

Yeah, I will try again bleeding the system at some point. Hoping it's because we didn't give it enough time. Will definitely try what everyone suggested.

 

Read this thread thoroughly and follow the instructions provided. Billman is a longtime S2K mechanic and guru. His procedures will never disappoint!

https://www.s2ki.com/forums/s2000-un...bleed-1067218/