Hey guys, I've just bought my first Honda (a '91 EF hatch with the D15) a couple days ago, and it being winter here in Alberta, I decided to start out with a 195* thermostat.

When I first picked the car up, the heat was good, warm, but not hot and my buddy who owned an EF before me said the heater in his was mentally retarded in terms of heat production so thats what spurred me to get that kind of heat since I love nothing more than being toasty warm. The temp would maybe get 35% of the way into operating temp then start to dive once the car sat idle.

I changed out the thermostat (after mistakenly removing the upper rad hose fitting from the front of the head thinking it was the t-stat housing ) with no issues, used a new o-ring I guess. Upon refilling the coolant, I popped the 12mm air bleed valve and added coolant 'till it flowed bubble free from the valve, then I tightened the valve and topped up the rad and was on my way. After this the heat was a bit better than before, but still not ******* saggingly hot, so I figured something was up.

So tonight, I popped off the rad cap and revved it up for about 30 mins, letting any coolant that wanted to bubble over, bubble over. Throughout this I saw some small bubbles surfacing. I ran the engine until I felt the lower rad hose get hot (surefire way of knowing the thermostat has opened) then let the car idle, topped up the rad and overflow and went for a test drive.

All I can say now it wow. It's -21*C here right now and I simply could not comfortably drive the car with the switch at anything over "2" it's blisteringly hot.

What I gathered from this process is that the bleed valve is not 100% sure fire for getting all the air out of the system. Also it's worth pointing out that that little jiggle valve on the thermostat always goes up in order to let air bubbles float through.

 

Ya it's pretty nice huh? My ef (90std with sohc zc) has a heater from hell (in a good way.) If I turn it all the way to 'Hot,' it'll get blazing hot. Feels good man. I had to bleed out the bubbles on an incline + idle/little revving sometimes. Probably wasn't the best for you to But what the hell .

 

park the nose higher than the rest of the car and idle it out till the thermo opens and bubbles are gone. hasnt failed me yet

 

Buy a "spill free funnel" set-up and just use it,they only cost about $20 and work great.

 

Reving it to 2000k with no load is not going to hurt anything. Like saying you shouldn't drive for more than 30 mins at 2000rpm haha.