'02 Civic Si - No heat at idle.
 

I've got no heat at idle but good heat at revs. Rad is full. Any help would be appreciated.

Re: '02 Civic Si - No heat at idle.
 

USA Si, 2.0 engine?

Check that the lever on the water valve moves about 90 degrees as the HVAC system is switched from full cold to full heat.

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Heater core probably has an air lock (air bubble) in it.

How would that have happened?
Was the cooling system serviced recently or since the last time it did have good heat?

Re: '02 Civic Si - No heat at idle.
 

Don't know when the cooling system last serviced. What is the fix if air locked? Bought the car in Oct. I call it the nightmare before x-mas. So far $2500.00 in parts.

Re: '02 Civic Si - No heat at idle.
 

Water valve moves with no problem.

Re: '02 Civic Si - No heat at idle.
 

Two words: "Prepurchase Inspection."

For what, pray tell? What has been done to it?


Get the air bubble burped out. There's a variety of ways to do it, and sometimes you have to study the system in order to figure out which way might work best. Each case can be different.

Sometimes one can leave the radiator cap off and run the engine through a few fan cycles, I have a 'funnel-fill' that I attach to the radiator neck and keep half full, this aids in keeping the system completely full and keeps it from making a huge mess while running the engine.

sometimes one can raise the front of the car really high to get it to burp,

sometimes one can manually manipulate the hoses at their high points to "push" trapped air out

Sometimes you have to open up the hoses to let trapped air out

I've even managed to burp some just by driving in 1st and 2nd gear up to redline a few times.




There's also the possibility that the heater core is plugged up with junk.

Re: '02 Civic Si - No heat at idle.
 

Struts & shocks (Bilstein), steering rack (can you say ouch) air/fuel ratio and oxygen sensors. Trusted that the dealer wouldn't falsify the inspection. World's worst Honda dealer.

Re: '02 Civic Si - No heat at idle.
 

An electric power steering rack? Those have been damn reliable here. What was wrong with it?

Doesn't sound like any of those should necessitate draining the coolant....maybe...unless someone took hoses off at the heater area to get the rack out..


Sadly, sometimes "inspection" means "the average sucker will not notice anything wrong".... it isn't like a military aircraft inspection....Sometimes it's more so the sales department has some idea of what all a prospective buyer might find wrong with the car and try to bargain with.

Re: '02 Civic Si - No heat at idle.
 

Rack has play at center and does not return to center. Great for driving in circles with no hands. Don't know what was wrong with the original rack. Car has a reman/rebuilt in it. Can't find a reman anywhere so had to buy from Honda.

Re: '02 Civic Si - No heat at idle.
 

Cooling system seems to have new coolant in it. Probably got done when the rack was changed. Does anyone have a more vehicle specific method for "burping" the system?
It got cold outside.

Re: '02 Civic Si - No heat at idle.
 

Bled the cooling system by putting the front end 2' up in the air. Let it idle for 45 min. and it had heat. That lasted til I put it back on the ground.
Need more ideas please.

Re: '02 Civic Si - No heat at idle.
 

Man, I can't see what you have to work with. Combinations of the previously mentioned stuff may be needed

Just idling doesn't always work, higher RPM causes the water pump to make more pressure in the system, hope is to purge any air on through.

I use this all the time. I put the funnel-fill funnel in the neck of the radiator and fill it up to half full, this keeps the radiator full and helps prevent messes. It also raises the static fluid pressure which makes purging by hose removal easier.

http://revlimiter.net/blog/wp-conten...3/DSC_1249.jpg
http://i451.photobucket.com/albums/q...Y/IMG_2126.jpg





If the heater core hoses have low spots as to keep air trapped in the core, they may have to be opened up to let trapped air out

Raise the front end up high again and hold the RPM at 3000 for maybe 30 seconds then let it idle.

Put the heater and fan on full blast.

See if the vent temperature cools off at idle. If it cools off at idle, there's still air trapped.
Try again, this time holding RPM at 4000 or 5000.

(I did an Integra engine swap on a 93 Civic once, that heater trapped air and I ended up getting it purged by driving, accelerating the engine to its 8000 RPM redline a few times.)



Oh yeah, make sure the oil is full before you do this.

Don't forget the possibility of other problems, like a clogged core.

Re: '02 Civic Si - No heat at idle.
 

i think this is the most likely cause here,

the coolant isnt flowing through the core fast enough, so your blower fan is cooling it down causing the air temp to drop

Re: '02 Civic Si - No heat at idle.
 

Started the car yesterday and no heat at idle. took off the rad cap to check for flow and also filled the overflow to max, got warm air coming out of the vents with the cap off. This is without raising the front of the car. Today I went out and started it up and had heat after about 10 min. at idle with the cap on. This is confusing the crap out of me. The rest of the suspension and steering parts should be here Monday. Any thoughts on changing the rack in an EP3?

Re: '02 Civic Si - No heat at idle.
 

My guess would be that something is causing air intro into system, ie overheats, gaskets etc. Other than that take the hoses off and see if you can flush through the core with a garden hose. A clogged core is unlikely if you know what's been there, ie only A/F and distilled or a mix. Plain water such as is used often when there is known leaks is highly corrosive and deposits junk everywhere, like heater cores. As for a check while running, put your hand on each hose. They should be roughly the same temp. If not either the water control valve as ezone said is suspect or a clog is noted. An air lock acts just like a clog. On an engine with a big water pump an air lock is unlikely, but these things have babies...