Aloha everyone. So on my 99 Em1, like many other Ek civics, theirs 2 heater core hoses which extend out from the firewall and the one on the left which has the cable attached to it comes hot when I touch at normal engine temps but the other one to the right of it, stays cold......is my heater core blocked/plugged? I'm wondering also cuz on cold starts, my idle will be normal for a minute and slowly climb and stay at 2k but If I turn off my car, and turn it back on, idle is fine and normal, coolants good, iacv is fine as well, I jus thought the 2 heater core hoses would both be hot......

 

The part with the cable is the valve that controls flow through the heater core.

Does your heater selector move that lever properly or is the lever not moving when you push your heater selector to hot then back to cold?

 

The feed hose comes out of the cylinder head and goes to the valve, connected to the heater core. Basically the water pump moves the fluid from the head into the heater core then back into the cylinder head from the return hose back into the inlet behind the thermostat.

Long story short, with the valve closed no fluid will move either direction into the heater core

 

My civic is a 99 00 Ek so it's the turn style heater **** but ya, it dosent get hot. So I assume the valve is bad?

 

First you have to verify your turn *** moves the cable of the valve.

Until you do that, you don't know a few other things.

I didn't get into any other details until you answer whether or not your hot cold selector adjusts the cable connected to the valve. We need to know that before we can proceed.

 

The cable at the valve which moves the lever should be pulled back when the dial is on hot, and extended for cold. The key has to be on during this test since the mechanism is partly electric.

If that works, the next step would be to make sure the valve is open, then disconnect both heater hoses from the engine and try to flush water through the valve and heater core with a garden hose. If a "stop leak" product has been used in the cooling system it is likely that the core is blocked.

 

It's opposite for my 96-98 manual lever cars. All the way pulled is closed, all the way in is open. I've had to replace a broken cable connector to the blend door

 

 

So I tested the heater ****, with ignition on and the heater valve both opens and closes, I disconnected the heater hoses and back flushed the the heater system, filled the system,cap off,new thermostat, started her up and idle started normal and rose to 2k and stayed their, fan kicked on twice while I had it all the way on heat, but no hot air still. After turning it off and reatarting it, car idles fine. Jus no hot air

 

You need to purge the system of air. Overheating, inconsistent idle speed, and heat from the heater only when you rev up the engine are all classic symptoms of having an air bubble in the top of the engine. The purging procedure is well written up in many places.

If you keep getting air bubbles, the head gasket may be leaking.

 

I'm not getting any hot air from within the cabin, I have a thermometer that I leave in the vent for AC work,etc. Oil is fine with no mix, I thought proper purging of air was to have the cap off. Let the fan cycle 2 times and shut off, top off and then good to go....?

 

It is, with the heater set to max heat so the heater core valve is open, which you stated operates correctly.

You also stated you "back flushed" the heater core. What you did not state is if water passed through the core and came out the opposite hose that water was supplied to. Your statement implies that it did, but to be certain, you should state all your findings and results.

 

Tis true ma fren haha. Wen I back flushed, a lil grimy coolant came out and then fresh water came out ;-)

 

Okay, next thing to check, when you are purging the system with the heat selector on max hot. Once the fan kicks on, feel both heater hoses, are they both hot?

 

I believe that also includes raising the front end of the car so any air bubbles in the system can migrate to the radiator and be removed.

 

Parking on a level surface should be sufficient to make the radiator the highest point. If you have an uphill spot, or want to drive up on ramps, it wouldn't hurt. Definitely don't try it with the car parked facing downhill.

If while you are running the engine with the cap off and you get a constant stream of bubbles, or even coolant gushing out, that gets worse when you rev the engine, it is very likely a leaky head gasket. This is usually the only symptom of a small leak. To see white smoke from the tailpipe or coolant in the oil means there's a much larger leak.

 

I'll check that on my way to work, and I'll again, try to purge the system fellas ;-) I'll keep in touch and again, big mahalos to all of you for chiming in ;-) :-)

 

If both hose are not hot, you are going to have to set the valve to open (max heat setting) and undo the hose going to the head and the opposite hose from the heater core and see if you can back flush the core through the control valve.

You will have to purge the system after that test anyway. If you are not overheating. You might wait to "repurge" until after the valve back flush test.

If you cannot back flush through the valve, the valve is not opening.

If you can back flush through the valve, then the problem is not in the valve or the heater core.

 

The inlet hose with the heater valve is hot but the return remains cold, even after all I've mentioned yesterday/earlier in my posts. Engine temps have remain good and normal,jus no heat and the return hose remains cool. Sounds like my heater core is pooped? The valve does open and close as I verified wen I had the hose of, I watched it open and close.

 

You said water flowed through the core when you put the water hose to it. This would indicate the core is not clogged.

You say you see the valve lever operate which would indicate the valve lever motor works.

You have not opened the valve and tried to flow water through the valve with a water hose.

You do not know if the valve actually opens internally as far as I can tell with your statements and what you have done so far.

 

Was the core able to pass the full flow of a garden hose through it, or just a trickle? To work properly, it needs to be unrestricted. The water pump on the engine doesn't make a lot of pressure.

And I was saying to disconnect the hoses at the engine end so you are flushing / testing the valve and the core together. Did you not do that?

 

I fed water threw both hoses to confirm my suspicious of water flowing through both the inlet and outlet hoses, both flowed water the same as the hose pressure. And yes the valve opens and closes fully ;-)

 

if water flows through the core then does it flow through the hoseed back to the engine, if you get good flow through the core with the valve open then is stands to reason that BOTH pipes would get hot unless its either eadiated heat to the inlet or theres a blockage in the outlet, put the hose onto the hose going into the engine, I have a feeling it will not be flowing. The core has flow through it so I would look elsewhere but it certainly looks like a blockage on the outlet heater pipe going back to the engine

 

What everyone is saying to you is you needed to test the flow with the water hose to see if you had full flow at these points of the coolant system circled in red:



If you have good flow out of these tubes when you put the water hose solidly into one of them, then the blockage has to be in one of the metal tubes or just inside the head (unlikley) on the front metal tube that is directly in the head.

More than likely, I suspect mk378 hit the nail on the head with the partially clogged heater core that restricts too much for the water pump to pump through.

 

Burp the cooling system. You most likely have air in the lines.