heater valve change .. drain Antifreeze???

[gator]

Hey all !! I am about to change my interior heater control valve so that I can tlk in a lower voice when I drive this winter ... Do I need to drain my Antifreeze????

Thanks ...Bruce

[kenz240z]

Hi Bruce,

When I changed the control valve in my '73 I drained the radiator. Even with the radiator drained, the heater hoses and heater core will still have a bit of coolant in them. Take out the carpeting and padding on the passenger side so coolant doesn't spill on them. Have plenty of rags or a catch can handy, although it's kind of a tight spot to work in.

If you have any kind of fluid pump, you may be able to remove a heater hose on the engine side, snake a smaller tube down the hose into the valve and suck out most of the coolant.

[gator]

crap .. that wasnt the answer I wanted ... it is cold outside !!! I was hopping to rip the old one out and shove the new one in and run back inside to warm up. haha

Thanks for the answer tho ,,..Ü

[gator]

ok .. I am back inside now warming up ... I took the fan motor off .. and it looks like the valve has 2 pipes one it .. in and out ... that are not connected to anything. I think I will assume the lack of heat is from a clogged heater core. I guess someone before me bypassed the valve. Am I seeing this right or am I missing something?

Thanks ..Bruce

[EScanlon]

Draining and /or Changing Anti-Freeze isn't necessary, but it DOES take some preparation.

Get a couple of those rubber corks being used on the more common wine. I've gotten mine from dinner's out, but you might have one or two on hand. Enjoy the party. Be sure to sleep off the effects of getting the wine corks

Remove the Carpet and carpet mats from the passenger foot well area, then lay a thick pile of very absorbent rags under the area where you'll be working.

First remove the control wire at the Valve coming from the HCP. This way you won't be fighting that. Then using either a crescent wrench or a pair of vise grips (or any kind of clamp), pinch the hose(s) near the firewall one by one and remove from the Water Valve. Once removed, insert the rubber cork into the hoses. If you're having trouble you can always return the hose onto the valve for the amount of time necessary to fix the cork so it will work. Once the cork is in, tighten the hose clamp on the hose around the cork. Do the other hose.

Swap out your part and reverse the process.

The key thing here is that you'll be working on your back, (or gut if it's either big or small enough, you intermediate types like myself....give up) and you want to minimize the amount of liquid that drops (and it WILL) is minimized. Otherwise you'll be contributing to the possibility or the problem of rust.

Alternatively, disconnect the control wire from the valve and disconnect the hoses at the engine, then feed them through the firewall hose seals (and do be careful as those seals are V E R Y easy to destroy if not new) and be very careful while you contort every which way to avoid turning one of the hoses up-side down and get anti-freeze splashed all over the place. ( By the way, has anyone mentioned the dangers of pets sniffing and licking anti-freeze spills? It smells good and tastes good ... for a poison. It WILL kill in very small amounts.)

OR

You can drain the system as Ken says. Be aware that it isn't unusual for water to be caught in the Heater Core (open your heat valve all the way while draining).

But in either case you'll be minimizing the spill.

E¢

[LanceM]

ok .. I am back inside now warming up ... I took the fan motor off .. and it looks like the valve has 2 pipes one it .. in and out ... that are not connected to anything. I think I will assume the lack of heat is from a clogged heater core. I guess someone before me bypassed the valve. Am I seeing this right or am I missing something?

Thanks ..Bruce

Yep, bypassed. You may have air in the system which has collected in the heater core, happens to my wife's Olds. Open up the radiator cap and run the engine up to temp to open the thermostat, watch the fluid in the radiator for bubbles, and have the heat on. Once the air is out you should have heat, if not then it's probably blocked.

[EScanlon]

...that are not connected to anything...a clogged heater core. ..

But there are hoses going to the heater core from the engine?

If so, then probably a combination of clogged core and possibly a shot thermostat valve. If you're connected directly to the engine and still not getting enough heat is the engine getting warm? Warm enough that it's heating the water to where it would heat the car?

If there are no hoses connected from engine to heater core, then the problem is that there is no water going to the core. (Maybe this was a prior "fix" for a leaky Water Valve.)

Lastly, if the engine is hooked up directly to the core, then check to make sure that one of the hoses has a break in it with a nipple inserted joining both halves of the hose. Otherwise, you'll have to come up with a section of hose for you to be able to insert your new control valve.

[gator]

Thanks guys .. I have changed my thermostat first with a lordco one that ran too hot and then bought one from Nissan that I think runns too cold. I have properly purged the system on air when I changed the thermos .. so I am up for a new heater core. This funny thing is that I bought a new heater valve cause the old one is stuck and thought that was the problem. I guess you never know for sure till you rip into it hey?

[EScanlon]

Save yourself some work.

Disconnect enough hoses to allow the heater core to drain into a pan or bucket. Once the stream of coolant has reduced to single drops, use your air blower to blow into one of the hoses while catching the other end in a balled up rag. The rag will absorb the moisture that is still in the core, but more importantly you'll be able to ~feel~ the strength of the return air.

The less you can feel air the more likely that the core is plugged. Now be careful and don't use 90 psi right off the bat, start off with 10-20psi, that will give you the best feel and indication as to whether a higher pressure would help or not.

E¢

[Marty Rogan]

Just another tip that could save you some bucks. Take your heater core to a radiator shop. They will usually check it out for you for a nominal fee. In my case, they did it for free. I ended up not needing a heater core after all, as it was just the bad valve theat the PO bypassed. Just go back to them when you need real work done.

Good luck.

Marty

[mlc240z]

listen to Marty.

when i tore mine down, i had a leaky core and went to a local rad shop. for $35 they boiled it out, soldered the leak, tested to 20 lbs of pressure, and even repainted it!!

very reasonable, good work and with the pressure check i gained piece of mind.

[sblake01]

When I did mine I also had the heater core redone. I tried to buy a new one but, at least in my research, new 280Z heater cores are NLA.