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Discussion Starter #1
So the heater in my 68 doesn't seem to get very hot. Is this normal for these cars? I've replaced the heater control valve and it is clear there is hot coolant running through it and to the heater core. My blower motor runs well and puts out a lot of air but it is always lukewarm at best. Short of tearing apart the heater box and taking out the core, are there any other typical things to check before I embark on that endeavor?
 

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It’s most likely your core. My 66 did the same. Rebuilt the heater box and now it puts out a LOT of heat.

Allen
 

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Discussion Starter #4
It’s most likely your core. My 66 did the same. Rebuilt the heater box and now it puts out a LOT of heat.

Allen
Thanks for the tip--did you find your seals worn out and rebuilt the box? I'm thinking if I am going to go through the hassle, I may as well replace the heater core.

You could try disconnecting the hoses, then back flushing the core with a garden hose.
That's a good idea, I was thinking maybe it's clogged and not getting enough flow. Will give that a try when I get a chance.
 

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The rebuild was an afternoon thing. Redid the whole box. Now I’ll never have to do it again. So I think even if you try flushing first, you still may end up needing to redo the heater box. So my recommendation would be just to rebuild and be done.
 

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What engine thermostat are you using? The cars originally had a 190 to 195 I believe. I run a 180 in the deep south. I once tried a 160 and it messed up my heat and the engine was never happy.
 

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Discussion Starter #7
What engine thermostat are you using? The cars originally had a 190 to 195 I believe. I run a 180 in the deep south. I once tried a 160 and it messed up my heat and the engine was never happy.
I have no idea what's in it right now. I'll have a look over the weekend and see if I can figure it out. Are there any tell tale markings to figure out which themostat I have? I do notice my engine temp never reads past about 1/3 of the temp gauge.
 

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The gauges are basically design for a normal range but don't actually indicate temperature, not terribly consistent one to another. You'd hafta take the Tstat out and see if it's marked, possibly even submerge it in water (but don't let it sit directly on the bottom of a pot) brought nearly to a boil and you can use a candy thermometer or another good instrument like infrared or laser to measure the temp at which it opens. Buy a quality Robertshaw thermostat and be confident.
 

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Discussion Starter #9
The gauges are basically design for a normal range but don't actually indicate temperature, not terribly consistent one to another. You'd hafta take the Tstat out and see if it's marked, possibly even submerge it in water (but don't let it sit directly on the bottom of a pot) brought nearly to a boil and you can use a candy thermometer or another good instrument like infrared or laser to measure the temp at which it opens. Buy a quality Robertshaw thermostat and be confident.
What I'll probably do is just replace the thermostat anyway when i flush my system out to clean it...lots of gunk in there right now just looking into the radiator fill neck.
 

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Drain it all and flush with water until clean water is all you see then drain that. Fill the entire system with white distilled vinegar, run it until operating temp, then let it sit overnight. Drain all that and flush everything with clear water until that's all you have again. You may want to use a panty-hose leg as a filter on the upper hose after the Tstat to protect the radiator as YOU WON'T BELIEVE the stuff that comes out of the block, and be prepared to empty that multiple times. Maybe even another panty hose filter between the radiator and bottom hose to keep what's in the radiator from going into the engine, have it flushed professionally, or just replace it. There are lots of crannies for stuff to hang in there. When it is all completely clean, drain all the water including in the block, and refill the system with 50/50 or 60/40 coolant/distilled water.
 

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i had this issue for years and no one was able to figure it out.
the car was always luke warm

turns out a vac hose under the dash was snagging on the slider so it was never reaching its full travel

tie wrapped it it up and now car is hot as hot can be

so check behind the ventilation cluster
 

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Discussion Starter #12
Drain it all and flush with water until clean water is all you see then drain that. Fill the entire system with white distilled vinegar, run it until operating temp, then let it sit overnight. Drain all that and flush everything with clear water until that's all you have again. You may want to use a panty-hose leg as a filter on the upper hose after the Tstat to protect the radiator as YOU WON'T BELIEVE the stuff that comes out of the block, and be prepared to empty that multiple times. Maybe even another panty hose filter between the radiator and bottom hose to keep what's in the radiator from going into the engine, have it flushed professionally, or just replace it. There are lots of crannies for stuff to hang in there. When it is all completely clean, drain all the water including in the block, and refill the system with 50/50 or 60/40 coolant/distilled water.
That's quite involved! Maybe more of a summer time project...does vinegar freeze like water does? There's definitely floating gunk in my radiator already, mostly brown stuff mixed into the green coolant. Thanks for the tips, I think I'll start with flushing the core and seeing if it is clogged. My experience with this car so far is don't fix it if it ain't broke...I swear every time I touch something that was fine, something else goes wrong.

i had this issue for years and no one was able to figure it out.
the car was always luke warm

turns out a vac hose under the dash was snagging on the slider so it was never reaching its full travel

tie wrapped it it up and now car is hot as hot can be

so check behind the ventilation cluster
I had a similar thought where I wondered if the vacuum to the heater control valve was strong enough to pull the valve open all the way. I will have a look under the dash! Thank you for the tip.
 

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There will be some warm days you could do the flush. But for whatever you can see in your radiator, you can bet there is 1000 times that much crap you can't see in your little heater core, the block, and is abrasive to your water pump impeller and seals. Good time to inspect or replace hoses and clamps, too. I did mine this last January after discovering a leak in my radiator and seeing all the crap in it.
 

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Discussion Starter #14
There will be some warm days you could do the flush. But for whatever you can see in your radiator, you can bet there is 1000 times that much crap you can't see in your little heater core, the block, and is abrasive to your water pump impeller and seals. Good time to inspect or replace hoses and clamps, too. I did mine this last January after discovering a leak in my radiator and seeing all the crap in it.
I hear you on that! Is this as simple as hooking up a water hose and pressurizing the system and letting a hose on the other end drain it all out? What about those "radiator flush" products everyone seems to peddle at the auto parts store--snake oil?
 

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...does vinegar freeze like water does?
Vinegar removes rust. It's used to remove rust from the water passages in the block, not as an anti freeze. Leave it in for a day as noted.
 

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I tried the store-bought stuff when I was a kid and it didn't do much. When I learned about the cheap vinegar, I was AMAZED. You should drain the radiator at the petcock, drain the block at the lower hose and the lower block plugs. I put a garden hose on my heater hose end and against the nipple on the intake to flush from the top down, and flush from the block plugs up, to be sure I loosen as much gunk as possible, drain everything from as many points as possible. When you can't get anything else out with just water, drain it all and fill it with the white vinegar. Let it run until it gets in normal operating temp, let it sit 24 hours, drain all that, and keep flushing with water and dumping your filter until you get no more crap. Drain one last time and fill with the good stuff. That will last for years.
 

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So, what do you folks do with the water flushed out of the engine / radiator? Just let it go down the sewer? IIRC this is considered hazardous waste (heavy metal contamination).

Hint: don't do the flush on your concrete driveway unless you want impossible to remove rust stains on the driveway.

Also, since no one has mentioned this yet, as an alternative to the panty hose filter, you might want to look at the Tefba filter.
 

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Discussion Starter #18
Vinegar removes rust. It's used to remove rust from the water passages in the block, not as an anti freeze. Leave it in for a day as noted.
I tried the store-bought stuff when I was a kid and it didn't do much. When I learned about the cheap vinegar, I was AMAZED. You should drain the radiator at the petcock, drain the block at the lower hose and the lower block plugs. I put a garden hose on my heater hose end and against the nipple on the intake to flush from the top down, and flush from the block plugs up, to be sure I loosen as much gunk as possible, drain everything from as many points as possible. When you can't get anything else out with just water, drain it all and fill it with the white vinegar. Let it run until it gets in normal operating temp, let it sit 24 hours, drain all that, and keep flushing with water and dumping your filter until you get no more crap. Drain one last time and fill with the good stuff. That will last for years.
The temps here are getting into freezing so I'm not sure I should leave any vinegar in the system overnight...maybe a spring project then.

So, what do you folks do with the water flushed out of the engine / radiator? Just let it go down the sewer? IIRC this is considered hazardous waste (heavy metal contamination).

Hint: don't do the flush on your concrete driveway unless you want impossible to remove rust stains on the driveway.

Also, since no one has mentioned this yet, as an alternative to the panty hose filter, you might want to look at the Tefba filter.
My local auto parts and shops will usually take coolant to dispose of. I don't think water with some metal in it is that hazardous (assuming it doesn't have tons of antifreeze in it)?

(Also re: Tefba...$75 for a mesh screen inside a plastic tube? I am in the wrong business...)
 

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I take old antifreeze to a friend's shop or a nearby oil change place. Old oil goes there or to local parts place.
 
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