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I just replaced the radiator and water pump, and now there's coolant smelling missed blowing from the vents. Left a misty film on the inside of the windshield. What are the odds that this is NOT an issue with the heater core? I have no idea whether or not this has been replaced when the previous owner was doing restoration work.
I have a ball valve plumbing shut off on the heater supply hose for summer driving. So I'm considering bypassing the heater core to see if that fixes the problem. In the event that I do decide to tackle the core itself, does anyone know if this heater core from AutoZone is compatible? I've seen other threads that say the aluminum ones don't fit properly.
My bet zero.
You need 2 shut offs to seal heater core.
good luck..whatever you choose plenty of threads and caution to pressure check after tube alignment.
Diy doable but tedious and tight. I don’t know about your year
My bet zero.
You need 2 shut offs to seal heater core.
good luck..whatever you choose plenty of threads and caution to pressure check after tube alignment.
Diy doable but tedious and tight. I don’t know about your year
Thanks for the quick reply!
1972 coupe 350 manuel with A/C.
I have the supply side shut off just to prevent flow through heater core in the summertime. Other post have suggested connecting the supply and return lines together to bypass the heater core. That's what I'm thinking about doing as a temporary fix, and check to verify that this is the issue. I'm thinking I may be able do this without having to completely drain the system.
I have no issues with my competency getting job done.
My bet zero.
You need 2 shut offs to seal heater core.
Why 2? When the General built these cars new way back when their engineers decided a single heater control valve was more than sufficient. And I don't want to hear the tired old line "they were being cheap".
No hot coolant is flowing to the heater core.
The outlets look right for an A/C car. I'd go for it if you have a way to pressure test it to 20lbs (12-15# are what our cars operate with).
BTW, I think it's totally plausible that your recent work made the weakness in the heater core reveal itself. The higher flow of the new parts put stress on the Hcore.
FYI:
72 w/A/C the heater core comes out from the interior/passenger compartment.
You'll be removing the passenger side, the entire center cluster, along with all the A/C duct work in order to access the core.
A little searching on the replacement on this forum will give you all the details.
Why 2? When the General built these cars new way back when their engineers decided a single heater control valve was more than sufficient. And I don't want to hear the tired old line "they were being cheap".
No hot coolant is flowing to the heater core.
Lots of things that were sufficient when the car was new, turned out to be insufficient when these cars reach 10 times the expected service life.
Whether hot or cold, that coolant is still at 15 psi, and will leak out of a leaky heater coil. Unless you block the heater loop completely, via plugs, or two valves.
Agree with above; pressure test. Also, heater cores usually leak onto the passenger footwell. Sometimes tell-tale stains of a leak can be seen on the front end of the HC by looking up at it from under the car. First aluminum replacement didn’t fit. If I recall correctly, I found a well-fitting copper one on rockauto; posting a picture of the warranty. Found an excellent step-by-step for HC replacement somewhere on this forum. Definite while-your-at-its are 1)cleaning out the AC evaporator; compressed air to the downstream side, vacuum on the upstream side 2) optimizing the firewall insulation 3) under-dash rattles.
Lots of things that were sufficient when the car was new, turned out to be insufficient when these cars reach 10 times the expected service life.
Whether hot or cold, that coolant is still at 15 psi, and will leak out of a leaky heater coil. Unless you block the heater loop completely, via plugs, or two valves.
Without documentation, which I have provided in other threads regarding heater control valves, that is just an opinion, nothing more. My comment was regarding the heater control valve, not the leaking heater core.
Without documentation, which I have provided in other threads regarding heater control valves, that is just an opinion, nothing more. My comment was regarding the heater control valve, not the leaking heater core.
If you were replacing the mixing valve in your shower, would you only shut off the hot water?
You need two valves to seal off the heater core, which is exactly what @interpon posted. Even though there isn't "flow", there is still pressure, that will go somewhere. Most likely, through the leaking heater core, and out onto the passenger-side carpet.
A brand-new 04-06 GTO heater valve might actually provide the bypass you expect, but there is zero chance that an OEM heater valve is stopping or bypassing 15 PSI.
Install this valve and it will allow water flow on the backside of the LS thermostat (valve closed position) to allow the thermostat to open properly. The in the valve open position, water is directed water through heater core when needed.
Technically that is one valve, but one that functions as designed (probably).
2020 Corvette of the Year Finalist (performance mods)
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You said you just replaced the radiator...was it leaking? Probalby was for a while which keeps the pressure low. Now that its fixed your heater core was the next weak link. Pull up your passenger carpet. I bet its wet
If you were replacing the mixing valve in your shower, would you only shut off the hot water? Comparing apples to watermelons.
You need two valves to seal off the heater core, which is exactly what @interpon posted. Even though there isn't "flow", there is still pressure, that will go somewhere. Most likely, through the leaking heater core, and out onto the passenger-side carpet. Again, an opinion.
A brand-new 04-06 GTO heater valve might actually provide the bypass you expect, but there is zero chance that an OEM heater valve is stopping or bypassing 15 PSI.Once again, I was speaking about the need for 2 valves, not the leaking heater core.
One shut-off will stop unwanted heat in the cabin.
But two valves are needed if an actual leak begins at the core.
Another option for temporary repair is a heater hose splice fitting.
One end of the black plastic adaptor is 5/8" the other end 3/4", less than $10.
Most of us figured out that one valve will do, to replace the crappy original valve and contain summer heat.
Some, insist on an overkill of two valves, just in case. (of a leak)
2 valves let’s you drive car without heat and troubleshooting and isolating the heater core. Of course there are other ways like looping hose etc. i shut both valves for summer.
post your details and bet others will share experiences..
Perhaps my original post was confusing as to the main question.
Is there something else, besides the heater core, that could be causing the coolant mist to be blowing into the cabin through the HVAC vents? I want to rule that out before I pull out the core.
There is enough mist that in the right light, it appears as steam gently coming out of the vents. Because it's blowing through the vents I assume it's the heater core. I don't know how that much coolant would get into the duct system any other way, without some type of visible leak.
I'm not sure how a pressure test will help me. I know there's a leak. I just can't tell where it's coming from.
Thanks again for the replies. I do appreciate all the help.
I went out to a Corvette show and I saw a brand new Brass/Copper heater core for my 1968 Corvette at a great price and I bought it, 30 years ago. I have no need for it since my heater core is still good and working after 58 years of service.
On the 1968 C3 without A/C, it will take me 10-15 minutes to swap out my heater core that is in an engine compartment filled with a 427 with long tube headers. I am not sure why they decided to bury the heater cores in later C3's inside the dashboard when they know that it will wear out and eventually need to be replaced.
On my daughters Camaro they removed the windshield to access the heater core (easier for the mechanic) after it failed with 34,000 miles on the car. That heater core was the thinnest aluminum material and I couldn't find any solder anywhere. GM is not getting any smarter as time goes on, what a shame.
If I had a problem I would simply plug the system off and get rid of the extra hoses. I did bypass it one year and it made no difference in my car during the summer months, so I don't bother with it.
So, If you keep a spare heater core, the odds of the heater core failing drops, pretty dramatically. It worked for me....
I went out to a Corvette show and I saw a brand new Brass/Copper heater core for my 1968 Corvette at a great price and I bought it, 30 years ago. I have no need for it since my heater core is still good and working after 58 years of service.
On the 1968 C3 without A/C, it will take me 10-15 minutes to swap out my heater core that is in an engine compartment filled with a 427 with long tube headers. I am not sure why they decided to bury the heater cores in later C3's inside the dashboard when they know that it will wear out and eventually need to be replaced.
On my daughters Camaro they removed the windshield to access the heater core (easier for the mechanic) after it failed with 34,000 miles on the car. That heater core was the thinnest aluminum material and I couldn't find any solder anywhere. GM is not getting any smarter as time goes on, what a shame.
If I had a problem I would simply plug the system off and get rid of the extra hoses. I did bypass it one year and it made no difference in my car during the summer months, so I don't bother with it.
So, If you keep a spare heater core, the odds of the heater core failing drops, pretty dramatically. It worked for me....
That is great! I'm always looking for ways to defeat Murphy! One of my favorites is, don't ever clean up or put away any tools until I have thoroughly tested whatever it is I was working on.
Now it's the heater core?
