I've searched this board and found out it's common to always have warm air blowing on your feet because of air forced past the heater core, even if you have your settings on cold.

That sure is annoying! It even gets warm on the feet with the windows down and t-tops off!

I want to cut off the coolant supply to the heater core during summer, but I DON'T want to just disconnect the hoses and butt them together. I want something like a valve shutoff that I can turn off and on by just reaching into the engine compartment. Sometimes I do need to use my heater!

Can I just stick in a plastic shut off valve on the heater core inlet line? Will that damage the water pump? Some posts seem to indicate you can just block the heater core lines and it's OK.

Should I install a heater diverter valve like on post 87 cars? How does it work, does it require a vacuum source?

Or would it be best to bypass the core and recirculate the coolant with a shunt (similar to the stock heater diverter valve)?

I'd like to just stick in a shut off valve from Home Depot. Simple, and easy to turn off and on. I just don't know if coolant HAS to flow through that part of the system.

 

All you need is a simple on/off valve. The later models just have a simple valve, but operated by vacuum.

 

The 87+ cars have a diverter valve, it sends the coolant somewhere else, it doesn't just block it.

So can I just block the coolant flow with a simple on/off valve? What does the water pump do when I block it?

 

I can't imagine why it would need diverted. The water pump isn't 'positive displacement', so it doesn't have to move any fluid. The pump will do exactly what it does when the thermostat is closed--not move any coolant.

 

Well that makes it simple if it doesn't have to be diverted. I can just put in a valve and block the flow I guess.

Since the 87+ cars have a "diverter" valve, I thought it might be bad to just block the flow.

Thanks for the help!

 

You don't want to stop coolant flow...but rather circulate it. It never hurts to circulate coolant, especially when on a stock car, the return goes right back to the radiator...flow is never a bad thing

So help the coolant do its job...

 

But this wouldn't stop the coolant from circulating through the block, just the branch that flows to the heater core. I suppose the heater core acts as a small radiator in itself, but I doubt this will raise my coolant temp that much.

Besides, it sounds like the 87+ cars did the same thing from the factory!

 

Where does the stock feed line to the heater core come from? The back of the intake, front of the intake or the WP?

 

IIRC, the front of the water pump. The return line goes to the intake (I don't remember if it's front or back). Or maybe it's the opposite.

I could confirm tonight.

 

In the summer, flow through the heater core can be bad. Stopping the heater core flow hurts nothing--the heater core won't help cool the engine at all, unless the heater is turned on. Stopping the flow to the heater core helps keep your feet cool in the summer. My guess is that he doesn't have a radiator return hose. I need to look to be sure, but on mine I think the heater core flow comes from the intake and returns to the pump.

 

Hey 82camaro,

If you are overheating in stop and go traffic, do you want to get out and turn on your manual valve for the heater core? Of course the heater core will help cool your engine...it is simply enhanced when you turn on the blower because it transfers the heat out of the coolant faster.

All the heater core is is a mini-radiator...I like the idea of a remote controlled valve though...

 

OK, I took a look at the hose layout.

Starting from the water pump, I have the large line running between the bottom of the pump to the bottom of the rad. I assume water flows Pump>Rad?

Top of the pump has a smaller line (5/8?) running to the heater core. Other line from the core returns to the front of the intake. Of course, there is a large line from the top of the rad to the front of the intake.

So I assume the inbound line to the core is the Water Pump>Core and the return line is Core>Intake?

 

No doubt the heater core is a 'mini' radiator. It's a very, very small radiator. Turning the heat on is a way to 'help' cool down an engine, but when the selector is to 'heat', the fan is at least on the low setting. Heat has to get transferred to the air to do any cooling, with all the ductwork around it just heats all the air directly around it(and the ductwork). Let the radiator do the cooling and the heater core do the heating. Me, I never overheat in traffic. If you do overheat in traffic, fix the problem.

The pump sucks from the radiator through the lower hose(why it usually has a spring in side to prevent collapse). The water is then pumped into the engine, out the t-stat housing, through an upper hose(smaller than the lower hose) and back to the radiator. Flow can bypass the thermostat and radiator via the heater hose connected to the intake(this happens to a greater extent when the stat is closed). You want to install a valve on the intake to the heater core hose--not a problem. If you want to install a diverter, it needs to return to the radiator to do any good, and you probably don't have a return connection on the radiator.

 

Thanks for the explanation! If the stat is closed, and I close off the line to the heater core, then the pump can't move any coolant. I assume that's OK by your explanation. I guess that doesn't damage the pump.

I don't have any overheating problems either, so I'm not worried about losing the cooling effect of the core. I'm sick of that warm air constantly on my feet!

 

Just out of curiousity, what kind of engine combo are you running? I ask because with my 406 that I have had in 3 different vehicles now (2nd gen f-body, g-body and my GTA) idling in stop and go traffic for a while is a problem. It may not be a problem if you are running an LG4 or L69 with far less cubic inches.


Actually coolant flows through the block when the T-stat is closed...if you look at a water pump, you will see a small water bypass hole designed to allow coolant to circulate when the T-stat is closed. A performance mod that enhances cooling is to drill 4 small holes in your t-stat to ensure coolant flow at all times (especially when t-stat is closed) and then plug the block coolant bypass hole.


Quote:

"Flow can bypass the thermostat and radiator via the heater hose connected to the intake(this happens to a greater extent when the stat is closed). You want to install a valve on the intake to the heater core hose--not a problem. "

How again does coolant flow through the heater core back into the intake if you shut off all flow into the heater core? Or do you mean without the shut-off valve?

It still seems like leaving the heater core connected and operational is the best recommendation that I have seen...granted this is if you actually intend to put some miles on your car and not just have it for an occasional weekend toy or track car. I believe in doing what you can to make it drivable under a lot of different conditions. Also, with my cubic inches and HP, cooling is more difficult so I may seem to be a bit extreme to someone with a milder combo.

 

Also, I agree that simply installing an on/off valve will not damage the pump, but having the heater core available for emergencies is nice...

In responding to kanuck...with your LG4, I would say, go ahead and install the on/off valve. That engine is so mild that you probably will never have to worry about heat, even in traffic.

Good luck.

 

Interesting discussion. I can see how a 406 may cause you more cooling issues.

My car is never winter driven. In fact, this is the first time I've licensed it in three years since I bought it, which is why I never noticed this before.

I figure most of the time I'll block the heater core flow as I'll rarely have the car out in cool weather. But I do want to leave it operational for those cool evenings! Hence the valve rather than a disconnection.

 

Just out of curiousity, what kind of engine combo are you running? I ask because with my 406 that I have had in 3 different vehicles now (2nd gen f-body, g-body and my GTA) idling in stop and go traffic for a while is a problem. It may not be a problem if you are running an LG4 or L69 with far less cubic inches.

Fairly stout 350. It used to run hotter around town. Bigger radiator, better fan, now it runs 190 stopped in traffic with the ac on in 100 degree weather. I don't think the car in question has any cooling problems either.

Actually coolant flows through the block when the T-stat is closed...if you look at a water pump, you will see a small water bypass hole designed to allow coolant to circulate when the T-stat is closed. A performance mod that enhances cooling is to drill 4 small holes in your t-stat to ensure coolant flow at all times (especially when t-stat is closed) and then plug the block coolant bypass hole.

Helps cooling while the stat is closed, mine would never warm up in cold weather(20 below or something). It is a mod if your cooling system isn't quite keeping up.


Quote:

"Flow can bypass the thermostat and radiator via the heater hose connected to the intake(this happens to a greater extent when the stat is closed). You want to install a valve on the intake to the heater core hose--not a problem. "

How again does coolant flow through the heater core back into the intake if you shut off all flow into the heater core? Or do you mean without the shut-off valve?

Without the valve of course, just explaining how things usually work.

It still seems like leaving the heater core connected and operational is the best recommendation that I have seen...granted this is if you actually intend to put some miles on your car and not just have it for an occasional weekend toy or track car. I believe in doing what you can to make it drivable under a lot of different conditions. Also, with my cubic inches and HP, cooling is more difficult so I may seem to be a bit extreme to someone with a milder combo.

Your cooling problems are a different story. If you have to run the heater in traffic to keep the engine cool even after upgrading the cooling system as much as you can--then I guess you have to have hot water to the core. For me it's never an issue(as well as others I'm sure). I know of plenty of fast street cars that don't ever have to run the heat to keep it cool. If I ever had to run the heat in traffic to keep her cool, my next mod would be cooling system upgrades. Why? IMO, running the heat to keep the engine cool is a band-aid to cooling system inadequacy.

FYI, every sbc 400 I've been around always ran hotter than any other engine--even big blocks putting out more power. I know some will disagree, but it's what I've seen.

 

I really view the heater core as a minor backup actually. If I had to run it consistently in traffic, then I agree it is a band-aid...but the way I am explaining/understanding it...it seems to be a safety measure, nothing else...I figure it is insurance in case I really do start to overheat...then it may help with 20 degrees reduction in temps.

Yeah, 400's do seem to run hotter, hence my "overengineering" approach...

"Fixing" the cooling system to some means a Be-Cool radiator and Expensive aluminum water pump...

Lucky for me, I just bought a Griffin dual 1 1/4" rad setup and a slightly used Edelbrock Victor Jr. WP from Derfrank who is upgrading his cooling system for a SC setup.

I probably now will consider installing a shut off valve, but hesitate to with my past experience...granted that was with other vehicles, not my stout GTA

 

After checking my shop manual, I verified I only need a shut off valve, not a diverter valve. I bought mine at Home Depot for a few bucks and spliced it in. So far so good. Once I shut it off, even if I turn the HVAC to full heat, I get cool air. It's about time!