Does Heater Core help with engine cooling?
 

Sooo a couple of questions around this one…my heater core is leaking pretty bad inside the car? I removed my AC as I never used it but I kept the heater core as I was told it would help with engine cooling. How true is that? Also do I have to remove it if it’s leaking or can I just cut the hoses and bypass it?

Also, I image a leaking heater core would effect engine cooling also correct? Thanks as always!

It really only cools the engine some when you’re forcing air through it with the heater blower fan on. Just as much as you’d expect a tiny radiator to cool a large passenger car engine, not much.

Otherwise no.

Bypassing it is fine. Think about how the factory built some cars with heater delete, bypassed completely because they had no heater core.

Thank b-man….I didn’t think it would make to much of a difference either but thought I’d ask being in florida and on the hot days I’d want all the help I could get….also, If I left it in and bypassed it would it still be sitting there leaky full of coolant? Or does it return or dry up? Thanks

There would be old coolant sitting in there unless you blow it all out using compressed air.

It’s nice to have heat and be able to defog your windshield, personally I’d want a working heater setup.

When you’re on the verge of overheating on a very hot day I suppose it’s a good thing to be able to utilize that heater core to try and take the edge off, and cook your feet a little at the same time. ;)

And nothing better stuck in traffic on a hot blistering day when it's also just as stinkin' hot inside the car to slide the heat lever all the way over and hit the fan on high and share in the 230+ degree engine heat.

That's another one of those things we all did once but most of us never did again...

Theoretically yes. Practically, not even a little.

How would you blow it out with it in the car? Just stick the air into the copper opening coming out of the firewall? For now I’m thinking just bypass it :cool:

You could bypass it for now and if the inconvenience of not having warm air for your defroster becomes an issue later, install a new heater core then. I've bypassed them before without blowing out the remaining anti freeze in the old core. I don't remember it causing any problems.

Yes, do this. I had a leaky one I didn’t blow out and left me with a little bit of rust in the floorpan. Also recommend pulling the carpet back and soaking up any moisture.

Family friend road raced an MGB for his setup the heater core made a difference in the temp the motor ran. Looked pretty cool with fender flairs and road race slicks!

The combination of the extra capacity and running the heater had a small effect on mine in the cold.

Last year if I drove the car in the cold with no coolant in the core and the water pump nipple capped off the car would still get up to the thermostat at 180 albeit slowly. This year with the heater hooked up and on it won’t get over about 155-162 degrees while driving. It’s actually annoying because I don’t think my Terminator comes off the cold enrichment until 160*. So to watch it sit there at 158* feels like it’s taunting me.

In the summer there was no notable difference.

My experiences with running the Heater to avoid overheat were not so helpful. Yet everyone should try it.

On hot days at the track I’d run the heater in the staging lanes for a few minutes until the air coming out cooled off. Started the engine to circulate coolant, shut it off, and turned the blower back on. Repeated as necessary. Seemed to help cool the engine down faster between rounds.

I would go for the correct repair before the delete option. You’re in Florida, say you get caught in a downpour. The windows are going to fog up for sure, especially if your clothes got wet from the rain, and you’ll want the defroster to be working. Why not just replace the heater core with a new, non-leaking unit? Have you investigated where exactly the leak is coming from? It could be an easier fix than you think. Consider the resale impact too if you fix it correctly or just delete it. My .02!


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Issue with is you leave the leaky heater core in the vehicle, where does the water that was in the heater core go? I know the answer.

It sloshes around and eventually rots out the floorboard on the passenger side of the vehicle.

Always replace the thing if it leaks but can't imagine unless you are in the panhandle you ever would need a heater in Florida in the winter time.

Or that you would drive your car in the rain.

Tom V.

I used to get stuck in the tapanzee bridge on my way home from E town. Every Pontiac day or NETO event. My 70 Chevy big block pick up would get hot. Right in the edge of over heating , I’d pop on the heat and fan and it would save the day every time . So absolutely it does help in a pinch . It’s just a small radiator w a fan blowing across it like any other radiator. My wife would have her feet up on the seat and I’d be burning my feet on the floor .

Thank you all you guys so much for all your replies….do you have any old threads or links to best ways to remove/replace the core? I’ve seen where it calls for removing the fender and seems quite a lot involved

To be fair the heater core is probably not much smaller than the radiator lol. My fathers TR6 certainly has a small radiator.

(Joking of course. Kind of)

Whenever I've tried it, it helped for a very short time only. Whatever the underlying cause for the overheating still exists. So adding a small volume of additional fluid to the system won't fix it.

Short simple answer is yes you can bypass it. , it gives you a little more coolant volume and in an inch can be and extra cooler but only if heat is on.
If all is working well it shouldn’t hurt anything. If your engine is getting hit check the divider plate to impeller gap .
.

X2. Can't pull off to the side on a bridge. Got boxed in by crawling traffic after some spirited driving and the hotter the car got, the better that heater worked. My sneaker's sole actually separated, a geyser of coolant would've been so much worse.

My FIRST engine overhaul, which then immediately went a thousand miles to visit a girlfriend. Wandering through the mountains, the heater core/heater fan was turned on and off depending on grade. The heater core was reliably removing about ten degrees from the temperature, which means more heat than that because I was only using it on the uphill sections when the engine was under additional load.

Higher load...but lower temperature. The heater core/heater fan can remove a significant amount of heat. The downside is that it removes that heat by making the passenger compartment almost un-livable.

"I" would not want to be without that heater core. But then, this is the Seasonally-Frozen Wastelands, not Florida. I've had ALL I can take of driving around with little candles on the dashboard to keep the windshield clear.

First Question is F-Bird or A-Body, or other.

It can be done on a A-Body without removing the front fender 64-67 Body.

Tom V.

This thread/debate is educational for me....she runs a little hot but only on the hottest days with a four core...

IMO, I would not want to go without the option to have heat or defrost so I would fix it. My 69 400 likes to run hot especially when stuck in traffic so I installed an electric push fan in front of the radiator and that helps a lot. The good thing is that you can't see it and the wiring is hidden so no one knows it's there.

Just a reminder about your vacuum advance. If it's connected to a ported source it will run significantly hotter at idle (like in heavy traffic or a parade). Made huge difference in my car. Like 180 vs 210 or more.

FWIW, because I went through the same thing. I can say for absolute certain that having it hooked up is the right thing to do. I let mine go for years because I didnt want to deal with replacing the blower. Not so much the heat, but not having the defroster really affected me driving the car. There were times around here that even in nice weather mornings I would crest a hill and the windshield would instantly fog over. So it made me scared to drive the car in the mornings or any time I felt the air might be too humid.

I hooked it up a few months ago and dont know why I waited so long to do it.

It’s F body …77 TA….I’ve been search for a good step by step….if you got any good links

Here is my experience further explain. I've had heater cores leak 2-3 times in my life. I discovered the leak by finding coolant in the floorboard. Those heater cores were in daily drivers that I used for work so I bypassed the cores until a more convenient time to replace. In my case, I cleaned the coolant up dried the carpet. Done deal. Never noticed any more coolant on floor after initial clean up. I have never had rusted out floorboard due to a bad heater core. The residual water left in the cores if any was left, evaporated over time. How much fluid does a heater core hold? Bypassing has stopped new fluid from entering the core.

Back then I didn't have the option not to drive my cars in the rain as they were my main mode of transportation. I've never owned a "show car". Too poor lol.

I lived 56 years in north central fla, central fla and the last 5 in the panhandle.

You do need a heater in Florida the same way you need AC in Michigan. It's a convenience. It freezes in central fla. Just ask the citrus farmers.

With the humidity in fla the warm defroster is a must for me.

I can only comment on my experience, but respect and appreciate others opinion on the subject.

Better to have and not need than to need and not have
 

As others have stated; attempting to drive with fogged windshield from not having heater is very inconvenient.

I lived with that many years until getting A/C delete box on my 1969 Firebird.

I also thought that my engine was cooling better than when it was capped at rear of passenger head and at timing cover.

I live in Las Vegas and summer heat is well above 100 degrees.

It adds probably 1-2 quarts to the cooling system and adds a fan so running a heater core will give you some edge in a marginal cooling system on a hot day. As far as rotting the floor out, that won't happen, because antifreeze has rust inhibitors in it. Eventually the coolant evaporates, even if you don't dry the carpet, done it many times.

If you're in a climate that needs a heater, then the coolant should have antifreeze too, not straight water. It's also smarter to run a rust inhibitor to protect the inside of the cooling system against corrosion.

Yes, I have bypassed heater cores as a temporary measure to get home, and get a new core installed. Heater cares are easy on some cars, and incredibly hard on others, A/C usually complicates installing them. I've also dumped pepper into the cooling system for a temporary stop leak, it usually holds about a week. Use Bars Leaks pellets if you want it to last longer. It doesn't clog heater cores, because I have it in several of my daily drivers for years, heaters still work excellent.

Always living near the great lakes, I usually need a heater core to keep moisture off the inside of the windshield. Even in Phoenix AZ in January it was 40 degrees a few mornings, Florida the same way, in February when I went to the Daytona 500 and stayed in the panhandle for a week, 40 degrees wasn't unusual.

If you're not going to store a car from October to March you'll need a heater core at sometime. When we go to dirt tracks even during summer months I need a heater to keep moisture off the windshield after the sun goes down.

:2cents:

I had a rust free 64 GTO convertible in Missouri.
Moved to Kalamazoo Michigan to attend college there.
My Uncle was a Pontiac Dealer for 67 years in Michigan.

5+ years in the Michigan Salt killed my convertible frame.

So I can relate to having to drive my Pontiac vehicle in cold weather.

A rust free Georgia Frame was purchased and installed later on.

Car is never driven in the winter these days. Car has heater delete
now.

I respect your requirements for the car too.

Tom V.

Guys , he has a Factory AC - 77 TA
He probably just removed the compressor and brackets , not the whole HVAC box.
Pain in the ass and pain/slices on the hands and fingers to replace that heater core.
fwiw

If you have some spare hose , put a piece back on each core nipple , blow into the upper hose and let the lower hose drain into something. Get as much out as possible with some compressed air.

Take the fuse out for your blower motor for a while if your windshield has been getting fogged or filmed from the leaking core. They run on a slow speed at all times in your type of car , even when in the Off position.

Go to a car wash and use their vacuum on passenger side carpet.
Maybe pour some extra water on it a couple times to dilute it , and vacuum some more.

You can replace the core some other time if you need to have it.

This^^. The heater core DOES add coolant capacity, which can help a small amount. But cars with no heater seem to run at the same temps, so.....

my owner's manual says to turn the heater on if the engine starts to overheat.

It works in the movies. Watch the chase scene in the 1971 movie Dual where Dennis Weaver plays a businessman terrorized by an 18 wheeler while driving thru the desert in his Dodge Dart.

Thanks Tom V.

I learned about it from an episode of Simon & Simon before I even owned a car.
That is about the only thing I remember from any episode of their show.
The older brother was running the heat on high on a 100+ day
and the younger brother was going nuts about it.
It was an old Dodge truck

For some reason it always stuck with me. :stupid:

No matter how hot the interior gets with the heater on. it still beats walking. :D

As I found out trying to get my dirt track cars to run cooler, every little bit of increased coolant capacity helps an engine to cool longer before it hits the critical point. In my quest to keep race cars cool, adding an extra gallon of capacity makes a great deal of difference.

Oh that was a classic!

Stupid quesiton; if the temp gauge goes into the danger zone in traffic are you better off to pull over and shut her down to cool off or put on the heat and try to get moving?

Just run the blower fan backwards so the hot air goes outside the car instead of in the cabin. Just kidding, won't work that way but if it did....

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In my case if I can get moving my temp goes down pretty fast but if I can't get going I will find a place to pull over and pop the hood or find a side street to get up some speed. Using the heater does help but not enough because it doesn't stop the temp from rising but only slows it down.

It's time to diagnose and fix that situation.

My 455 runs cooler when I block off the Heater Core. About 7*F cooler. I have a hose pinch I use in summer, to stop flow to it. Spring and fall I use for heat. But, the heater core is just a constant bypass. From head, through core and back to water pump. In summer, there is no cooling being done by core. Its just recirculating some hot coolant.

I ended up by passing mine after this ordeal and it’s running cooler now than before it was going through the leaky heater core