heater box leak

[1966FLEETSIDE]

i got home yesterday,and noticed she was leaking water from bottom of heaterbox.is it shot already or can that be repairable?

[GVDobler]

The most likely is that the core (looks like a small radiator) is leaking. There is no water other than that core. Not very hard to fix. It was a mystery to me until I took mine apart, real simple design.

If you don't have pictures, go to LMC truck website on about page 34 is a diagram of heater parts.

[Rufton]

I would install the delux (larger) heater core.
Local store only had small core so I bought it. It works ok but the delux would put out more heat.
Make sure heater core nipples are not in a bind.
I had to heat nipple solder to re-position.

[1966FLEETSIDE]

awsome thx bud.

[Bigru]

Oreilly's auto has the larger heater core, just look it up under a C20 instead of C10. Just picked mines up 2 days ago.

[1966FLEETSIDE]

awsomw thx

[tincan1966]

The size of the core does not mean more or less heat. The correct thermostat and circulation of water and airflow is the key to having good heat. Make sure while you have the heater apart to completely clean everything out from leaves, debris, etc.

[Rufton]

The larger core will transfer more heat unless there's another issue.
While I was at it, I replaced the blower motor.
The new blower was cheap, quite, very powerful and had lifetime warranty FWIR.

[1963c-10]

Originally Posted by tincan1966

The size of the core does not mean more or less heat. The correct thermostat and circulation of water and airflow is the key to having good heat. Make sure while you have the heater apart to completely clean everything out from leaves, debris, etc.

x2, larger core will not give you more heat. Thermostat/blower motor only.

[par4tom]

I just had to replace my heater core...the inside of the truck looked like Niagara falls!

After pulling the box, the old core was beyond repair. It had been pretty much sitting for 20 years.

Go to the LMC website, they do a good job of describing which core you need. I got mine here in California within a week.

The only real challenge I had was getting the brackets that hold the core, lined up with the holes in the box. After that, it was a piece of cake.

Good luck!
T

[1963c-10]

NAPA has them on the shelf also...

[Rufton]

Originally Posted by 1963c-10

x2, larger core will not give you more heat. Thermostat/blower motor only.

Maybe we can agree to disagree

[luvbowties]

Originally Posted by Rufton

Maybe we can agree to disagree

I've never run a scientific test to determine whether bigger means warmer. But, I've heard for ages that a bigger radiator cools an engine better than a smaller one(within limits, of course). So, where did that extra heat go?

Seems logical that the same reasoning would apply to heater cores.(??)

I do know I've pretty much always managed to get plenty of heat from OEM cores--just by manipulating the t'stat etc. One exception was my '48 Chevy with its under-seat heater!!!

So, I still do not know; but I'd agree to disagree also!
Sam

[Rufton]

Large heat exchanger transfers more heat (BTU) than it's smaller brother.

If hole is sized delux then I'd suggest installing a DIY flat shroud under core to prevent cold air bypass. If hole is too small the larger core will have marginal benefit.

I could be wrong.

[1963c-10]

I have had both cores in the same truck. I have also had the deluxe heater (came factory in my 63) and converted to the standard heater in my 63. The standard heater provided more heat as its recirculating and not fresh air. The fresh air heater takes outside air (which is colder than the air in the cab) and has to heat it. The recirculating heater takes the ambient temp cab air and heats it. I had noticeably warmer air with the standard heater core. The deluxe core may have more mass, but on the same token just as a radiator needs air to cool, it would take more air from the blower to push more air over the core to get more heat out of the deluxe core. I don't think that cooling and heating are good comparisons, as larger radiator equals more volume of fluid and larger surface space for air to cool. The standard factory fan will not give you more heat out of a different core. The temp is regulated by the thermostat. You have to have either more air flow over the core or a higher thermostat to get more temp out of the heater. Larger heat exchange does you no good unless you can move the air. Its just basic physics. But I agree to disagree and these are just my opinions.

[Rufton]

My new blower from advance auto produces high CFM.
Enough to make a large temperature change between core inlet and core outlet.
In my case, I'd be willing to bet increased BTU from larger delux core.

[1963c-10]

Id have to agree with you on that Rufton due to the larger blower motor CFM.

[tincan1966]

The blower fan has nothing to do with heating other than providing air flow. The core, no matter the size is only going to be as warm as the fluid in it- - so that is directly determined by the thermostat and cooling system, NOT the blower motor.
If your engine is only running @ 180 degrees, you will be lucky to get 130 to 150 out of the heater.

Average automotive heater output temp is around 160 degrees at the floor vent.
If you want to try to apply the "size matters" principle -our trucks heater cores are
approx 6" X 8" X 2", and rarely achieve those temps
An '88-'98 chevy truck uses an aluminum heater core that is only 1" X 5" X 7" yet they produce the heating temps of 160+

Most aftermarket heat/AC combo units have a core less than 1/2 the size of the OEM, yet they heat great.

Another misconception is that more air is more heat. Not true- you can have fantastic heat, but no air flow, therefore the truck doesn't get warm- it's not lack of heat, it's distribution. If the blower motor quits or does not run, you do not have "no heat" you have no air flow. Big difference.
Understanding how the sytem works and how to make it efficient are the keys.
I absolutley hate having to run a heater on high speed fan all the time to have heat, so I insulate well and make the system work efficiently(using the proper thermostat, keeping trash out of the air box, etc)

I know I will be argued with, but fact is fact. 25+ years of installing AC/heating units, everyday practical knowledge and hands on work prove results.

The reason why most think the core alone made huge difference- they cleaned out 30+ years of leaves, etc from the heater assy while they were in there.

[Rufton]

Heat transfer from a heater core is a function of surface area, change of fluid temperature, fluid specific heat, fluid flow rate, yada yada.

In other words size does matter, just like the ladies said But other parameters matter also.

[tincan1966]

You'll get the same amount of heat(temperature) with either core, is the point- it's only going to get as hot as the engine coolant allows.

But I am obviously wasting my time.
Glad I am leaving these forums after my paid membership expires.

[Rufton]

Temperature (F) and heat (BTU) are different animals.
Ok, we can agree about wasting time
Can also agree there are more important topics.
Not trying to make you upset.

[tincan1966]

Experience and practical knowledge are totally wasted in these forums anymore.

Most cannot identify the problem, let alone understand a resolution.

[Rufton]

Your probably right but I've managed to keep small fleet including 1964, 1966, 1967, 1989 and 1999 vehicles road worthy.

[65c10restomod]

lets say I have a heater core the size of a quarter in my truck would one the size 11 shoe box be better