Guess this mean I need a heater core

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Keystone

Keystone

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I have my slanted 6 to Magnum swap basically complete. Still working through a few issues, but it's driving.
HC1.jpg


The last couple test runs I've comeback from, I found a small puddle of coolant on the floor.
HC2.jpg



It wasn't leaking before i started the project, but way it went (two steps forward and one back the whole way) it would be par for the course.

I confirmed the hoses aren't leaking at the firewall. In fact it's all dry there.
HC3.jpg


And it's even dry on the inside.
HC4.jpg



But after getting under it, I did see a few drops where these pieces of sheet metal come together
HC5.jpg



So before I tear into it, does heater core sound correct? I can't see any coolant leaking from the cylinder head, and I did go back and apply some thread sealer on the rear header bolt, but that didn't change anything. I always figured when they go you get a wet passenger side carpet but I guess it's possible for them to leak in a way that the coolant runs outside and not inside. I guess my problem is I don't really know how it's all put together in there. But again, I'd just like a second opinion before I go through the hassle of adding more work to this already very long project.
 
Hey Keystone,

Take the heater hoses off and by-pass the heater core by running a small length of hose between the outlets on the manifold and water pump, or put a piece of pipe between the two hoses after you remove them from the heater core inlet and outlet nipples.

Fire up the engine and see if you still have a leak.

Also, if you have a compressor, force air into one side of the core ,It will push remaining coolant in core back out through the other open nipple.

With no coolant left in the core, if you still see liquid on the floor , you will know its not the core.
 
Check the heater hose clamps are tight, they can send a fine spray in the most unbelievable directions, and thru the firewall .
 
I would do as super-cuda said.

But I would pull the pass front seat and the front carpet on that side.
 
You could pump 16 lbs of pressure onto the heater core and see how long it holds.

For months my mini van had a smell of rad fluid. But no wet, no drops, no signs of a leak anywhere.

I thought the heater core had a leak and was draining out the condensation drain.

After months, I finally found some fluid and could find liquid up high on a fitting on a hose.

I replaced the part and no more leak.

I put a vacuum on the fitting and it held.
I pressurized the fitting and it held.

I put the fitting in boiling water got it hot and it didn't hold.

The PLASTIC fitting changed its characteristics with heat
 
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Thanks guys. Good tip on trying to bypass it. That's an easy to do check, so as soon as I get some free time... I can't believe how long this swap has taken. Pretty much an entire year, but to be fair part of that was pacing myself by buying the parts as I had the money available. So close to being done. I'll post back when I find out what going on.
 
I finally got some time to get back on this. I tied the hoses together with one of these:
HC7.jpg


I put a short hose over one of the heater core fitting, with the other end into a bucket, then gently blew some compressed air into the other fitting. After getting as much of the coolant out as I could, I found the same puddle on the floor in the same spot. So heater core right?

I went ahead and removed the box (it actually was fairly simple, thanks to some tips I found on here like removing the glove box liner and getting that hidden hanger bolt off) and sure enough... it was perfectly dry and NOT leaking:
HC6.jpg


So what I learned is, I'm not very smart. Oh wait, I already knew that. I learned that any coolant leaking near the header tubes, that runs onto them, will follow the tubes down to the collector and drip off there. So what I spilled when disconnecting the hoses appeared to be further back and fooled me.

I did take if for a drive with the hoses tied this afternoon and there is now no coolant leak whatsoever. So that's a big relief. I was starting to think it could have been a freeze plug at the back of the head, or maybe a head gasket. Just a dumb leak at one of the hoses I wasn't able to detect.

Thanks everyone for the advice, even though it turned out to be something I should have figured out myself. On to carb tuning.
 
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Oh, I thought I put these here, for future help to anyone who may have to remove the heater box. I found some people who mentioned the hanger hook bolt, but this is where it actually is, and what it looks like.
HC8.jpg


With my phone stuck up inside there for a better view:
HC9.jpg
 
Keystone said:
I finally got some time to get back on this. I tied the hoses together with one of these:
View attachment 1716212594

I put a short hose over one of the heater core fitting, with the other end into a bucket, then gently blew some compressed air into the other fitting. After getting as much of the coolant out as I could, I found the same puddle on the floor in the same spot. So heater core right?

I went ahead and removed the box (it actually was fairly simple, thanks to some tips I found on here like removing the glove box liner and getting that hidden hanger bolt off) and sure enough... it was perfectly dry and NOT leaking:
View attachment 1716212596

So what I learned is, I'm not very smart. Oh wait, I already knew that. I learned that any coolant leaking near the header tubes, that runs onto them, will follow the tubes down to the collector and drip off there. So what I spilled when disconnecting the hoses appeared to be further back and fooled me.

I did take if for a drive with the hoses tied this afternoon and there is now no coolant leak whatsoever. So that's a big relief. I was starting to think it could have been a freeze plug at the back of the head, or maybe a head gasket. Just a dumb leak at one of the hoses I wasn't able to detect.

Thanks everyone for the advice, even though it turned out to be something I should have figured out myself. On to carb tuning.
Click to expand...

Glad you were able to find and fix your problem.

Dont worry about it, many of us on here have made mistakes as well.

As for the "smart" bit , you were smart enough to ask for help on here where we have some of the most experienced A-Body owners on the planet.

Personally, I consider that very smart!!

Cheers!!
 
Next time, or for others reading this thread, use a cooling system pressure tester. A friend may have one or you can rent one from a rental store or parts store. It can help you find the leak without taking unnecessary things apart.

pressure tester2.jpg
 
If it's leaking down the header tubes, it might be coming from one of the end exhaust studs at the cylinder head. They go through to water and should have sealant on them.
 
Another way to test your heater core is to turn your heater on full hot. Hot air = good hc Cold air = bad hc

Another test. Hit the high heat in defrost mode.
Window fogging up ? Bad hc.
 
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