heater/cooling system... GRRR

[midnightrider78]

It never ends. 1972 C20 with A/C.

New heater and radiator hoses.
100 miles later the water pump goes.
Replace the water pump and fan clutch.
20 miles later, I have a new leak that is baffling me.

I came home last night and when my headlights shone under the truck I noticed a wet spot on the driveway behind my right front tire. It was antifreeze. Oh great!
Shine a flashlight underneath and see where it has run down the firewall and dripped on the fender apron.
Open the hood and feel under the heater/AC case. Dry as a bone. Weird. Also dry inside just for reference.
Only damp place I see at all from the top side is a little on the bottom of the blower motor mounting flange. ???

I would have already pulled the blower motor to check further, but it appears that I have to remove the hood hinge to get the blower motor out.

Any direction you guys can offer on this clusterf?@# is appreciated.

[OregonNed]

FWIW I rebuilt mine - non-A/C and got it back together - all good, then I had an intermittent leak like you mentioned. I did not want to pull the Heater box out again! Got to figuring one of the screws to mount the little brackets to hold the Heater core might have somehow punctured the heater core itself, but being intermittent, I kept an eye on it. Turns out the lower hose on the heater must have been loose enough or inefficient so I ended up with two hose clamps to fix the issue. It too would leave just a little coolant on the bottom of the box, and I think it might have migrated inside too, even though the sealing foam was there. Hope you find it!

[VetteVet]

If you need help on pulling the heater core out you might refer to this thread.

http://67-72chevytrucks.com/vboard/s...r+core+with+ac

The AC unit complicates the problem considerably.

Pne post in this thread mentions pulling the inner fender on the right side. You might still have to pull the hood hinge to get to the lower bolts. The fan should come off without pulling the housing it attaches to but with AC I can't say.

Do you have an inspection mirror you could see under the housing with?

[midnightrider78]

Originally Posted by OregonNed

FWIW I rebuilt mine - non-A/C and got it back together - all good, then I had an intermittent leak like you mentioned. I did not want to pull the Heater box out again! Got to figuring one of the screws to mount the little brackets to hold the Heater core might have somehow punctured the heater core itself, but being intermittent, I kept an eye on it. Turns out the lower hose on the heater must have been loose enough or inefficient so I ended up with two hose clamps to fix the issue. It too would leave just a little coolant on the bottom of the box, and I think it might have migrated inside too, even though the sealing foam was there. Hope you find it!

I started the truck and let it warm up a little today. As soon as it got warm, it started leaking near that lower heater hose. Although, I still was not able to determine the exact location of the leak(hose connection or something wrong with that tube of the core?). Figured I'd try the obvious and tighten the hose clamp a bit since it looked questionable. If I can motivate myself tomorrow(it's supposed to be 30 degrees colder than today), I'll warm it up again and see what happens. If it still leaks, I'll try a second hose clamp like you suggested before I dive in to the misery of tearing it all apart.

[midnightrider78]

Originally Posted by VetteVet

If you need help on pulling the heater core out you might refer to this thread.

http://67-72chevytrucks.com/vboard/s...r+core+with+ac

The AC unit complicates the problem considerably.

Pne post in this thread mentions pulling the inner fender on the right side. You might still have to pull the hood hinge to get to the lower bolts. The fan should come off without pulling the housing it attaches to but with AC I can't say.

Do you have an inspection mirror you could see under the housing with?

I don't believe there is any sort of inspection cover. I can get to all the fasteners for the blower motor, but there is only an inch or so of space between the motor and the hood hinge. So I don't see any way to remove it with the hinge in place. I hope it doesn't come to that.

[toolboxchev]

Heater Core, I know, do not wish that one on anyone.

[Pearly72]

Hi Midnight,
I know it's been 2 years and hopefully you can respond or remember how you remedied this issue. Im having the same issue. 72 C10, 350sb w/ 700R4 (converted from manual by PO). I just replaced the hoses and added a shut off valve about 4" from the intake nipple. I'm getting a leak at the exact same place. I DID FORGET to hit the lines with steel wool before I put the new hoses on.

[Stocker]

Midnight's most recent board activity was 06-13-2018. Hopefully you'll get some help. My only thoughts are to clean the nipple really well, use a new heater hose, and apply a thin coat of silicone grease before assembly. Maybe a different type hose clamp would help. My K20 has worm gear clamps there, but I prefer wire-type clamps because they never loosen... they always maintain pressure on the hose connection.

[Pearly72]

Originally Posted by Stocker

Midnight's most recent board activity was 06-13-2018. Hopefully you'll get some help. My only thoughts are to clean the nipple really well, use a new heater hose, and apply a thin coat of silicone grease before assembly. Maybe a different type hose clamp would help. My K20 has worm gear clamps there, but I prefer wire-type clamps because they never loosen... they always maintain pressure on the hose connection.

Thank you for the insight. I'll give that a try! I'm hoping the issue is that I didn't clean the nipple when i put the new hose on. I'll also try the silicone grease.