Leaking coolant - help!!! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jd21476 · 11-15-2014, 09:25 PM

I drove home the other day and smelled what I thought was coolant. I parked my truck and came out about a half hour later to find a puddle under the passenger side by the firewall. I immediately thought I must have lost my heater core.

I finally got around to pulling it out today (about a week later) and it still looks good. I ran some air through it and could not find a leak and then filled it with water and could not find a leak.

I got under the truck and could not find any leaks in the lines or anything. What else could it be?

**** Also, I have not been getting any heat from the truck lately so that also made me think the heater core was bad.

**old Rusty C10** · 11-15-2014, 11:11 PM

check for a pinhole in the hoses.. especially where they connect

tucsonjwt · 11-16-2014, 06:37 AM

Any green oxidation on the copper nipples of the heater core or elsewhere on the core? I would check right after parking after a long drive and check closely with a flashlight and inspection mirror. Something leaking that much should be noticeable at its source.

donut · 11-16-2014, 08:25 AM

May still be bad. Lost mine on Friday. Current only leaks under pressure.

Mine leaks when I shut the truck off after driving, when the pressure would be highest. I also get the "foggy window" thing. Currently only leaks when I shut the truck off. Obviously I also can't use the heat and am stuck with driving with the wing window open, luckily it's not my daily.

I may get lucky that it's only a hose, but not holding out hope as the HC is 25 yrs old.

**Corts60** · 11-16-2014, 12:09 PM

Sometimes a solder joint in the heater core will only leak when it is hot due to expansion. Replace it, you're there anyways.

jd21476 · 11-16-2014, 02:05 PM

Yeah, I think I will just replace it. Its only $25.

Bigstevex4 · 11-16-2014, 06:37 PM

Replace it any way got it out 25 bucks and your heat will improve.

11-15-2014, 09:25 PM	#1
jd21476 Registered User Join Date: Aug 2013 Location: San Diego, CA Posts: 236	Leaking coolant - help!!! I drove home the other day and smelled what I thought was coolant. I parked my truck and came out about a half hour later to find a puddle under the passenger side by the firewall. I immediately thought I must have lost my heater core. I finally got around to pulling it out today (about a week later) and it still looks good. I ran some air through it and could not find a leak and then filled it with water and could not find a leak. I got under the truck and could not find any leaks in the lines or anything. What else could it be? **** Also, I have not been getting any heat from the truck lately so that also made me think the heater core was bad. __________________ 1973 Chevy K20

11-15-2014, 11:11 PM	#2
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,310	Re: Leaking coolant - help!!! check for a pinhole in the hoses.. especially where they connect __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

11-16-2014, 06:37 AM	#3
tucsonjwt Registered User Join Date: Jul 2007 Location: Tucson, AZ Posts: 3,189	Re: Leaking coolant - help!!! Any green oxidation on the copper nipples of the heater core or elsewhere on the core? I would check right after parking after a long drive and check closely with a flashlight and inspection mirror. Something leaking that much should be noticeable at its source.

11-16-2014, 08:25 AM	#4
donut Registered User Join Date: Aug 2009 Location: S.C. Posts: 1,593	Re: Leaking coolant - help!!! May still be bad. Lost mine on Friday. Current only leaks under pressure. Mine leaks when I shut the truck off after driving, when the pressure would be highest. I also get the "foggy window" thing. Currently only leaks when I shut the truck off. Obviously I also can't use the heat and am stuck with driving with the wing window open, luckily it's not my daily. I may get lucky that it's only a hose, but not holding out hope as the HC is 25 yrs old. __________________ '86 C-30 dually, 454/tbh400 '73 K-20 350/350/205 (sold ) I'm kinda like duct tape- no real purpose, but handy to have around.

11-16-2014, 12:09 PM	#5
Corts60 Just here to tinker Join Date: Jun 2008 Location: Holland, MI Posts: 3,697	Re: Leaking coolant - help!!! Sometimes a solder joint in the heater core will only leak when it is hot due to expansion. Replace it, you're there anyways. __________________ 78 C10 SWB Diesel #1 (wrecked)http://67-72chevytrucks.com/vboard/s...1978+silverado 78 C10 SWB Diesel #2 (sold)http://67-72chevytrucks.com/vboard/s...d.php?t=650751 60 GMC Suburban (sold)http://67-72chevytrucks.com/vboard/s...d.php?t=445526 60 GMC 1000 (sold)http://67-72chevytrucks.com/vboard/showthread.php?t=298235 67 GMC 1500 (sold) http://67-72chevytrucks.com/vboard/s...d.php?t=803695 73 Chevy C20(Daily)http://67-72chevytrucks.com/vboard/s...d.php?t=852767 86 Suburban(summer unit) http://67-72chevytrucks.com/vboard/s...d.php?t=810697 88 Suburban 4x4(sold)

11-16-2014, 02:05 PM	#6
jd21476 Registered User Join Date: Aug 2013 Location: San Diego, CA Posts: 236	Re: Leaking coolant - help!!! Yeah, I think I will just replace it. Its only $25. __________________ 1973 Chevy K20

11-16-2014, 06:37 PM	#7
Bigstevex4 Registered User Join Date: Oct 2014 Location: Spearfish South Dakota Posts: 407	Re: Leaking coolant - help!!! Replace it any way got it out 25 bucks and your heat will improve.

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