Heater core is leaking

[Aaarrghh]

I bought a new core, and am studying how to do the swap, but I don't relish doing this at a campground. It involves removing the splash panel inside the fender, and worst of all raising or removing the dashboard. There is no glove box, so there's no easy access to undo the controls, etc. I'll be in a better place in a couple months. My question is, would using a radiator stop-leak product be an effective temporary fix? Are there any risks to using it?

[Rickf1985]

I would use Barr's Leaks and use it according to the directions. The main issue with those types of products is clogging of the heater cores. Kind of moot point for you since that is what you want. Can't you just pull the hose off the heater core and bypass it right to the radiator return? I would take both hoses off of the heater and put a pipe fitting between them and clamp it in there, Done. No water at all going through the heater.

[Aaarrghh]

Thanks, Rick, but the hoses are different sizes. I was thinking of buying a bolt to fit in the end of each one, then putting a hose clamp on. That would stop the flow. Would there be any issue with the water pump, then?

[BamBam]

Do that! Your just removing the hoses to the heater core, bypassing it and taking it out of the picture. The rest of the system will be fine even with a bolt or other type plug. Where the 2 hoses come out of the motor, you can just take a hose and make a big U and plug it that way too. Hot Rodders do that a lot to delete the system. Good Luck

[Rickf1985]

There will be no consequences. When the heater control valve is working correctly it closes off the flow when no heat is called for. In your situation there is still pressure in the system even if there is no flow so the leak continues. So blocking the hoses will stop the leak and not cause any problems.
In addition, once you do that you can flush the core with fresh water and that way any residual water that leaks out will not smell like antifreeze. It should all be leaking out through the air conditioner drain and not inside the passenger compartment correct?

[Aaarrghh]

Thank you all for your helpful suggestions.
Well, I just came from the O'Reilly Auto Parts store in Apopka, FL, and I have to say, that Tracy knows her stuff. She must've been raised on a farm, fixing things. She turned me off of the Barrs' and showed me a hose connector that would accommodate both hose sizes. Yay Tracy! Problem solved for now. I'm glad I don't have to pollute my coolant. I paid a lot for a new brass and copper radiator 2 years ago, and I'm fussy about keeping it in good shape.

By the way, there is no valve to control the flow of juice to the heater. The temperature of the air into the cab is controlled by a 'blend door' that combines cold outside air with the hot air from the heater core. It would have been so easy to just turn down the temperature control to stop the leak, if that was how it worked. I tried it, no luck.

[Aaarrghh]

It should all be leaking out through the air conditioner drain and not inside the passenger compartment correct?

No, it drips onto the floor. I pulled and rinsed the carpet, but I've had to keep wiping up the coolant. What a pain.

[Rickf1985]

Odd, Most GM products from that era had a heater control valve in the inlet line and the outlet would go to the return which is on the passenger side of the radiator. No matter. Even if it had the valve you would have still had the leak because all the valve did was stop the flow of hot water, in your case you had a leak so the pressure would still be there on the other side of the system and it would backfeed from the return side. I would still flush it out with fresh water since if the leak is at the bottom of the core it will continue to leak until it is empty. At least this way it will be fresh water instead of coolant. And Barr's Leaks has no effect on radiators at all, that is why I recommend that particular brand. In 45 years as a mechanic I never had any issues with Barr's Leaks other than a couple clogged heater cores and the reason they clogged is because they were totally jammed with crap. Once I flushed them out all was good. So Tracey may know her stuff in a parts store but I doubt she was raised on a farm or she would surely know about Barr's Leaks. NOW, If she was talking about the head gasket repair product then that is a totally different story. THAT stuff is bad news! The other name for it is engine glass and it is what you put in a car with a leaking head gasket and then sell the car quickly!!

[Aaarrghh]

I agree it should be flushed, next week I'll camp where there's water so I'll do it then. There's still probably a puddle of juice left in the cavity below the core that will slosh until it dries, so it will be a while before the carpet can be put back.


The hose connector I got was thin plastic. Better get a spare. Hm? Good excuse to visit Tracy again  W%

BTW the new core I bought in a panic is aluminum. I'd prefer a copper and brass one. Anybody want this aluminum one?

[Rickf1985]

The aluminum is stronger and will give better heat transfer. The copper ones you get nowadays are from China and are half the thickness of the originals. Everybody dissed aluminum radiators when they came out but those of us using them will tell you first hand that they are much, much better than the copper ones. Cheaper and a LOT lighter also.

[TerryH]

The aluminum is stronger and will give better heat transfer. The copper ones you get nowadays are from China and are half the thickness of the originals. Everybody dissed aluminum radiators when they came out but those of us using them will tell you first hand that they are much, much better than the copper ones. Cheaper and a LOT lighter also.

X2

[Aaarrghh]

The aluminum is stronger and will give better heat transfer. The copper ones you get nowadays are from China and are half the thickness of the originals.

What about corrosion resistance and proper anti-freeze? I'm using O'Reilly Conventional Green (or Zerex Original Green recommended for my vehicle, when I can find it), partly because till now there's been no aluminum parts in my system. My new radiator as I said is copper and brass, like the original.

[Rickf1985]

Modern coolants are formulated for aluminum radiators since that is all that is used anymore. If you have any concern just read the label and it will tell you if it is or isn't compatible. And be sure to use brand name coolants, once you start going to the cheap stuff all bets are off! Coolant is something that only needs to be changed every five or six years so buying a better brand is money in the bank. And also buying the concentrate and mixing it 50/50 yourself will save you a bundle! I cannot believe they charge more for a gallon of premix than they do for a gallon of concentrate that will make two gallons of the premix! Talk about a racket!!!! Considering how many vehicles I have plus side jobs I always watch e-bay and Amazon and I can usually get Prestone or one of the other name brands of concentrate by the case for about half of what you pay at the big box stores. A case is six gallons.

[Froggy1936]

I asked a counterman at the parts store NAPA why the cost is more for mixed he answerd quickly they mix with distilled water Frank

[Aaarrghh]

Ha ha ha! So what's a gallon of distilled cost at a grocery store, $1? Rick is right, what a racket!

OK, on the label, the O'Reilly's Conventional Green states, in part, "provides rust and corrosion protection to all cooling system metals, including aluminum ...", so I guess the aluminum core will be alright. I don't consider it "cheap stuff." It's recommended for Ford and Chrysler, 2000 and older, and GM and all others, 1995 and older. I use it because I can usually pick up a gallon wherever I happen to be, if I need it. The Zerex, my first choice,  has to be ordered by the case. I don't have space to keep that much bulk.

Ditto of course on the concentrate. When my overflow tank needs a little topping off, I just pour in a plastic cup of concentrate and a cup of water, to keep the 50/50 mix.

Actually, since the water evaporates more readily, my mix is probably more concentrate. Hmmm.

[Rickf1985]

With a closed system and a overflow bottle there should be no loss through evaporation since the fluid has very little air contact other than the tiny bit of air in the recovery bottle. And that is not enough to show any loss of fluid over at least a year. If you are loosing fluid then you have a leak somewhere.


And anyone who has an air condition or dehumidifier has plenty of free distilled water supplied from those units which just normally goes down the drain or on the ground.

[Aaarrghh]

If you are loosing fluid then you have a leak somewhere.

Well, I darn sure did!