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Another heater core thread

Volatile

NAXJA Forum User
Location
Delaware
Hi all.

My 91 Laredo was starting to smell a bit like coolant inside the last winter I drove it (4 years ago). After getting her running in the summer and driving it this winter, the coolant smell intensified. I first bypassed the HCV after going through three of them in a matter of two weeks. I'm concerned it's the heater core now, since when the thermostat opens, I immediately get a strong odor of coolant that lasts for about 30 seconds. I can also smell it with the defroster on, and I'm getting some buildup on the bottom section of my windshield. The floor isn't wet anywhere and I haven't noticed a loss of coolant, so I'm hoping this isn't urgent yet. Before I get my AC discharged and start tearing apart the dash, I wanted to get some second opinions, if there are any.

I've watched many, many videos about this job, and I found one where the guy only seems to take out part of the dash: https://www.youtube.com/watch?v=XdSgWt1Qi5Q&t=318s

My 91's dash looks the same, so could I get away with following this? Is there some other good resource for this? I searched a lot but when I find a good thread all of the photos are gone from photobucket.

Thanks
 
Rent a test rig and pressure test the entire cooling system. Could be dead varmint remains, mold from stagnant condensate water and dead leaves in the duct work box, LOL
 
Rent a test rig and pressure test the entire cooling system. Could be dead varmint remains, mold from stagnant condensate water and dead leaves in the duct work box, LOL

Well it sat outside, uncovered for close to four years in a driveway in the woods so that is definitely not out of the realm of possibility. I wasn't aware gunk in the system could cause the same symptoms. Could I first try flushing just the heater core to see if it's partially clogged? If it's filthy I could then flush the whole system, since I haven't done a proper complete flush since getting it back on the road (I know, stupid). The coolant is a healthy green color, so I haven't been too worried. My heat works great and is plenty hot, if that gives any other kind of indication.
 
You are talking about the inside of the heater core, I am talking about the outside of the core, in the air box duct work it sets in. You could have rat colony making a homestead in there.

Well it sat outside, uncovered for close to four years in a driveway in the woods so that is definitely not out of the realm of possibility. I wasn't aware gunk in the system could cause the same symptoms. Could I first try flushing just the heater core to see if it's partially clogged? If it's filthy I could then flush the whole system, since I haven't done a proper complete flush since getting it back on the road (I know, stupid). The coolant is a healthy green color, so I haven't been too worried. My heat works great and is plenty hot, if that gives any other kind of indication.
 
Possible, but fogging windows is pretty indicative of a failed heater core.

Or high humidity inside the cab caused by Humans breathing, and cold air outside on the windows making the water vapor condense inside on the windshield. A working AC solves that by operating the defrost mode if the AC system works?

BTW, if you have a small leak, adding BARs leaks dry round brown fiber pellets to the cooling system can seal the leak.

If you rent (they are free rentals) and use a pressure tester, you pump up the system with air, like a tire and come back later to see if it held pressure or not.

Then if you have a leak, the next question is where is the leak.
 
This worked for me on my 85 XJ.

creative-auto-tuning-60.jpg
 
Or high humidity inside the cab caused by Humans breathing, and cold air outside on the windows making the water vapor condense inside on the windshield. A working AC solves that by operating the defrost mode if the AC system works?

BTW, if you have a small leak, adding BARs leaks dry round brown fiber pellets to the cooling system can seal the leak.

If you rent (they are free rentals) and use a pressure tester, you pump up the system with air, like a tire and come back later to see if it held pressure or not.

Then if you have a leak, the next question is where is the leak.

Is the Barr’s stuff safe for our cooling systems? I’ve heard good things about the fine silver powder stuff not gumming up the system. I was considering using something like that until the weather is decent, then renting one of those pressure testers and fixing it permanently.
 
Is the Barr’s stuff safe for our cooling systems? I’ve heard good things about the fine silver powder stuff not gumming up the system. I was considering using something like that until the weather is decent, then renting one of those pressure testers and fixing it permanently.

You'll be sorry.............
 
Well I hadn’t really committed to trying it, considering the risks involved. I’ll more than likely just drive it as little as possible until I can get the heater core out, along with some other worn out parts that need attention.
 
I have used Bars leaks for 45 years. The dry round pellets are what the OEM folks have used in the radiators of all brand new cars since the dawn of Man (WWII) per the folks at Preston (1994- 2 hour interview I did with one of the old timer chemical engineers at Preston when I had a US DOE R&D grant), to keep them from leaking till the warranty runs out.

It works in tandem with the ingredients in the coolant (Silicates in our case) to seal leaks by forming a composite silicate-carbon fiber patch in the pin hole of any leaks. I have never ever had any water pumps or radiators clog up, or die in 45 years using it on over 40 rigs. Some I had for 15+ years with the same water pump and radiator and heater core. I used it to seal a leaking head gasket for 30,000 miles and 18 months on a Ford once. Never had any issues with the heater core or radiator the next 12 years after replacing the head gasket and cracked heads (The head cracks etc, happened before we used Bars leaks to drive it in limp mode).

The brown pellet fibers in Bars Leaks also helps stop head gasket leaks from even starting per Preston, and I can explain why if you want to know? The silicates in the old style conventional antifreeze also do this. They work as a team!!!! In fact the fibers in a paper head gasket are similar to the fibers in Bars leaks!!!!

What will fork up the entire system is USING TAP WATER!!!!!

Well I hadn’t really committed to trying it, considering the risks involved. I’ll more than likely just drive it as little as possible until I can get the heater core out, along with some other worn out parts that need attention.
 
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I have used Bars leaks for 45 years. The dry round pellets are what the OEM folks have used in the radiators of all brand new cars since the dawn of Man (WWII) per the folks at Preston (1994- 2 hour interview I did with one of the old timer chemical engineers at Preston when I had a US DOE R&D grant), to keep them from leaking till the warranty runs out.

It works in tandem with the ingredients in the coolant (Silicates in our case) to seal leaks by forming a composite silicate-carbon fiber patch in the pin hole of any leaks. I have never ever had any water pumps or radiators clog up, or die in 45 years using it on over 40 rigs. Some I had for 15+ years with the same water pump and radiator and heater core. I used it to seal a leaking head gasket for 30,000 miles and 18 months on a Ford once. Never had any issues with the heater core or radiator the next 12 years after replacing the head gasket and cracked heads (The head cracks etc, happened before we used Bars leaks to drive it in limp mode).

The brown pellet fibers in Bars Leaks also helps stop head gasket leaks from even starting per Preston, and I can explain why if you want to know? The silicates in the old style conventional antifreeze also do this. They work as a team!!!! In fact the fibers in a paper head gasket are similar to the fibers in Bars leaks!!!!

What will fork up the entire system is USING TAP WATER!!!!!

Yes I learned tap water is a no-no with cooling systems, I used distilled last time. I am interested in why the Bars stuff is different. According to their website, they recommend this stuff: https://barsleaks.com/product/liquid-aluminum-cooling-system-stop-leak/ which is what I've read around on various Jeep/XJ forums as being (relatively) safe. Is the brown pellet fiber product different entirely?
 
There is a copper and aluminum version. They both have the same brown fiber as in the brown tablets. Just not in a tablet form, and they have small amounts of copper or aluminum coated onto the fiber. All you need is the fiber and the silicates in the antifreeze/coolant. The key is the fiber!!!! The fiber is soft, non-abrasive, and is made up of long thin organic (tree like) fibers, the kind used to make head gaskets. They circulate in the coolant and anywhere there is a leak, the fiber gets hung up in the exit, and dries out with the silicate soaked into the fiber and forms an organic (Thing carbon fiber, but organic) silicate complex patch that is like concrete in the leak spot. It seals leaks as they form before you know they ever existed. The Preston guy said the Pellets were what the OEMs have used since since WWII in radiators on new cars. I switched from the copper powder like version to the dry pellets after that chat in the 1990s. I would not use the aluminum my self, maybe the copper in a pinch.

Oh, and Bars leaks liquid with the black oilly stuff and pellets is just the same fiber pellets, chunks of them with water soluble oil (lubricant), and I used it once or twice ages ago in the 1980s with no problems. Cracked black pepper (spice in the spice isle at the grocery store) is the fiber the race car drivers used ages ago.

Yes I learned tap water is a no-no with cooling systems, I used distilled last time. I am interested in why the Bars stuff is different. According to their website, they recommend this stuff: https://barsleaks.com/product/liquid-aluminum-cooling-system-stop-leak/ which is what I've read around on various Jeep/XJ forums as being (relatively) safe. Is the brown pellet fiber product different entirely?
 
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