Lessons Learned... or, how I discovered Bar's Stop Leak and what I used to fix the brand new heater core it clogged up.

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Jan 7, 2021
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Howdy ya'll, long time lurker, first time poster. Fair warning, I'm not new to forums and can be a little long-winded.

I figured I'd make my introductory post here by detailing my recent overheating debacle, the mistakes I made, and the fixes to all of my issues. The vehicle in question is a 2013 Ram 1500 with the 4.7L V8 motor.

So, I'm stationed in South Carolina and we were planning to visit family over the Christmas and New Years holiday. About 4 hours into the drive on December 19th, shortly after rapidly accelerating after a restroom break at a Love's truck stop, my dash started flashing an overheat warning. I got off at the next exit and stopped at an Autozone (first building off the ramp thankfully), stopped the truck, and promptly watched the overflow bottle boil over. After letting it cool down, I was able to get the rad cap off, top it off, and limp it down the highway to my inlaws' house. It was definitely only being air cooled for the last 1.5 hours of that drive. If I touched the gas, the temp shot up and if I was coasting the temp slowly dropped. The truck has a nice digital cooling readout in the dash, so I was able to observe the temp fluctuating between 225 and 250, however the overheat light never came back on so that tells me it was way hotter than that when I did get the overheat light.

After speaking to my mechanic uncle, I swapped the thermostat. Didn't fix anything. Swapped the water pump. Didn't fix anything. Now, let me pause to say that I'm generally very mechanically inclined. I've been an aircraft avionics technician for almost 14 years and digging into things like this doesn't phase me. That being said, my uncle had mentioned that I may have a blown head gasket and I decided to dump about 3/4 of a bottle of Bar's Head Gasket Repair into my radiator (without searching google beforehand). It was kind of a knee jerk reaction and a mistake. I'm sure most people here know this, but DO NOT USE THIS STUFF IN YOUR VEHICLE. Immediately, my overheating issue became exponentially worse and I couldn't drive the truck a half mile without the temp skyrocketing to 260 degrees and overheating.

At this point, we rented an 18 foot trailer and hauled my truck to an auto shop down the road. They tested the coolant and determined that I did not have a blown head gasket, thankfully. They diagnosed and extremely clogged radiator as well as a shot fan clutch. I agreed to their replacement solution (at 4pm on a Tuesday) and they called me at 10am the next morning saying my truck was fixed. Out the door price was $499.35 which included the coolant diagnostic, radiator, fan clutch, and labor. The caveat to this is that they said the heater core was extremely clogged up and there was little to no heat blowing.

I tried flushing the heater core out with vinegar and CLR, but neither worked. Ordered a heater core from Rock Auto and had it in two days. We actually had to drop the steering column, pull the entire dash, and evacuate the AC system to get the HVAC unit out in order to replace the heater core. After replacing it and re-assembling everything else, I was optimistic as I started getting warm air as the system started to come up to temp. However, after running the system a few times while trying to burp out air bubbles, it became apparent that residual Stop Leak crud was clogging up my brand new heater core.

Jump to a few days ago, back home in South Carolina, and I remember watching a video of a guy on YouTube swearing by a product by IronTite called Thoroflush to get Stop Leak out of your system. After driving 6 hours in 40-50 degree weather with no heat with a wife/baby on board, it was time to try something besides vinegar and CLR. During this whole process I also discovered the auto shop put universal green coolant in, so that was in the plan to swap out as well.

I started by draining the radiator completely. I then installed a flush kit on the heater inlet hose and flushed the whole system for nearly 10 minutes, until the water flowing out was completely clear. I then removed the thermostat (which was caked up with all sorts of stop leak fibers) and reinstalled the housing. Filled the system with water again, then followed the instructions on the bottle of Thoroflush. Drain a gallon of fluid from the radiator, mix the thoroflush with a gallon of warm water, shake well to dissolve the crystals, then pour into radiator. If you don't have spill-free funnel at this point, get one! Absolutely the best thing ever made for burping a coolant system. Anyways, after the truck got up to temp, I set a 12 minute timer, revved the motor several times to circulate the product, then turn off the truck at the 12 minute mark. After letting it cool down, I drained the entire system and flushed absolutely everything for several minutes with a garden hose, then blew out as much hose water as I could with low pressure air. You would not believe the amount of crap that came out of this thing. It looked like someone dumped a few cups of beach sand into the system. Thoroflush did its job for sure. After priming the water pump and heater core, then filling the radiator and reservoir with fresh, up to spec (MS-12106) coolant, my heat has never blown hotter and the truck has never ran cooler. My average temp after a few days of driving in 50 degree weather is around 200 degrees and my heat is blowing nearly 150!

I mainly made this post to help out others. After doing a few google searches, there really isn't much documentation on how well Thoroflush works so I wanted to help our those search results for folks that have clogged up radiators and heater cores or for those wanting to rid your system of Stop Leak products. For around $20 and a few hours of my time, my truck is running great!

- Matt
 
Yep my dad used to swear by that sealer stuff for the cooling system and head gaskets and everything then we realized how bad it was and never used it again. And never will. And being made by a reputable company we thought for sure it was good stuff wrong. At least you know now and hope you will tell others too.
 
What I read is that you are making a blanket recommendation to avoid this product. I am questioning if the main problem was user error.

- You added the product to a poor functioning system that you did not diagnose and fix properly first. It seems that the root cause of overheating was the bad fan clutch? It might be that the product does not work well in a system malfunctioning like yours was.
- Is there any chance that your "topping off" and/or subsequent addition of differing coolant chemistry may have contributed to clogging problems?
- Maybe there was air in the system when you added the product?

Your information regarding Thoroflush is certainly helpful. I would contact Bar's Leak, tell them your story, and request their opinion why your radiator and heat exchanger clogged. It seems that you took a bad situation and made it worse, maybe not because the product is bad, but because you used it in unfavorable conditions.

Thanks for sharing. Many may find it difficult to read the very long thread to extract the facts.
 
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What I read is that you are making a blanket recommendation to avoid this product. I am questioning if the main problem was user error.

- You added the product to a poor functioning system that you did not diagnose and fix properly first. It seems that the root cause of overheating was the bad fan clutch? It might be that the product does not work well in a system malfunctioning like yours was.
- Is there any chance that your "topping off" and/or subsequent addition of differing coolant chemistry may have contributed to clogging problems?
- Maybe there was air in the system when you added the product?

Your information regarding Thoroflush is certainly helpful. I would contact Bar's Leak, tell them your story, and request their opinion why your radiator and heat exchanger clogged. It seems that you took a bad situation and made it worse, maybe not because the product is bad, but because you used it in unfavorable conditions.

Thanks for sharing. Many may find it difficult to read the very long thread to extract the facts.
I guess I should amend to say you should only be using this product as a last result for a known problem if you have to limp your vehicle somewhere. It wouldn't be a bad idea to bypass your heater core in the event you need to use it as well.

- I truly believe the radiator was already partially blocked. I initially followed your logic that the bad fan clutch was the root cause, but this vehicle has a dual fan setup and the electric fan works as it should. I'm leaning towards a combination effort between the fan clutch and radiator, but again, that's just speculation.
- When I topped it off, I used the correct spec of coolant, however I'm fairly certain the truck had the legit Mopar 5-year stuff and I added in the Valvoline equivalent.
- I suppose there could have been air in the system somehow, but I've had the truck for 3 years and never touched the cooling system. From my understanding, the Bar's Leak stuff activates when it encounters air in a pressurized system, so that's a fair point.

I've looked on Bar's Leak's website and they claim that their products should not clog a heater core. I'd nearly argue that to be true for a new vehicle that hasn't had time to build up any gunk in the system. There is, however, tons of anecdotal evidence scattered across the internet of many instances where stop leak clogs up all kinds of stuff.
 
Great story, thanks for sharing.
Did you ever discover the root cause of the original problem?
Not really, I'm leaning towards a partially blocked radiator and a bad fan clutch. I know the heater core was already partially blocked up because the passenger side always blew hotter than the drivers side. It's a known issue with these trucks. The way the HVAC unit routes air, the driver side pulls from the outlet side of the core and the passenger side pulls from the inlet side. The outlet side tends to block up first, and voila, bad heat on driver's side. By that logic, its not too far of a stretch to assume the radiator had some inefficiencies from buildup over the years as well.
 
FCA introduced their new 10 year OAT coolant in 2013, so your truck might have been either the 5 year HOAT coolant or the 10 year OAT. Making matters worse, that first year (2013) some of the new 10 year coolant was orange-ish (FIAT sourced) and some was purple/pink (Mopar sourced).

This is a good, educational thread and it's not my intention to bust your chops! :)
 
Bar’s Stop Leak has been around a long time. I always had good luck with it, but that was when cooling systems were not as sophisticated as today.

Good story here. Back around 1964, I had a 57 Ford that I used to drive between Norfolk and Rochester. One day, something went THROUGH the radiator. Coolant pouring out. Shoved a cloth into hole with a pencil. Left it there, then poured a small bottle of Bar’s in radiator. Stopped leak completely. Worked so good, after a week or so, I cut the extra cloth and extra pencil off, leaving most in the radiator. Lever leaked.
Worked for me who did not have much money at the time.
 
Not really, I'm leaning towards a partially blocked radiator and a bad fan clutch. I know the heater core was already partially blocked up because the passenger side always blew hotter than the drivers side. It's a known issue with these trucks. The way the HVAC unit routes air, the driver side pulls from the outlet side of the core and the passenger side pulls from the inlet side. The outlet side tends to block up first, and voila, bad heat on driver's side. By that logic, its not too far of a stretch to assume the radiator had some inefficiencies from buildup over the years as well.
So if the original problem was an already partially blocked radiator and heater core, and an inoperative fan clutch why did you add the stop leak? At what point was the system leaking? I can't find a mention of a leak anywhere in your posts.
 
So if the original problem was an already partially blocked radiator and heater core, and an inoperative fan clutch why did you add the stop leak? At what point was the system leaking? I can't find a mention of a leak anywhere in your posts.

Sounds like that was added to "seal up" a possibly bad head gasket.

But, wow, overheating a 4.7 that many times. That's asking to drop a valve seat ... or 16
 
Also good to note is that the product that the OP is talking about is not the Bars Leak radiator sealer, but is actually a Bars Leak product marketed for head gasket repair. It contains sodium silicate.

 
FCA introduced their new 10 year OAT coolant in 2013, so your truck might have been either the 5 year HOAT coolant or the 10 year OAT. Making matters worse, that first year (2013) some of the new 10 year coolant was orange-ish (FIAT sourced) and some was purple/pink (Mopar sourced).

This is a good, educational thread and it's not my intention to bust your chops! :)



^^^^^^^^^^^^^^^^^^^^^^^^

Really well stated and very nice post.
 
I guess I should amend to say you should only be using this product as a last result for a known problem if you have to limp your vehicle somewhere......

- I truly believe the radiator was already partially blocked......

- I suppose there could have been air in the system somehow, but I've had the truck for 3 years and never touched the cooling system.........
Focusing on these points it appears the condition of the coolant is/was questionable. I have used the tablets with fresh coolant for more than 20 years in my family's vehicles primarily for maintenance purposes. Most new autos have the tabs installed at the factory. This is the only Barr's product I use
I would never use any product in contaminated or otherwise dirty coolant. Especially with an overheating issue.
My grandson visited us recently and his overflow tank was empty. He had recently had his oil changed at the Valvoline center and they topped his tank. He had driven nearly 200 miles to our home.
I couldn't find the source of leak. Upon opening his radiator the level was low but the coolant was clean and protection was -24. I added a full gallon of Prestone which put him just barely above the full line and dropped in the tablets.He drove back home and for more than a month now, no more coolant loss. So far so good and the fix may not last but it got him home.
The product has never plugged any of my heater cores or others that I have used the product in. It is designed to pass through a 24 gauge screen. With dirty coolant I am sure that plugging could occur.
I always check to make sure there's no coolant in the oil which would be a sign of a faulty head gasket.
No disrespect to the OP but it would appear the wrong treatment was applied for an unknown condition.
 
Also good to note is that the product that the OP is talking about is not the Bars Leak radiator sealer, but is actually a Bars Leak product marketed for head gasket repair. It contains sodium silicate.


My understanding is that the Bar’s (or alumaseal) ginger powder IS used by OEMs, and a small amount is ok for use. IIRC, GM even recommends its use as PM.
 
Thanks for the "Throflush" education. I'd never heard of it.

RELATED POINT: Sis' '88 Jeep had 6 different colors of hardened ooze hanging off the radiator's backside.
The heater core was plugged with grey, putty-like material.
In desperation I tried gasoline on a chunk that came out and it dissolved.
I put a foot of scrap hose on the core's in and out nipples.
Slow trickle of gas dissolved the putty.
Dangerous, I know, but it was Winter and I did it outside and caught all the excreta in a jug.

That was one time I accepted payment from my sister.
 
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I used this same product (Bars Leak HG fix) on an engine that was on it's way out just for 'fun', and had the same result-clogged heater core, no heat. Reverse flushing the heater core completely unclogged it, no cleaning products needed-just water!
 
My understanding is that the Bar’s (or alumaseal) ginger powder IS used by OEMs, and a small amount is ok for use. IIRC, GM even recommends its use as PM.
I have used GM's vegetable based sealer with good results. First on a 3.0 vulcan that leaked around the front cover. The other was the Buick in my sig. After an accident, radiator mount tabs on one side cracked and seeped, now leak free for 3 years.
 
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