Stop leak for the heater core?

[Viking Jeeper]

2006 with 4.0 and 26,500 miles. I recently did a thermocure cooling system flush and it sprung a very small leak in the heater core. After the flush I found a large amount of liquid under the passenger carpet, just once. Since then I have kept the carpet out to monitor the leak and the cooling system has been filled with Mopar HOAT coolant. I see a small amount of coolant on the floorboard infrequently (every 8 drives or so) and very little when I do. I would like to put off a heater core swap. Has anyone had any luck with a stop leak product? I am slowing collecting every cooling system component and plan a complete refresh but would like to get some more time on these components before upgrading everything.

 

[RMETeeJay]

Since you’re in FL, just bypass it until you’re ready. Don’t put any sealer in your cooling system.

 

[Zorba]

Stop leak didn't work for my heater core. Its now bypassed until such time I'm ready to deal with it. Being that this is Florida, that time may or may not be 10 minutes short of "never" - we'll see.

 

[Viking Jeeper]

I have what I need to bypass the core but still use it at times in the winter.

 

[Viking Jeeper]

Stop leak didn't work for my heater core. Its now bypassed until such time I'm ready to deal with it. Being that this is Florida, that time may or may not be 10 minutes short of "never" - we'll see.

what product did you use?

 

[Sancho]

I wouldnt put gunk in the cooling system.

 

[Zorba]

what product did you use?

To be honest, I don't remember. I know my late father had good success with stop leak in a couple or three of his vehicles. The one that I remember best was the '80 Mazda GLC that sprung a radiator leak. Stop leak stopped the leak, and he never did have to do anything else to it - and it was years and an engine rebuild and it was still OK.

But it didn't work for me and the heater core. I figured it didn't hurt to try it - neither myself, my father, nor anyone else I know ever had any problems whatsoever with a cooling system thus treated, despite all the hand wringing one often hears on this subject. YMMV and all that...

 

[Viking Jeeper]

I figured I would get a lot of good advice that says dont put additives in your cooling system and I was right. If I do plan to replace everything at some point is there any harm in giving a stop leak product a try?

 

[jeepguy03]

Since you’re in FL, just bypass it until you’re ready. Don’t put any sealer in your cooling system.

+1

DO NOT and I repeat DO NOT put stop leak in your cooling system. It will clog the radiator, the heater core, the cooling passages in the head, and the cooling passages in the block. I worked on a family member's truck who put this stuff in there. We replaced the radiator, he had the heater core replaced, and it has been flushed several times, yet that stuff still remains in there. The only thing that kept it clean enough to cool adequately is a coolant filter. I can't tell you how much money he has spent just from that small bottle of stop leak. One shop he went to actually just told him they won't touch it and guarantee their work unless the entire engine block is replaced.

Just bypass the heater core for now, I can't stress this enough.

 

[Z06]

Getting ready to try some in mine. Only getting smell of coolant when first turning on heater. No visible loss of coolant yet. Hope to at least get it through the winter. High of 28 tomorrow so really don’t want to bypass yet. As Zorba mentioned I have never seen anything detrimental to overall cooling system using stop leak. Most off the time it won’t plug a pin hole so chances of plugging anything up is pretty slim. If it doesn’t work it will get flushed out of the system when replacing the heater core anyway. OP has 26000 miles and bad heater core. Way to go Chrysler.

 

[Z06]

+1

DO NOT and I repeat DO NOT put stop leak in your cooling system. It will clog the radiator, the heater core, the cooling passages in the head, and the cooling passages in the block. I worked on a family member's truck who put this stuff in there. We replaced the radiator, he had the heater core replaced, and it has been flushed several times, yet that stuff still remains in there. The only thing that kept it clean enough to cool adequately is a coolant filter. I can't tell you how much money he has spent just from that small bottle of stop leak. One shop he went to actually just told him they won't touch it and guarantee their work unless the entire engine block is replaced.

Just bypass the heater core for now, I can't stress this enough.

Yeah right. And yet it usually wont stop a pinhole.

 

[SkylinesSuck]

I have always been skeptical of stop leak stuff and just like fixing stuff the right way to begin with. I developed a very small coolant leak from one of the freeze plugs in the back of the motor inside the area covered by the bell housing after I installed my new stroker. The stroker guru (Russ P) suggested GM coolant tabs. They look like miniature hockey pucks made from saw dust or something. They were evidently used from the freakin factory on certain year Corvettes due to known machining tolerance variations causing leaks. They dissolve and plug the leak or just continue to float around if they never see air. He assured me there was nothing in the system small enough to get plugged up by then except a small leak. I tried them and it stopped my very small weep and have had no issues otherwise fwiw. My coolant also looks brand new still. The amount is very miniscule. I still would never pour in a bottle of they metallic looking sludge stuff they sell at the parts store.

 

[Viking Jeeper]

I see some tablets that sound similar on Amazon. Some reviews say they are in many factory cooling systems although I find that hard to believe.

https://www.amazon.com/dp/B000KKND3Q/?tag=wranglerorg-20

 

[SkylinesSuck]

Yeah those look pretty much the same. I think the consistency might be a little different between brands but I'm not sure that matters. I could crush the gm ones into dust with my fingers.

 

[SkylinesSuck]

https://www.amazon.com/dp/B000QIH3C4/?tag=wranglerorg-20

 

[Viking Jeeper]

https://www.amazon.com/dp/B000QIH3C4/?tag=wranglerorg-20

No shit! AC Delco.

 

[JEEPCJTJ]

If you live where it gets too cold to bypass your heater core you need to move further south.

Seriously, if you're going to replace everything at the same time eventually anyway I wouldn't worry too much about giving a stop leak product a try.

Two different times I heard from someone that used way too much and/or had a leak that was way too big for this stuff too fix no matter what while many of the poor reviews I've read are from people that are mad about wasting less than $10 while trying to fix a leak that was also too big to fix.

 

[Mr. Bills]

My two cents:

Bypass the heater core.

Don't use "stop leak" products, especially the ones that look like mouse turds. "Stop leak" products are intended to get you home in an emergency so you can perform proper repairs, not to drive around while you collect parts.

 

[jeepguy03]

Yeah right. And yet it usually wont stop a pinhole.

Don't say nobody warned you. I'm sure my uncle who has spent thousands on his truck would wish he never used it. Don't be lazy, fix it right the first time. Do yourself a solid and watch some youtube videos on what stop leak can do to an engine.

 

[Rubicon88]

Aluminum dust is the only thing I'd even remotely consider abd that is on a "if I really had to"