Stop leak for heater core?

[mikez71]

Haven't noticed my coolant level dropping, but I have been smelling coolant for about 10 days now. Usually when first getting in the car. Smell quickly disappears, usually catch one or two good whiffs of it before I can't smell it anymore. Running the hvac fan I can't smell it coming through the vents at all. Heater t's are dry, and any grime that is on the pipes does not smell of coolant.

Thinking about using stopleak of some kind. Leaning towards blue devil or prestone. Any suggestions or estimates on how long stopleak repairs can last?

It's gotta be a tiny tiny leak that seals when hot and opens as it cools leaving a tiny amount for the next startup. A couple days I didn't notice it, then it came back.
Also thinking about bypassing the heater core..

 

[89Suburban]

Could be a Tee fitting at the heater core connection ready to jump the shark on you. Or a slow weep on the radiator tank. Small enough not to drip on the ground but enough to get a whiff.

 

[Doubeleive]

Haven't noticed my coolant level dropping, but I have been smelling coolant for about 10 days now. Usually when first getting in the car. Smell quickly disappears, usually catch one or two good whiffs of it before I can't smell it anymore. Running the hvac fan I can't smell it coming through the vents at all. Heater t's are dry, and any grime that is on the pipes does not smell of coolant.

Thinking about using stopleak of some kind. Leaning towards blue devil or prestone. Any suggestions or estimates on how long stopleak repairs can last?

It's gotta be a tiny tiny leak that seals when hot and opens as it cools leaving a tiny amount for the next startup. A couple days I didn't notice it, then it came back.
Also thinking about bypassing the heater core..

didn't you post about this already?
if you are 100% certain it is the heater core, you could run some stop leak thru it but I would isolate the heater core from the rest of the system while doing it.
easily done by removing the t's and connecting hoses to the heater core and some kind of cheap harbor freight electric pump and a bucket

 

[mikez71]

yep, that was me. figured id watch it for a week, gotta be heater because i only ever smell it inside. somewhere i heard gm uses bars leak tablets at the factory..?

 

[George B]

Use the AC Delco Radiator Tabs.

ACDelco GM Original Equipment 10-108 Cooling System Sealing Tabs - 4 g (Pack of 5) https://a.co/d/dkhkvmg

 

[bill1013]

yep, that was me. figured id watch it for a week, gotta be heater because i only ever smell it inside. somewhere i heard gm uses bars leak tablets at the factory..?

Barr’s Pellets are the one for me. One bottle usually seals it nicely.

 

[mikez71]

Awesome! Yep I heard those AC Delco are rebranded barrs. Will go with delco anyhow. Thanks!

 

[me88]

Use the AC Delco Radiator Tabs.

ACDelco GM Original Equipment 10-108 Cooling System Sealing Tabs - 4 g (Pack of 5) https://a.co/d/dkhkvmg

I thought GM only used those for the Northstar V8 that was famous to leak everywhere. Remember that they will discolor the coolant a little bit, and one application supposedly is enough for the lifetime of the vehicle. You are not supposed to add more when you replace the coolant at some point for example.

 

[mikez71]

easily done by removing the t's and connecting hoses to the heater core and some kind of cheap harbor freight electric pump and a bucket

Sounds like it may need heat, tells you to run engine for 15-20 mins.. that and pressure will be missing if i isolate and manually pump? Also since it seems to leak when cold and sitting overnight, Im wondering if it will work now.. I think I'll chuck a couple tabs in the heater feed line.. maybe a couple times. not worried about radiator clogging as its old and due for replacement soon..

 

[mikez71]

I thought GM only used those for the Northstar V8 that was famous to leak everywhere. Remember that they will discolor the coolant a little bit, and one application supposedly is enough for the lifetime of the vehicle. You are not supposed to add more when you replace the coolant at some point for example.

good to know, thanks!