Radiator Stop Leak

[namwob]

I have a leak in the heater core on my cummins ISC. Can I use "Stop Leak" to solve this problem? What type... copper or aluminum?

[Clay L]

I used a GM stop leak product for my heater core about two years or so ago and it has worked well so far. It was recommended by Workhorse.

I have over four gallons of coolant in my system because I have the EngineAid option.
EngineAid keeps the water in the water heater hot while driving and also provides heat in the rear of the coach (I have a gasser). That requires enough coolant to go go from the front of the coach to about 2/3 of the way back.

Because of the additional fluid I used all six pellets in the package instead of the two recommended by the instructions for a car.

[Alan_Hepburn]

As I understand things the stop leak products get dumped into the radiator and they seal holes - I've never been able to figure out how the product knows which holes to seal. I mean there's holes in the cooling system that are supposed to be there to allow coolant flow - seems to me they'll get sealed along with the holes that aren't supposed to be there...

[Ray,IN]

Stop leak is a bandaid not a solution. It can plug passageways in the radiator in addition to plugging small leaks. On the other hand, with today's plastic and aluminum radiators it is much cheaper than a new one because they, for the most part, cannot be repaired with reliability.

[jimkate]

I've used Stop Leak many times over the years. Sometimes it was great, sometimes it didn't help at all. It seems to me that if it's a small crack, or pinhole, then it will work great. I know this isn't talking about it very technically, but I think when the chemical leaks out to air, it dries quickly, forming a leak barrier. That explains to me why it will plug holes that leak out to air, but not plug holes that are internal in the coolant system.

I have noticed that if I change the coolant, the leak may return if I don't put in new Stop Leak.

I have an old loader tractor that had a leaking radiator about 25 years ago, sealed with Stop Leak. It hasn't leaked a drop ever since.

[Gary RVRoamer]

None of this answers the original question: does he need aluminum or copper Stop Leak for the heater core in his coach (note - he is asking about the HEATER, not the Radiator).

This is not a Cummins question either - the heater is typically supplied by the body manufacturer and the radiator by the chassis manufacturer. Neither one comes from Cummins with the engine.

Sorry - I don't know the answer either. If you can identify the heater core brand, the manufacturer can help with the alum vs copper question.