Heater Core / "Stop Leak"

My heater core has a slight leak which I can smell but see no noticible loss of coolant. I just assumed that I would replace the heater core but have learned what a big job that is. Bar's Leaks brand of radiator stop leak claims to be compatible with OAT/HOAT extended life antifreeze. Are there any problems with trying that first?

#1 it is not likely to work.
#2 it will probably clog things up and make a mess of your cooling system.

Make sure it is actually the core and not something else before you start tearing things apart too much.

I don't know if it's the heater core or perhaps a connection at the core but either way I have to go in. What I know is that when I call for heat the air coming over the core and into the cabin smells like coolant. AC odor is fine. No coolant leaks engine side.

I'm worried about adverse effects from the "stop leak" but I assume all normal openings are large enough to be not effected.

CTDieselHead said:

I'm worried about adverse effects from the "stop leak" but I assume all normal openings are large enough to be not effected.

Click to expand...

Not a safe assumption... radiator and heater cores have been known to get clogged by this stuff...

Yuri.

Don't do it.

Live with it until you have a weekend to do it. I'd do the fan and resistor pack while in there too. Cheap and since it's apart....Hey Where's AZGolf to BIT** me out for suggesting replacement of good parts....THE HORROR!

Check thermostat first. This is an OFTEN OVERLOOKED problem, causing temperature and pressure extremes. You have aluminum head which conducts heat much better than iron so the temperature excursions during high load conditions like accelerating onto the highway. Your temp gauge isn't fast enough to indicate these excursions but the thermostat, if inhibited, will not flow enough to meet demand. This causes pressure excursions.

Second, check pressure cap. Air pressure into the reservoir will show pressure relief range and volume.

Finally, you can block off and drain the heater core, then check it with air pressure to see the range of leak down. If it is a polyamide tanked, aluminum core, the most common leak is gasketing. Most of the time, these leaks will hold at lower pressures, leaking only at higher pressures. A leak in the core, from say corrosion of the brazed joints, will have total leak-down.

Take the o-ring out of the cap so you don't have pressure in cooling system.

joetdi said:

Take the o-ring out of the cap so you don't have pressure in cooling system.

Click to expand...

I don't think is a good idea ,the o ring is there to seal the system if you remove it it will leak , is like leaving the cap loose or out.

That is what I thought to. I have not had a pressureized cooling system in years. This is something you cannot do in high altitude though.

I have found that components like the radiator and heater cores last for almost ever without a leak. The constant expanding and contracting is what make them fail and most of the time it is at a seam.

As long as you have the correct mixture it does work well. However it will leak out if the car over heats but, if it over heats at sea level with the proper mixture you got others problems anyway.

If you are going to try a stopleak stick with Bars Leak. It has a good reputation and is less likely to cause a problem than some of the others. At one point I had a tech bulletin from Suzuki requiring that you use Bars Leak by name on their watercooled dirt bikes. Thats a really small radiator! Also, much older, I have seen a TSB from Jaguar stating that they had incorrectly blamed a batch of bad coolant hose on Bars Leak but when they stopped using it determined it was impossible to seal their engine completely without it.
You already know what the correct repair is but if that just isn't in the cards and you have to use a stopleak use Bars Leak or nothing.

Like the $40 bottle of stuff you use in all the 4.0 rover engines for the 120K mile head gasket issue.

use it as a LAST RESORT

I used this (Barr's) once in the radiator of a GM

sure stopped the leak... but it didn't stop the DEATH-KEWL coolant from turning into sludge