Coolant Smell In Cabin (again)

[BlueMustang]

Hey all, I have a 98 S70T5 with 212K miles. I have replaced the heat exchanger (heater core) once, probably 2 years ago from FCPGroton. We have been having a coolant smell in the car again. I just removed the heater core to see if it was leaking again and did NOT notice any obvious signs of leaking - or a source for the smell. Both carpets are bone dry and there is no indication of any leaking into the tunnel. Plus the bottom of the core appeared perfectly clean too.

Is there any other place in the cabin (besides the heater core) that has coolant flowing through it? I'm wondering if there is a different coolant leak "somewhere else"????

Is it possible that the core is leaking very little and not leaving behind telltale stains (pinhole leak) or something?

I want to make sure that if I replace the core again, that I am fixing this problem.

Thanks.

Jim B.

P.S. I think I already know the answers, but wondered if anyone else had more insight.

[TM850R]

What brand heater core did you buy from FCP?

[BlueMustang]

Nissens. Does that matter???

What brand heater core did you buy from FCP?

[Serge]

Well, coolant smell in the cabin does not necessarily mean the heater core. When my radiator was leaking I would get a MASSIVE coolant smell in the cabin, same thing with my leaking expansion tank.

Nissens is pretty much an OEM brand, so it shouldn't have gone bad in 2 years.

When you replaced it, did you put in new o-rings and clips? There might be some coolant evaporating into the cabin from those seals.

[RZT5]

I'm having the exact same issue with my car now. no signs of leaking at all, but when you turn the heat on you smell coolant for a few seconds right after you turn it on right?

my mechanic said the seals in the heater core are probably leaking a very tiny amount, just enough to make it smell. he said i can replace the core and o rings or try using a coolant system conditioner, i forget the name of the one he recommended. so i'm going to try that first, i'll post results

[BlueMustang]

Hmm, I honestly don't remember if I did (or did not) replace the seals when I last did the core. Assuming I did NOT replace them, if it were leaking there at the seals, wouldn't there be telltale leakage on the center hump or carpets? Both were bone dry and leak/stain free.

LiquidKernel: As far as "clips", I'm not sure what you mean? I replaced the core (and maybe the two corresponding o-ring seals - not sure). What clips are you referring?

If we're leaking under the hood, it's a very small amount. The coolant level remains fairly constant. I'll check again for obvious leaks in the expansion tank and the radiator.

Perhaps it's time to try the coolant system "conditioner"...

Thanks. Jim B.

Well, coolant smell in the cabin does not necessarily mean the heater core. When my radiator was leaking I would get a MASSIVE coolant smell in the cabin, same thing with my leaking expansion tank.

Nissens is pretty much an OEM brand, so it shouldn't have gone bad in 2 years.

When you replaced it, did you put in new o-rings and clips? There might be some coolant evaporating into the cabin from those seals.

[uclamark]

Hmm, I honestly don't remember if I did (or did not) replace the seals when I last did the core. Assuming I did NOT replace them, if it were leaking there at the seals, wouldn't there be telltale leakage on the center hump or carpets? Both were bone dry and leak/stain free.

LiquidKernel: As far as "clips", I'm not sure what you mean? I replaced the core (and maybe the two corresponding o-ring seals - not sure). What clips are you referring?

If we're leaking under the hood, it's a very small amount. The coolant level remains fairly constant. I'll check again for obvious leaks in the expansion tank and the radiator.

Perhaps it's time to try the coolant system "conditioner"...

Thanks. Jim B.

I had a similiar issue like yours just recently. I was losing coolant over time and my cabin smelled like maple syrup when I had turn the heat up. I checked all the lines and found no leaks except for a slight drip on the petcock of the radiator. Once that was corrected, I still had a loss of coolant over time. To address that issue, I had to correct the maple syrup smell since I was probably losing coolant via the heater core. I'd proceeded with buying a new heater core with new o-rings.

When I replaced my heater core, it did not show any sign of leaks (ie precipitate on the fins of the heater core, but when I checked the o-rings, the o-rings were a bit brittle which may have allowed a small amount of coolant leakage. Once I'd replaced the heater core and o-rings, the maple syrup and coolant loss issue was resolved.

By the way, I'd used a Behr heater core.

Mark