So, I could smell that sickly sweet coolant smell with the heater on. I had the same problem a few years ago. At that time it turned out to be the heater core. Frustrated I ordered another heater core which arrived yesterday. I had a few days before prepped everything by disassembling the base pieces required to get the HC out.

Today I took it all apart and much to my dismay, the heater core appears to be intact and functioning normally. Since I already had the whole thing apart, and since I already had the new core, I am putting it back together.

When I took all the carpet and bolsters and such out, everything is dry as a bone under neath.

What could be generating this smell if the HC does not appear to be leaking? This has been an expensive endeavour. HC here in Canada are about 250.00

BTW: I tried the green silicone O rings on the tubes and they started leaking almost immediately, so out it comes again, arrggghhh!

I have to confirm the advice from another poster to place a garbage bag under the heater core before you remove it to capture the fluids that will come out of the core and the tubes, great tip.

 

its back together and remarkably the smell is no longer present.
The HC must have some very small and not noticeable hole present, because there was nothing visual to indicate it was leaking.

I guess it would difficult to pressure test this old HC?

I am baffled.

 

I have known heater cores to seep and last for years this way.
Sometimes they put off just enough to give you the odor of coolant that no one else in the car ever seems to smell.

Glad you solved the problem

I have never bench tested a core, only pressurized the entire system while it is still attached.

Defects can occur...sad that you had to do it again

 

Thanks.

I think what has in fact happened, but have yet to confirm is the rad is now leaking at the lower right corner, it is very minor. I can again smell a coolant smell. Perhaps it was the rad and I was getting the smell through the cabin air intake which is under the hood. I only noticed the rad leak because the front lower cowl was catching the coolant, until it accumulated enough to start falling. I feel bad because I know how bad AF is for the environment, so I will remedy right away.

I have tried the epoxy method as I read in another thread as a stop gap for the moment.