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Coolant smell 2009 Jeep Grand Cherokee

I have a distinct coolant smell inside my Jeep (2009, 60k miles). I popped the hood and couldn’t spot any leaks nor was there any fluid underneath the vehicle. I took it into a mechanic and they smelled the same thing and put the coolant system under pressure (as well as doing a visual inspection), and could not find any leaks nor was there any evidence of fluid by the vents. They also noted that my coolant levels were still full and I had not added anything to the car. The current theory is a pinhole leak in the heater core (the smell is definitely worse after the car has been driven a bit).

I have had one suggestion to add Bar’s Stop Leak to the radiator, but the mechanic said this was a Bad Idea (his argument being that since there was no visible leak in the system it would likely just gum things up). Since the vehicle seems to be otherwise operating fine, I’m hesitant to replace the heater core, but there’s a good chance it’s still under warranty, so I could go that route.

So, could it be something other than the heater core? Should I have that replaced or would the Stop Leak be a good idea?

A warranty on a 7 year old vehicle?
Are you sure?

In any event, I can tell you from personal experience that aerosolized coolant is very bad for your lungs, and even if you have to bite the bullet and pay for this yourself, paying for the repairs is better than giving yourself and your passengers serious respiratory problems by continuing to drive with that type of situation.

Just be prepared for a very large repair bill, as this is one of those situations where the part costs…maybe…$90, but the labor amounts to several hundred $$.

As a test you could disconnect the hoses to the heater core and tie them together with a connector, thus removing coolant and pressure from the core.
If the smell goes away you have your answer.
This will leave you with no heat and winter approaches, but it’s only a test.
Or just pretend you’re driving an early Beetle.

I agree with the comments so far. You don’t want to breathe this for long. Also, as this gets worse, you’ll probably find a hard-to-clean film on the inside of your windows reducing your visibility in some conditions.

I’ve been noticing a very faint coolant smell from the engine compartment of my Corolla for about 8 months, but no signs of a leak. I have had to put a cup of coolant in the plastic bottle every 6 months, but that’s the only hard evidence there’s a leak. Then the other day I noticed a drop of coolant on the ground under the car. Turns out on further inspection there’s a leaky gasket where a metal pipe connects to the water pump. So it doesn’t take much of a leak to create a noticeable odor.

I concur w/your shop to not use any stop-leak products. Do a little more experimentation to make sure the source of the odor is actually inside the cab. If there’s a leak in the engine compartment it could conceivably be pulled into the cab through the air vents under the windshield. Especially if you had the AC set to Fresh Air. If you decide it is definitely source inside the cab, best to go for a proper fix. It’s possible the heater core isn’t leaking, instead it is just a connector to the heater core is springing a little leak.

Edit: One other idea, It might be possible for a clever shop to rig up a way to pressure test just the heater core.