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Discussion Starter · #1 · (Edited)
So the other day I was bleeding my coolant system and I saw a plum of steam come out of my heater vents, I thought it was my contacts and dismissed it and went about my day. Later on I was driving with the ac on and I heard a spewing sound coming from behind the dash. Now tonight my windows were all staying fogged with the defrost on, and ever since ce the bleeding issue I have been smelling coolant inside the car. I want to know is there an easy way to bypass the heater core, and also if you bypass the heater core would you retain the use of the ac, would stop leak work, or should I strangle my wallet and tackle the diy right away. Also is the any other part that could be broken on my car that might be easier to fix than a heater core that consider the same symptoms. Thanks for any and all help guys.

· // Quandt AG (Retired) //
3,667 Posts
You need to see if the heater core is leaking or possibly just one of the connections. Hopefully it is just a connection.

To buy time while you investigate you could bypass the heater core by connecting the out and in hoses at the firewall together with a connector like the picture. Remember that you won't have any heat while you bypass the core but it will allow the coolant to continue to circulate.

Don't use any sealer. It will destroy your heater core and cause other coolant component issues. The small tubes in a heater core have spiral bars inside to slow down the flow of coolant and transfer more heat to the metal. Sealer clogs this. One of the reasons I always test the heater of a used car at idle is to see if the heater blows hot air. If it doesn't often the core is blocked from a sealer - usually to mask symptoms of a blown or leaking head gasket.

You might want to start looking in behind the fan blower from the engine bay - you can get a fairly decent look at the heater core from there and you might be able to diagnose where a leak if any is originating.

As I said - I hope it's just a connection as the heater core is a PITA to swap out. Fortunately you live where it's not too cold.

Edit - I just re-read your post - YOu may not have a leak at all - when you were bleeding if you did not fill correctly then you might have an airlock at the core - this will gurgle and interfere with proper heat - if you don't have evidence of a leak then you might not. I would raise the front end and bleed again - if you have a leaking core then you'll get coolant in the cabin. The smell through the vents could just have been spillage sucked in and through -
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