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2006 Malibu over heating and leaking on passenger floor board

My car has been leaking water like crazy into the passenger floor board and over heating. I need to fill the container every time I need to drive anywhere and by the time I get there, the car is starting to over heat… I just had the water pump and radiator replaced 2 months ago and everything was fine up until last week. If I turn the heater on, it stays cool until I start idleing at stop light… by the time I get home, it’s over heated and blowing smoke out of the air vents. The passenger floor is like a little swimming pool every day, and takes forever to dry it up as best as I can… I’m not sure what it could be cause I’ve been told many different things… any help would be greatly appreciated…

Most likely the heater core.

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I was afraid of that… not a easy fix from what I’ve read

Not a easy fix but a needed fix.

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Wow, that’s a serious leak! When in a bind, I’ve disconnected the inlet and outlet hose from the heater core, connected them together with a fitting and hose clamps, and bypassed the heater core. Your car will run fine and your floorboards won’t get wet. Of course you’ll have zero heat. I believe I’d do that if I was planning on driving the car and not repairing pretty immediately.


Not only is the heater core leaking, but the leak is lowering the coolant level as well as preventing the coolant from not boiling. The pressure in the system that the system is designed to allow raises the boiling point of the coolant, allowing the engine to run above 212F without boilover. Thus, your engine overheats.

Until you DO fix it, you can run some heater hose from the heater core input directly to the output, bypassing the heater core. You won’t have heat, but you won’t have floods either, and unless the engine has been overheated one too many times it should be fine too.


You should fix this immediately. First, today’s engines don’t like to be overheated repeatedly. You could end up with a large repair bill that could have been avoided. Second, it’s dangerous to breathe in coolant fumes for very long.


I see a jug of water
What are you refilling radiator with?
50/50 coolant?
What climate are you in? Cali? Ny?

Yep new heater core pronto. Sometimes installing a new radiator that holds pressure will cause a leak in a weak heater core. The system was compromised before but increasing the coolant pressure to normal, caused the leak. When my heater core went out, I was driving about two miles from the NAPA store to home with a new heater core and by the time I got home the car was so fogged up I couldn’t hardly see. Installing it was easier than I thought after following the factory service manual. Not like the half hour job of yesteryear but still not bad. Just depends on the car though. Some Fords I hear you almost have to cut the car apart to put one in.

I replaced the heater core in a 94 Silverado (easy) and a 98 Dodge Ram (had to drop steering column and remove entire dash). I think a shop quoted me $600 to do the job on the Ram, but that was 8 or ten years ago. I imagine a dealer would easily be over a grand.

The radiator leaked at the end tanks in the Ram, and after replacing the radiator, the heater core began to leak. I bypassed the heater core until I could take a day off work to replace the core in order to avoid what happened to Mr. Bing up there driving from the Napa lol.

As a side note, a dash assembly in a 1998 Dodge Ram is kinda heavy and quite cumbersome.

Man, I dread doing that job again in the future on a newer vehicle. The newer the vehicle is, the more the heater core seems to be hidden. I don’t see a real reason why unless they’re trying to keep folks from doing the work themselves. Really, how hard would it be to put the core where it could be accessible through a removable panel or something?

Yep I remember the old GMs were accessed from under the hood. If I remember right, just pull the heater motor that was also right there, pull off the housing, and a few more bolts and the core popped right out. Biggest thing was getting the old hoses off and draining the coolant.

1994 GM trucks (and I guess back to 1988), you had to go inside the cab to change the heater core. You had to lay in the floor and all that, but at least there was a cover you could remove from the HVAC plenum to get to the heater core. Kind of a pain in the butt, but not a big deal. Newer vehicles (or the ones I’ve had experience with), you get to take out the entire dash. Yay! Not sure what the technological advancement in that is, or why it has to be that way.