Losing coolant when the heat is turned on.
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HT4100 4.1, 4.5, 4.9 Discussion, Losing coolant when the heat is turned on. in Cadillac Engine Technical Discussion; Hello, I have a 1993 sedan deville, haven't had a problem with the coolant levels until yesterday. I ran the ...
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    medicz28's Avatar
    medicz28 is offline Cadillac Owners Fanatic
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    Losing coolant when the heat is turned on.

    Hello,
    I have a 1993 sedan deville, haven't had a problem with the coolant levels until yesterday. I ran the heat for the first time this year, nothing but cold air for about an hour of driving. I checked the fluid levels when I got home. I ended up putting 3/4 of a jug of antifreeze in the car and a bottle of bars anti-leak pellet stuff. I drove the car with the heat on for 25 minutes and re-checked, it was down enough to have to fill the rad. cap. topped off and drove to school this moring (60 miles, no heat on), levels are fine. Is this a heater core issue or more likely a heater hose issue? Thanks for your help.

    P.S. No warning lights, overheating, rough running of any type and no wet carpets, just the smell of anti-freeze every now and again from outside the car.

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    daedalus__ is offline Cadillac Owners Member
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    Re: Losing coolant when the heat is turned on.

    i had similar problems before and it eventually turned out to be my heater core. sorry i can't be more help im learning myself :P

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    awadecki is offline Cadillac Owners Enthusiast
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    Re: Losing coolant when the heat is turned on.

    You're going to have to find the source of the leak, which shouldn't be too hard since it sounds bad. If the leak is big enough, your cooling system will suck in air, causing an air bubble, and hence, no heat.

    Look under the car for the antifreeze drips. If you don't have wet carpets, then it's probably not a heater core, but it could be one of many things (leaking hose, water pump, cracked radiator, etc.)

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    Re: Losing coolant when the heat is turned on.

    thanks fo rthe reply, the water pump is fairly new GM water pump. Gonna change the core and rad. cap and see if that helps. Prod. needs it anyway.

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    Re: Losing coolant when the heat is turned on.

    I had a busted control valve in mine. It was dropping fluid onto the block and burning off immediately, so I smelled it but could not see it.

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    NickySantoro is offline Cadillac Owners Fanatic
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    Re: Losing coolant when the heat is turned on.

    Quote Originally Posted by medicz28 View Post
    thanks fo rthe reply, the water pump is fairly new GM water pump. Gonna change the core and rad. cap and see if that helps. Prod. needs it anyway.
    Before you do that, put a pressure tester on the system. Pump up to cap pressure. Typically, the leak will manifest itself quickly. Lots cheaper than a core and a rad cap.

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    Re: Losing coolant when the heat is turned on.

    the way I look at it the core and cap are thirteen years old, besides it's less than 40$ for both out the door. I just got back from school (60 miles, with no heat on) without a drop in level. So I'm thinking core or hose, I hope core the hose looks like a nightmare to replace. What's this control value mention earlier?

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    daedalus__ is offline Cadillac Owners Member
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    Re: Losing coolant when the heat is turned on.

    i didnt have wet carpets until my heater core went completely out it did other funny stuff first

    also the hoses aren't as bad as the heater core no way

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    HUF
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    Re: Losing coolant when the heat is turned on.

    Turning heat on has no effect on the flow of the coolant inside the system. It just turns a fan on to create an air flow through the heater core.

    The potential points of leaks are cracked radiator end tanks, a tiny crack on the heater valve (the plastic T), hose connections and the heater core. The reason you do not have heat is most likely clogged heater core. Mine started leaking AFTER I flushed and back flushed it. So I had to replace it with an aftermarket allmetal unit ($30). Not an easy job, but doable. A leaking heater core will eventually drip on the carpetor and even steam inside the cabin.

    I noticed coolant fountaining from a tiny crack on the heater vave (T) only after increasing RPMs to some 3000 with open hood (gear selector in P).

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    Re: Losing coolant when the heat is turned on.

    is this heater value next ot the firewall?

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    HUF's Avatar
    HUF
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    Re: Losing coolant when the heat is turned on.

    Quote Originally Posted by medicz28 View Post
    is this heater value next ot the firewall?
    Yes, on top of the engine. It connects three heater hoses.

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