98 Seville STS, help please
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Cadillac Seville / Cadillac Eldorado Forum Discussion, 98 Seville STS, help please in Past Cadillac Vehicle Discussion; Hi, For some reason I cannot get any heat from the heater, it only blows cold. I can hear the ...
  1. #1
    Roosterace is offline Cadillac Owners Member
    Automobile(s): 1998 STS Seville (RHD)
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    98 Seville STS, help please

    Hi,
    For some reason I cannot get any heat from the heater, it only blows cold.
    I can hear the controls working the baffles, but no heat !!

    With the coming of winter I would really welcome any advice please.

    many thanks

    Red

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  3. #2
    Pete315 is offline Cadillac Owners Fanatic
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    Re: 98 Seville STS, help please

    air pocket in engine. head gaskets are bad. welcome to the club.

  4. #3
    Roosterace is offline Cadillac Owners Member
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    Re: 98 Seville STS, help please

    I don't think its that, I've had the head gaskets changed, and I'm getting no symptoms of head gaskets problems as I had before.
    I've just checked the heater hoses and one's hot the others cold, this may point to a valve or something?

  5. #4
    TimmyC is offline Cadillac Owners Connoisseur
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    Re: 98 Seville STS, help please

    Quote Originally Posted by Roosterace View Post
    I don't think its that, I've had the head gaskets changed, and I'm getting no symptoms of head gaskets problems as I had before.
    I've just checked the heater hoses and one's hot the others cold, this may point to a valve or something?
    That points more towards a clogged heater core. That happened to me too. I unhooked the hoses in an accessible place and blasted a garden hose through it in both directions. A bunch of crap came out and the heat worked fine ever since. Try that.

  6. #5
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: 98 Seville STS, help please

    First be sure that the purge line is clear and flows coolant. If that is OK, then flush the core. Was the block Timeserted when the gaskets where changed?

  7. #6
    Roosterace is offline Cadillac Owners Member
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    Re: 98 Seville STS, help please

    Quote Originally Posted by TimmyC View Post
    That points more towards a clogged heater core. That happened to me too. I unhooked the hoses in an accessible place and blasted a garden hose through it in both directions. A bunch of crap came out and the heat worked fine ever since. Try that.
    Thanks,much appreciated.

  8. #7
    Roosterace is offline Cadillac Owners Member
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    Re: 98 Seville STS, help please

    Quote Originally Posted by Ranger View Post
    First be sure that the purge line is clear and flows coolant. If that is OK, then flush the core. Was the block Timeserted when the gaskets where changed?
    Sorry, but but you lost me on the first count, where and how do I check the purge line?
    The gaskets where changed by a Caddy dealer, so I don't know about Timeserted, or even what it means, sorry !!

    Sincere thanks for your help though.

    Red

  9. #8
    Mark C's Avatar
    Mark C is offline Cadillac Owners Connoisseur
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    Re: 98 Seville STS, help please

    The purge line is the 5/16" rubber line that runs from a nipple on the waterpump housing to the top of the surge tank, on my 97 it runs under the beauty cover since my surge tank is on the opposite side of the engine from the waterpump, not sure where a 98 surge tank is located. The line purges air from the waterpump so it doesn't become airbound. With the engine cool, pull the hose off the fitting on the surge tank and stick it in the open top of the surge tank, then start the car and observe the flow of water. You should have a pretty solid stream of water and the volume will increase as the engine speed increases. If you don't have a good stream of water then the line is probably clogged at the fitting on the water pump end of the line. Pull the rubber line off that fitting and claen out the inside of the fitting with a small nail or some weedwacker string. You will need to get into the fitting about 2" to get to the main water passage. After that put the line back on at that end and try it again. Once you get water flowing out the other end, hook that end back to the surge tank.

  10. #9
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: 98 Seville STS, help please

    The purge line is the 3/8 " line that runs from the water pump to the side of the surge tank (near the top). Pull the line (engine cold) and stick it in the surge tank. Have someone start the car and watch for flow. If not, locate and clear the restriction.

    EDIT: Oops, looks like I was too slow.

  11. #10
    Roosterace is offline Cadillac Owners Member
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    Re: 98 Seville STS, help please

    Thanks Mark & Ranger, yes, I know exactly what you mean now.

    sincere thanks to both.

    Red

  12. #11
    chubbyranger is offline Cadillac Owners Connoisseur
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    Re: 98 Seville STS, help please

    If one hose is hot and the other not I'd suspect a problem in the heater core. There is no valve.

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