92 Deville Heat Problems
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Cadillac DeVille 1985 to 2005 including:
1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, 92 Deville Heat Problems in Past Cadillac Vehicle Discussion; I have a 92 Deville. I cmae out here and saw the other threads about heating problems. Well I took ...
  1. #1
    djackson is offline Cadillac Owners Member
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    92 Deville Heat Problems

    I have a 92 Deville. I cmae out here and saw the other threads about heating problems. Well I took my car into Midas and had them do a "flush and fill". They put it on a machine and said that it would flush the heating core too. Does anyone know if that machine actually flushes the core, because I have the same problem. Midas is saying that the core needs to be replaced. Does this sound true or is Midas trying to get more money out of me.

    Cold in STL

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    BeelzeBob's Avatar
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    Re: 92 Deville Heat Problems

    General coolant system flushes do little to flush the heater core specifically. The heater core is normally orificed so as to protect it over the long run from too much flow.

    You need to disconnect the heater hoses (at the engine end is much easier than at the firewall) and flush the heater core circuit specifically to make sure it is clean. It is very unlikely that a heater core is plugged with gelled coolant and particulates to the point that it will not clear if flushed in both directions with hot water from a garden hose.

    Other things can cause the heat to not work, also. Have you read the issues about the tee in the system that feeds the heater circuit??

    See the info below copied from another post....

    Two things to check.

    Has the plastic tee at the junction for the heater water feed circuit every been replaced with a generic plastic tee?? If so, the heat will not work as the generic tees do not have the correct orifice in them to bypass adequate coolant to the heater core.


    Is the heater core plugged?? Disconnecting the heater hoses (at the engine end is much easier than at the firewall) and flushing in both directions will usually remove the gelled coolant and particulates that plug the heater core.

    Find the thermostat housing and the 1 inch heater hose that leaves the engine immediately by the thermostat. Follow it along and about 1 foot away is a plastic tee. One leg of the tee goes to the heater core at the firewall. The other leg of the tee goes toward the front of the engine and is the coolant bypass circuit. The coolant bypass circuit needs to have a 1/4 inch orifice/restriction in it for the heat to work. YOu can do a quick test to see if the problem lies in this area by clamping the coolant bypass circuit leg of the tee off with a pair of visegrip pliers on the hose. Clamp the hose shut and drive the car and see if the heat works better. clamping off the bypass ciruit will force more coolant thru the heater core and may even clear the clog out if there is one.

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    Re: 92 Deville Heat Problems


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    djackson is offline Cadillac Owners Member
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    Re: 92 Deville Heat Problems

    Alright bbob before I attempt this I have a few more questions. Here is a quote from one of your other postings:

    Disconnect at the tee. Follow the other hose from the firewall connections to the heater core and disconnect it at the engine end where it is easier to get at. Use a garden hose and normal water pressure to flush the heater circuit in both directions alternately. Blow as much water out of the heater circuit as you can. Reconnect the hoses. Run the engine and top off the coolant. After running awhile check the coolant concentration to make sure it was not diluted by the water used to flush the heater circuit.

    Should the engine be running during the time I am flushing the heater core?
    Both directions? What do you mean... will I know when I see it?
    Blow water out of the heater circuit, take the hose and blow with my mouth?

    Thanks for your help.

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    Re: 92 Deville Heat Problems

    [QUOTE=djackson]Alright bbob before I attempt this I have a few more questions. Here is a quote from one of your other postings:

    Disconnect at the tee. Follow the other hose from the firewall connections to the heater core and disconnect it at the engine end where it is easier to get at. Use a garden hose and normal water pressure to flush the heater circuit in both directions alternately. Blow as much water out of the heater circuit as you can. Reconnect the hoses. Run the engine and top off the coolant. After running awhile check the coolant concentration to make sure it was not diluted by the water used to flush the heater circuit.

    Should the engine be running during the time I am flushing the heater core?
    Both directions? What do you mean... will I know when I see it?
    Blow water out of the heater circuit, take the hose and blow with my mouth?

    Thanks for your help.[/QUOTE


    If you find the tee (which is pretty obvious) follow the hose that leads to the heater core fitting at the firewall. Disconnect that hose at the tee (because it is much easier to get to). Follow the other heater hose from the firewall to a place where it is accessible and easier to disconnect than at the firewall and disconnect it there. Flush in both directions with a strong flow of hot water from a garden hose. Do not start the engine to do this....if the hoses are disconnected and you start the engine it will blow all the coolant out of the system so leave it off. This way you are just flushing the heater core circuit...which is the idea. When done flushing in both directions (put the garden hose to each of the heater core hoses alternately) blow as much water out of the heater core using lung power as possible. This is just to prevent diluting the engine cooling system with plain water by removing as much as possible. Hook the hoses back up, start the engine and top off the radiator with fresh 50/50 coolant/distilled water.

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    djackson is offline Cadillac Owners Member
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    Re: 92 Deville Heat Problems

    Well I tried to flush the core yesterday to no avail . I could not get the hose off of the engine block by the passenger side wheel well. I got the clamp off, but the hose wouldn't budge. In the meantime I had to replace the tee because the restrictor broke off in the heater core line when I took it off. Unless you have some suggestions on how to get the hose off, I guess I will be without heat on one side of the car.

    Thanks anyway for your help.

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    Re: 92 Deville Heat Problems

    Quote Originally Posted by djackson
    Well I tried to flush the core yesterday to no avail . I could not get the hose off of the engine block by the passenger side wheel well. I got the clamp off, but the hose wouldn't budge. In the meantime I had to replace the tee because the restrictor broke off in the heater core line when I took it off. Unless you have some suggestions on how to get the hose off, I guess I will be without heat on one side of the car.

    Thanks anyway for your help.

    ????????????

    Can't get the hose off?? Shove the end of a larger plain screw driver into the gap at the end of the hose and twist it to force the hose off the nipple. Grab it with a pair of pliers around the hose and twist it on the nipple to break it loose. Cut the hose off at the end of the nipple (if there is 1/2 inch slack in the hose) and reterminate it. Work a small screw driver under the open end of the hose and down between the hose and the nipple surface to break the hose loose. Get the end of an air nozzle from a compressed air source into the end of the hose at the joint to the nipple and blow the hose off. Heat the hose up with a hair dryer or heat gun to make it more pliable so it will twist and expand easier to get it off. This is not that difficult..... There are a lot of ways to get a stubborn hose off a hose fitting.


    One thing you say does not make sense...."In the meantime I had to replace the tee because the restrictor broke off in the heater core line when I took it off.".... There is not supposed to be a restriction in the heater core feed hose. The restriction is supposed to be in the leg of the tee toward the front of the engine. If the restricted leg of the tee is toward the heater core the heat will not work correctly. Did you mean that the "nipple" of the tee broke off in the heater hose instead of the "restrictor"....big difference. The tee you used as a replacement was the OEM tee with the restrictor in the leg of the tee toward the front of the engine....NOT towards the heater core.


    Did you catch the end of this thread...???? http://www.cadillacforums.com/forums...163#post226163 It does work. So does this... http://www.cadillacforums.com/forums...196#post226196

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    djackson is offline Cadillac Owners Member
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    Re: 92 Deville Heat Problems

    When I took the tee off the restrictor was going toward the heater core (into the hose that goes to the firewall). Are you saying that the restrictor should go to the other hose that goes back toward the thermostat housing? If you are I will change that this evening and see if that fixes it. Man you are good if this works .

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    djackson is offline Cadillac Owners Member
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    Re: 92 Deville Heat Problems

    OK I changed the Tee around... it appears the heat is working now. The high temperature in STL was 67 yesterday. Tomorrow (Friday) will be the real test because the high temp is supposed to be 20. I will post to let you know how it works then.

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    Re: 92 Deville Heat Problems

    Maybe it is fixed.....

    Just the clearify what is in the previous posts...

    There are three legs to that tee. The leg coming from the thermostat housing does NOT have an orifice. The leg going to the heater core connection at the firewall does NOT have an orifice. The leg going toward the front of the engine (the coolant bypass circuit) is the leg that MUST HAVE the orifice.

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    crestviewpb is offline Cadillac Owners Member
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    Re: 92 Deville Heat Problems

    Believe me as I tried for two years to get around it, just put in a new heater core. I did and I have all the heat you could want. I busted the old core open and no amount of flushing would have helped it. It took me about two hours total to replace it. There is a thread here if you do a search with good instructions and pay attention to the breaking off of the heater hoses at the firewall as it will save you very much grief and time. It is very easy to get to the core behind the glove compartment so it is not a bad job at all.

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    100
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    Re: 92 Deville Heat Problems

    Quote Originally Posted by bbob
    There are three legs to that tee. The leg coming from the thermostat housing does NOT have an orifice. The leg going to the heater core connection at the firewall does NOT have an orifice. The leg going toward the front of the engine (the coolant bypass circuit) is the leg that MUST HAVE the orifice.
    Oh, really? The tee I had in my car (it was there before I purchased the car) had an orifice in the leg going to the heater core... That was the tee that broke while I was driving a few months ago and leaked coolant all over the engine...

    I suppose that tee was not a genuine part and that might be the reason that it broke like that. Now I have a 1 inch metal tee without any orifice in it (because I didn't like the way the plastic piece broke), but I feel safe to buy a genuine plastic part to replace then (well, I should because there is no orifice in the tee now). I thought the quality of the original was poor.

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    Re: 92 Deville Heat Problems

    Quote Originally Posted by 100
    Oh, really? The tee I had in my car (it was there before I purchased the car) had an orifice in the leg going to the heater core... That was the tee that broke while I was driving a few months ago and leaked coolant all over the engine...

    I suppose that tee was not a genuine part and that might be the reason that it broke like that. Now I have a 1 inch metal tee without any orifice in it (because I didn't like the way the plastic piece broke), but I feel safe to buy a genuine plastic part to replace then (well, I should because there is no orifice in the tee now). I thought the quality of the original was poor.
    Yes, really....the restriction has to be there for the heat to work correctly. Sounds like someone either replaced the tee with the wrong part, a generic part and/or put the tee in wrong. The restiction is definitely NOT suppossed to be toward the heater core. Since you found it with the tee restriction toward the heater core it is obvious that someone meddled with it at some time before you got the car...

    You can keep the metal tee with no orifice if you like. Just make a restriction to put in the hose in the leg toward the front of the engine as described. Use a cutoff bolt or short piece of steel or aluminum dowel that will fit snuggly into the hose. Drill a 1/4 inch hole thru it and insert it into the hose on the leg of the tee toward the front of the engine.

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    100
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    Re: 92 Deville Heat Problems

    Thanks bbob,

    That was a very good information. I am using a stainless steel tee there. I assume as long as I use stainless steel or aluminum in the coolant line, they are fine with the (green) coolant, right?

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    djackson is offline Cadillac Owners Member
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    Re: 92 Deville Heat Problems

    Nope it is not fixed , and it is freezing 6 degrees today (Monday). I still think the tee is wrong according to your previous post. The tee has three hoses on it.
    #1 goes to the left and towards the fire wall (originally had restrictor, but I have since changed it to #2)
    #2 goes to the right and towards the thermostat housing (top of the engine, now has restrictor).
    #3 goes down, not really sure where it ends haven't looked. (Is this where the restrictor should be?)

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