91-93 (94-95?) Fleetwood FWD and DeVille Heater Core Flushing Procedure - Page 2
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Cadillac Tech Tips - How to fix it Discussion, 91-93 (94-95?) Fleetwood FWD and DeVille Heater Core Flushing Procedure in Item Specific Cadillac Discussion; Well my 93 deville from above still doesnt have heat. I tried flushing again today with NO luck what so ...
  1. #16
    behind-bars is offline Cadillac Owners Connoisseur
    Automobile(s): 93 Sedan Deville 4.9L
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    Re: 91-93 (94-95?) Fleetwood FWD and DeVille Heater Core Flushing Procedure

    Well my 93 deville from above still doesnt have heat. I tried flushing again today with NO luck what so ever, have been without heat all winter so far and thought I would take another crack at it. I have the right T with the restrictor correctly oriented, so I know that should be good.

    I really didnt want to flush the entire system but the coolant is nasty even though it is only a few months old. I am going to flush the whole system good since I know the previous owners really neglected it. I tried flushing with vinegar and will try with CLR aswell. Using the method above I get no flow at all in the hose from the T to the Firewall. flushing into the bypass hose that goes straight down it flows out supply end of the T. I put a hose on both ends of the T as above to keep but cant get any flow coming out of the other hose. If I flush into the non bypass hose it all comes back out the top of the same hose. I tried the air compressor method like before by blowing into the blocked hose and a bunch of brown sludge came flying back out that hose.

    I really dont want to pull the whole core so hopefully the vinegar/clr combo will do the trick

  2. #17
    N0DIH's Avatar
    N0DIH is offline Cadillac Owners Master
    Automobile(s): 94 Fleetwood Brougham
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    Re: 91-93 (94-95?) Fleetwood FWD and DeVille Heater Core Flushing Procedure

    For my 91 Deville I bought a core and figured I would just dig into it. After 20 min or so, I gave up and took the core back.....

    A friend picked up a 90 Deville, and the core was fairly easy to do, maybe 30 min worth of work.

    The 90 and 91-93 might look similar, they are FAR from it.

  3. #18
    behind-bars is offline Cadillac Owners Connoisseur
    Automobile(s): 93 Sedan Deville 4.9L
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    Re: 91-93 (94-95?) Fleetwood FWD and DeVille Heater Core Flushing Procedure

    Quote Originally Posted by N0DIH View Post
    For my 91 Deville I bought a core and figured I would just dig into it. After 20 min or so, I gave up and took the core back.....

    A friend picked up a 90 Deville, and the core was fairly easy to do, maybe 30 min worth of work.

    The 90 and 91-93 might look similar, they are FAR from it.
    Yep, mine is a 93 and I gave up on replacing the core. My flushing attempts failed. The core was clogged when I bought the car,Then I could get some flow through it, but not much. This time I couldnt get any flow, I blew air into it and it shot out brown sludge that looks like the bars-leak tabs. I think when I added the tabs last time they all got stuck in the heater core clogging it for good.

    So next time anyone changes their coolant I would make sure that your heater core is cleaned aswell to avoid clogging it further with bars-leak.

    I dont see why they used the hose clamps that require vice-grips to remove on the 2 hoses on the firewall. If they were screw on clamps I think I would have been able to remove them. It is a tight area, but I could get my hands on the hoses, just no room for tools. I probably could have gotten a screw driver down to loosen them up though.

    I thought about cutting the hoses off, but I knew once I did that their was no turning back, Had I cut the hoses and flushed the core, then used new hoses the core may have started leaking in which case I would have to do it all over again to install a new core.

    Luckily in Texas a heater isnt a necessity, I can only think or 7 or 8 days I would have really liked the heat, other then those days it would have just been a bonus.

  4. #19
    91WhiteDeville is offline Cadillac Owners Member
    Automobile(s): 91 Sedan Deville
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    Re: 91-93 (94-95?) Fleetwood FWD and DeVille Heater Core Flushing Procedure

    I have to warm up this thread once more:

    I do have the same problem and recognized that I didn't have a Tee with restrictor in it, so I went to Oreilly real quick and bought the one previously mentioned. I see the arrow, and read that the restriction has to be on the left side. So far so good, this is exactly what I see when I look at this part. But: I learned that the hose going down is the bypass and the hose going to the left feeds the heater core. Why should then the left side of the Tee be the one with restrictor, can this be right? For me this sounds like the left side going to the heater core will be the only restricted side?!

    If I connected the Tee this way, I would see: to the left the smallest diameter (looking inside of the pipe, you see instantly that the diameter is about 1/2 of the right side), to the right the biggest diameter, and to the bottom something in between, a little bit smaller than to the right).

    Any thoughts after 3 years in life of this thread? thx

  5. #20
    behind-bars is offline Cadillac Owners Connoisseur
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    Re: 91-93 (94-95?) Fleetwood FWD and DeVille Heater Core Flushing Procedure

    The way I remember it is the arrow points toward the passenger side fender. It comes from the engine at full force, hits the restrictor and which pushes some down. If it was restricted coming from the engine then the flow would be the same at both outlets, just a smaller volume.

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