Coolant loss/coolant temp

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Cadillac Seville / Cadillac Eldorado Forum Discussion, Coolant loss/coolant temp in Past Cadillac Vehicle Discussion; Guys, Please tell me if this makes any sense..My 95 sts with 85K miles, had an external water pump leak, ...
  1. #1
    tech0707 is offline Cadillac Owners Member
    Automobile(s): 1995 Seville STS
    Join Date
    May 2011
    North Carolina

    Coolant loss/coolant temp

    Guys, Please tell me if this makes any sense..My 95 sts with 85K miles, had an external water pump leak, small, but after getting angry about the shop quote, I replaced it myself, along with the thermostat. No more antifreeze smell, no more external leaks. However, I would still have to add coolant every 3 or 4 days ( about half gallon, maybe less ) . I had the local shop to check "purge line" for blockage anf flush the radiator. Well, still had to keep adding a little coolant and the temp would go to 215-220 alot....So out of curiosity, I ran the heater wide open for about 30 minutes. ) It was 90 degrees outside).. Now, everything seems to be normal. Temp stays around 200 and havent had to add coolant in a couple of weeks. Does this make sense and if so why??

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  3. #2
    MoistCabbage's Avatar
    MoistCabbage is offline Cadillac Owners 10000+ Posts
    Automobile(s): 2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
    Join Date
    Sep 2010
    East Boston MA.
    It isn't uncommon to have to add coolant after the system has been drained and refilled, as it purges trapped air. But not nearly as much as you were adding (and FWIW, the heater core is full flow at all times, so running the heater has no effect on coolant flow or bleeding the system). The coolant was going somewhere. How high we're you filling the surge tank? Full is to the "FULL COLD" line, about half way, where the two tank halves meet. Any excess coolant will be purged through the overflow.

  4. #3
    Moneypit is offline Cadillac Owners Fanatic
    Automobile(s): '94 Eldorado '83 Fleetwood
    Join Date
    Feb 2010

    Re: Coolant loss/coolant temp

    You know not to overfill the reserve tank. You might have a small steam leak when temperature and pressure go up. You might solve the problem by giving the hose clamps a turn or two.

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  6. #4
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
    Automobile(s): White Diamond '03 DHS (with DTS floor shift)
    Join Date
    Jun 2004
    Woodstock Ill.

    Re: Coolant loss/coolant temp

    If you have to add coolant, you have a leak, either internal or external. Common external leak points are the surge tank purge line nipple and the radiator side tanks. Remember, the condenser is mounted in front of the radiator, so the front of the side tanks are not visible. My '97 had a hairline crack at the nipple that was so fine, it was undetectable until the system heated up and pressurized. Only then would it seep ever so slightly. If you can't find a leak you may have to borrow a pressure tester from AutoZone and pressurize the system cold so as to avoid evaporation of the leaking coolant before it is spotted. All this of coarse is assuming that you are not overheating. 215 is not hot, but if it starts going much higher (try some WOT), then a block test may be in order.

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