Losing coolant, no visible leaks.... long description
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Cadillac Seville / Cadillac Eldorado Forum Discussion, Losing coolant, no visible leaks.... long description in Past Cadillac Vehicle Discussion; Ok so here it is. 1993 seville sts, 4.6 northstar 149,000 miles. I am 3rd owner of this car. I ...
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    cliff77 is offline Cadillac Owners Member
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    Question Losing coolant, no visible leaks.... long description

    Ok so here it is.

    1993 seville sts, 4.6 northstar 149,000 miles.
    I am 3rd owner of this car. I have had it about 6 months. I have only put about 5k miles on it. Been in and out of the shop for ignition problems and a lot of vacuum leaks. I don't know when(if any) maintance was done on the coolant system.
    I got the car, check coolant level, it was low added about a gallon. drove it a little bit (300 miles) everything was fine. Changed oil, checked trans fluid, etc... all good. Until a few weeks ago. it's been local driver (ignition problems) now it's a daily driver. 200 miles a day.
    I had intake gasket put on it about 2 weeks ago, prior to that. I added about 1 1/2 gallon of coolant. now i have added about 2 gallons since the intake gasket.It's been about 2 weeks since the intake, about 2k miles. The low coolant light comes on and it takes about 3/4 gallon. So a total of 3 1/2 gallons in 6 months, 5k miles.

    No visable leaks. I park in the same parking spot at work and at home, no leaks on the ground. I have been all around the motor with a light, nothing. No coolant in oil or trans fluid. The coolant is bright green when I top it off. There is no puddles, no white smoke, or sweet smell. It doesn't overheat or run hot. The passanger side floor is dry. 192 degrees the whole time it's running.
    I have seen very small ( 1/8 " ) particles floating in antifreeze when I top it on, a few 2-3
    I heard on the northstar motors, when the head gasket goes, the coolant and oil don't mix ???
    Oh.. I had pressure test done on system 2 days ago. 15 psi held for 25 mins with no dropping off at all....

    ANY IDEAS ???

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    stoveguyy is online now Cadillac Owners Connoisseur
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    Re: Lossing coolant, no visable leaks.... long decreption, but alot of details in it

    radiator side tank cracked? they are plastic. they do age. 200 miles a day is 4 hrs? lots of time for coolant to slowly wisp out. your car is 20 yrs old. i think you need a new radiator. dont hurt. not free but its one less thing to worry about when your cruizin down the hwy

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    Re: Lossing coolant, no visable leaks.... long decreption, but alot of details in it

    On a 1993 Northstar setup - Does the cooling system use a coolant reservoir with a twist - lock - push down - twist off cap ?? Like an old 'radiator cap' ?? - and does the reservoir have a coolant overflow tube (NOT the purge line to the water crossover) - a coolant overflow tube that drops down toward the ground ??

    If so, suspect the reservoir cap.......... and the proper coolant level is halfway up in the reservoir, cold. NEVER check or adjust coolant level with the engine warm or hot.

    A cracked radiator side tank, losing that much coolant, would make a real mess of half of the engine (depending on which side might be cracked)........... but that idea begs the question: "Do you ever smell hot coolant anywhere around the car?"

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    Re: Losing coolant, no visible leaks.... long description

    It does not sound like a HG problem. You probably have a very small leak that evaporates before it drips. Radiator side tanks are one possibility. Another known leak point is the two heater pipes (#5 & 6) that run along the rear head. They tend to rust out. Impossible to see and very difficult to change.


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    cliff77 is offline Cadillac Owners Member
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    Re: Losing coolant, no visible leaks.... long description

    The coolant system has a seal radiator with a old syle twist and lock cap on the side tank. no reservor tank. Sealed radiator, It has an overflow tube that comes of the side and just hangs by the pullies against the strut pillar. The pillar shows no sign of ever being wet.
    I looked at all the heater hoses and connections. Found every thing dry. No evidance of any leaks now or past. nothing is wet or has a resdue on it.
    Q: If the radatior was cracked it would show under pressure test, right ?
    Are # 5&6 plastic, metal or rubber? I will look as soon as it stops raining here.

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    Re: Losing coolant, no visible leaks.... long description

    The heater pipes (#5 & 6) are steel.

    Q: If the radatior was cracked it would show under pressure test, right ?
    Theoretically yes, but you have to take into consideration heat and expansion. It is "possible" (not probable) that could affect the outcome of the test.

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    cliff77 is offline Cadillac Owners Member
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    Ok. I'll look at those 2 pipes this afternoon. I'm going to get a new cap. Just because.

    ----------

    Also I smell nothing in or around the car. I've had cars with bad heater cores and leaking water pumps. I know the smell of antifreeze. The car gets 3 plus hours of highway time a day. So I would think a leak should show with that kind of drive time. Idk ??

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    stoveguyy is online now Cadillac Owners Connoisseur
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    A 93 NS does NOT have a surge tank? The pic (item #1) shows the heater hose going to that area?

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    cliff77 is offline Cadillac Owners Member
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    It's not a surge tank it goes to. Its the overflow hose from below the cap. The coolant system is closed. No overflow tank. I'll upload a picture of my motor in a little bit

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    Re: Losing coolant, no visible leaks.... long description

    Not "overflow tank" - surge tank - reservoir. It's pressurized, unlike the old coolant recovery system that used a radiator cap and a line to a vented jar.

    According to two parts sites, your radiator does not have a pressure cap - the surge tank does.

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    cliff77 is offline Cadillac Owners Member
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    Sorry I got the terminology wrong. Yes closed system. The cap is on the tank, not the radiator. The overflow hose hangs on the strut tower

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    Re: Losing coolant, no visible leaks.... long description

    Quote Originally Posted by cliff77 View Post
    Ok. I'll look at those 2 pipes this afternoon. I'm going to get a new cap. Just because.

    ----------

    Also I smell nothing in or around the car. I've had cars with bad heater cores and leaking water pumps. I know the smell of antifreeze. The car gets 3 plus hours of highway time a day. So I would think a leak should show with that kind of drive time. Idk ??
    Hope and pray to the Northstar Gods that you have a hard to find external leak somewhere. You do not want the alternative.

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    cliff77 is offline Cadillac Owners Member
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    Update.
    I replaced the thermostat and radiator cap due to age and being proactive. 180 degree stat. Filled up with coolant and let it run and within 3 mins coolant leaked out of the overflow tube.
    Now I know some is going to leak until it levels out.
    2 questions. ...
    Why is there no reserve tank to hold extra coolant. Like most cars.
    Could I be losing enough coolant from here as I drive, to cause low coolant warning to come on.

    Now temp is around 200 on interstate. About the same as before.

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    Re: Losing coolant, no visible leaks.... long description

    You have said there IS a coolant surge tank, that the "radiator cap" is not on the radiator itself.

    The proper level of coolant in that surge tank is half full, cold. The surge tank is part of the pressurized system - there is no "coolant overflow bottle" or "coolant expansion bottle" as in older, obsolete coolant recovery systems.

    You overfill that surge tank, and as the coolant expands normally during warmup, it WILL bleed off coolant. Half full, cold.

    Is there a legend molded into the top/side of the surge tank "FULL COLD" with a flat line/arrow going over and down the side to about the mid-seam ???

    200 degrees running temp is perfect - right in the midle of the desired 188 - 210 range.


    Zoom in on this page from the 2002 service manual - the surge tank - see the number 1 and line to the tank mid-seam ??? That's the proper cold fill level. (The Note on supplements is deleted and obsolete)

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    cliff77 is offline Cadillac Owners Member
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    Yes, surge tank style. No overflow holding tank..
    Thanks for all the info. Very informative

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