97 Deville Idle and Coolant

ubamelubamel Member Posts: 1
edited July 2014 in Cadillac
For the last year I have had problems with my coolant, always having to put it in. Almost a year ago I had a new radiator put in and that seemed to of solved the issue, recently my light to "check coolant level" has popped up. My other issue within the last week is my service engine soon light has came on and off and my car has been idling rough when I come to a light and whatnot. Today the SES light was flashing on and off and car is still idling. PLEASE help me if you have any advice.


  • bolivarbolivar Member Posts: 2,316
    With your coolant at the correct level, does your Cadillac run hot when running at high speed (65mph or so) or when going up steep hills?

    If so, you possibly have a bad head gasket. Which is a known problem with Cadillac Northstar motors. And, is very expensive to repair.

    Of course, you might just have another simple leak of coolant somewhere.

    You can 'pull the codes' yourself on your Cadillac. You can put the instrument panel into a 'diagnoistic' mode and it will display the error code/s that is causing the check engine light to flash. There are other online sites where you can get a 'basic' definition of what the error codes mean.

    Or, many auto parts houses will hook up a 'scanner' and 'pull the codes' for no charge, and give you the basic descriptions for the codes.

    If you want to attempt to pull the codes yourself, reply here and I will post a link to a site which has the instructions.

    Cadillacs are great cars, until they break. Then they can be complex and expensive to repair.
  • bolivarbolivar Member Posts: 2,316
    Ok, I have pasted in below the procedure to enter diagnoistic mode for your Cadillac. Get a pencil and paper read and write down all the codes, especially any 'Current' codes. The "History" code probably can be ignored. There are a lot of things displayed, and you might have several codes.

    The codes will have the prefix shown in the last paragraph below, plus a 4-digit number. Post any of the 'currect' codes back here, and I will try to look them up for you.

    But, as I said in the first message, it is very important to know if your car is overheating!!!!



    To enter diagnostic mode, proceed as follows:
    1.Turn ignition “ON.” Engine can be either OFF or RUNNING.

    For cars equipped with the Digital Instrument Panel Display (Digital

    2.Simultaneously press the “OFF and “WARMER” (red) buttons on climate control center (CCC) until all display segments (IPC and CCP) are illuminated

    For cars equipped with the Analog Instrument Panel Display (Analog IPC):

    3.Simultaneously press on the Climate Control Panel (CCP) the “OFF” and “PASS WARMER” (up arrow) button.

    After the segment display test, the driver message center displays all set DTC, current and history, in the following order:

    A. PCM DTC Power Control Module (?)
    B. IPC DTC Instrument Panel Control
    C. ACM DTC Air Conditioning
    D. SDM DTC Air Bags
    E. TCS DTC Traction Control System
    F. PZM DTC Body Control Module
    G. IRC DTC
    H. RFA DTC Radio
    I. CCP DTC Cell Phone
    J. MSM DTC
    K. MMM DTC Memory Control (The “Set 1, 2” Panel on Arm rest.)
    L. PHN DTC
    The RSS, CCP, MSM, MMM and PHN DTC’s appear only on vehicles equipped with these options. Press the FAN DOWN button in order to bypass the DTC display.

    On the OBD II cars) the prefixes you’ll see are: “IP” for the IPC instrument panel; “AC” for air conditioning module; “TC” for traction control; “RS” for the road suspension system; “SD” for the air bags; “PZ” for the body control module~ “CC” for the cell phone; “RF” for the integrated radio system.
  • firstlast1firstlast1 Member Posts: 1
    My 2000 DeVille (64,000 miles) supposedly overheated (no indication). At 57,000 miles "check coolant" message displayed. It was taken to the dealer who replaced the water pump, thermostat, etc. The newly replaced water pump (after 7,000 miles) supposedly malfunctioned and caused the engine to overheat blowing the head gaskets (again no guage indication). Could this be related to the GM Dex-Cool problem reported in Missouri and Canadian class action lawsuits (www.modexcool.com) relative to the use of Dex-Cool coolant and gasket failure? GM settled this lawsuit in March 2008.

    Anyone having a similar problem and related information?
  • bolivarbolivar Member Posts: 2,316
    I recently read the Missouri suit, and it does NOT cover Cadillac engines. It covers mainly 3.1 and 3.4, with a few 3.8, liter iron GM motors with 'silicon' gaskets.

    I sure don't understand your 'no indication' of an overheating situation.

    If a Northstar overheats, you will see it on the guage, there should be DIC messages, and you will get large amounts of coolant blown out of the surge tank.

    Northstars blow head gaskets. This is a well known problem. And the water pump does not have to be failing for this to happen. It is a design problem, the gaskets fails, allowing combustion gas to get into the coolant passages, causing overheating.
  • sspeissspeis Member Posts: 1
    I'm hearing different opinions. What is normal operating temp. for a 1997 Cadillac Deville with 4.6 Northstar motor? How expensive is it to repair head gaskets on these motors? Mine seems to run hot. Between 196 and 220 degrees. It can go higher if I run it harder. The radiator uses about a half gallon of coolant for 30 miles but I see no leaks. Dipstick is not milky and no coolant smell or in tailpipe. I do see what looks like white exhaust when idling (especially in the mornings) but not when accelerating. I don't know however if it's smoke or just that it's kind of cold in the mornings. Can anyone help shed some light for me? Tanks in advance.
  • bolivarbolivar Member Posts: 2,316
    Ok, about the 'normal' temperatures. With the Air Conditional 'On', the button in the 'Norm' setting, the fans will run all the time and it will attempt to maintain the thermostat value, which is 197 degrees. With the Air Condition 'Off', the button in the 'Econ' setting, the fans will not run and the computer will allow the temperature to rise to about 220 degrees and it will then turn the fans on until the temp drops to about 197 degrees. So, in general, your temp values are running ok, if you are using the 'Econ' setting. If you have the AC in the Norm setting, it is running hot at 220 degrees.

    But, you other symptoms point to the early stages of a blown gasket - just not blown severely yet. If the coolant is not leaking, the only place it can be going is into the engine. A half gallon per 30 miles is a lot of coolant going somewhere. Northstars bad head gaskets do not put coolant into the oil. It goes into the combustion chamber. And, combustion gas goes into the coolant, causing overheating. Massive overheating as the gasket gets worse. And the higher temps when running hard is a usual symptom. If you drive up a steep hill, it will also overheat - basically the more you load the motor, the more it will overheat.

    My guess - you've got a head gasket problem. It will get worse. No kind of 'Stop Leak' will seal it.

    Repair will be $3,000 or more. The motor must be pulled. Heads removed. All 20 head bolt holes bored out. Then rethreaded. Then a special insert called a Timesert is screwed in. The motor is then reassembled, with new headbolts screwing into the Timesert inserts. New gaskets of course. Most of the cost is labor because the motor must be pulled, the rear head cannot be worked on in the car.

    This is about 50% of what a 97 Deville is worth. There are a lot of Cadillacs scrapped because of a blown headgasket, and what the cost of repair is. But, if a Timesert operation is done, this usually fixes the headgasket for the remaining life of the car.
  • donjuan3donjuan3 Member Posts: 1
    Where do you find these Timesert's?
  • bolivarbolivar Member Posts: 2,316

    Where else?

    Google is your friend.
  • clint0221clint0221 Member Posts: 2
    Passenger side mirror unfortunately broke when it scraped against garage siding. It is still functioning. The assembly is still attached due to the electrical wirings. Replacement plus labor quoted at approx $800. Any do-it-yourself suggestions / advice on remedying this situation? Thanks.
  • bolivarbolivar Member Posts: 2,316
    Uggg.... A junkyard.

    Take the inside door panel off. You can then get to the bolts that hold the mirror to the door.

    If the outside door skin has been badly dented up when the mirror pulled off, then you have a problem that only a body shop can fix.
  • clint0221clint0221 Member Posts: 2
    Thank you much Bolivar. That could be a start to see how extensive the problem is. And maybe, just maybe, I can McGyver it and save some bucks. Thanks again.
  • bena8837bena8837 Member Posts: 26
    I have read in the owner's manual of this vehicle not to add anything other than Dex-Cool 50-50. I have also read on another forum that they talk about adding the GM Coolant System Seal Tabs. What is the proper thing to do?
  • bolivarbolivar Member Posts: 2,316
    I comes from the factory with orange Dexcool. That is what GM recommends.

    By 2002, I think Cadillac may have stopped recommending the coolant tabs. On older models, there was a sticker on the motor/plastic fan cover/somewhere under there, that gave the part number for the tabs.

    You only need to add tabs if you dump all the old coolant out. Since you can't get all of it out by opening the radiator or pulling a lower hose, I only put three in.

    DON"T PUT THE TABS IN THE "OVERFLOW" TANK. (It really isn't an overflow tank, because it is pressurized and has the rad cap on it. It is correctly called the 'surge tank'.) PULL A RADIATOR HOSE AND PUT THE TABS IN THERE. There is not enough coolant flow thru the 'surge tank' to move the tab material out of there, and it is mainly useless if put in there.

    The tabs are used mainly for very minor leaks - seepage type, or porisity opening in the block/head castings. The tabs were developed for the earlier 4.1 and 4.9 motors and carried over into the Northstar motors up until about 2001 where there were some redesigns made to the Northstar and I think GM no longer recommends their use.
  • bena8837bena8837 Member Posts: 26
    Thanks for the info., appreciate it!
  • hagerhorsthagerhorst Member Posts: 1
    my coolant ran up to 260...i shut the engine off. mechanic replaced surge tank, thermostat, and radiator for 800 bucks parts and labor. now heat does'nt work and i ran up to the steamin' 260 again...of course i shut down and the mechanic says he will look at it again. he says there are no signs of a blown headgasket and will have to look into it some more. before i left he said he had it idle for two hours with no problems...that my coolant problem was fixed. he also suggested that i replace all those parts in order to fix the problem! two questions...what could the problem possibly be? what obligation does this shop have after telling me the problem was fixed? he said there were no signs of a head gasket problem.
  • bolivarbolivar Member Posts: 2,316
    You have to 'load' the motor before a leaking head gasket starts to cause overheating. (Unless it is really bad leak.)

    If driving slowly does not overheat, but going to high speed (60mph+), or driving up a hill, does start an overheat - blown head gasket problem.

    There might be a problem with the small belt that drives the water pump. This is driven off the rear of the left head cam. Which means it it near the front of the car on the driver's side. This belt is under a metal cover. Or might be a problem with a sticking thermostat or bad water pump. But these usually don't cause a problem.

    I don't understand why this causes the heat to fail. I'm not going to get into whether or not the mechanic owe you anything for the problem continuing. This is between you and him.
  • jpix1jpix1 Member Posts: 2
    Every 5-6 days had to add about 1-1.5 gallons of water to system. Water has been leaking from left front of vehicle for abour 2 months. the other day on 60 min drive engine heated up to 260 degrees and warning light came on. got home and had to add about 2 gallons of coolant. could the water pump be leaking? dont think this model has a weep hole like others. The pump is the type that sets in the housing and seals with an o-ring. Any help?
  • bolivarbolivar Member Posts: 2,316
    The water pump is leaking. Replace the water pump. It comes with a new o-ring seal. It takes a special tool to remove. It has 'left hand' threads when removings. An auto part house should loan you the special tool.

    Or, the cross over pipe is leaking. Much more involved to repair.

    Both are on the left front on the motor area (Essentially the 'rear' of the motor since it sits in there cross-wise).

    What aren't you fixing this leak? You are going to burn the motor up if you continue to run it while low on coolant. Or blow a head gasket - which is already a weak point of Northstar motors, and very, very expensive to repair.
  • jpix1jpix1 Member Posts: 2
    Thanks Bolivar. replaced it today. It only overheated the other day. I guess the pump got so bad that it lost more coolant that one time. Couldn't tell if the pump was bad when I took it out and replaced it. But did it anyway. Figured that could be the only place leaking.... No leaks so far.
  • bullet6bullet6 Member Posts: 1
    I am replacing my head gaskets on a 99 northstar motor. My kid and I are decent mechanics. He has been on the net looking into the take down, BTW we have it down to the point of pulling the heads. The problem is the timing chains. How do I take them off with out pulling off all of the passenger side of the engine parts? I.E. powerstreering pump, vibration damper etc. I find it hard to believe that they would be that shortsighted on the repair of this. Can or should you pull the timing gears off the cams or is this a bad idea? Any help here is greatly appreciated. I really can't afford the cost of the repair in a shop.
  • bolivarbolivar Member Posts: 2,316
    All I know is what I read.
    I can't help with the disassembly of the cams.

    But I CAN tell you about the head gasket (from long reading forums about CAdillac Northstar motors.)

    You CANNOT just replace the head gaskets on a Northstar!!!!! The problem is that the heads have loosened up - steel headbolts into an alumium block. And, when you unbolt the heads, more bolts will probably strip out their threads.

    You MUST put a Timesert kit into this car. This is a kit where you must drill out all the headbolts, rethread the holes, and then screw in a special insert, a Timesert. Then, new head bolts can be screwed into these inserts. This will 'fix' the head gasket problems.

    Search for Timesert on the internet. If you just slap a new gasket on the head, it is not going to work!

    The Timesert kit is about $400. This gives you a bolt-down jig to aid in the drilling and tapping, and one set (20, both heads) of the special inserts. You will have to pull the motor to get to the rear head
  • dgarcia77373dgarcia77373 Member Posts: 1
    i have a 99 deville with the northstar. i recently replaced the upper water hose, lower water hose, used radiator (6 month ago), water pump (1yr 6 months ago), over flow coolant bottle (1yr ago). This car was fine (199- 205 degrees) for about a 25 mile drive and around on the 26th mile it started to overheat to 212, 215, 212, 219, 215, 222,215, 233, 222, 238, 221, 243, 233, 245, 235, got to 251 and stayed at that temp for last mile and never dropped till after i parked and let it cool. It didnt overflow. it did steam the windshield for bout 15 seconds then the overflow bottle gargled bout 10 secs and that was it. if i let it sit 8hrs while im at work. then drive home it does the same thing. it will be good for the 1st 25 miles then start overheating the same way. i checked the oil it looks fine, i chainged the thermostat and same thing. however on the back of the engine, up aganst the firewall side of the engine, i noticed a trace of seepage and a steam sound after it overheats. my mechanic says its a chanel that runs across the block thats leaking, not the heads but idk wat to do. the fans do kick on at 222 and one of them blows on high the other at normal speed. any clues? thanks 4 ur time peeps! im at work now today it got to 261 when i parked. only ran it at that temp for maybe last 10 secs of drive. and also no check engine light. i am in houston, tx i work in the medical center for st lukes hospital [email protected] :sick:
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