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Cadillac STS/STS-V Maintenance & Repair

gman8gman8 Posts: 1
edited October 2019 in Cadillac
Bought a 2002 certified sts w/10,000 miles. After 18,000 miles low oil message light came on. Dipstick indicated hardy any oil present. Still 27 % oil life left. Dealer said that this was a common problem with the northstar engine and oil should be changed every 4000 miles. What's going on? Is he blowing smoke? Another issue is that mileage is only 22 mpg on the highway, based on previous 1995 northstar engine I was getting 27 highway. Are these common issues ?


  • jlb2jlb2 Posts: 18
    My 2000 deville northstar V-8 uses qt. of oil every 1500mi,I do a change 3000 to 4000mi.And will do a honest 30mpg at 70mph highway.What a ride.
  • ambler01ambler01 Posts: 2
    This “maxed out” Cadillac STS is technologically extravagant and really fun to drive. The features I appreciate the most are: remote start, heads up display, cooled seats, adaptive cruise control, and performance braking. My particular vehicle was assembled in mid October, and delivered end of November, 2004. It is plagued with two anomalies. One, unprovoked, the car evidences three problems at once: Radar cruise not ready/service brake assist/service stability system. The dealer is unable to repair. Two, the Voice Command feature has never worked, except for "Windows Down" or "Windows Up."

    I need to know if these problems exist in “maxed out” STS’s assembled recently. Thank you for any feedback.
  • What's your opinion on the cooled seat function? Are they comparable to the corollary heated seats option? And how many functions does the voice command system control?
  • ambler01ambler01 Posts: 2
    Here in South Florida. I use the A/C seat feature almost every day. It is fabulous!

    I have used the heating function as a heating pad on a long trip.(!)

    The Voice Command system is one of the "firsts" on a production unit. It does not work well at all. She (the computer is a female voice) is slated to control about a hundred functions, ranging from changing radio stations to changing virtually any electronically controlled feature. The voice recognition software simply does not understand clearly spoken commands. Cadillac is working with the software house to resolve this. I have had several new versions installed; they still do not have it fixed. The routine is: you stipulate, she repeats, she implements. There is NO opportunity, after she repeats, to cancel. About 90% of the time, she gets the command wrong, and does something you do not want, and have not asked for.

    The old fashioned,simple Voice Phone Dialing system, however, works perfectly.
  • stilesstiles Posts: 6
    We have a 2 month old STS, belive the cool seats are an extra but we never heard anything about voics command, is that an extra also?
  • mnjoemnjoe Posts: 36
    Had mine 10 days. No evidence of any of those problems as of now. knock on wood.
  • stratstrat Posts: 1
    I was wondering if anyone has tried to replace the shocks on this car with after market units. Mine are shot on all four corners.
    The original Cadillac shocks cost $1500.00 Canadian per corner! I am hoping to pull the fuse on the stability system and install regular gas shocks. I have already installed custom rear springs so that I don't have to rely on the air-shocks for load leveling.
    It would have been nice to have the shocks rebuilt but I doubt that is possible.
    Any suggestions will be welcomed.
  • i recently rebuilt the 4.9l engine in my 92 seville sts. the problem is i have the same low oil pressure i had before i rebuilt. pressure is about 5-7 psi. at idle. owners manual calls for 11 psi at idle. journals were all miked and i plastigaged all bearing clearances when installing and all were well within spec. has anyone ran into this problem before? is this just normal for this engine? i am running 10w30 oil was there ever a bulletin saying to use heavier oil? i will appreciate any info. thanks.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    did you rebuild the oil pump or at least measure it for excessive clearance?

    Oil pressure at idle isn't so terribly important if it's really strong at highway speeds running at operating temperature.
  • oil pump was new. cam, lifters, bearings,timing chain and gears and oil filter adapter were all new also. the biggest problem i have with the oil pressure is the sensor that belongs in it where i have the "wet" gauge right now. with the pressure so low it brings a message up on the dash "low oil pressure shut off engine". i would like to sell the car in the near future but that is not a good selling point.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    Did you put in new rods? If you didn't, or didn't reconditionthe big ends, that's possibly the problem. The rod big ends might be distorted when they warm up. My first guess was cam bearings, the most likely culprit.
  • For about 5 weeks the fuel gauge will start at F on a full tank drop to 3/4 back to F to 1/2 to 3/4 to 1/4 to 3/4,ect.Any suggestions?
  • jaymannjaymann Posts: 3
    I had same problem on my '97 STS. Service advisor suggested we try GM's fuel line cleaner (not exactly sure what is was called). He put two bottles - approx. $12 each and it solved problem avoiding need to replace guage float in tank. Worth trying before spending a lot of money.
  • I recently replaced all the suspension shocks and struts, etc with aftermarket non-air ride on a 94 Eldo.
    It rides a little harder but the "service ride control" message on computer is driving me crazy. So far no joy in removing it from anywhere. :cry:
  • my car will run great as long as it's sitting still. but if i put it in drive and the engine gets to 200 degrees it starts jerking and cuts off. i've replaced the temperature sensor and thermostat. how can i fix this problem?
  • I have been experiencing intermittent engine failures in my 2000 STS, they happen usually when coming to a stop but I have also had it happen when slowing down on a highway ramp they do no occur reguarly but I have had it a happen about six times in the last 6 months.... anybody have similiar situations and have a fix?
  • limaslimas Posts: 1
    This 96 seville has 70k miles and runs great but quite frequently it needs a shot of ether to start, especially after sitting for a while. Once it starts it runs fine. Fuel pump pressure is good, Two second start up pump solenoid works. Any suggestions as to what this problem could be would be appreciated.
  • My STS is a 98 model and when accelerating, a sound of water or some other liquid is heard from above the footwell on the passenger side. Any ideas of what it is and how it can be eliminated?
  • Hello all. I am brand new to this forum, so I hope I'm posting this in the correct area.
    I am in the process of buying a '96 STS from my inlaws. The car looks perfect and, when running, runs perfect as well.

    About 6 months ago, the car began having problems that, when it would sit for a couple days, the battery would run down and the car would need to be jump-started. Since the car never really sat for more than a couple days, it wasn't that inconvienient.
    The past 2 weeks, however, (since I have aquired the car) the problem has increased. My wife can drive it for 45 minutes, go inside a store, come out 15 minutes later and the battery is dead.
    A mechanic said he went over the car with a fine tooth comb and can't figure out what's causing this problem.

    If there is any advise or ideas of what this problem might be, PLEASE, post up and let me know. For the price I'm getting this car for, it is well worth dropping money into to get it fixed and I'm willing to do that.

    Thanks for your time!
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    If the battery is more than 4-5 years old, that could be your problem right there. Otherwise, there are simple tests for battery drain. You can also have your old battery "load tested" if someone has that tool.
  • Thank you SO much! I've gone out and bought a new battery today. I'll put it in this weekend and keep my fingers crossed!
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    Let us know how you make out with that and if you have any more trouble.
  • I have a 96 STS with 135K mile. There a a lot of rattling at low speeds from the front end over moderate bumps in the road. Does anyone have any ideas what might be the cause: worn out bushing, grommets, or shocks? Or all the above.
  • My car ('97 STS) had a problem similiar in description to your problem pfkaiser. The noises could originate from any number of things I supose, but in my case the culpret was a sway bar bushing. Cost of part: $20. Note that the sway bars come in different diameters, and the sway bar diameter must be known for the corret bushing. Good luck.
  • dueyddueyd Posts: 1
    i have a 90 sts that is in A-1 condtion. I'm having a bugger of a time with the climate control system though. It seems that the blower works fine when in AC mode but will not blow in heat mode. To make matters worse the hot air does not stay hot. As you drive it the air goes from hot to barely warm. I live in Wisconsin so this gets to be a mite chilly. I have had the car for 7 years now and this problem just started occuring. First with the blower and now with the heat. Anybody have any suggestions????
  • dyates773dyates773 Posts: 24
    Many thanks to all of you who have repeatedly posted your comments on the well known issue of Northstar head bolts losing thread integrity in the block leading to head gasket issues. I own a 1998 Seville STS with 194,000 miles. The car is in excellent condition except...... at sustained highway speeds the coolant is forced out of the coolant tank cap. The car will overheat when the level drops enough to stop flowing or gets "air bound". This car is in good enough condition to drive everyday, runs great, but cannot be driven at sustained speeds over 60 mph. Its age and condition does not warrant installing a long block or a major teardown on such a high mileage engine, the cost alone would be more than the car is worth. For those of you in my situation I have engineered a less than perfect but workable solution. My thinking was how to vent the exhaust gas and pressure to prevent forcing out the coolant. Being a Chemical Engineer I'm very familiar with industrial hot water systems. Many of these systems cannot tolerate air in the piping. Most of them have air vents in the piping system. They are high pressure and high temperature. I have installed a 1/2" NPT float type air vent into one of the cooling system bypass hoses that now vents the trapped combustion gases. The vent is rated at 50 PSI and 250'F. It has worked for over 1000 miles in the last month. It does not pass liquid, only air. Today I drove home on the Interstate at 70MPH for over 40 miles with an outside temperature over 80 degrees. No overheating. I will post a picture if there is any interest. Good luck.
  • yes please post pics. Thx. Can i assume this fix will work on 1995 model as well..?
  • My 1995 Sev. STS has a strong fuel odor in the passenger cabin. Instinct told me fuel leak, but never found evidence of this. Until it was parked in a drive way with a slight grade (about 25% angle). I've backed the car in this same driveway many times no odor, no dripping. Parked head first for about 3-4 hrs, went to start it and experienced what could best be described as "out of gas" started real hard. Once it was running, was almost overwhelmed w/ fuel odor, backed out and for the first time saw a wet spot in the driveway, hopped out to check what it was and "bingo" my fuel leak. Turned around backed the car in same driveway overnight, next morning no odor, no dripping. Any thoughts, Anybody..? (Fuel Rail on this year has a recall, is this evidence of this..?)
  • klerk183klerk183 Posts: 2
    Hello, I am Siem from the Netherlands, and I followd your lost off coolant.Ther is however one problem,when there is a leak in the headgasket, coolant can escape, butt can also reach the cillinder when engine is shut of after using it.
    So in the future you whil get problems whit emissions and catalysator.
    But I am courious to see your solution, in one of the bypass piping.
  • tateostateos Posts: 36

  • hillisshilliss Posts: 1
    I have a 1996 with the same issue, except I have never seen any fuel. I would think a fuel rail leak, with be very small, and never make it to the ground. You can lift the plenum (cover) by removing four 1/2 inch nuts, and check for smells, or fuel from the fuel rail. If your fuel rail is nylon, the recall has not been performed.
  • criaturacriatura Posts: 1
    HI, every one, I recently get an a 1996 STS with a new engine on. But have theft system problem. This means the car Crank but not star, I been doing every thing to try to clear the theft security system, and not succefull. Can one of you tell me how can I fit the problem...Thanks
  • mantagmantag Posts: 47
    Hello all. Have a 99 STS - Big Red as I call it. 71000k.

    I keep hearing about the dreaded "Service Ride Control" message in the info area on dash. I have not have this pop up yet, but does anyone know if this message is tied to when a certain number of miles is driven or is it by time or when there is a problem with the ride control? Thanks.
  • I have a 96 STS with 160,000 miles and have been experiencing the same problem. A lot work just short of
    a tear down has been performed. the only thing left
    would be the head gaskets, and I'm not going that deep.
    could you explain which bypass line you tapped into, supply
    or return and possibly post a photo or two ? You might have
    something here with the pressure blow off.
  • I'm looking forward to picture ( float type air vent). Please post. Thanks
  • This type of head gasket leak is very rare. Only the high pressure combustion gases seem to pass into the coolant system. If anything other than a tiny amount leaked into the cylinder head, upon cold startup the engine could misfire if the spark plug was wet. My experience and research says the coolant doesn't leak from the engine, only from the tank.
  • A/C blows cold, but when I try to use the heater it just blows cold. I checked all fuses Ok. What should I be looking for?
  • Look for low coolant level or air in the system. Your low coolant sensor is in the bottom of the fill tank. There is an electrical connector that could be off if you have no low coolant indicator on the dash but the tank is in fact low. One last item, the STS thermostat allows water to flow back to the engine, which is the reverse of moast engine designs. The Northstar relies of a very high recirculation of coolant.
  • mb500mb500 Posts: 1
    I have a 2000 sts.The lights on the steering wheel and overhead console are out.Anyone know the problem.
  • My 2000 Cadillac STS has been saying coolant low...It has even overheated on time while on the highway with the AC on. It said Engine Hot...Shutting down AC. It had no smoke...I let it cool down and I put coolant in it...It started saying low coolant within a week or so...Still can't run ac for very long...before engine gets hot. Only one time I noticed a small amount of coolant on the garage floor. Mechanic can not find a leak...said to replace the radiator cap. That may help? Now the interior lights keep going dim...I can not see the digital speedometer or the clock. during the day and at night and then sometimes it jsut comes on...then off again???? Is this the alternator? What could this be...My father is a mechanic and so is my brother-in-law and funny but know one can tell me what is wrong!!! HELP!
  • sls002sls002 Posts: 2,788
    My guess is that coolant is leaking from the head gaskets or the head gaskets are blown/leaking. You need a better mechanic, I suggest going to a Cadillac dealership with a decent service department. Replacing the head gaskets will cost about $2000 or so is my guess. Replacing the engine will be more.
  • lac601lac601 Posts: 1
    I have a 96 seville, runs good until you get to about 65mph. Then the rear right wheel start vibrating and bouncing up and down. As speed increases vibration gets worse. Hit a bump and car wants to sway badly. Wheel bearing, stablizers, everything appears to be tight. Is there any idea what this could be. Thanks!!!
  • It could be the fuel pressure regulator.
  • where do you get the air vent? which bypass hose did you put it in?
  • I have a STS 2008. Less then 10k miles and the dealer is replacing the engine due to a crack in the header. We took the car in because onstar said the tire pressure was low. The car never notifed us of this. When they looked the car over for saftey they found no coolent, it was gone. So they were going to repair it. The car nor onstar ever warned of low or no coolent. While doing the repair they found a crack in the block which means the car was overheating. The car never warned of over heating.

    When asked about the sensors that did not go off, the dealer is saying it was just a fluke. My question, if just a fluke, why did it go on for so long? Normaly flukes last an hour or two, or a day, but not this long. Any ideas? The car has been in for many other repairs as well. I think the dealer is trying to keep me in the car past a year or 12k miles so I will not qualify for the lemon law. I am very frustrated.
  • Can anyone tell me why these cars are overheating, I read most of these post and im having the same problem.
  • thats what I wanta know too!!!!!!!
  • rokntaroknta Posts: 2
    it has been awhile now,just wondering how it is still running.i am thinking on trying your fix and would like some input.What line is it put on,top or bottom.In doing this fix isnt it just a temporary fix until the headgasket fully goes?thanx...
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