99 STS Running Hot - Page 6
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Page 6 of 9 FirstFirst 1 2 3 4 5 6 7 8 9 LastLast
Results 76 to 90 of 134
Like Tree8Likes
Cadillac Seville / Cadillac Eldorado Forum Discussion, 99 STS Running Hot in Past Cadillac Vehicle Discussion; Originally Posted by nelson480 You can remove the T stat and unplug the level sensor from the surge tank , ...
  1. #76
    Submariner409's Avatar
    Submariner409 is offline If it won't run, stick on fender vents
    Automobile(s): 2002.5 F55 STS/65500mi, 2004 Ford F150 SuperCab4x4
    Join Date
    Feb 2006
    Location
    MD Eastern Shore - Kent Island
    Age
    75
    Posts
    45,944

    Re: 99 STS Running Hot

    Quote Originally Posted by nelson480 View Post
    You can remove the T stat and unplug the level sensor from the surge tank, it will run with the fans on all the time.
    To reinforce Mark C's post..............

    Not good advice
    - NEVER run a 4.6 Northstar FWD without a thermostat: The cooling system is set up quite differently from what is "normal", and the thermostat is a very integral necessary part of maintaining proper coolant flow through the block and heads.

    The level sensor has nothing to do with fan control or speed - the PCM, ECT sensor and/or the current setting of the HVAC system controls fans. (and, FWIW, so does high transmission temperature)

  2. #77
    nelson480's Avatar
    nelson480 is offline Cadillac Owners Member
    Automobile(s): 2002 Escalade Red Raven
    Join Date
    Nov 2011
    Posts
    71

    Re: 99 STS Running Hot

    Well actually the level sensor DOES have something to do with the fans. In the aurora it does anyways, i would imagine it would be the same with these cars, am i wrong?

  3. #78
    maiahsdad's Avatar
    maiahsdad is offline Cadillac Owners Fanatic
    Automobile(s): 05 STS AWD 1SG
    Join Date
    Apr 2009
    Location
    Fishers, Indiana, USA
    Posts
    473
    Thread Starter
    Quote Originally Posted by Seafunk99
    I didnt read entire thread, but my 99 started running hot and spewing from surge cap...thought it was hg's but replaced the cap with the correct 18lb and it has not happened since. Runs perfect again.
    But would it contaminate a block test? Still a little fuzzy as to why MY block test ( looked just like the dude at the Caddy pro shop) did NOT change color, and his changed barely to see a hint of green.

  4. #79
    nelson480's Avatar
    nelson480 is offline Cadillac Owners Member
    Automobile(s): 2002 Escalade Red Raven
    Join Date
    Nov 2011
    Posts
    71

    Re: 99 STS Running Hot

    I know somebody whose car has a small head gasket leak, and his car is still okay to drive.
    What all have you done for this?
    Surge tank cap replace?
    Radiator replace?
    T Stat replace?
    Coolant replace?

  5. #80
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
    Automobile(s): White Diamond '03 DHS (with DTS floor shift)
    Join Date
    Jun 2004
    Location
    Woodstock Ill.
    Age
    66
    Posts
    74,777

    Re: 99 STS Running Hot

    The coolant level sensor simply turns on a LOW COOLANT warning message. Nothing more.

  6. #81
    Submariner409's Avatar
    Submariner409 is offline If it won't run, stick on fender vents
    Automobile(s): 2002.5 F55 STS/65500mi, 2004 Ford F150 SuperCab4x4
    Join Date
    Feb 2006
    Location
    MD Eastern Shore - Kent Island
    Age
    75
    Posts
    45,944

    Re: 99 STS Running Hot

    There is no such thing as a "small head gasket leak". Either fix it properly or junk it. Throwing cooling system parts at a "small head gasket leak" will NOT repair the underlying cause of overheating or coolant loss.

    The coolant level sensor has nothing to do with fan control. Trace out the wiring diagram in your car's GM service manual.

  7. #82
    maeng9981's Avatar
    maeng9981 is offline Cadillac Owners Connoisseur
    Automobile(s): 14 SRX, 12 Sierra, 00 SLS, 99 Deville 50-year Anniversary
    Join Date
    Mar 2009
    Location
    Dallas, TX
    Age
    23
    Posts
    3,290

    Re: 99 STS Running Hot

    Quote Originally Posted by submariner409 View Post
    There is no such thing as a "small head gasket leak".
    If it's blown, it's blown.

  8. #83
    nelson480's Avatar
    nelson480 is offline Cadillac Owners Member
    Automobile(s): 2002 Escalade Red Raven
    Join Date
    Nov 2011
    Posts
    71

    Re: 99 STS Running Hot

    Well he still drives it, and it doesnt overheat so im just trying to help this guy out...

  9. #84
    maeng9981's Avatar
    maeng9981 is offline Cadillac Owners Connoisseur
    Automobile(s): 14 SRX, 12 Sierra, 00 SLS, 99 Deville 50-year Anniversary
    Join Date
    Mar 2009
    Location
    Dallas, TX
    Age
    23
    Posts
    3,290

    Re: 99 STS Running Hot

    Blown head gaskets will render the car unusable eventually. It doesn't just "have a small leak" and stay there - it will get slowly worse to the point that the system overpressurizes so quickly and runs out of coolant. High coolant temperatures and airbound cooling system can damage the engine. Also if coolant is getting into cylinders and if it is bad enough, it will have the same effect as hydrolocking. Noticeable coolant level drops usually happen when you start having other general early stage HG symptoms such as high load overheating, cold start erratic idle and engine vibration, and etc.

    But this is all a very slow progress - it does not just start overheating at some random day. It is usually first noticed by slightly higher running temperatures (we are talking something like 225-235 here) when loaded. It will do that for a long time. And then you notice that the coolant level is dropping with no external leaks, and then you may get cold start erratic idle. That erratic idle becomes an engine vibration and cold start misfire. At this point you will see a lot of white smoke coming out of exhaust upon startup. The temperatures will reach 255-260 upon acceleration and the car will display to idle or stop engine. At this point the coolant can boil over through the overflow. The coolant level will be going down quicker, and the car will overpressure the system and lose coolant quick.

    Blocked purge line or blown head gasket will NOT be remedied by fans running all the time. The fans run when it gets hot anyway. Removing the thermostat is a guaranteed overheating as mentioned above. Bottom line: Do NOT jury rig the cooling system.

    The best bet would be to follow already-mentioned suggestions, clear up whatever is blocking the purge line plumbing. Blocked purge line and an airbound cooling system will quickly overheat the engine in about or less than 5 minutes. I don't think you are at the very last stage of HG failure, if you are even having HG problems.

  10. #85
    maiahsdad's Avatar
    maiahsdad is offline Cadillac Owners Fanatic
    Automobile(s): 05 STS AWD 1SG
    Join Date
    Apr 2009
    Location
    Fishers, Indiana, USA
    Posts
    473
    Thread Starter
    Quote Originally Posted by nelson480
    Well he still drives it, and it doesnt overheat so im just trying to help this guy out...
    Appreciate that. Next, it's hard to look at the car now because it's dark out and I have no garage space to work on it either.

    When I took off the large radiator hose that connects to the engine, coolant came pouring out of the engine. But when I took the smaller hose off (connected to the hollow bolt) no coolant ran out.

    A person at my job wants to sell me their 2007 CTS. First thought says I don't want a slow car. And I think the CTS is a car that LOOKS good but won't do shit for performance. I don't have other options though other than a $2500 beater if I can find one somewhere.

  11. #86
    maeng9981's Avatar
    maeng9981 is offline Cadillac Owners Connoisseur
    Automobile(s): 14 SRX, 12 Sierra, 00 SLS, 99 Deville 50-year Anniversary
    Join Date
    Mar 2009
    Location
    Dallas, TX
    Age
    23
    Posts
    3,290

    Re: 99 STS Running Hot

    Quote Originally Posted by maiahsdad View Post
    When I took off the large radiator hose that connects to the engine, coolant came pouring out of the engine. But when I took the smaller hose off (connected to the hollow bolt) no coolant ran out.
    Few posts ago you mentioned that the wire hanger is too think to go around the curves. At this point try to clean the side before the hollow bolt. Take the hollow bolt out, and stick the straightened wire hanger in the hole where the hollow bolt used to be, trying to clean it. No curves. If your cooling system is full, and if the blockage is gone, you should see some coolant coming out of the hole even when the engine is off (hollow bolt is lower than the top of the system). That is the indicator that the hollow bolt will flow coolant.

    And then, reconnect the purge line completely and turn the car on, give it a few revs and see if any fluid is coming out of the surge tank-end of the purge line. If nothing, temporarily substitute the entire purge line with an adequate length of 3/8" reinforced rubber hose, starting from the hollow bolt to the surge tank nipple. Skip the heated throttlebody until you can clear the blockage.

  12. #87
    Submariner409's Avatar
    Submariner409 is offline If it won't run, stick on fender vents
    Automobile(s): 2002.5 F55 STS/65500mi, 2004 Ford F150 SuperCab4x4
    Join Date
    Feb 2006
    Location
    MD Eastern Shore - Kent Island
    Age
    75
    Posts
    45,944

    Re: 99 STS Running Hot

    The basic check for a clogged purge line or the hollow bolt nipple has been posted many times..............With the engine cold, the cooling system filled, the reservoir properly filled to halfway - cold - you remove the purge line from the top side of the reservoir (the plastic nipple). Remove the reservoir cap and insert the end of the purge line in the open reservoir neck. Reach in and start the engine. The purge line should spit, then flow a steady stream of coolant into the reservoir.

    If there's no flow either the line itself is plugged or the hollow bolt is. Use a proper sized drill bit to carefully clean it out, or, if the line is plugged, either try to blow it out with compressed air or get a whole new length of proper sized reinforced fuel hose from any parts store in town. New screw clamps, too.

    A clogged purge system WILL cause air binding in the coolant system and WILL cause water pump cavitation, leading to overheating and coolant blowoff.

    nelson 480, Read all three pages of posts in this thread - we're all trying to help, and there has been a LOT of 1999 FWD Seville advice given......... if you have ever stuck your head under the hood of one of these cars you'll see that it's quite unlike any RWD setup on earth.

  13. #88
    nelson480's Avatar
    nelson480 is offline Cadillac Owners Member
    Automobile(s): 2002 Escalade Red Raven
    Join Date
    Nov 2011
    Posts
    71

    Re: 99 STS Running Hot

    Quote Originally Posted by maeng9981 View Post
    Blown head gaskets will render the car unusable eventually. It doesn't just "have a small leak" and stay there - it will get slowly worse to the point that the system overpressurizes so quickly and runs out of coolant. High coolant temperatures and airbound cooling system can damage the engine. Also if coolant is getting into cylinders and if it is bad enough, it will have the same effect as hydrolocking. Noticeable coolant level drops usually happen when you start having other general early stage HG symptoms such as high load overheating, cold start erratic idle and engine vibration, and etc.

    But this is all a very slow progress - it does not just start overheating at some random day. It is usually first noticed by slightly higher running temperatures (we are talking something like 225-235 here) when loaded. It will do that for a long time. And then you notice that the coolant level is dropping with no external leaks, and then you may get cold start erratic idle. That erratic idle becomes an engine vibration and cold start misfire. At this point you will see a lot of white smoke coming out of exhaust upon startup. The temperatures will reach 255-260 upon acceleration and the car will display to idle or stop engine. At this point the coolant can boil over through the overflow. The coolant level will be going down quicker, and the car will overpressure the system and lose coolant quick.

    Blocked purge line or blown head gasket will NOT be remedied by fans running all the time. The fans run when it gets hot anyway. Removing the thermostat is a guaranteed overheating as mentioned above. Bottom line: Do NOT jury rig the cooling system.

    The best bet would be to follow already-mentioned suggestions, clear up whatever is blocking the purge line plumbing. Blocked purge line and an airbound cooling system will quickly overheat the engine in about or less than 5 minutes. I don't think you are at the very last stage of HG failure, if you are even having HG problems.
    And thats what i thought, my car was running 215-220 with plenty of air, completely abnormal when the car would always run 210. First thing i changed was the thermostat and now it runs a happy 195. Somebody on here said that a "happy northstar" runs 215-225. I think they are dead wrong. Especially being an aluminum engine, the cooler the better.

  14. #89
    Submariner409's Avatar
    Submariner409 is offline If it won't run, stick on fender vents
    Automobile(s): 2002.5 F55 STS/65500mi, 2004 Ford F150 SuperCab4x4
    Join Date
    Feb 2006
    Location
    MD Eastern Shore - Kent Island
    Age
    75
    Posts
    45,944

    Re: 99 STS Running Hot

    Quote Originally Posted by nelson480 View Post
    And thats what i thought, my car was running 215-220 with plenty of air, completely abnormal when the car would always run 210. First thing i changed was the thermostat and now it runs a happy 195. Somebody on here said that a "happy northstar" runs 215-225. I think they are dead wrong. Especially being an aluminum engine, the cooler the better.
    The factory FWD Northstar thermostat is set to begin opening at 188 and be fully open at 206. Without some A/C or DEFROST function set, fans go to SLOW at 224 and FAST at 236. IF you're sitting in slow or stopped traffic and fans go to SLOW the system cools to 213, fans shut off, and the cycle repeats. The desired GM operating range for the engine is 195 to 225. Being an aluminum engine has nothing to do with design operating temperatures. If you want to monitor coolant temps in real time either set up an onboard computer data logging system or invest in a ScanGauge-II (www.scangauge.com)

    Click on my username, open my profile. Two picture albums there with annotated pictures of the cooling system, parts, and a late Seville/Deville temperature gauge with annotation.

  15. #90
    maiahsdad's Avatar
    maiahsdad is offline Cadillac Owners Fanatic
    Automobile(s): 05 STS AWD 1SG
    Join Date
    Apr 2009
    Location
    Fishers, Indiana, USA
    Posts
    473
    Thread Starter
    Quote Originally Posted by maeng9981
    But this is all a very slow progress - it does not just start overheating at some random day. It is usually first noticed by slightly higher running temperatures (we are talking something like 225-235 here) when loaded. It will do that for a long time. And then you notice that the coolant level is dropping with no external leaks, and then you may get cold start erratic idle. That erratic idle becomes an engine vibration and cold start misfire. At this point you will see a lot of white smoke coming out of exhaust upon startup. The temperatures will reach 255-260 upon acceleration and .
    Exactly what happened to mine in that order. Except that I could RAISE the RPMs and cool the car down. If at a light, I could put it in neutral and kick the RPMs to 1800-2000 and it would cool the car down.... Until the day I revisited this thread. Raising the engine speed no longer helped.

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting