beaubjames Posted April 15, 2013 Report Share Posted April 15, 2013 Ok ..you guys seem to know your stuff ...Got a 99 Deville ..approx 140,000 miles on it ..Couple mos ago water pump went out and found a leak in the radiator..Replaced radiator,water pump,thermostat, flushed system ...worked fine for about 2 or 3 mos ...then one day (about a week ago) it said "check coolant level"...so I added about 1/3rd gallon of dex ..the next day is started overheating ...took it back to the shop and had them change the thermostat again and change the "sensor" ....it over heated when the mechanic "test" drove it ...they did a pressure test and it was good ...they threw up their arms and said that it must be head gasket and I should put a gasket sealant it and go trade it in ...not gonna do that !! If it IS the head gasket and I have to take it out and shoot it than so be it ...but,.first let me explain some symptoms ...the temp will spike from like 215 to 250 in like 1/2 mile and subsequently go from 250 back to 215 in a matter of seconds but, drove it all day today and had no problems ...one time(today) it went to 235 but then back to 210 again is a matter of about 1/2 mile ..a couple days ago it got hot going up a hill ..today it got cooler when i went up that same hill !! .. oh, and one more thing , no leaks that i can tell and coolant level seems to be holding ..no white smoke,always starts right up ..when it did get to 260 degrees once(before i took it to the shop the second time) there was no steam or antifreeze smell and when i pulled over and put it in park the temp whet back to 220 in about 15 seconds ..I know it still could be a head gasket issue ...but , it would be really bad if I scrap it and all it was was something simple ....PLEASE HELP !! Thank You !! Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted April 15, 2013 Report Share Posted April 15, 2013 Sorry to hear your Cadillac is overheating. The classic test for head gasket is a test kit for exhaust gases in the coolant. You can get these from auto parts stores or from that link on Amazon. The fact that it cools down when idling doesn't rule out a head gasket issue -- sometimes the heads only 'open' when under torque. If there is not a head gasket leak, but it overheats when moving and not when stopped would suggest a problem with air flow across the radiator. Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
Jenny Webster Posted April 15, 2013 Report Share Posted April 15, 2013 I don't know much about cars, seriously! But, for what it is worth... this is exactly what happened to my 99 when it was around 145K --did everything you did. Actually, the best part of the story was I had just put $1,500 into it (and that is a lot for this broke girl) Fixing some electrical, a/c, coolant stuff.. and body work from when I had wrecked it the previous winter. And the NEXT DAY was when it started overheating. Changed the Thermostat... yadda yadda... the eventually ruled it to be a head gasket. It was also throwing some tranmission error and I was getting ready to move half way cross country... so I sent her to her grave Link to comment Share on other sites More sharing options...
Cadillac Jim Posted April 15, 2013 Report Share Posted April 15, 2013 I think my car went to Heaven. It has a new home as the coddled pet of BodybyFisher. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted April 15, 2013 Report Share Posted April 15, 2013 There is a way to know exactly what is happening but you have to follow a disciplined diagnostic approach. Until you test you don't know what the cause of the overheating is, and disposition of the vehicle is premature Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
Cadillac Jim Posted April 15, 2013 Report Share Posted April 15, 2013 If you want to rule out a head gasket leak you can test the coolant for combustion byproducts now. A quick check is with your nose: if you don't smell exhaust in the radiator surge tank, and you don't smell coolant in the exhaust when you start the car in the morning, it probably does not have head gasket problems. More common problems are low coolant or leaking cooling system, less than 50% antifreeze, the radiator cap not holding pressure, clogged bypass, clogged radiator, blocked radiator, clogged heater core, stuck or bad thermostat, slipping water pump belt or bad water pump, etc. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
koushka Posted May 14, 2013 Report Share Posted May 14, 2013 Sounds to me like an air bubble moving around your temp sensor. Might try clearing the bypass/purge line. Not sure if that year has the bolt with the hole in it but I think that is the purge line bolt and should be free flowing to get the air out of the system. Just a thought, good luck, koushka Link to comment Share on other sites More sharing options...
300_800_bowler Posted May 19, 2013 Report Share Posted May 19, 2013 1998 Cadillac Deville - Northstar About 3 months ago the Caddie overheated on a small trip out of town. The temp reached 250 degrees on the inboard dash display. After in cooled down, I refilled it with water and continued to my sister-in-laws house. The next morning I changed the water pump and replaced the thermostat and refilled with Dexcool - on my test drive the car still overheated - knowing all the time that I should just replace the head gaskets, but I still didn't have any water in the oil so I just kept looking for another cause for the overheating. This Deville only has 81000 miles and runs great except for the overheating. I found a crack in the radiator and replaced it. I also found a crack in the recovery tank and replaced it also. I replaced the intake manifold with a Dorman Intake Manifold because the OEM showed signs of leaking water pass the gaskets. Then went for another test drive and it still overheated. The next thing we did was to replace all the gaskets on the water crossover between the two heads - the OEM's were made out of plastic and one was complete destroyed and leaking water. So as of today, we did another test drive about 80 miles going from 500 feet above sea level to 4000 feet with the air on and doing about 75 miles per hour and the temp never got over 223 and then when we got back to town it stayed around 208 to 212 degrees. So, I'm still not convinced that the problem is fixed with the overheating - I'm going to drive it next week and if it acts up again - I guess I'm going to do the big job - replace the head gaskets and the headbolts - Any Idea's as to what else we can do ???????? Link to comment Share on other sites More sharing options...
Cadillac Jim Posted May 19, 2013 Report Share Posted May 19, 2013 First, the Northstar doesn't have a credible path from the oil to the coolant except in the oil cooler in the left radiator tank. Second, there's a lot of little things you have found so you shouldn't jump on the head gaskets until you are certain that your cooling system is OK. Third, a common problem with the same symptoms is a clogged by-pass, usually the "bolt with a hole" at the water crossover near the thermostat housing. Fourth, another common problem is an electrical problem with the fans. You should look at the OBD codes before you buy any parts that don't specifically fix something you can see, like the leaking crossover gaskets. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
BodybyFisher Posted May 19, 2013 Report Share Posted May 19, 2013 1998 Cadillac Deville - Northstar About 3 months ago the Caddie overheated on a small trip out of town. The temp reached 250 degrees on the inboard dash display. After in cooled down, I refilled it with water and continued to my sister-in-laws house. The next morning I changed the water pump and replaced the thermostat and refilled with Dexcool - on my test drive the car still overheated - knowing all the time that I should just replace the head gaskets, but I still didn't have any water in the oil so I just kept looking for another cause for the overheating. This Deville only has 81000 miles and runs great except for the overheating. I found a crack in the radiator and replaced it. I also found a crack in the recovery tank and replaced it also. I replaced the intake manifold with a Dorman Intake Manifold because the OEM showed signs of leaking water pass the gaskets. Then went for another test drive and it still overheated. The next thing we did was to replace all the gaskets on the water crossover between the two heads - the OEM's were made out of plastic and one was complete destroyed and leaking water. So as of today, we did another test drive about 80 miles going from 500 feet above sea level to 4000 feet with the air on and doing about 75 miles per hour and the temp never got over 223 and then when we got back to town it stayed around 208 to 212 degrees. So, I'm still not convinced that the problem is fixed with the overheating - I'm going to drive it next week and if it acts up again - I guess I'm going to do the big job - replace the head gaskets and the headbolts - Any Idea's as to what else we can do ???????? Replacing the intake manifold was unnecessary no water flows in the intake. Check the purge line to see if it is flowing, if it is clogged air can not get out of the system If the purge line is clear, the cap is holding pressure and the system is holding pressure do a block test for combustion by products go to NAPA and purchase a BalKamp block tester, easy fast test, you will know if you have a bad head gasket for $50 Dont do a head gasket job WITHOUT testing the coolant for combustion by products or you will waste more money Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
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