Inconsistant temp

07-11-2015, 05:11 PM
I am new-first forum,first post. I have just purchased an 04 DTS(2 months ago) It has 83k. Had good service records. for prevent maint. I just had cadillac dealer flush coolant. here is what's happening around town temp stays at 12 oclock straight up and never moves. I get on the highway and go 75-80 and some times the temp will go up slightly to not quite 1 Oclock. It does'nt over heat just slightly goes up, then may come down but while still going 75mph may go up again. This does not happen around town,lower speeds, or bumper to bumper. The fan's are running! I am a little for mechanically inclined and car savy than most people. To me the hwy should be when it's at its coolest with all that air passing. My instincts tell me maybe the thermostat is going bad or radiator needs to be replaced? But why only at fast speeds does this happen? Any help would be much appreciated. I am worried I know the history with Cadillac's and overheating, and that it needs to be prevented. Getting it fixed is not an issue, but what need's fixed?

Blue Bowtie
07-11-2015, 09:38 PM
Welcome Aboard!

Take a close look at the nose of the vehicle, specifically the underside of the radiator support and the sides of the radiator where they are fit to the support. There should be baffles snapped in place on the bottom and at the sides to keep air from bypassing the radiator (and AC condenser) and an air deflector on the lower edge of the radiator support to create a differential pressure across the radiator while moving. The lower deflector can be broken away from parking too close to parking curbs and raised sidewalks - It's a common mistake. Replacement parts are inexpensive, but the shipping is never free.

Parts numbers 8, 13, 14, 15, and 18 are important:

07-12-2015, 09:12 AM
Thank you very much I am going to check it out right now!

07-13-2015, 08:46 PM
Ok. You were right. If there is supposed to be a lower air dam. Mine is missing! Additionally one of the fog lights is ready to fall out and the push pins that probably held on the air deflector are just hanging(all loosy goosy) so something is going on down there. Plus I noticed it is missing the radiator cover. Now I have to start ordering and replacing parts. I get a company vehicle thru my employer. And barely drive the Cadillac So it may take me a few weeks to get it taken care of. I will post updates. Thank you so much for the advice

07-14-2015, 10:01 AM
I would be checking salvage yards first before ordering new.

07-27-2015, 05:08 PM
Ok to update I was not missing the lower air dam, On the Dts its painted the same color as the body. I was looking at pic's of other Devill'e on the Internet and they had a black one, I thought mine was missing but it was not. What was missing was the radiator site sheild/cover. I have since ordered, and installed it. Sat. I took about a thirty five min trip in the morning and it was pefect(remember the temp never changes around town). I thought it may have been fixed? But toward the end of the return trip at 5 O clock and 100 Degrees the temp went to 1 O clock. Even when I exited and got on side street's it stayed at 1. When I got home the temp was 1 O clock. I put it in park, revved the motor a little and it promptly went back to 12 on temp. Gauge. The next day I drove around town(not on the highway) And as allway's the temp stayed at high noon. If no one has any idea's? Next weekend I am replacing the thermostat. If that does'nt fix it then it's of to the cadillac dealership. I love the car, Want to keep it for a long time, But I know this can't keep happening or I could damage the motor

07-27-2015, 05:10 PM
Something about High speed, aggressive driving that makes this happen

Blue Bowtie
08-01-2015, 09:24 AM
At least you now know the air is moving through the radiator. The thermostat replacement is not a bad idea, and it will probably also involve a flush/refill. That might be a good time to aggressively reverse flush the radiator. It may also be helpful to wash through the air side of the radiator to insure there is no debris between that and the AC condenser.

08-03-2015, 05:37 PM
Great News(sarcasm) So rather then replace the radiator, I took it to Crest Cadillac to diagnose the problem. They couldn't get it to overheat(it only happend in certain situations) But then they did a block test. They say the headgasket is blown. It was leaking exhaust gas into the combustion causing it to heat up. I was in shock. I did alot of research before buying the car. I knew about the head gasket situation. That's why I got an 04 with 82k. The dealership got the price down from $5500 to $4600. on the repair, I told them to do it! They will install the time sert's replace head stud's, all the gaskets and anything else that should happen while the motor is dropped. When I was considering buying a used cadillac/northstar I told myself you have to be prepared to spend money on it, I even thought if the headgasket goes you need to be prepared to fix it if you are going down the used cadillac road. The car is really clean, no its perfect is this a systemic problem with these car's? After my research I thought by choosing an 04 that it would not be an issue. Never the less It is what it Is Hopefully I will get year's of trouble free service out of It. Something about the big Cadillac's I have always loved. Mainly the leg room as I am 6'6" and the luxury,ride,power. If i had it to do over again, I would take a block test to any used Cadillac before buying

08-14-2015, 04:12 PM
So To update I picked up my car from Crest and on the way home the temp gauge started to go up again but even worse then before and I could smell coolant under the hood. I immediately took it right back to the dealership. They are looking at it. Any one every get their head gaskets repaired, the block time serted and then right away the head gasket's blew again?

08-22-2015, 02:25 PM
Ok then it needed a radiator. Appears to be working fine.

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