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2006 Cadillac DTS Luxury III 135K
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453 Posts
maybe not enough coolant going thru the system, maybe head gasket problems check to see if there is any coolant in the oil and it could be that the thermostat is bad
 

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2006 Cadillac DTS Luxury III 135K
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453 Posts
check to see if there is any mayo like substance on the oil lid, does the heater blow warm in the car
 

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'98 STS (RIP @ 206,xxx miles)
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4,854 Posts
The car overheats
Can you put a temperature value on "overheats"?

....and coolant leaks out of the reserve tank.
Is there an obvious crack or hole in the reservoir?
Is the pressure cap sealing properly?

Don't get side tracked and take the leap to a "headgasket" catastrophe based on what could be minor overheating and an external leak. Be systematic and determine the causes.
 

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cadillac seville sts
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24 Posts
Discussion Starter · #8 ·
The surge tank is not cracked and the cap is a couple years old. I have a noise (water bubbles) coming from the console when I accelerate or rev up to 2000 rpm in park.
 

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cadillac seville sts
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24 Posts
Discussion Starter · #10 ·
The gurgling, bubbling noise can be heard just through the dashboard, like fluid rushing into another chamber.
 

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1997 Cadillac STS (BOSE w/AUX In, Massage Seats, URPAS, "Z")
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6,405 Posts
How is your purge line?
I know you mentioned the TC and WP were serviced recently, first of all why? Second, make sure the small WP belt is fine.
How is overheating...in 3-5 minutes after startup, when you are strangled in stop and go traffic and at low speeds, under heavy acceleration and up the hills?
HG is not as common as the Internet would make you think, also N* will not mix coolant with oil, so no point looking for "mayo" in your oil.
 

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cadillac seville sts
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24 Posts
Discussion Starter · #12 ·
Mechanic checked the puge line and said its fine. Thermostat I changed because it was never done before and the water pump went on the car so I had to replace. Temp gauge is at the 225-250 after 15 min of driving and will go up and down. Then will go to redline after an hour. Mostly redlines on the highway and have to pull off to let it cool down. But all this varies and redlines even city driving if I've been on highway for 30 min.
 

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1997 Cadillac STS (BOSE w/AUX In, Massage Seats, URPAS, "Z")
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6,405 Posts
What you say is not what I would like to hear (for your sake). Disconnect the purge line from the coolant tank end and put it into a 2l bottle. Start the car and let it idle. Do you see a nice steady (laminar) flow or a bubbly flow?
If is bubbly then the next step is a exhaust gas test for the coolant tank. There is a kit from any large parts store that goes for around ~$50. You can do more than one test though. Drive the car for a day or two (don't let it overheat or you warp the heads) and then perform the test. The negative test ends with the same bluish color of the fluid as the one you started. Maybe a slight hint of green (just a bit) is still OK. A green yellow fluid is BAD.
Just DON'T add coolant before the test (if you do the test will be negative).
 

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Super Moderator
2010 DTS
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88,148 Posts
:yeah:
It's called a block test. I hate to say it, but it sure sounds like the head gaskets are going.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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73,446 Posts
Northstars with failing head gaskets do not usually put coolant in the oil, so there will probably be no milky froth on the dipstick and there will be no chocolatey gum inside the oil fill cap.

The proper coolant level is halfway up in the reservoir, cold. There is probably a cold fill legend and arrow molded into the reservoir top and side. DO NOT check it hot. The pressure cap is either 16 psi or 18 psi, depending on year. I think yours is an 18.

"Thermostat and water pump were changed last month"...........were there ANY of these symptoms before the change, and why did you do the change ??? OK - I see water pump. Is the thermostat in correctly ??


www.sjdiscounttools.com/lis75500.html - cylinder block/head gasket test kit.
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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73,446 Posts
Forgot this - water pump cover/thermostat housing.
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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73,446 Posts
Can the head gasket be changed without pulling the motor out?
Given the machine work and just plain access involved in drilling out all 20 head bolt holes and installing inserts or studs, NO. Some can do the job with the engine in the car, but it's made far, far easier if you drop the whole drivetrain out the bottom of the car.
 
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