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2016 XTS4
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Discussion Starter #1 (Edited by Moderator)
Well my 2004 DeVille DTS has a blown head gasket. I knew the price was too good to be true :) anyway I love the car and it's immaculate in every other way so I'm inclined to fix it even though that may not be entirely rational.

So any Canadians know of a good independent mechanic to get this done at a good price in the Ottawa area? Or is it the stealership?

Cheers

I have a 2004 Deville DTS. It's leaking exhaust into the coolant. It is not burning or losing coolant at all. The temperature gauge (analog) is in the normal position most of the time, and has only ever gone up one notch after being stopped in traffic. It cools down as soon as the car is moving again. The heater no longer works at idle but does blow hot air when driving. There's no white smoke and no problems with the condition of the oil.

How long can I drive the car in this condition while I organize the HG repair? I've read that driving it gently provided it's not burning coolant or mixing oil and coolant is ok.

If anyone knows of a good mechanic in the Ottawa, Canada area that would be helpful too...

Cheers
Clive.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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How do you know it's a bad head gasket ? Have you done a cylinder block exhaust gas test ?

Northstars do not usually mix oil/coolant due to a bad head gasket.

No loss of coolant, how hot is "overheating" ?? Temperature rising while stopped or in heavy traffic is perfectly normal.

A partially clogged purge line could well be the source of poor coolant flow through the heater core - or overuse of system sealers.

(Threads from 2 different forums merged.)

Here's your temperature gauge and notations - what's your "overheat" area ????
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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So seeing as you have zero signs of HG failure, what makes you think you have an HG issue?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Re: Ottawa Cadillac Mechanic for HG Repair

The temp gauge moved in heavy traffic.
 

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2016 XTS4
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Discussion Starter #6
The cooling system is pressurizing rapidly when the car is started, even before it gets warm, and remains pressurized when cold. I haven't tested yet but will do that today or tomorrow, however the build up of such large pressure in the surge tank is what makes me think it's exhaust gases in the cooling system. Would the purge line issue cause that too?

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Overheating is to the 230 mark, no higher.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Re: Ottawa Cadillac Mechanic for HG Repair

The rapid pressure rise throws a different light on the problem. Do the exhaust gas test.
 

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2016 XTS4
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Discussion Starter #8
I bought the test kit and will run the test tonight, that said, with the pressure in the system I'm 99% sure it's the HG. So, any advice on the original question? Dealer in Ottawa wants $3,500 to fix... There are no independent specialists here as far as I can see, but there is a place about 4 hours away that quoted significantly less. Would I be safe to drive the car down there? Can I still do my daily 10km commute for a while?
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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Best option would be Jake at Northstar Performance. Not sure how far that is from you (He's in Canada) but if there's a problem, you're in the very early stages. Perfectly safe to drive.
 

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Discussion Starter #10
Yeah I was looking at Northstar Performance or a shop a little closer to home that sells the same stud repair. Jake is a six hour drive, but it sounds like I could do that safely. I've been in touch with him and will have to see when he could potentially fit the repair in. I'm a first time Cadillac newbie - English immigrant - and I've always dreamed of owning this car. It's all I hoped it would be apart from this, so although the repair is probably getting close to what the car's worth I'm still going to do it. It's in immaculate condition otherwise.
 

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Have you asked Jake if there's a shop closer to you that has installed his studs before? There's also a list of recommended shops on the NP site.
 

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Discussion Starter #12
The closest place is still about 5 hours so I might as well go straight to the source :) He's booking me in. He's told me since the car is just beginning the problem it should be ok to drive gently until I get it there. Just keep the coolant topped up, don't let it overheat (which I now realize it hasn't done thanks to the gauge explanation above). Needle's never gone past the S mark on that picture. I did get a low coolant warning today for the first time and topped it off to the cold fill. Thanks for all the advice.
 

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Discussion Starter #13
Ok... Confused by my block tester. I bought the kit but the fluid in the bottle was green to begin with. Ran the test and it turned blue. But lots of gas bubbling up through the tester when the engine is revved. Was the fluid off? Does the presence of so much gas indicate combustion products even though the fluid stayed blue?
 

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White Diamond '03 DHS (with DTS floor shift)
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I bought the kit but the fluid in the bottle was green to begin with. Ran the test and it turned blue.
The fluid is old or contaminated.

Does the presence of so much gas indicate combustion products even though the fluid stayed blue?
Yup
 

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Discussion Starter #15
Figures. Jake had told me that a pressurized cooling system even when cold was diagnostic by itself. So off to Northstar Perfomance we will go. In the meantime new tires.
 

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Discussion Starter #16
One other item of interest, my engine is a JKA code, which means it should have the 2.0 threads... am I super unlucky, since I thought these resolved the head gasket issues?
 

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Yes, the course thread bolts did virtually eliminate the issue. Unfortunately, any engine can develop any issue.
 

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Discussion Starter #19
So the plot thickens. I stopped hearing from the one place I had in mind to fix the car and I was headed out of town for a week on a business trip so I handed the car over to a dealership here in Ottawa. Out of an abundance of caution they ran a combustion gas test twice - fluid stayed blue. A coolant pressure test was also fine.

So, left with the only symptoms being pressure remaining in the cooling system even when cold and a lack of hot air at idle, they did a full coolant flush, backflushed the heater core and suggest I keep driving and see how it goes. I do now have warm air at idle, although it still gets hotter when driving or revving. It's too soon to say whether the cooling system will be pressurized when the car is cold tomorrow morning.

But the dealer says essentially there's nothing wrong with the engine. So I will see how it goes I guess. Just watch for loss of coolant and maybe run my own combustion gas test every few months just in case?
 

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Re: Ottawa Cadillac Mechanic for HG Repair

No definitive answer to this that I can find: Has anyone ever checked for proper purge line flow ?

If that line does not flow a small, steady stream at idle all other bets are off.
 
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