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I have owned a 2000 DeVille for about 3 years now.  It currently has just under 100,000 miles.  I drove it everyday for 5 months, then multiple issues started to occur.

First issue was a misfire.  I plugged in a code reader, which told me the misfire was in cylinder #7.  I pulled the spark plug and found oil on it.  

THE valve cover gasket, that sealed that specific port, had fallen off.   I replaced the valve cover gaskets and all 8 spark plugs. The misfire continued.  I changed the coil pack.  ALL IS WELL.

2 weeks later, the engine overheated. The coolant reservoir was empty.  I filled with water.  Then every 10 miles I drove, the engine would start to overheat again.   

I have flushed out the coolant system with a water hose.    I have used the snake-oil coolant flush kits.   It didn't help any.  I filled system with Dexcool coolant only, after being flushed out, but no change.  I have also replaced the thermostat twice.

Please guide me, where I can find the proper instructions (for a dummy) to take me through the coolant flush procedure, including the heater core.  The Hane's manual says anytime the coolant is changed, that some kind of SEALING tablets shall be installed with the new coolant.   I have not been able to locate those.  

NOTE: Before realizing my many mistakes, with trying to be a Cadillac mechanic for myself, I have used additives, cleaners and sealers (snake oil) in both, the oil and the coolant systems.   I feel all, or most, has been flushed out since then.

Sorry for such a random post.... advice would be fantastic.   

PS. Please don't criticize my ignorance on my Cadillac or on how to post issues on here.   

Thanks in advance.

 

Edited by MyCaddyNeedsTLC
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Disconnect the purge line from the surge tank and put it into the neck of the surge tank.  Start the engine and verify that coolant is peeing out of the line.  If it is not, then there is an obstruction in the purge line - most likely at the water pump cover where the hollow bolt connects the hose to the cover.  Trace the line from the surge tank across the top of the engine, through the throttle body and to the water pump cover.

If the line is flowing coolant, then I would test the coolant for combustion gasses.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Well.... I put water in it.... before I read your response.  ?  I also just changed the oil.

 

I pulled the purge line from the tank, then let it bleed back into the tank.  It's hot water and flowing fine.  When I had my son tap the accelerator, the flow pressure increased... now I am confused.

 

 ALSO....here is a pic...  I THINK these are the lines that go to/from the heater core.  These bell-type fittings is where the coolant blows out, when it gets hot, I'm reasonably sure....

 

 

 

 

20170521_125140-640x640.jpg

Edited by MyCaddyNeedsTLC
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Sorry.....that was stupid.  Those don't have anything to do with the coolant system.  ?

The coolant must have been coming from the manifold underneath those fittings.  I apologize for my lack of knowledge and common sense.  ?

You can see, in the picture, where the coolant has exploded onto the hood liner a few times.  

 

20170521_132444-540x540.jpg

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4 hours ago, KHE said:

If the line is flowing coolant, then I would test the coolant for combustion gasses.

Sad to say.... There is a big risk the motor must come out and heads of. New threads from "Time Sert"!

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Buy a Balkamp block tester from NAPA it is $47. Follow the directions and do the test.  The kit works very good and I have had mine for many years and did many tests.

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

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Hey, the infamous BodyByFisher.  ?

I read a thread from 2008, where a guy was rude to you, because he didn't like your suggestion about oil and fuel octane.  Then there was a small army of your supporters that posted about it.   ?....Good times.  

Thanks for that info.  Is this an online purchase, or is it at a local auto parts store?

Side note: I changed the oil and added water to the coolant system this morning.  It has been running at idle, with full heat for 2 hours, then I drove it for 1 hour.... not overheating yet...?  

 

Edited by MyCaddyNeedsTLC
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It doesn't make sense that the coolant is puking on that side of the engine unless there is a leak at the water crossover gaskets or one of the silicone heater hose couplers.  You might want to borrow the cooling system pressure tester from Autozone and pressurize the system when it is cold to see where it is leaking.

Autozone has a block tester in their loan a tool program - you just need to buy the test fluid for $12 or so.  You shouldn't do the test if you've added coolant recently as it may result in a false negative result.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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