Question about 1999 Cadillac DeVille

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99 Deville coolant issues

I recently have bought a 99 deville, had it about a week before car over heated and had the delearship replace gaskets. It has been a about two months and a low coolant light comes on, i filled it back up and now around two weeks later it has came back on. Ever since I got the car back from being fixed it runs rough when I start the car and goes away after fifteen minutes or so of driving. I am afraid my gaskets are going bad again and need to get an opinion of someone who knows more.

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  • aromero975 Dec 23, 2008

    Kind of hard to tell I live in Colorado and it stays pretty cold. But from what I can take it is no more then other cars

  • aromero975 Dec 23, 2008

    Thanks I will definetely do that and hopefully figure the problem out soon. I have two more questions.

    1. If it is the gaskets is it a total loss and should I drive it till the car finally goes completely bad?

    2. What is the testing I need to have done to find out if it is the gaskets? diagnostics, compression testing etc.


  • aromero975 Dec 23, 2008

    I appreciate it, I will definetely check that tomorrow or the next day. Will have to get the right sockets to remove them.


  • eckley1970 Mar 10, 2009

    There are two things the 4.6 north-star is famous for and the is liking it's oil and a blow head gaskets. The engine is sweet when it works but there is such a small ridge between the coolant and the cylinder wall there is't much head gasket even holding. The other problem with changing the head gasket is the 80% of the threads come out with the head bolt and if the person that replaced the head gaskets didn't repair the thread properly it wouldn't take long to blow again. Another thing you can do with out a compression test (since your leaking that much) is start your car with full coolant and cold, let it run for just a few min then take the cap off, I would bet there is pressure which comes from exahast fumes that pass from the blow head gasket. Mine was a small pin hole on Cylander # 2. The reason it is running ruff is probably the coolant in one of the cylinders. You will more than likely not see any coolant in the oil.

    You can pick up a good used engine in a salvage yard for around $900 depending on millage, make sure you can here it run before it is pulled. The car is worth putting another motor in, It can be changed out if you know what you are doing in a weekend.


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  • 449 Answers

Do you have a cloud of white smoke out of the tail pipe?

Posted on Dec 23, 2008

  • Jerry Parmanand Dec 23, 2008

    sounds like a gasket problem do me a favor remove all the plugs and look at them tell me what you notice with the color and also when your engine is cold remove the radiator cap and tell me if you see any signs of oil in the antifreeze. good luck have in mind engine needs to cool off before doing this. happy holiday

  • Jerry Parmanand Dec 23, 2008

    do what i ask and tell me the result and i will tell you what's wrong don't worry.


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I have a 99 deville w/ 32valve north star engine and i have problems with it over heating i changed the water pump the radiator and thermostat i have no leaks but it still wont stopover heating

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99 deville head gasket leak?

A head gasket leak is usually indicated (among other things) by continous overheating of the motor, and subsequent loss of coolant.
It can also be indicated by the presence of engine combustion gas bubbles in the coolant resevoir.
Ensure the coolant system has no external leaks, such as faulty hose/s, radiator etc.

Ensure motor tune or other motor mechanical condition is not the cause of overheating.
I assume the motor is actually running hot.

Check cooling fans are operating ok (as necessary when car warms up):- if not check
1) fuse,
2) relay operation,
3) heat sensor switch.

Check/replace the thermostat,
Check the coolant pressure cap is serviceable & of correct rating,
Ensure cooling system is correctly filled, bleed off any airlocks as necessary when re-filling,
Ensure radiator hose on suction side of waterpump is not collapsing at engine revs above idle (due softening),
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99 cadillac deville overheating put in new radiator,thermostat,waterpump. it stays cool at idle for a hour running.drivin about 15-30 minutes it overheats. is not using hardly any coolant to speak of.

Jan 05, 2009 | 1999 Cadillac DeVille

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Over heating/ loss of coolent

If you are not loosing coolant on the ground. You may have a problem of a bad intake manifold gasket or worst a bad head gasket. The two things to look at are coolant in your oil, manifold gasket. Coolant out the exhaust, head gasket.

Jul 05, 2008 | 1999 Cadillac DeVille

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