Last post on Mar 10, 2010 at 6:30 AM
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Cadillac DeVille, Sedan
#6 of 23 overheating?
Apr 09, 2008 (11:43 am)
I'm hearing different opinions. What is normal operating temp. for a 1997 Cadillac Deville with 4.6 Northstar motor? How expensive is it to repair head gaskets on these motors? Mine seems to run hot. Between 196 and 220 degrees. It can go higher if I run it harder. The radiator uses about a half gallon of coolant for 30 miles but I see no leaks. Dipstick is not milky and no coolant smell or in tailpipe. I do see what looks like white exhaust when idling (especially in the mornings) but not when accelerating. I don't know however if it's smoke or just that it's kind of cold in the mornings. Can anyone help shed some light for me? Tanks in advance.
#7 of 23 Re: overheating? [sspeis]
Apr 09, 2008 (9:16 pm)
Ok, about the 'normal' temperatures. With the Air Conditional 'On', the button in the 'Norm' setting, the fans will run all the time and it will attempt to maintain the thermostat value, which is 197 degrees. With the Air Condition 'Off', the button in the 'Econ' setting, the fans will not run and the computer will allow the temperature to rise to about 220 degrees and it will then turn the fans on until the temp drops to about 197 degrees. So, in general, your temp values are running ok, if you are using the 'Econ' setting. If you have the AC in the Norm setting, it is running hot at 220 degrees.
But, you other symptoms point to the early stages of a blown gasket - just not blown severely yet. If the coolant is not leaking, the only place it can be going is into the engine. A half gallon per 30 miles is a lot of coolant going somewhere. Northstars bad head gaskets do not put coolant into the oil. It goes into the combustion chamber. And, combustion gas goes into the coolant, causing overheating. Massive overheating as the gasket gets worse. And the higher temps when running hard is a usual symptom. If you drive up a steep hill, it will also overheat - basically the more you load the motor, the more it will overheat.
My guess - you've got a head gasket problem. It will get worse. No kind of 'Stop Leak' will seal it.
Repair will be $3,000 or more. The motor must be pulled. Heads removed. All 20 head bolt holes bored out. Then rethreaded. Then a special insert called a Timesert is screwed in. The motor is then reassembled, with new headbolts screwing into the Timesert inserts. New gaskets of course. Most of the cost is labor because the motor must be pulled, the rear head cannot be worked on in the car.
This is about 50% of what a 97 Deville is worth. There are a lot of Cadillacs scrapped because of a blown headgasket, and what the cost of repair is. But, if a Timesert operation is done, this usually fixes the headgasket for the remaining life of the car.
#8 of 23 Re: overheating? [bolivar]
Jun 25, 2008 (9:26 am)
Where do you find these Timesert's?
#9 of 23 Re: overheating? [donjuan3]
Jun 25, 2008 (11:09 pm)
Google is your friend.
#10 of 23 how to replace passenger side mirror
Sep 09, 2008 (10:47 pm)
Passenger side mirror unfortunately broke when it scraped against garage siding. It is still functioning. The assembly is still attached due to the electrical wirings. Replacement plus labor quoted at approx $800. Any do-it-yourself suggestions / advice on remedying this situation? Thanks.
#11 of 23 Re: how to replace passenger side mirror [clint0221]
Sep 10, 2008 (9:40 pm)
Uggg.... A junkyard.
Take the inside door panel off. You can then get to the bolts that hold the mirror to the door.
If the outside door skin has been badly dented up when the mirror pulled off, then you have a problem that only a body shop can fix.
#12 of 23 Re: how to replace passenger side mirror [bolivar]
Sep 12, 2008 (5:44 pm)
Thank you much Bolivar. That could be a start to see how extensive the problem is. And maybe, just maybe, I can McGyver it and save some bucks. Thanks again.
#13 of 23 2002 Cadillac Deville 4.6
Oct 27, 2008 (7:05 am)
I have read in the owner's manual of this vehicle not to add anything other than Dex-Cool 50-50. I have also read on another forum that they talk about adding the GM Coolant System Seal Tabs. What is the proper thing to do?
#14 of 23 Re: 2002 Cadillac Deville 4.6 [bena8837]
Oct 28, 2008 (11:28 pm)
I comes from the factory with orange Dexcool. That is what GM recommends.
By 2002, I think Cadillac may have stopped recommending the coolant tabs. On older models, there was a sticker on the motor/plastic fan cover/somewhere under there, that gave the part number for the tabs.
You only need to add tabs if you dump all the old coolant out. Since you can't get all of it out by opening the radiator or pulling a lower hose, I only put three in.
DON"T PUT THE TABS IN THE "OVERFLOW" TANK. (It really isn't an overflow tank, because it is pressurized and has the rad cap on it. It is correctly called the 'surge tank'.) PULL A RADIATOR HOSE AND PUT THE TABS IN THERE. There is not enough coolant flow thru the 'surge tank' to move the tab material out of there, and it is mainly useless if put in there.
The tabs are used mainly for very minor leaks - seepage type, or porisity opening in the block/head castings. The tabs were developed for the earlier 4.1 and 4.9 motors and carried over into the Northstar motors up until about 2001 where there were some redesigns made to the Northstar and I think GM no longer recommends their use.
#15 of 23 Re: 2002 Cadillac Deville 4.6 [bolivar]
Nov 03, 2008 (8:16 am)
Thanks for the info., appreciate it!