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256K views 511 replies 289 participants last post by  jmlcaton 
#1 ·
I have a 97 DeVille with 107400 original miles, which I know is not much compared to some of you. To figure out whether or not I can expect much more out of this engine, I would love to see how many of you have Northstars with higher mileage. If your engine is not the original, please let us know. Any major problems along the way would also be helpful, with mileages. I think that a thread like this could really help some of us anticipate problems and estimate the life of our engines!

Thanks,
Jim

My entry:
107400 miles original
no known major problems
now leaks a little oil (began around 100k)
 
#284 ·
Are you still under the impression that there is anything wrong with properly maintained DEX-COOL ? Your question would appear so .........

Here's 2 quarts of 50/50 DEX-COOL from the truck engine with 88,900 miles on it (the engine) - the coolant is 3.5 years old. Just changed it all. Look like anything wrong there ?????
 
#285 · (Edited)
It looks beautiful--almost good enough to drink! (edit: make sure to put skull and crossbones on it if you have any children in the family). Alas, I'm not concerned about the coolant itself more so than the head gasket. Tearing the engine down and looking at the head gasket would give a better picture of how well it is protecting it.

The silicates in conventional green coolant coat carbon/carbon composites [graphite composite headgasket] and are used to make it oxidation resistant. Dex-Cool is a silicate-free coolant. It is wonderful in protecting aluminum, brass, cast iron, steel and copper, but offers no carbon/carbon protection. Our composite head gaskets are made of graphite (carbon), copper/brass, and felt, and a good portion of them are soaked in coolant.

Other large manufacturers saw this protection void (and the lawsuit due to deterioration of silicone rubber and nylon gaskets), and opted to add silicates to their versions of long-life coolants, and they are now called Hybrid organic acid technology coolants. The added silicates coat and protect what the potassium 2-ethylhexaonate (hexaonic acid) doesn't. Toyota, Honda, Ford and probably others use this type of hybrid coolant. They prohibit the use of anything else, quite emphatically in some instances.

How many 93-96 Northstar's have HG failure vs 97-99 before the better headbolts? They are otherwise virtually the same engine--are they not??

**edit: I'm not saying that there aren't any failures on 93-96 or that the observation negates the other flaws such as torque-to-yield head bolts, or a flaky gaskets. I'm saying those head gaskets may be very vulnerable to fail in as it is with all the expanding and contracting cycles of the aluminum or the graphite and the steel bolts... The straw that breaks the camel's back or rather precipitates the failure could be a coolant that lacks corrosion/oxidation protection to graphite. A renowned polymer expert I work with confirmed it for me: graphite does in fact corrode/oxidize readily if uncoated, it burns or flakes.
 
#298 ·
i cant compete with drivendeville but my 98 Eldorado has 165,100 miles and blew the head gasket at 97,000 miles. 1 Water Pump, new filler neck, rear knuckle bushings, new rear shocks, new door panel, cat converter, rim and abs pump other then that the car is original and the interior has hardly any wear to it other then warped dash cover and rear panels
 
#299 ·
Well the STS I just got in October is ar 138000. The only engine issue (knock on wood) is the front valve cover leaking oil and I need to replace the oil pressure sending unit.I have replaced the fuel level sensor,both outer tie rods,right front hub,replaced the EBTCM.
I was really second guessing the purchuse of the 2002 STS. I had sold my 1994 Fleetwood Brougham ,after I had a fellow that wanted it more than I did,and I ended up buying this STS. So far after spending a little time and money to get it to a nice daily driver I am very happy with it.It does n ot come close to riding like the Fleetwood,but with the FE-3 and F55,this car almost feels like it is on a rail. Living in the BlueRidge Parkway this car is a blast on the mountain roads,it is hard to believe that the 300hp can get up and go in this size car.
So far I have made one 1000 mile trip and was only able to pull out 23 on the open road. The worst part is the Fleetwood with the LT-1 I could get 26 with no problems. So I am hoping that it will get better,but still with 300hp and 23 mpg I am a happy camper
 
#300 ·
Long highway runs using 87 octane should get you just about 24.6 - 25 mpg. That's what I get on Shell 87 between MD and FL on I-95, running at 80 - 85 a fair part of the way.

Check the air filter (WIX), the band clamps on the intake ducting, and the correct placement of the air intake resonator. When were the AC Delco #41-987 plugs last changed ? Is TCC engaging ?? - - - flat road, 60 mph = 1980 rpm in D.

Look in my albums for hints on how to get rid of that stupid resonator plus other stuff.............

You're gonna think I'm crazy, but simply changing an apparently perfectly fine fuel pressure regulator netted me another mpg.
 
#301 ·
I am going to replace the plugs when I recieve the valve cover gaskets within the next week. I did replace the air filter with a Fram extra Gaurd
I did check the F/P regulator and there was no fuel in the vacum line so I just marked that off of the list.Now as for the gas I have been tying to run Exxon regular for about 90% of the time. If I am in town that is all I will get and from the same station.When i make the trips to the eastern part of NC I try to get most of my gas from Sheetz. I really think that all the 10% Ethonal that is in gas is what is killing gas mileage!
 
#303 ·
Wow good to see these cars are racking up big miles okay my turn my 5 devilles

1997 cadillac deville d'elegance: 220000 miles motor replaced at 160000 miles

2000 cadillac deville: 205000 miles

2001 cadillac dts: 165000 miles no problems

2001 cadillac dts: 110000 miles getting the motor studded at the moment (this ones caused me more headaches then the others combined)

2004 cadillac dhs: 60000 miles this one has been the most reliable hands down but then again it's very low milage

As you can see I love devilles I wouldn't drive anything else I test drove a xts just isn't the same I like my devilles more. These cars are reliable if you take care of them if you don't that's when you start getting problems with them.
 
#305 ·
You have me beat:

2001 Deville 169K I did the head gaskets earlier this year with Norms inserts

2001 Deville (a twin for above) 139K

2005 Deville (Mary Kay pink) 90k

Also had a 1998 Deville (replaced head gaskets) and a 2002 Deville with only 50k on it, traded it for the 2010 DTS Lux. Great car, doesnt feel quite like the older Devilles do though.
 
#307 ·
I have a 2000 Deville with 228,000 miles on her. I do have some significant problems, however, and I am reviewing if it will be cost-effective to replace the transmission and motor. I've found a shop that replace them for 1,500

For the past 10k, the transmission overdrive solenoid has been out (throws a code on the dash)
I was informed by my mechanic that I have a 6 inch crack in the block, which he felt was likely from a pothole. He said that this was not all that uncommon. I never ran it hot, though it did momentarily spike, before I could get off the highway (Camel mode never came on?!?), and now I also apparently have a blown head gasket. I replaced the thermostat, which may have been sticking, and caused it to run hot/hotter before replacement. She runs kinda ruff, but still chugs along, and I can drive around town - at least during the colder weather. If I am faithful to make sure the overflow tank is full, I can drive about 40 miles on the interstate, though it sometimes starts to climb going over a mountain that I go over. I am pretty sure that she will begin to consistently overheat when the weather gets warmer. I am blowing gas into the coolant (verified at a radiator shop) but it seems to be clearing off the excess heat, at least for now.
 
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