: Considering used Northstar- need advice



jt99
07-23-07, 12:53 PM
I'm close to pulling the trigger on either a '02 or '04 Deville. Both have approx 55K on them and are in almost pristine condition. My question has (of course) to do with the Northstar reliability. After reading this forum and seeing the amount of failing head gaskets reported, I'm wondering if this model is even worth considering. Can someone confirm whether the 2000+ yr heads & gaskets been redesigned or not? I've seen two posts on '00 up failures with relatively low miles, few compared with the 90's vintage, but is it just a matter of time? I know the coolant should have been changed by now, but should it have something other than DexCool?

Cadillacboy
07-23-07, 01:00 PM
In my Seville, I have been using normal coolant not Dex Cool .I think logic of it that neither Dex cool or extended life coolant thingy don't run to Northstar engine considering you will have to change the coolant no late than every 2 years .With the green or blue Castrol coolant change it 1-2 years .
I believer '03 and up Northstar engine yet to be reported bad headgasket .
I don't know but if I were you I'd pick up '04 DEville .

Ranger
07-23-07, 01:55 PM
In 2000 they changed the head bolt length and thread pitch to make them more reliable, but there are no guarantees in life. Use Dex and change it at the required intervals or sooner.

jadcock
07-23-07, 02:39 PM
I think logic of it that neither Dex cool or extended life coolant thingy don't run to Northstar engine considering you will have to change the coolant no late than every 2 years .

Huh?? :confused:

Cadillacboy
07-23-07, 02:52 PM
Huh?? :confused:

LOL, you know Dex Cool is said to change 5 years or 100 K miles ,right ? In other words it requires no maintenance or less maintenance to other stuffs However Northstar requires to change the coolant every 2 years or sooner .So if this is the case let's say you put a Dex in it and haven't changed it 5 years hence . What would happen ?
Most likely your heads would go bad ,this is very contradiction of what Dex cool says :alchi:

AJxtcman
07-23-07, 05:48 PM
I am 100% sure you can do more damage changing the coolant than leaving it in!:rant2:
I can prove it 100%
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The coolant does not dissolve the head gaskets!!!!!!!:rant2:
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Come on guys. Just think about it. Coolant is not some magic solution.
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If you get an air bubble in the cooling system when performing a cooling system service you can over heat the engine and do more damage than the Magic Fluid ever could do. One hot cycle and if you add cold water or premix then you could really do it in.
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The only way to add coolant in a Northstar in MY opinion is to pull a Vacuum about 20"+, draw in the coolant premix, pull a Vacuum again about 25"+, Draw in the coolant again, You could do it one more time if needed. I have done it 3 times several times. Two times is all GM calls for.
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theory: Carbonation is held in soda pop under pressure. If the coolant has air in it or even microscopic air bubbles it can become trapped. If you release the cap on the soda the carbonation will come to the top. If you pull a vacuum it will lift the air to the top and the soda will be flat. The same goes for the air trapped in the cooling system. I pull a vacuum on master cylinders to get microscopic air out of the system. I do it to power steering systems also. It takes about 25 t0 30" before it really pulls out the fine air.
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If you leave air in the system that does more damage than coolant could ever do. I have a lot of Facts on this and the magic orange stuff. The way it is made out on this forum it is like battery acid.

Mountie
07-23-07, 07:17 PM
Vacuum? I dropped a good/used North* in my '93 STS a year & a 1/2 ago.

My car has 130,000 miles and running great ( old engine had 121,000 - new replaced had 122,000 ). Please explain your coolant method?

Also, I found out ( upon removal ) that my tranny was rebuilt less than a year before I got the car. I suppose I should change the tranny fluid, but the coolant thing I'd like to hear about.

I believe in servicing the car, but "don't fix which is not broken".

AJxtcman
07-23-07, 08:25 PM
VAC-U-FILL
http://216.182.211.32/TechLink/images/issues/feb06/TLFeb06e.html#story1

http://216.182.211.32/TechLink/images/issues/feb06/feb_06.pdf

AJxtcman
07-23-07, 08:37 PM
Old fill proceedure
Cooling System Draining and Filling
Tools Required
J 26568 Coolant and Battery Tester

Draining Procedure
Caution: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The cooling system will release scalding fluid and steam under pressure if radiator cap or surge tank cap is removed while the engine and radiator are still hot.

Remove the coolant pressure cap.
Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
Remove the front air deflector. Refer to Front Air Deflector Replacement in Body Front End.
Place a drain pan under the drain cock.
Open the radiator drain cock.
Drain the cooling system.
Remove the surge tank. Refer to Radiator Surge Tank Replacement .
7.1. Clean the outside of the surge tank.

7.2. Pour out any fluid.

7.3. Thoroughly clean the inside of the surge tank using soap and water.

7.4. Thoroughly flush the surge tank with clean water and drain.

Install the surge tank. Refer to Radiator Surge Tank Replacement .
Inspect the coolant condition.
Follow the appropriate procedure based on the condition of the coolant.

Normal in appearance--Follow the filling procedure.

Discolored--Follow the flush procedure. Refer to Flushing .

Filling Procedure
Notice: The procedure below must be followed. Improper coolant level could result in a low or high coolant level condition, causing engine damage.

Close the radiator drain cock.
Install the front air deflector. Refer to Front Air Deflector Replacement in Body Front End.
Lower the vehicle.
Important: Use a 50/50 mixture of DEX-COOL antifreeze and clean, drinkable water.

Slowly fill the cooling system with a 50/50 coolant mixture. Refer to Approximate Fluid Capacities in Maintenance and Lubrication.
Install the coolant pressure cap.
Start the engine.
Run the engine at 2,000-2,500 RPM until the engine reaches normal operating temperature.
Allow the engine to idle for 3 minutes.
Shut the engine OFF.
Allow the engine to cool.
Top off the coolant (1) as necessary.
Inspect the concentration of the engine coolant, using the J 26568 .
Rinse away any excess coolant from the engine and the engine compartment.

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Document ID# 1258545
2005 Cadillac DeVille
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http://www.fiero.nl/forum/Forum2/HTML/082514.html
more on the VAC-U-FILL

Ranger
07-23-07, 09:19 PM
I am 100% sure you can do more damage changing the coolant than leaving it in!
Please tell me you are not suggesting that we don't change the coolant. It does loose it anti corrosion capabilities after a while.

This is the first time I have ever heard of pulling a vacuum in a cooling system. The Northstar is self purging as I think most systems are (assuming of coarse that the purge line is not clogged). I've never had a problem with air in the system.

AJxtcman
07-23-07, 09:38 PM
Please tell me you are not suggesting that we don't change the coolant. It does loose it anti corrosion capabilities after a while.

This is the first time I have ever heard of pulling a vacuum in a cooling system. The Northstar is self purging as I think most systems are (assuming of coarse that the purge line is not clogged). I've never had a problem with air in the system.

It should be changed at normal service intervals.
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How could you get the air out?
how do you mix the water and coolant?
You don't shake the contanter to mix them together do you?
That would be like shaking a bottle of brake fluid and then adding it into the brake system.
The Vacuum lifts the air out of the system.
this is a picture of brake fluid
33430

Ranger
07-23-07, 10:14 PM
How could you get the air out?
I let the system purge itself like it is supposed to.


how do you mix the water and coolant?
I premix it. Yeah, I think I do shake it, but the bubbles come to the top long before I pour it in. I have never had a problem.


That would be like shaking a bottle of brake fluid and then adding it into the brake system.
Brake fluid I could understand, but coolant is a lot thinner than brake fluid.

Mountie
07-23-07, 10:23 PM
Please tell me you are not suggesting that we don't change the coolant. It does loose it anti corrosion capabilities after a while.

This is the first time I have ever heard of pulling a vacuum in a cooling system. The Northstar is self purging as I think most systems are (assuming of coarse that the purge line is not clogged). I've never had a problem with air in the system.

I wanted to check out the vacuum method, but when I replaced my engine, there was not a drop of coolant.... I had no problem.

But thanks for letting me see what you were talking about.

Mountie
07-23-07, 10:29 PM
About brake fluid...... I removed the dirty fluid at the top, pour in fresh fluid. and did what my motorcycle mechanic suggests...... Quickly pat the brake lever ( or peddle ) really fast, and watch the air pulse out of the return hole).

AJxtcman
07-24-07, 05:00 AM
I let the system purge itself like it is supposed to.


I premix it. Yeah, I think I do shake it, but the bubbles come to the top long before I pour it in. I have never had a problem.


Brake fluid I could understand, but coolant is a lot thinner than brake fluid.

The best car to watch it on is a Craptera. I will get a picture of a Deville. My point is that the air gets trapped in the coolant. If it take one high heat cycle to get it out. that can do more damage than 3 or 4 year old 36k coolant.

jadcock
07-24-07, 06:55 AM
LOL, you know Dex Cool is said to change 5 years or 100 K miles ,right ? In other words it requires no maintenance or less maintenance to other stuffs However Northstar requires to change the coolant every 2 years or sooner .

Where'd you read that? That is mis-information. Vehicles built in model year 1995 and prior required coolant changes every 2-3 years, filled with conventional coolant. Vehicles built in model year 1996 and later require coolant changes every 5 years or 100,000 miles, filled with Dexcool. The Northstar doesn't require a different (or shorter) coolant change interval than any other Dexcool-filled GM engine.


So if this is the case let's say you put a Dex in it and haven't changed it 5 years hence . What would happen ?
Most likely your heads would go bad ,this is very contradiction of what Dex cool says :alchi:

No, it's not a contradiction. The recommended service interval for Dexcool is 5 years or 100,000 miles. Your heads don't "go bad" when using Dexcool. At the furthest stretch of that argument, you could say that the coolant could use its anti-corrosion properties over time and natural processes would then start to eat away at the head gaskets. But that's the very POINT of Dexcool. It doesn't loose its anti-corrosion properties nearly as quick as conventional fluids. That's why you had to change conventional (green) coolant in 2-3 year intervals. Your engine would start to corrode otherwise. Dexcool doesn't require a change until 5 years, because its chemical composition is different from conventional chemicals. It's an OAT coolant -- Organic Acid Technology. Different from old green coolant.

clarkz71
07-24-07, 06:59 AM
I had no problem with "trapped air" when changing my coolant or the coolant
in any other Northstar Cadillac. I've worked on MANY different cooling systems
in my 25 years as a technician and don't see the Cadillac system as difficult regarding trapped air.
The key is measuring the amount of coolant drained so you know how much will fill the sytem
back to where it was before draining it.
Then slowly filling the surge tank until you have replaced the entire amount.
If it doesn't take it all, let the car cool and usually the level will drop and it will take the rest.
Like Ranger said, make sure the purge line is clear if you have a problem.

Now I once replaced a cylinder liner in a Renault R5 turbo and after getting the
engine back together had a hell of a time bleeding that cooling system.
It's a rear/mid engine car with a front mounted radiator.

jt99
07-24-07, 10:34 AM
:alchi: Holy crap. I just wanted to know whether the heads were different. Suffice it to say there is some debate about changing the coolant. I'm guessing the '03's up haven't showed up with blown gaskets because most don't have the mileage on them yet. Not sure whether I want to get involved in something that needs this much debate over what should be normal maintenance. :confused:

Ranger
07-24-07, 10:58 AM
Don't let this discussion scare you. We are knit picking. The Northstar requires the same cooling system service as any other engine for the same reasons. Neglect them and they'll suffer the same consequences.

jadcock
07-24-07, 12:32 PM
Not sure whether I want to get involved in something that needs this much debate over what should be normal maintenance.

There SHOULDN'T be this much debate. It's all spelled out very simply in the owner's manual. There are those who chose to not follow the owner's manual, and there are those who do. That's all the debate is about.

Buy one of those used DeVilles with confidence. When I was looking for a car to replace my '97 (sold, not broke), I looked at various model years from 2000 to 2004. Not once did a question of head gaskets arise in my mind. I haven't looked back since. :thumbsup:

Cadillacboy
07-24-07, 01:17 PM
Where'd you read that? That is mis-information. Vehicles built in model year 1995 and prior required coolant changes every 2-3 years, filled with conventional coolant. Vehicles built in model year 1996 and later require coolant changes every 5 years or 100,000 miles, filled with Dexcool. The Northstar doesn't require a different (or shorter) coolant change interval than any other Dexcool-filled GM engine.



No, it's not a contradiction. The recommended service interval for Dexcool is 5 years or 100,000 miles. Your heads don't "go bad" when using Dexcool. At the furthest stretch of that argument, you could say that the coolant could use its anti-corrosion properties over time and natural processes would then start to eat away at the head gaskets. But that's the very POINT of Dexcool. It doesn't loose its anti-corrosion properties nearly as quick as conventional fluids. That's why you had to change conventional (green) coolant in 2-3 year intervals. Your engine would start to corrode otherwise. Dexcool doesn't require a change until 5 years, because its chemical composition is different from conventional chemicals. It's an OAT coolant -- Organic Acid Technology. Different from old green coolant.

Holy crap, I knew Northstar or not all the aluminum engines require changing their coolants every 2-3 years (after the very first maintenance 100 K miles) whether you use Dex Cool or other orange stuffs .The reason behind is that being an aluminum ,coolant begins to eat heads in a certain amount of time and what is worse even Dex can not make marvels .
You say other way ,I ain't an expert so can't insist on that I am right in here

Ranger
07-24-07, 01:32 PM
Don't know where you heard that, but it is a complete fallacy.

Cadillacboy
07-24-07, 01:38 PM
I read that somewhere on the net .I wish I had saved that crap .Anyway, changing the coolant in an aluminum engine is a must I asked this question a few machanics and all approved this .

jadcock
07-24-07, 02:28 PM
Ranger is right -- that's a total fallacy. There is a lot of mis-information out there. A lot of mechanics also swear that the oil life monitor is really a mileage counter and that Dexcool ruined the GM 4.3L engine.

Don't believe everything you read, unless you find it in your owner's manual. That owner's manual was written BY Cadillac FOR your Cadillac. It should be the last word on the subject.

jadcock
07-24-07, 02:35 PM
Holy crap, I knew Northstar or not all the aluminum engines require changing their coolants every 2-3 years

That is just simply not true. This misnomer probably stemmed from this fact:

Long ago, back when most engines were all-iron, you could visually tell when it was time to change your coolant: rust and scale would start to appear in the coolant. The coolant was green, the rust was red/orange; it was obvious. Coolant change intervals were always 2-3 years, but most owners just changed it whenever it looked dirty. Fine.

When all-aluminum engines started to appear, folks would do as they always did: they'd wait until the coolant looked rusty before they changed it. The coolant didn't change -- it was still 2-3 year coolant. Corrosion inhibitors depleted shortly thereafter and a change was required. But wait -- there's no "rust" in an aluminum engine. Aluminum doesn't rust -- it just corrodes away, slowly but surely. So you never had a visual indicator of when a coolant change was required. Folks started having problems.

That's when auto makers engineered the long-life coolants. Folks didn't like the idea of having to change their coolant every 2 years. They never did before with their old iron-block 350s, why should they with their new aluminum engines? The long-life coolants give a longer change interval between each change because the corrosion inhibitor package lasts longer.

That's all there is too it. There's no magic. There's no voodoo. It's simply different chemistry that doesn't break down as quickly. GM uses Dexcool, an OAT (Organic Acid Technology) coolant. Other automakers use a HOAT, or Hybrid Organic Acid Technology, coolant. One isn't "better" than the other; different automakers also use different metallurgies and compounds in their engines. Each coolant is appropriate for its intended use. Our 2007 Chrysler Town & Country has Chrysler HOAT coolant. It's good for 5 years or 100,000 miles. When the time comes, I won't put Dexcool in it, I'll put Chrysler HOAT in it. Our 2001 Cadillac STS has Dexcool in it. When the time comes for a coolant change, I won't use Chrysler HOAT or Prestone yellow universal coolant or anything else; I'll use Dexcool.

Just as motor oils have advanced DRAMATICALLY in just the last 10 years, so have engine coolants. The old change intervals that we grew up with no longer apply to modern mechanicals and materials.

Cadillacboy
07-24-07, 03:00 PM
Thanks ,things're clear then .Heck, I changed my coolant in Seville every two years lol

Ranger
07-24-07, 08:27 PM
I read that somewhere on the net .I wish I had saved that crap
No loss in not saving it. You hit the nail on the head. It's crap. Lot of that on the internet.

AJxtcman
07-25-07, 06:10 AM
Like Ranger said, make sure the purge line is clear if you have a problem.

Now I once replaced a cylinder liner in a Renault R5 turbo and after getting the
engine back together had a hell of a time bleeding that cooling system.
It's a rear/mid engine car with a front mounted radiator.
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That is my point Clark. If you get air trapped in the reverse flow U system of a Northstar you could damage it. You can not always go off the remove 1 gallon then added 1 gallon theory. If the pump becomes air bond it will not circulate and that can cause a hot spot.
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:alchi: Holy crap. I just wanted to know whether the heads were different. Suffice it to say there is some debate about changing the coolant. I'm guessing the '03's up haven't showed up with blown gaskets because most don't have the mileage on them yet. Not sure whether I want to get involved in something that needs this much debate over what should be normal maintenance. :confused:
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JT99 03+ have a much better head bolt thread pitch. Sorry about the arguing.
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Holy crap, I knew Northstar or not all the aluminum engines require changing their coolants every 2-3 years (after the very first maintenance 100 K miles) whether you use Dex Cool or other orange stuffs .The reason behind is that being an aluminum ,coolant begins to eat heads in a certain amount of time and what is worse even Dex can not make marvels .
You say other way ,I ain't an expert so can't insist on that I am right in here

Cadillacboy
Dex-Cool is the same Ethylene Glycol as green. All they did was remove the sand so it did not ruin water pumps. That is a fact. Since the silicate does not build up and take out the water pump you do not need to change the coolant.
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The Government and environmentalist went to the major manufacturers of cars and coolant. They asked to find a solution to the massive amount of coolant being disposed of improperly and being produced. Dex-Cool was one part. If you make less you charge more.

Cadillacboy
07-25-07, 07:06 AM
In my 'FWB despite 22 K miles on it I had the coolant changed .We flushed all the coolant and surge tank as well . You should have seen how sludges come out of it .I saw some sand like things
I ascribe it they never changed the Dex and some sludges ,residues collected into the tank .
Just a note :)

jadcock
07-25-07, 07:24 AM
There should be NO sludge in the coolant after only 22k miles. When I changed my coolant at 92k miles in my '97 SLS with the water pump, there was no such sludge. Sludge in the system at early is a symptom of a problem. Perhaps a failing radiator cap or something. That's what caused sludge in so many of the 4.3L engines (bad radiator caps). You might consider installing a new pressure cap; the original cap may have been part of the bad batch of caps on the 4.3L engines?

Cadillacboy
07-25-07, 07:39 AM
You know Dex is said 5 yrs or 100 K miles whichever comes first .The car is now 12 yrs old so I think that was the reason what built up some sludges .I dunno for sure .Anyway, we cleaned all the system but that was a hard work .
I read many horror stories on the 4.3 engines and all was said it was from Dex . This could be wrong too .
Now ,I reckon if Dex was such a terrible product ,GM could have stop using it

jadcock
07-25-07, 08:26 AM
If the coolant in your 1996 FWB was just recently changed for the first time, at only 22k miles, then yes I agree -- time was the factor there. I didn't know the car had such low miles. I would imagine that any coolant left in the car for 12 years would start to form sludge.

The problem with the 4.3L engines was a batch of faulty radiator caps. The caps didn't hold pressure, and the systems would leak down over time. Dexcool does not "plate" the internal engine components like conventional coolant does with its silicates. This left the internal passages of the engine to corrode, and rust started to appear in the coolant (remember that these are iron block engines). Folks blamed the coolant. The only thing the coolant couldn't do was protect the engine when it wasn't present (level too low). I suppose you could call that an "advantage" of the older coolant. The level of Dexcool must be full for it to protect the engine.

This is really the only widespread problem GM has had with the coolant, and it wasn't really the coolant's fault anyway. There were some initial issues in the very beginning on some Saturn models, and that was traced back to an incorrect chemical formulation from the manufacturer at the time (Havoline).

The fact that Dexcool has stood the test of time, so to speak, in pretty much every engine in which it has been installed speaks of its worth (to me). When kept at the proper level, and changed at the proper interval, Dexcool performs as it should. The same can be said of any motor oil. It can't protect properly if the level is let to be low or if it's not changed in accordance with the appropriate recommendation.

Ranger
07-25-07, 09:37 AM
The "sludge" you saw was likely just GM cooling system supplement aka sealant tab residue.

clarkz71
07-25-07, 10:07 AM
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That is my point Clark. If you get air trapped in the reverse flow U system of a Northstar you could damage it. You can not always go off the remove 1 gallon then added 1 gallon theory. If the pump becomes air bond it will not circulate and that can cause a hot spot.



That pretty much applies to any car, not just a Northstar. I was going through that
in the early 80's with Mercedes V8's. Nothing new to me.
Maybe that why I never have problems with Northstar cooling systems.
I apply what I learned 20+ years ago with imports.

Bottom line is slow filling of the system, run the engine a few minutes
shut it down, let it sit and top it off. I like to run the heat/defrost while filling the system.
If I don't feel warm air within a few minutes, I know I have air pockets.
It's just like a baby, you have to know when to burp them.