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In my opinion a Northstar with 40,000 miles will not give you grief for quite a few miles. In 2000 they made improvments to the headbolts making them longer and coarser thread. Maintaning the coolant is important (I'll probably get flak for saying this) Dexcool turns acidic when air gets into it which will damage aliuminum.Personaly I have switched to the all purpose anti freeze anytime I changed the anti freeze in any car that runs Dexcool. Buy the car and enjoy it why worry about what might or might not happen?

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My headgaskets failed on my 94 Concours at 165,000 miles. I do not consider that unusual. I bought it for $6500 and put over 100,000 miles on it. I have 165,000 miles on my 97 Deville now, I am not expecting it to fail anytime soon. I only paid $4000 for it and have put around 76,000 miles on it. Actually I expect it to go well over 200,000. Buying used is always a crap shoot. You win some and you loose some. Research is the key and good service records. Buy it and don't look back.

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Thanks for all the great repies,guys.I've gotten a lot of insight concerning this headgasket issue.I am leaning towards getting the northstar and not worrying about it.I have heard about the dexcool becoming acidic if you open the cooling system and exposing it to air too much.I am going to do or have it done,the block test to see if there are any problems currently.If not I will most likely buy the car.I would plan to change the coolant just so I know for sure what is in there.What are some good alternatives to the dexcool?

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In 2000 they made improvments to the headbolts making them longer and coarser thread.

The head bolts where lengthened in 2000. The coarser thread did not come until sometime in '04.

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What are some good alternatives to the dexcool?

Stay with the Dexcool. If you use the green conventional stuff you will risk damaging your water pump seal, AND you will need to change antifreeze every two years.

My statement does not consider the Chrysler or Foreign additive (long life) technology. Since those are based on similar chemical composition HOAT or something, I'd say they would be susceptible to air intrusion as well. Just look at all those Lexus cars with bad head gaskets for proof of that. Just remember that you are dealing with an all aluminum block and it will NEVER appear rusty like in the old days no matter what you use or how infrequently you change it.

Never underestimate the amount of a persons greed.

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http://www.aa1car.com/library/2004/us120426.htm Read this article on anti freeze, make your own decision. Or stick with the Dexcool just change it every few years. Caddy did put a line in the cooling system to purge air out of the system so that is a plus to help keeping the air out of Dexcool.

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.

I have been monitoring all the comments made on this post and feel I have gotten some really good information. I wish to thank everyone for their efforts in enlightning me.

I have a question concerning JimD post.

A head gasket can fail in such a way as to simply push combustion byproducts into the cooling system.

Worst case is a head gasket fails in such a way as to allow coolant to come in contact with the head bolt threads. The coolant acts as an electrolyte and promotes/accelerates the predicatable oxidation

Have they redesigned or modifyed the head gasket so that the above is no longer a problem? Also would I need to be aware of this when I purchase a new head gasket so as not repeat the same failure?

Edited by Paul S
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Have they redesigned or modifyed the head gasket so that the above is no longer a problem? Also would I need to be aware of this when I purchase a new head gasket so as not repeat the same failure?

I have no idea if the gasket has been redesigned. But if you buy gaskets for your year model engine from a GM parts counter, you will have the latest/greatest/up to date gasket available.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Sorry if the subject annoys you,but if "enough is enough" as you say,just change the channel.

Not sure where you got the idea that it annoys me???

The reason the Northstar headbolts must be replaced is there is a microencapsulated threadlocker that is applied to the threads and the washer faces and underside of the bolt head. The threadlocker acts as an anti-sieze lubercant as well as a threadlocker. There is no practical way to re-apply the coating in the field so the service procedure is to replace the bolts. The threadlocker is specific to the application and is required. Loctite is not an acceptable substutute for the original coating on the bolts.

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

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No,KHE,that was to whoever it was that said "enough is enough".I know this topic has probably been discussed to death,but my searches didnt turn up some of the "basics"of the issue.More discussions from a standpoint that those talking knew the basics.I did appologize for dragging it up again.I did get a lot of great info and I do appreciate all the good responses,I havent frequented this board in a while but the info here is always topnotch.I was able to learn enough about it to make a reasonable decision.I found out that the dealer did do the "block test",even tho he got the car from a good friend,who is the son of the original owner who passed away.I know the car was well maintained and will be buying it sometime this week.Thanks again to all who contributed.

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not saying anything bad about your dealer... but if it was me buying it, I would do the block test "MYSELF"... just for my own peace of mind.

It is cheap to do... less than 10 bucks.

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I might,not because I dont trust him,I trust him 100%.Looked it up,$7.95 for the test fluid,$25 for the tool.He said he has the tool,if I bring the fluid he'll do it for me again if I want to see it done.I plan to change the coolant and oil anyway,always do just for my own peace of mind and to know I'm starting fresh.

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Great to hear it passed the block test, and hope you enjoy the car. Even a new car is not a guarantee of satisfaction, but you seem to have done a good job researching and they are great cars. I would expect a LOT of enjoyment.

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I do expect to airmike.The 92 Seville I have now had about the same mileage when I got it in '03 and I've put 100k on it with very little problems,I do expect the same from this car.I know a used car is a crap shoot,but you really increase the odds with a low mileage Caddy.Thanks for all your input here.

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I might,not because I dont trust him,I trust him 100%.Looked it up,$7.95 for the test fluid,$25 for the tool.

You can borrow the kit for free from AutoZone or any other parts store that has a loan-a-tool program and just pay for the test fluid.

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  • 4 weeks later...

Okay,I've had the car a couple of weeks,everything is good.Did have to charge up the AC,dealer took care of that.I am looking for a service manual now,but in the mean time I want to change the coolant.I plan to use Prestone Dexcool.Any other advice I need before doing this.I've read where you shouldnt open the system allowing air into it.Anything I have to do when filling it that will prevent air mixing,or should I not worry about it?Like I said,I dont have a manual yet,is the drain plug in the normal place,I havent even looked yet.If I use a sealant additive,like Barsleak or whatever,does it really matter where it is added?Any other tips/omments would be appreciated.

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OK, I'll give this a shot. Don't worry too much about the air getting into the system.....it's just not that big of a deal. You will do much more GOOD than harm by changing the coolant. This is a 2001, right? I DO think the sealant was still required in 2001, but not 100% sure. At any rate, I WOULD recommend that you use one tube of BAR'S LEAK POWDER, and it DOES matter where it goes. Maybe, more correctly, it matters where it DOES NOT GO. It should never be put into the reservoir tank, and my second worst choice would be into the radiator. The proper place for it to end up is in the block itself. Therefore, the best place for it to go is in the lower radiator hose, as it goes into the water pump suction.

As for the drain plug, it should be on the lower left side of the radiator, accessible through a small hole in the lower air dam/shield. It can be opened and closed with an 8 - 10" piece of broomhandle with about a 3/16" slot cut into the end (about a 1/4" deep). IF you are lucky enough to have a drain, things get REALLY easy. You will need ONE gallon of straight GM Approved Dexcool, and ONE gallon of distilled water. If you prefer, you will need TWO gallons of 50/50 premixed GM Approved Dexcool. The proper ratio of coolant to distilled water is in fact 50/50, do not stray very far from that point (70% Dexcool is MAX). All you need to do then is open the drain, remove as much coolant as you can WITHOUT FLUSHING ANY ADDITIONAL WATER THROUGH THE SYSTEM, close the drain, remove the lower RAD hose from the water pump suction, add the Bar's Leak Powder (one tube or a little less will do), reattach the hose to the water pump suction, open the reservoir cap and refill with the 50/50 mix. Go for a short drive, rev the engine several times above 3000 RPM, and let it cool. Next morning, bring the level to the COLD mark before starting the car, and your done. (Check for leaks)

Happy Motoring!

Never underestimate the amount of a persons greed.

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.I've read where you shouldnt open the system allowing air into it.Anything I have to do when filling it that will prevent air mixing,or should I not worry about it?

I don't know where you read that, but it's false. No way you can avoid getting air into the system, but it's no big deal. The system is self purging. Just check the coolant level a few times after you rfill it as it may need a slight top off.

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absolutely. I hate trying to get to the petcock though so I find it easier to pull the lower radiator hose.

Buy premixed coolant or straight and equal of distilled water. Tap water isnt very good for the system.

do all of my vehicles every 2 years no matter what they call for

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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One of the earlier responses in this thread stated that "Dexcool turns acidic when it mixes with air".I figured there is no way to change it without getting air in the system and wondered about that.

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After reviewing the complete series of posts in this thread, yes Caddypete did in fact say that. You really need to consider exactly why he said it from his veiwpoint. Firstly, there is a LOT of misinformation out there in regard to Dexcool. Any of us can fall victim to internet misinformation. Dexcool was blamed for a LOT of things as soon as it was introduced to the motoring public. Some misconceptions live on today, much like the 3000 mile oil change which is total nonsense today. I think even one of your posts said that you might switch to green coolant...not a good idea either.

Secondly, his statement may be true, IF in fact "air" (which is commonly introduced as combustion gasses into the coolant) is left unchecked for LONG periods of time under the heat of an operating engine block. I'm talking months or years here. And we all know that combustion gasses contain a lot more than just plain old 80% nitrogen, breathable air. I'd say a little bit of common sense should prevail here. Dexcool can't turn acidic from short term exposure to breathable air, otherwise, you wouldn't be able to open the bottle it comes in.

Here is a link for some more detailed info about Dexcool, if you would like to check it. Furthermore, If after you complete the change, you would like to borrow my refractometer to see exactly what your coolant mixture is, I will lend it to you.

http://www.getahelmet.com/jeeps/maint/dexcool/

After rereading this thread,it became apparent to me that this is one of the best posts on the subject of coolant and headbolt failures that I have ever read, and I have been on this site well before the 2004 year that is attributed to most of us. Yes, sometimes you need to read between the lines a little, and a few small details may be left out, but as far as a truthful and informative series of posts, this one is the best on the subject.

Never underestimate the amount of a persons greed.

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Thanks Johnny,I was just curious about the air thing.No intention of using the green coolant,I'm gonna get the Prestone 50/50 mix.This has been a very informative thread,and it seems most agree the coolant is very important and possiby key in staving off problems.Thanks again for all the responses.

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I'd have found this thread very interesting also.

My Eldo has the 4.9 engine and not the Northstar.

My immediate curiosity is whether the 4.9 engine's (also aluminum block) coolant can be changed as easily as stated for the Northstar engine.

Specifically, with no need to fill the radiator with only water after draining out the old coolant mix, running engine for a drive, let cool, drain and fill with water, repeat and finally when it drains clean, replace with 50-50 mix of the new coolant.

It seems that the aluminum block engine does not leave residue in the coolant like an iron block engine. (?)

My 4.9 engine is required to use the green coolant and 'barleaks' powder.

I was planning on replacing the coolant myself this next time around.

BTW Stokes, congrats on the nice car purchase. Glad you went for it.

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I'd have found this thread very interesting also.

My Eldo has the 4.9 engine and not the Northstar.

My immediate curiosity is whether the 4.9 engine's (also aluminum block) coolant can be changed as easily as stated for the Northstar engine.

Specifically, with no need to fill the radiator with only water after draining out the old coolant mix, running engine for a drive, let cool, drain and fill with water, repeat and finally when it drains clean, replace with 50-50 mix of the new coolant.

It seems that the aluminum block engine does not leave residue in the coolant like an iron block engine. (?)

My 4.9 engine is required to use the green coolant and 'barleaks' powder.

I was planning on replacing the coolant myself this next time around.

BTW Stokes, congrats on the nice car purchase. Glad you went for it.

All you need to do with the 4.9 is to drain the coolant and refill with new colant mixrd 50/50 with distilled water. You must use the Bars Leaks powder in the 4.9 engine due to the o-rings at the top and bottom of the wet cylinder liners.

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

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