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Hi again, I tried to find a previous post regarding this specific subject, and came up with 0 answers, it may have been discussed before.....so here goes. I am wondering if anyone knows if there are certain years that the 4.6 Northstar didn't have the headgasket/ bolt problem, it seems to be more prevalent in the '97 to '01 engines, (from what I've read). I thought I heard or read somewhere that the '96 Northstar had fewer if no problems with the above issue, is that true? Also, I do believe that the Northstar of any year was an awesome engine...my opinion is that owners of these Cads either did not regularly use high test and switched to regular gas as the price went through the roof during those questionable years,which over time can cause problems, (read the owners manual!) as well as did not keep the cooling system up to date with coolant changes on a regular basis. And as they sat in sweltering heat, in traffic, with the AC cranked, the old acid coolant did it's damage and then they blamed the engine design. I could be wrong, I was once before (?!).  Any input on this, from you guys, who are way more knowledgeable, and experienced than I?  Thanks a million for any input, this is a great forum, Bill in VT 

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Some HARD to answer questions, and a lot of debate centers around the head gasket and head bolt issue. 

No vehicle, including Cadillac, is immune to head gasket problems. Any misuse or lack of maintenance can contribute to failures in any vehicle regardless of brand name or engine type. Statistically, there were some improvements in head gasket and head bolt design that improved the longevity, but those improvements still fall victim to poor maintenance.

There are a LOT of HIGH mileage " virgin " N* engines out there still pounding the pavement.

Dex-cool is an organic acid based coolant. Personally, I don't agree with the "recommended" change interval of Dex-cool. I feel that both "green" and Dex-cool should be changed at 30,000 miles, but I'm sure GM and a lot of other people don't care what I think. I suggest researching both types and forming your own opinion.

They are an "awesome" engine. I have 2 and both average 25 mpg hwy and 20 local .

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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99 was the worst that I can recall

I have 2 97s that were bad when I bought them

one was cherry with 98k miles on it

one was ok with 150k

My 96 failed at 230k but I ever tore it down.

All of them I well maintain. Likely why the 96 made it over 200k.

99 was the worst year because of the bolt holes being drilled too deep IIRC

They are good engines though. otherwise I would not keep buying them.

I only run non ethanol premium and change the coolant every 2 years regardless of what any book says

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Thanks to both of you guys for your input. Rockfangd, you say you have 2 '97's that were bad when you bought them....did you do the head gasket and or bolt repair, or are they driveable as is? Mine is a '99 Deville, now with 50k miles, pretty much mint, very nice car. But I'm worried about the future, and that bolt problem, is there anything that can be done (other than coolant changes) to prevent a breakdown in the future, such as longer bolts, or whatever? And currently, I'm considering purchasing a 1 owner low mileage "96 Deville, grey metallic/ cream, with a painted roof, lots of options, basically a cream puff....I just seem to recall someone stating the '96's had almost no issues as opposed to the '97- 01's. Thanks in advance, Bill in VT  

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I will start off with saying I loved my 96 Deville more than any car I have ever owned.

Even my cherry Seville.

I never worried about the issues. I just drove and maintained them.

My Seville had 4 head bolts pulled. All in the same area. Rear right side IIRC. I had the engine pulled, serted, and resealed. That was almost 30000 miles ago and I drive it like it is designed to be.

My current Deville I had the engine replaced with a known good southern donor. I dont worry about it for a second. As my DD it gets driven hard and alot. I love the highway and never skimp on the throttle.

How long have you had your 99?

If you are contemplating buying another one be sure to test drive it. Not in the city but hard on a highway. Trust me if there is a problem you will probably find out.

Person I bought my current Deville from tried to BS me and tell me it was fine. I test drove it and it was fine in town but the first hard pulling acceleration on the highway and it was over 260 in 5 seconds flat. 

I payed too much for it but it was worth every penny.

Honestly if I was worried I would not own one, let alone 2.

I just took my Seville 1100 miles over 3 days(do every year) through the hills of Vermont and never worried for a second. IT pulls hard and runs great.

Another tip I can give is dont let it overheat. If the coolant temp gets over 230 or so let it cool down and have it looked at. 

Both my 96 and 97 Devilles in good running have never gone over 225 and normally run spot on at 196. 

MY Seville has the needle gauge. So that barely ever goes over the 12oclock position (normal)

As for what can be done, maintain coolant, inspect waterpump Tensioner. I stress on the tensioner because I find that they tend to seize in place and may not apply enough tension under load. Dont let it overheat. Which as long as it does not get low on coolant, and your fans work properly, and your waterpump is happy, you should be fine.

If it is going to happen it will. It may go soon, or never. At least you are prepared if it ever does.

I put alot of blame on GM listing 10 years or 100k miles on coolant interval. That is just nuts no matter what coolant you have. 

Because of that alot of GMs had issues with cavitation, rust and corrosion, gelling, you name it.

I have bought cars with coolant that looked like mud. 60k miles with the original coolant.

Just my opinion

 

 

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Cool...so to speak! Thanks for that in depth response....in answer to your question, I've had my '99 Deville for 2 years now, and no problems. ( Bought it at 36k)  I keep an eye on the temp from time to time, in hot weather. It is just as it should be, at 196 degrees avg., but of course will climb to 221 or so (during hot weather, climbing steep hills in VT), and then the cooling fans kick on, reducing the temp to where it should be.  So all looks good, so far. Maybe I don't need to be so nervous, but what can I say?  It's white, white vinyl top, dark blue interior, lots of options for the year....it really drives like new. At 50k I just had the front brakes done, they were original, never touched. Next, the rear brakes. Believe it or not, the battery is original, no kidding! It has the date code stamped right on it! It starts in the coldest temps, never gives out. Any way, thanks again, all you guys (and gals) are great, I love this forum, and, any more input would be greatly appreciated! Bill in VT  

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I completely believe it.

Think of it this way. 

You have a low mile well built vehicle.

Even if you do have a engine or trans problem repairing it will still be cheaper and worthwhile to repair than to buy a newer vehicle.

50k is not even broken in yet let alone broken.

my 96 with over 230k still ran and drove wonderful. Extremely reliable, did not have to put alot into it. It paid for itself

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Hey thanks again guys for your help. I looked at a '99 Deville today, in good shape, 97k miles, and a known head gasket problem. The owner has driven this car for 6 years now, with no trouble, and one day, had an overheat. Had it towed to the mechanic, and was told it was the head gasket....it would be OK to drive it around town, just not up steep hills on the highway. So he's selling it for $400...?!  I started the car, let it sit while we talked, and after 15 minutes, the temp never exceeded 197 degrees. And still not, after a half hour. Cooling fans were on. The exhaust smelt fine, but it did smell of exhaust fumes in the coolant overflow tank (I think). I asked him if he ever changed the coolant..answer- no. I asked him if he used high test or regular- answer, always regular. Well, what do you know...in my opinion that's what caused his problems. So my question is, the car never ran hot while idling ( I thought it would) and I wondered if any of you guys have used a product called "steel seal"..it claims to be a breakthrough product, proven over 10 years, and they even have a N* formula....hmmm...sounds good to me. I know other products are a waste of time, but this one seems to have potential. I would buy the car for , I hate to say, beater, or for my 15  year old son to tinker with. The brand new tires and chrome rims alone are worth more than $400....There are many more good trim parts, non rusted doors, interior parts, etc. So, whaddaya think? Any input would be greatly appreciated! Even if you think I'm crazy ( or not) please let me know! Thanks in advance, Bill in VT

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That's the one that will get hot on a Vermont hill, in a New York minute.... Keep the coolant jugs in the trunk

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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No snake oil will work.

See it will idle and putt around town fine but once you put the engine under load the head in question will pick up enough to purge high temp exhaust right into the cooling system.

So even if a snake oil did work it wouldnt for long as it is not going to stop the head from moving under that load.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Thanks again guys for all your help...along the same topic, I do believe I read somewhere, that in 1999 some of the N* engines had the bolt holes drilled too deep, or something along the lines of bolt or bolt hole issues....and that some engines had the defect, and others may not have it. It was noted that you could determine if you had one of the engines in question by the VIN #.....any input on that topic? Thanks in advance for any more advice.....I'm sure it could benefit other readers as well. Bill in VT 

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i guess I'm going to answer my own post here, I actually found the above mentioned topic, for all to read under " 1999 deville campaign # 99086"...it gives a lot of info as to which VIN's were in question. Bill in VT

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