[djoneill]

Hi Guys,

Just want to put you on the lookout for a problem with late model Northstars. I was told by my dealer they see a lot of this problem, and there's a technical service bulletin out there on it.

The cylinder head bolts are stripped in the engine block bolt holes. This is either over-tightening at the factory or just a defective design. The steel bolts are threaded directly into the aluminum block.

GM has a "special program" for paying for 50% of the repair IF your car is under 70K miles (mine has 80k).

I was alerted to this problem by a "low coolant" indicator on the DIC. I added 2Q of coolant and made a mental note to bring it into the dealer.

The retail repair bill is $3800! The president of the dealership is a friend, so I'm getting an $800 discount.

Needless to say, I'm contesting the repair with Cadillac, and I'll be suing in small claims (or not so small claims) court to get the repair paid for.

I also have the dreaded half case oil seepage, but the additional cost of getting that sealed up was $1280, so I skipped it.

If any of you can point me to information (online or other places) providing more information about the cylinder head bolt hole stripping problem, it will be much appreciated!

Thanks,

Dave

Edit by Sal: Just to let you know, Dave - HTML code doesn't work here - BUT - vB code isn't much different. Instead of using a greater than or less than sign - use a straight bracket to open and/or close.

 

[Devil_concours]

could this have impact on oil consumption as well?

 

[Katshot]

This issue is not new by any means. The head bolt issue has plagued the Cadillac aluminum engines for years. From the HT4100 right through the Northstars.

 

[BeelzeBob]

What if the car is still under factory warranty?

 

[elwesso]

If its still under warranty, they will fix it. But his car is out of warranty, so it sucks to be him .

Anyway, this is a very common problem, and usually occurs to most northstars. The only way to prevent it is to make sure that the cooling system is PERFECT throughout its life. Seems too simple to prevent a $3800 repair??

And the half case, I think that is a bunch of crap. People go and buy a $40,000 car, and not very many miles later it leaks oil???? GM says that "it is impossible to get a perfect seaL" or something to that affect. Well, you dont see any infiniti's, lexus, or MBs leaking oil. Hell, my 94 infiniti Q45 doesnt use, or leak any oil at all, and it has 120k miles.

Granted, some cars are more prone to this than others. I have heard that the newer ones (2000+) have been fixed of this, do i know fosho, no.

 

[eehoepp]

djoneill, I feel your pain!

I just got bit by the same problem. I have a thread going in the General Chit-Chat section of the forum about my efforts at repairing the problem myself. This is a very involved repair. My first symptom also was the check coolant message.

If you are looking for official documents relating to the problem, I don't know where to find any.

The following site has some information on the problem and also a photo sequence showing the repair with the Time-Sert kit
http://www.caddyinfo.com/howto.html

FWIW, there are two Time-Sert kits available: the "first repair" kit and the oversize "second repair" kit. GM's first recommended repair was to use Heli-Coils in the head bolt holes. These also pulled out & then Time Fastener got involved & produced the two kits. The Tech Support people at Time Fastener were able to elaborate some of the history for me.
http://www.timesert.com/misc.html

Good luck in your fight.

 

[Devil_concours]

i heard this from a mechanic on another forum (tech forum)

Actually the transmissions that are used on the Northstars are considered to be one of the most reliable. The 4L80E/4T80E can handle quite a bit more power output than what the Northstar puts out. It's been a solid transaxle for GM and Caddy.

Now, as far as the Northstar itself, it has a few nitpick issues with it:

1. Oil control rings get carboned up and causes excessive oil consumption. This seems to be more of a problem on those cars that have been babied around. The cure for the problem is not too terrible so it's not really all that big of a deal.

2. The head bolts like to pull through on the block causing head gasket leaks, the repair on this is anywhere from expensive (new head gaskets and timeserts on the block to repair the stripped threads) to VERY expensive (new long block).


3. Fuel system issues that are varied. The repair can be expensive depending on if you take it to an experienced driveability tech or not.

4. Water pump leakage, not too bad of a cost issue there.


Now, despite these issues, the engine has been very good. I have seen more than a few with over 300K on the clock with nothing but a water pump and some injection repairs done to them. They were also still running VERY strong.

Rags

 

[Katshot]

I've also heard about some new issues. I've been seeing some block cracks in cars with 120K-150K miles. More to follow when I hear more.

 

[jadcock]

Do not use a Heli-coil on a Northstar! The Heli-coil is not long enough and will not provide the strength needed to keep the heads in place. I've never heard of GM ever recommending the Heli-coil. As far as I know, the Time-sert has always been a recommended part of every head gasket repair. At the very least, use new head bolts, but if you use a Time-sert kit, it'll be stronger than new.

The problem is there, but isn't really "common". Think about all the Northstars out there that are running just fine without even a valve cover having been off the engine in their 100k or 150k life. Maintain the cooling system (especially important with pre DEX-COOL cars) and the likelihood of this problem ever occuring to you is pretty slim. Obviously, it does happen, but it seems so common because you only hear about the basketcases. People don't usually come to a forum and brag about how reliable their car is.

 

[eehoepp]

I neglected to emphasize in my previous post that the Heli-Coil repairs proved totally inadequate.

FWIW, the GM factory service manual for my 94 STS lists all the part numbers for the heli-coil inserts, insert tool, tap, etc. I'm glad I found the correct info on the web before I tried to get the Heli-Coil repair set. I would have hated to have done this job twice.

 

[kcnewell]

I use quite a few Heli-coils in my shop but I would NEVER even consider using them for heads. As you say they're not deep enough. They're great for lots of stuff though!

 

[jadcock]

I neglected to emphasize in my previous post that the Heli-Coil repairs proved totally inadequate.

FWIW, the GM factory service manual for my 94 STS lists all the part numbers for the heli-coil inserts, insert tool, tap, etc. I'm glad I found the correct info on the web before I tried to get the Heli-Coil repair set. I would have hated to have done this job twice.

Huh! The service manual specifically calls out the "Heli-coil" brand? That really surprises me. I thought they always called specifically for the "Time-sert" brand -- because they're about twice as long as a Heli-coil. If they really call for the Heli-coil brand, I learned somethin' there!

 

[eehoepp]

Yep. Specifically Heli-coil. However, this is in the general thread repair section that covers every tapped hole in the engine. There is no section specifically for head bolt hole thread repairs. But there are specific heli-coil insert and tool part numbers called out for repairing the head bolt hole threads.

The only saving grace that prevented me from going down the heli-coil road was that Heli-coil does not list ANY 11mm repair kits in their e-catalog. I started searching the web & then found mention of the Time-Sert kit. Frankly, I had never heard of the Time-Sert before all this.

 

[Katshot]

The Heli-coil thread repair kit was adopted by Kent-Moore who does the GM "special tools". The original thread repair directive from GM specifically called for using the Kent-Moore repair kit.
Matter of fact, I still have one in my tool box at work. And it still has the "J-" part number on it. For those unfamiliar with my "J-" reference, GM special tools from Kent-Moore always had a "J-" prefix. Over the years we just started calling them "J-" tools.