: Torquing N* head



Tailfin
11-25-13, 12:59 PM
Well I have a Northstar down to the heads...that was not fun...but anyhoo :D....

Side note...this is a 97 service manual and I'm doing it on a 96...but I trust that doesn't matter--same engine.

I'm a little confused about the torquing procedure given in the service manual. I have scanned the page in question here...
163842

The highlited spots are the one I'm confused about. The first one just sais feet...not foot-pounds. I thought maybe they meant that anyway, but then the put "pound feet" by the other bolts, plus the conversions between the N-m and the feet/feet-pounds/whatever are different. Could someone clarify this bit for me?

98eldo32v
11-25-13, 01:40 PM
The 3 M6 bolts are the ones near the timing chain. The others are the head bolts themselves

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Which repair method did you chose?

Submariner409
11-25-13, 03:08 PM
DO NOT torque - or attempt to torque - those 3 bolts to 106 lb/ft. !!!!!!!

Use an online conversion engine to get lb/ft for Nm. Google "foot pound to newton meters"

The head bolt (10) sequence and degrees is correct. The initial torque establishes base bolt tension, the additional rotations set the bolt stretch. I hope you used either BigSerts or NS300L inserts.

USE NEW BOLTS !

Tailfin
11-25-13, 04:04 PM
I did the conversion and the first number seems to be correct... 30 N-m is 22.12... foot pounds...just seems like they messed up printing this. As long as it's the right number, I have no issue with it...but that's the sorta thing to make one nervous :rolleyes:. Seems kind of light actually, considering it's only getting another 120 degrees, but I'll follow. I just noticed taking some of the old ones out...they were really in there.

Yeah no worries. I have new bolts and I'm using the NS300L inserts.

Ranger
11-25-13, 10:16 PM
I am sure they simply (mistakenly) omitted "lb" in the first number. It should have read "lb/ft".

drewsdeville
11-25-13, 10:35 PM
I am sure they simply (mistakenly) omitted "lb" in the first number. It should have read"lb-ft".

Fixed :stirpot:

Fun fact - torque is equivalent to the force (lb) multiplied by the length of the moment arm (ft). There is no division. Interesting the the 'ft/lb' error is somewhat common, yet we never see the same mistake applied to the metric unit, shown as 'n/m'.

Tailfin
12-07-13, 11:07 PM
I've just put the heads back on my N*. I'm using the NS300L inserts...and I'm just a bit nervous on the experience. With the inserts, I carefully followed the instructions to the letter. The thread locker says to let dry 3 hours before putting in the head bolts...To remove doubt, I watied 2 days. I was also careful to use brake cleaner and compressed air to make sure the holes did not have oil residue.

What I don't like is while doing the second "60 degree" turns (as per the manual) in some of the bolts, I felt the wrench kind of "give" for just a moment, and had this unpleasant image of the inserts breaking loose inside the block. Now I don't understand why that would happen...because they claim that bolts have broken before these things give...and plus, I'm going clockwise...and I don't see why the inserts would want to go that way, since it would be pulling them further into the block...but I don't like that it acted that way, just the same. It's my first headgasket. Anyone had any similar experience?

98eldo32v
12-08-13, 08:12 AM
I know exactly what you mean by "give" when fastening the bolts back.

I understand that you have taken the utmost of care in the preparation of the block for the inserts, but again ANYTHING can happen sometimes.

You are now screwing a bolt into an insert. Rotating clockwise probably the same way the insert was installed.

I'm not saying those inserts don't work, they must have worked for a few people with great success but, that "give" feeling I've felt too often dealing with soft metals such as aluminum.

That is part of the reason I'll never use inserts, for me it's studs or nothing.

I don't know if you've ever had one of those studs in you hand, but once that is installed correctly it's not going anywhere. Again, anything can happen but the northstar is too much of a beast to work on to second guess.

I always say, fix it and forget it.

I truly hope you don't have a problem later...........

Good luck.

Tailfin
12-08-13, 01:09 PM
I actually e-mailed Norm (the guy who sells these inserts). He said it was not uncommon for this to happen, because the bolts are long and the bolt itself can twist a little, and then the threads catch up. I'm inclined to believe this because it does make sense to me, and it happened on severaly bolts.

I will post back if I do have a problem...if I haven't commited suicide lol

98eldo32v
12-08-13, 03:32 PM
He stated this was common?

WOW!!!

I think that would be a little unnerving when you go this deep into the motor KNOWING these things have head gasket retention issue, especially in the aluminum block area.

I pray you have no problem, my friend.

Studs....... to the end.

Tailfin
12-08-13, 03:34 PM
Well, it's not unnerving if the give is simply the flex in the bolt. If that is the cause, then it would still happen even if the block were steel. All the same, I too hope I have no problems :-P.

Tailfin
12-08-13, 03:58 PM
Ok lordy... I have a follow-up on this issue...these service manuals are making me as nervous as the engines themselves. I've just put the heads back on and followed the above procedure for torquing....that is, first pass 22 ft-lbs, then 2nd and 3rd pass, 60 degrees. I was reading through an old sticky thread on these head gaskets, and I found a post by AJ (the fellow who did a whole write-up on this subject) as follows:


Torque Specifications:

1993-1999 Head Bolt Torque

First Pass ----- 30 lb ft
Second Pass -- +70
Third Pass ---- +60
Fourth Pass -- +60 (190 Degrees total)




2000-2003 Head Bolt Torque:

First Pass ------ 30 lb ft
Second Pass -- +70
Third Pass ---- +60
Fourth Pass -- +45 (175 Degrees total)




2004-2008 Head Bolt Torque:

First Pass ------ 22 lb ft
Second Pass -- +60
Third Pass ---- +60
Final Pass ---- +60 (180 degrees Total)



Here is a link to the actual thread:

http://www.cadillacforums.com/forums/northstar-engines-system-technical-discussion/133429-root-cause-head-gasket-failure-fix-4.html

I'm finding this very disturbing... ALL of them have a 4th pass, and my manual page as I scanned up there, doesn't. Also, I have a 96 (97 manual), and the figures he posted don't even start with the same torque as my manual says. Can anyone help me clarify what's correct here? This is not a job I need to do twice :-P.

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Sorry edit post is messing up for some reason...I realize maybe he meant 30 N-m and put lb ft....but the last pass...that's really bugging me out...

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G'ah! I've just checked ALLDATA, which I have...and I found an "update" for this procedure....and the update has just what AJ put in his post...so it seems like GM screwed up printing, without exception, the most important torque specs in the manual...GRR. Next question...will it cause any problems for me to loosen the bolts and do it properly from there?

Submariner409
12-08-13, 04:19 PM
Northstar head bolts are torque to yield. Once used - even if improperly - you must use a new set.

98eldo32v
12-08-13, 04:25 PM
Now you see why per se' WHY I won't use inserts.

You're making three more passes torqueing the head in place, into an insert that may possibly move a bit?!


It's hard to say whether or not to redo them.

As you torque the head, you crush the gasket.

If you've only done 3 passes and there is a 4th, I'd say you'll be ok.

Yet, this is an area of repair that you don't what to have a shadow of a doubt about what is going on.

You may want to get new head gaskets and start all over for peace of mind.

Tailfin
12-08-13, 04:34 PM
Ugh... Yeah I see the issues at hand. Part of me likes the idea of just doing a 4th pass...but the updated service bulletin STARTS at a different torque...not much, but still. Plus, even the bolt order is different. I think if I were to loosen them, then that first torque setting would not be correct if the bolts are deformed. What a mess... This isn't a problem with the inserts... I don't mind the process of new bolts or even gaskets... I do mind the prospect of being out another $120 just because the GM manual people were morons...

98eldo32v
12-08-13, 04:42 PM
Humans will never be perfect, we are flawed by design.

No matter what we do/ make we may make a mistake or flaw because we are not perfect, so nothing we create will be perfect.

Nature of the beast.....

Good luck

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Are those bolts torque to yield design?

Submariner409
12-08-13, 04:45 PM
Are those bolts torque to yield design?

Post #8

Post #1, Procedure 3.

EDIT: To further muddy the waters, you can also use a set of ARP studs, nuts and special hardened washers with the NS300L inserts.

98eldo32v
12-08-13, 04:47 PM
Torque yield bolts........DAMN!!!!!

Another vote for studs.......

Tailfin
12-08-13, 05:03 PM
Yes yes, have to keep with the law here. Everything has gone wrong :-P. I think the bolts are a bigger concern than the gasket crushing, personally.

This little article explains them: http://freeasestudyguides.com/a1_4.html

..and explains how they're basically screwed after that third pass...the one I did...:-P

I really think there should be a sticky about that service manual error. That's horrible... I mean if I hadn't stumbled across that post, I would have had a HG failure after all this work and expense, owing to typos. As it is, of course I couldn't stumble across that yesterday...it had to wait until after I torqued my head LOL. Anyone have a use for 20 clean, slightly mal-formed Victor Reinz head bolts? :-D

EDIT: Oh, in case anyone was wondering, the typo on the M6 (smaller by the timing) bolts is that it's supposed to be 106 lb in

Submariner409
12-08-13, 05:19 PM
Your second thread on this engine problem was in Northstar. I just merged your essentially identical thread from Deville - since we're working on a Northstar engine.

Racecar ??? :sneaky: ^^^ next post .......

About the only reason racing engines use studs is because they are taken apart on a very regular basis. The ONLY reason studs are recommended for a Northstar top overhaul is to get away from the torque-to-yield head bolts and failed aluminum block bolt hole threads. If someone wanted to use NS300L inserts or Time BigSerts and good ol' HD head bolts from ARP you could take the heads off a Northstar and replace them to your hearts' content - using only new gaskets. (The trick would be to re-engineer torque values and make sure the head bolts and inserts had fine inner threads for more precise torque control.)

CadillacLuke24
12-08-13, 05:19 PM
Studs....... to the end.

BECAUSE RACECAR!! :sneaky:

Submariner409
12-09-13, 05:58 PM
Racecar spelled backwards is ...........

98eldo32v
12-09-13, 06:17 PM
lol......

Ranger
12-09-13, 09:41 PM
About the only reason racing engines use studs is because they are taken apart on a very regular basis.
:yup:

04GrandAmGT
12-11-13, 12:07 PM
if worse comes to worse and i believe those inserts are threaded for 5/8 coarse, our studs will still work you will just have to manage getting the insert out and because you have it drilled and tapped, you would just need our SNW kit which is $335 compared to the full kit being $549.00 all prices include xpresspost shipping from canada (3-5 Day)

Tailfin
12-11-13, 01:53 PM
Thanks for that information. That would mean completely dropping the engine...a feat which I've avoided due to lack of the hoist and such...but I will keep it in mind as an option opposite that of suicide if I have a problem :-P.

04GrandAmGT
12-11-13, 03:45 PM
we take the engines out of the top it isnt impossible and 90% of the time makes certain things easier such as never touching the subframe there is no chance for need of re-alignment, also dont have to touch brake lines or anything of that sort

Tailfin
12-11-13, 07:49 PM
Hehe yeah top or bottom, it takes equipment I wasn't prepared to purchase just yet. I'm doing it in the car. A few things are a real pain, but still didn't seem worth pulling everything to me.

vincentm
12-12-13, 04:01 PM
Hehe yeah top or bottom, it takes equipment I wasn't prepared to purchase just yet. I'm doing it in the car. A few things are a real pain, but still didn't seem worth pulling everything to me.

You cant do studs with the engine in the car, only TimeSerts..

Tailfin
12-12-13, 05:23 PM
Yeah that's what I just said a couple posts ago...here:


Thanks for that information. That would mean completely dropping the engine...a feat which I've avoided due to lack of the hoist and such...but I will keep it in mind as an option opposite that of suicide if I have a problem :-P.

I'm using the NS300L inserts...read too many bad things about TimeSerts. Plus, they practically admit it...by having BigSerts. Makes me nervous when they come out with a product to fix their first product haha.
I'm almost done. Just have to put a fan, the coils/wires, the surge tank and a few other mechanical viscera back on and then I pray haha.

04GrandAmGT
12-12-13, 05:42 PM
hope for all the best, if you have any technical questions feel free to ask Jake or I about it give us a call or im sure theres alot of people on here aswell that would help you in a heartbeat, i will do my best to answer your questions to the best of our knowledge.
888-800-9470

Tailfin
12-14-13, 04:54 PM
Well for the curious, it's running. Few kinks to work out on this thing, but not because of the headgasket...and I'll hope it stays this way :-P.

A few things I've learned along these weeks of pain which may help others:

1.) If you're doing this repair with the engine in the car, you will need some room to drill the holes in the rear (right) bank of the block. One way is to remove all the A/C and blower stuff and that big plastic piece that covers it all on the firewall. I did this job without discharging the A/C, and just removing the blower motor and tilting the engine cradle on 2 jacks (left the struts attached). You can drill the holes this way, but only if you have a good right-angle drill (not one of those beefy Harbor Freight Hole Hawgs that takes up just as much room as a hand drill :-P). I used a Milwaukee (1/2" chuck necessary) from Home Depot--$250. This will also be tight when you torque a couple of the back head bolts if you're using an angle gauge (which I did). If you have one of those fancy-shmancy torque-angle wrenches, this will be easy.

2.) I did purchase a new set of bolts after I had to retract the ones I torqued because of the service manual mistake, in case that comes into relevance. However, when I removed them, all the NS300L inserts in the left bank stayed fine, but 5 of them came up on the right bank. I'm not necessarily blaming the product here, but a few things should be mentioned which are not mentioned in the instructions that come with it. The thread locker...I had to buy more... And on the bigger package, it says to shake well before each use--not mentioned. Also, it says it fully cures in 24 hours. Norm's instructions say to wait 3 hours before installing the bolts. In addition, the 24-hour cure time is assuming 72 degrees F...which I surely did not have. Also, when cleaning the holes and inserts preparing them for the thread locker, make SURE they're clean and free of oil residue....use compressed air to blow them off, and then let them dry a bit. Also, I would use just a wee bit more thread locker than around one thread of the insert and the hole. There is some play in such coarse threads...and I read in the threadlocker data sheet...that it cures anaerobically. So if air pockets are there, it won't cure. None of this was mentioned.

3.) Again, if doing this in the car, do not even attempt to take the bolts off the firewall side exhaust manifold where it connects directly to the head...you will commit suicide. It's impossible :-D. This should have been obvious to me, but my wits were stretched and it wasn't. Disconnect the two larger pipes that connect the manifold to the pipe that goes to the cat...and take the whole head off with the manifold. It's a bit heavy, but you will save a life...whoever gets hit by the tool you will throw after trying to get at those bolts any other way....