: Head Bolt Torque Value?



danssts
06-28-07, 09:12 PM
Can anyone tell me what to torque the headbolts down to on a 1999 4.6 Northstar engine? I just timeserted the block, what should I put on the threads to prevent them from coming out?
thanks, Dan

Ranger
06-28-07, 09:22 PM
You don't put anything on the threads. They are already coated with a thread locker. You are using new bolts aren't you? I don't recall the torque exactly. I seem to recall 37 ft. lbs. and 60 degrees plus 60 degrees, but don't quote me ont that til someone verifies it.

AJxtcman
06-28-07, 09:48 PM
Document ID# 641058
1999 Cadillac DeVille


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Subject: SMU - Cylinder Head Tightening Specification Clarification #99-06-01-016 - (10/04/1999)



Models: 1993 Cadillac Allante, Sixty Special (FWD)

1993-96 Cadillac Fleetwood

1993-99 Cadillac DeVille, Eldorado, Seville

1994-99 Cadillac Concours

1995-99 Oldsmobile Aurora

1999 Marine

with 4.0 L or 4.6 L Engine (VINs C, Y, 9 -- RPOs L47, LD8, L37)




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This bulletin is being issued to clarify the cylinder head tightening specification listed in the following procedures in the Engine Mechanical 4.0 L and 4.6 L sections of the appropriate Service Manuals:

• Specifications -- Fastener Tightening Specifications

• Cylinder Head Replacement -- Installation Procedure

• Cylinder Head Installation

The torque specification and sequence for the cylinder head bolts (1--10) using J 36660-A is:

First Pass -- 40 N·m (30 lb ft)
Second Pass -- 70 Degrees
Third Pass -- 60 Degrees
Fourth Pass -- 60 Degrees (190 Degrees total)
The torque specification for the three front M6 cylinder head bolts is:

12 N·m (106 lb in)

Ranger
06-28-07, 10:24 PM
Close, but no cigar. Thanks AJ.

danssts
06-29-07, 02:09 PM
Okay Great so with new headbolts there is no reason to put anything on them? What about if I reuse the old ones?

AJxtcman
06-29-07, 02:44 PM
Okay Great so with new headbolts there is no reason to put anything on them? What about if I reuse the old ones?

I have always replaced them, But If you want to chacne it you can reuse them. You will need to put Thread Sealer on the threads and the base of the washer. Thread Sealer like Pipe Thead Sealer Not lock tight.

Ranger
06-29-07, 05:53 PM
Okay Great so with new headbolts there is no reason to put anything on them? What about if I reuse the old ones?

I have always heard that they are not reusable. That is why a gasket kit includes new bolts. I would not reuse them.

Harry Yarnell
06-29-07, 06:08 PM
Here's why you shouldn't reuse head bolts. They may look just fine, but they're 'stretched'. The tightening sequence requires a certain torque (40 ft-#?), and three incrimental degree tightening. This tightening puts tension (stretchs) the bolt. Doing it again, weakens the bolt.

AJxtcman
06-29-07, 06:51 PM
I have always heard that they are not reusable. That is why a gasket kit includes new bolts. I would not reuse them.

The bolts ARE NOT TORQUE TO YEILD!
They are Torque angle and can be reused.
The Rod bolts are Torque to yield.
Trust me on this I have been over the description for every bolt type on Northstars.
The reason GM recomends replacement is so the correct amount of sealer is on the bolt.

AJxtcman
06-29-07, 06:57 PM
Here's why you shouldn't reuse head bolts. They may look just fine, but they're 'stretched'. The tightening sequence requires a certain torque (40 ft-#?), and three incrimental degree tightening. This tightening puts tension (stretchs) the bolt. Doing it again, weakens the bolt.

I see you must have been trained by our goverment. The Army?
Do you have any idea how much money a Cadillac heavy duty tech makes?
We get paid well to know how to fix them.
The main bolts are torque - angle and they don't get replaced.
The oil pump bolts are torque - angled and we reuse them also.
Do you know what a torque - angle is?

dkozloski
06-29-07, 09:56 PM
Any number of engines have torque angle head bolts that are reused including HD Deutz diesels.

Ranger
06-29-07, 10:02 PM
I could swear I remember the Guru saying they should never be reused. That is what I based my answer on. Guess I stand corrected.

dkozloski
06-29-07, 10:23 PM
I remember *Bbob* saying that too. Maybe it does have to do with the sealant.

Ranger
06-29-07, 10:54 PM
Good to know it is not just me. I also thought he said that they where torque to yield, but I could be mistaken there.

Harry Yarnell
06-30-07, 07:24 AM
What do I know. I've been a GM wrench for 40 years. I've been told they were torque to yield, and should never be reused. I do as I'm told.

AJxtcman
06-30-07, 10:18 AM
Did you go to the Northstar Mechanical Systems trianing course?
Are you world class?
Guess what I am.
I have the Northstar book in front of me currently and it says they are Torque-angle

Harry Yarnell
06-30-07, 01:28 PM
Chill, my friend; don't get your balls in a knot. I've been taught to replace headbolts. When doing a Northstar, you don't want to make mistakes.
Since you're well trained, perhaps you could tell me who has the best prices on Timeserts?

AJxtcman
06-30-07, 03:18 PM
Chill, my friend; don't get your balls in a knot. I've been taught to replace headbolts. When doing a Northstar, you don't want to make mistakes.
Since you're well trained, perhaps you could tell me who has the best prices on Timeserts?

What Year and is it for the heads?

Harry Yarnell
06-30-07, 03:59 PM
The next one is a '93 seville. head bolts. 11155. Best price so far is from threadkits.com for $2.32

zonie77
07-01-07, 12:53 PM
From my research and having been corrected previously:

They are Torque to angle but not torque to yield.

They are replaced because of the special coatings on them, not because of metal failure. The guru said they reused them (and HG's) at times during testing on dynos but that was different than reusing them in your car.

AJxtcman
07-01-07, 01:33 PM
The next one is a '93 seville. head bolts. 11155. Best price so far is from threadkits.com for $2.32

I would not use GM/TimeSert insterts in a 99 and prior block!
I have installed them many times and I feel that the blocks are not made of the same quality of aluminum as the 2000+. They redesigned the complete engine in 2000 and the material used is better. I have not seen the same castin problems in the 2000+ as I have seen in the 99 and prior. I have used Norm's inserts. I feel they are a better insert for 99 and prior. I do have some issues with the tooling, but it is minor and can be watched for. His insert needs to be locked in place. It can not rotate after you begin to Torque to angle, because the OD threads are a different pitch and that would produce an uneven torque. The thread bite is so much better than Timeserts that it out weighs the down side. If you take the time and install a stop on the drill bit and the Tap or tap driver you will be good.

Please read all three pages
http://www.fiero.nl/forum/Forum2/HTML/075382.html

irebroff
07-13-07, 03:32 PM
Is it a mistake to use NEW head bolts? I don`t think so :)Which are the best head bolts? GM or Felpro or something else?

AJxtcman
07-13-07, 03:57 PM
Is it a mistake to use NEW head bolts? I don`t think so :)Which are the best head bolts? GM or Felpro or something else?

I work at a dealership so I have only used new GM head bolts everytime. I have never reused 1 head bolt.
The fact is the head bolts can be reused.

97Concours1
07-19-07, 05:06 AM
FYI - The Torque-to-Angle procedure can produce a yield (permanent stretch) in the head bolts, if the specified angle is high enough. They can be one in the same; Torque-to-Angle and Torque-to-Yield. The engineers who designed the engine know the specific characteristics of this head bolt. They know that if the bolt is torqued to the 30 lb-ft specification, all the slack will be taken out of the head-block joint. They also know that if the bolt is then turned 190 degrees total, it will be yielded (stretched) a known amount. This will produce a known maximum clamping force by the bolt. (Torque-Angle is a somewhat crude “service” procedure to simulate a much more sophisticated process used in production. The production process is computer controlled and will achieve exactly the same yield in every bolt. The Torque-Angle service procedure comes close, but is not as accurate as the computer-controlled production process.) Finally, the engineers also know that IF the yielded head bolts are used a second time, they will be stretched beyond their designed length and will not produce the same clamping force. This could cause the head gaskets to fail, so the engineers specify that the head bolts are not to be reused - and I’m guessin’ they probably mean it...

AJxtcman
07-20-07, 07:59 AM
FYI - The Torque-to-Angle procedure can produce a yield (permanent stretch) in the head bolts, if the specified angle is high enough. They can be one in the same; Torque-to-Angle and Torque-to-Yield. The engineers who designed the engine know the specific characteristics of this head bolt. They know that if the bolt is torqued to the 30 lb-ft specification, all the slack will be taken out of the head-block joint. They also know that if the bolt is then turned 190 degrees total, it will be yielded (stretched) a known amount. This will produce a known maximum clamping force by the bolt. (Torque-Angle is a somewhat crude “service” procedure to simulate a much more sophisticated process used in production. The production process is computer controlled and will achieve exactly the same yield in every bolt. The Torque-Angle service procedure comes close, but is not as accurate as the computer-controlled production process.) Finally, the engineers also know that IF the yielded head bolts are used a second time, they will be stretched beyond their designed length and will not produce the same clamping force. This could cause the head gaskets to fail, so the engineers specify that the head bolts are not to be reused - and I’m guessin’ they probably mean it...

I see that you have some information about bolts. If the bolts stretched to the point that they should not be reused. Why do the main bolts get reused and why do they break, but the head bolts don't. On a 3.6L main bolts you need to replace 16 bolts and reuse 8. After you get the 16 bolts you then will realize that the reason you are replacing 8 of then (they have sealer on them) the new bolts have no sealer on them. This would mean you just need to replace 8 and reuse 16. On the Northstar the rod bolts stretch and you know it. The fact is the bolts can be reused! The technical Information states they need to be replaced because of the thread sealer. I have the Northstar Mechanical system training manual in front of me and it show that they can be reused.
I have never reused them, but I have only bought one set. The customer is not given the option because we only sell kits.