Recent Topics
vibrating 330 polaris.l
by Chris142
04/24/14 09:56 PM
4.2 liter F150 starts then dies
by 97f150
04/24/14 09:48 PM
E-mail reply from Mills on CCW policy
by The_Eric
04/24/14 09:05 PM
Laptop brand, any suggestions?
by Rat407
04/24/14 08:05 PM
Oz Natural Gas prices.
by Shannow
04/24/14 07:53 PM
R.I.P Rich Hayward
by JR
04/24/14 07:36 PM
Volvo 5.7 2008 Main rear seal leak :(
by Yannick
04/24/14 07:30 PM
Short OCI for tow
by Camprunner
04/24/14 07:21 PM
sludge 2005 pontiac vibe lk toyota corolla matrix
by kwikrnu
04/24/14 06:43 PM
Blain's Farm & Fleet 4/24-5/4/14
by BrewCityR
04/24/14 06:12 PM
2,530 yard shot with Savage 110BA .338LM
by OVERKILL
04/24/14 05:01 PM
Fram Air Hog - what happened to them?
by copcarguy
04/24/14 04:07 PM
Newest Members
Rage2010, FenderGuy53, chevlvr, ashnlopez, venki
49688 Registered Users
Who's Online
107 registered (01rangerxl, 2stroker, 901Memphis, 97f150, 74DartSport, 2004tdigls, 8 invisible), 1625 Guests and 183 Spiders online.
Key: Admin, Global Mod, Mod
Forum Stats
49688 Members
64 Forums
212374 Topics
3329511 Posts

Max Online: 2651 @ 04/21/14 04:38 PM
Donate to BITOG

Page 1 of 2 1 2 >
Topic Options
#2744543 - 09/15/12 12:30 PM Torque to yield cylinder head bolts
Bobo23 Offline


Registered: 09/14/12
Posts: 9
Loc: SW Washington
Re: GM 3.4L V-6 with cast iron block and aluminum heads; new Fel-Pro PermaTorque head gasket & new Fel-Pro head bolts.

I had failed head gaskets on both heads of a 1998 Chevy Venture ( #1 & #2 cylinders). Upon installing the back head (the worst one to access) I torqued all 8 bolts to the updated 44 lb-ft and the 95 degree torque angle with the new torque sequence. I believed that I did it correctly but then after lunch just for "fun" I went back over the head bolts with my beam-style torque wrench to confirm that all the bolts didn't turn before the 44 lb-ft. One bolt (lower passenger-side corner of back head; coincidentally the end where the old gasket had failed. This bolt threads into the alignment dowel) turned before the beam torque wrench even got to the 44 lb-ft. I swear I torqued it properly in sequence and although it was a PITA to do, I felt that I also did the 95degrees pretty accurately on this bolt.

Question 1) So why would this one bolt turn at less than the initial torque? Has anyone had this problem before? I understand that these bolts undergo plastic deformation during the 95degree final torque, so given that, I am reluctant to re-tighten this one bolt to the 44 lb-ft and re-do the
95 degrees possibly stripping the bolt or block threads (alignment dowel threads). I am reluctant to buy a new set of bolts and redo the whole head and gasket especially because I believe I did it "by the book" this first time. Perhaps I could just tighten it to 65-75?? lb-ft (the old torque specs on this engines "pre-torque angle" predecessor) or . . . .

Question 2) The bigger question is HOW TO CONFIRM that torque-to-yield bolts are "tight enough"? In the old days of plain torque one could go back over the bolts and make sure they don't turn below the spec torque. But with torque angle--how does one check tightness?

Question 3) I am sure some engineer's handbook somewhere has torque (lb-ft or Nm) to torque angle "conversion" for these bolts with chased, clean, oiled threads, so where is it posted on the internet?

Top
#2744578 - 09/15/12 01:07 PM Re: Torque to yield cylinder head bolts [Re: Bobo23]
jkhawaii Offline


Registered: 06/03/05
Posts: 442
Loc: Oahu
about as tight as you can tighten the bolt by hand with an average 1/2 ratchet is usually about the same as torque + deg. So, if the bolt is turning before 44ft lbs, you ether forgot that one, something is wrong with the threads or bolt, something is posibly in the bolt hole (do not remember if any of those holes had sealed threads, if coolant is in a closed thread area the bolt will not tighten all the way down)
_________________________
Previous vehicle 2008 Pontiac G5 OLM and factory oil's mostly.
Currently 2013 GMC Terrain 2.4L FWD.
2012 Piaggio Fly 50 4T 4V. 2013 Honda PCX 150

Top
#2744583 - 09/15/12 01:11 PM Re: Torque to yield cylinder head bolts [Re: Bobo23]
Quest Offline


Registered: 12/19/04
Posts: 6082
Loc: beaver land EH?
regardless of torque-to-yield or conventional torque head bolts, there are steps/procedures that have to rigidly follows:

(1) find out exactly if the head bolts to be lubricated (lightly) or torqued dry.

(2) make sure that the threads on your block is clean and been chased with thread chaser (repeatedly) until it's absolutely clean. If, for whatever reasons, your block threads are contaminated by motor oil or coolant, make sure you spray them with solvent (after chasing/cleaning) and then blow dry with compressed air before you proceed.

(3) make sure your block and head surface is true. No use trying to install a fresh new head gasket (only to blow it again in very short service time) if either the block or the head is warped.

(4) find out how manufacturers want you to install the head bolts. It's mainly either spiralling from the inner-most bolt outwards, or criss-cross style.

(5) torque your head bolts following the manufacturer's pattern in small incriments. I do so by divvying it up to 1/3: for 75ft/lbs final torque, I do 25ft/lbs first too all the bolts in proper patterns, then 50ft/lbs, then finally, 75ft/lbs.

(6) go back and re-check all torque-to-yield's head bolt torque to be proper before you go through the final step of cranking it per degree angle.


There, you're done.

Q.

Last but not least: for clicker type torque wrench, it's best if you can have them calibrated by a shop or against a known, good beam type torque wrench before you start your head bolt job.
_________________________
"Internet discussion boards act as echo chambers for conspiracy dittoheads" A.Allen

Top
#2744616 - 09/15/12 01:46 PM Re: Torque to yield cylinder head bolts [Re: Quest]
Bobo23 Offline


Registered: 09/14/12
Posts: 9
Loc: SW Washington
Thanks all. I don't believe I forgot that bolt initially but that is the nature of mistakes. I did have the aluminum heads resurfaced but not the cast iron block. I chased the threads and the bolt screwed in smoothly. I cleaned all the antifreeze out of the blind hole so the hole was clean and dry to full depth, and the bolts were oiled as per instructions on the threads and under the bolt head. GM changed the tightening sequence from spiral to old-style criss-cross & I used the updated sequence. I will probably tighten it down as suggested which would be about 65-70 lb-ft, after all the whole big picture idea is to clamp the head down so that the gasket doesn't leak, and try not to worry too much about it.
Quest, I wish I had done your #6 of rechecking the torque BEFORE the angle tightening; good suggestion.

Top
#2744622 - 09/15/12 01:50 PM Re: Torque to yield cylinder head bolts [Re: Bobo23]
gassipper Offline


Registered: 04/30/12
Posts: 17
Loc: Detroit, MI
I had that happen to me on one bolt for whatever reason when I was tightening the cam tower bolts on my GM 2.4L LD9 (the engine is notorious for the bolts coming loose for whatever reason). The spec calls for so much torque plaus another 90 degrees or whatever. I was using a GearWrench electronic torque with angle wrench (recently calibrated from the factory) and all the other bolts torqued fine. I didn't try to rush it and followed the process to a tee but the one gave way. Maybe it was like the one poster mentioned about some [censored] in the threads, etc. Maybe it was a dud bolt. I was lucky I had spares. smile The spare torqued fine. (shrugging shoulders)


Edited by gassipper (09/15/12 01:52 PM)

Top
#2746461 - 09/17/12 12:47 PM Re: Torque to yield cylinder head bolts [Re: Bobo23]
mechtech2 Offline


Registered: 09/05/06
Posts: 19479
Loc: Chicago Area
Can you buy just one bolt?
Then start from scratch on that hole.
We don't know if it is stripped, or you did not tighten it before.
Maybe it's defective and stretched wrong [unlikely].

Top
#2746760 - 09/17/12 06:08 PM Re: Torque to yield cylinder head bolts [Re: Bobo23]
Kestas Offline



Registered: 06/04/02
Posts: 10721
Loc: The Motor City
It's easy to lose track of which bolts were torqued down, especially if you got distracted. Some people use a dab of paint on the head bolt to show that step was done.

Top
#2746783 - 09/17/12 06:36 PM Re: Torque to yield cylinder head bolts [Re: Kestas]
bdcardinal Online   content


Registered: 06/03/05
Posts: 6090
Loc: Santa Barbara, CA
Originally Posted By: Kestas
It's easy to lose track of which bolts were torqued down, especially if you got distracted. Some people use a dab of paint on the head bolt to show that step was done.


That is what I do on any bolt like that. Nice thing about ARP studs is there is no TTY spec, just go in stages using real ft-lb measurements.
_________________________
2014 Ford Mustang GT Track Pack
1995 Ford Mustang GT

Ford/Mazda Parts Guru

NRA Life Member

"Fear disturbs your concentration."
-Sabine Schmitz

Top
#2747761 - 09/18/12 07:29 PM Re: Torque to yield cylinder head bolts [Re: Bobo23]
mechtech2 Offline


Registered: 09/05/06
Posts: 19479
Loc: Chicago Area
If I have to pea ,sneeze, answer a phone call, or whatever, I wait until a torque sequence it done.

Top
#2747948 - 09/18/12 10:13 PM Re: Torque to yield cylinder head bolts [Re: mechtech2]
artificialist Online   content


Registered: 09/23/07
Posts: 5982
Loc: Florida
Originally Posted By: mechtech2
If I have to pea ,sneeze, answer a phone call, or whatever, I wait until a torque sequence it done.

I do too.

And even though I do that, I still put ink marks on each bolt to indicate what stage it has been torqued to.
_________________________
2010 Lancer Ralliart Sportback

Top
#2747981 - 09/18/12 11:22 PM Re: Torque to yield cylinder head bolts [Re: Bobo23]
Bobo23 Offline


Registered: 09/14/12
Posts: 9
Loc: SW Washington
I came back to this project a day later and noticed that all the bolts turned a little at less than the 44 lb-ft (which was the initial torque before the angle torque)so I guess that the bolts "relax" or the gasket compresses over time (?) I guess that GM & Fel-Pro know what they are doing and are aware of such relaxation (or whatever) and that it is all part of their plan (I hope). I will be torquing down the front head soon and you can bet I will double check everything. The front head is so much accessible to work on. I hope for no more blown intake or head gaskets. Thanks everyone.

Top
#2748563 - 09/19/12 05:13 PM Re: Torque to yield cylinder head bolts [Re: Bobo23]
mechtech2 Offline


Registered: 09/05/06
Posts: 19479
Loc: Chicago Area
Those bolts are like springs - measuring torque later is not valid.

Top
#2748662 - 09/19/12 06:33 PM Re: Torque to yield cylinder head bolts [Re: Bobo23]
bdcardinal Online   content


Registered: 06/03/05
Posts: 6090
Loc: Santa Barbara, CA
Something interesting about torquing bolts, ARP wants you to use a stretch gauge on rod bolts. Its pretty much a dial indicator and you tighten the bolt until the desired stretch is reached. It was weird at first, but pretty cool when I used it.
_________________________
2014 Ford Mustang GT Track Pack
1995 Ford Mustang GT

Ford/Mazda Parts Guru

NRA Life Member

"Fear disturbs your concentration."
-Sabine Schmitz

Top
#2750875 - 09/21/12 07:07 PM Follow-up [Re: Bobo23]
Bobo23 Offline


Registered: 09/14/12
Posts: 9
Loc: SW Washington
First, thanks everyone. Mechtech I am still trying to wrap my head (pun intended) around bolts as springs but I sort of understand. On second thought I don't believe these bolts are "torque-to-yield" bolts since the factory service manual (which I have) instructs one to clean the bolts as part of the cylinder head remove and replace procedure. If they were torque to yield, which I originally thought they were, they must be replaced as I understand it. So I "untorqued" the rear head and with the help of my 17-year old we painstakenly retorqued it; I feel we did a great job of it this second time. The problem I believe was me not used to using the Lisle Torque Angle Meter #28100 and a difficult to access location--the rear cyl. head under the cowling; I believe the dial was turning some instead of staying fixed the first time I tried angle-torquing the head. The engine was not run so hopefully the head gasket won't mind being untorqued/retorqued. We did the front head easily because it was very accessable. Again, thanks everyone.

Top
#2750922 - 09/21/12 07:34 PM Re: Follow-up [Re: Bobo23]
Shannow Online   content


Registered: 12/12/02
Posts: 25369
Loc: a prison island
We had a big discussion on TTY some time back.

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2016507&page=1

You can re-use them, and if you are going to "check" tighten them, back them off and go through the process again...can do that a couple of times usually.

Top
Page 1 of 2 1 2 >