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Finally a question that has nothing to do with fuel...
My B18 had an original AC. The AC unit was long removed, but the original owner left the pulley and bracket bolted to the head. JoeJump needs a pulley setup for his PV's AC, so as part of a trade, I decided to remove mine - after all, my cheapo FPR has been banging into it for over a year now.
Wait... this does have something to do with fuel... kinda...
So... I removed the two headbolts, but first I use my torque wrench to check the present headbolt torque. Both came in at 110-120 lbs-ft. So, after I removed the bracket and replaced the bolts (with appropriately shorter ones), I torqued them back to 110-120 lb-ft.
I grabbed my haynes manual later in the evening and check the spec. According to Haynes, the head should be torqued to 61-69 lb-ft. Is that correct?!??! That's way below where they started. Am I at any particular risk with the torque so high? I dont; want to loosen them for fear of blowing my head gasket. I'm already a bit concerned about that, but this engine will soon come out...
Incidently, here's a pic of the bracket for those of you who have been wondering...
--
1967 P220 (My every-other-daily driver...), 1971 P1800 (The Parts Car), 1972 145S (1993-1997), 1977 245 DL (1993-1999), 1983 245 (1998-2001), 1986 745 GLE (1997-2005), 1990 745 GL (2003-4), 1995 945 (2005-Present)....
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The manuals I have (several of them) say torque them to 29 ft-lb,
then to 58 ft-lb and finally to 65 ft-lb.
Breakout torques (in EITHER direction) will always be higher than the
original torque unless the bolt has worked loose or stretched somehow.
Among other things, the lube will gradually dissipate and you'll lose
the lubrication and get intimate metal/metal contact. Both of these
make the bond that gives you the "crack" sound when you break them loose.
When I put in headbolts or maincap bolts, I run a tap in the hole to make
SURE it is clean and not gritty, and then I put a little chassis grease
on the threads and on the clamping surface of the head. That way as much
as possible of the torque goes toward actually advancing the threads so you
get the maximum amount of tension in the bolt for the applied torque.
--
George Downs Bartlesville, Heart of the USA!
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George,amen to that!
I would loosen every thing gradually,clean somehow,
one at a time,with the head on,and retorque properly.
Gaskets are cheaper than heads,I would want to know
where I stand as a system. Does your manual show
order of tightening?
Ken
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White 86-245 DL, M 46, IPD bars & Wagon Overloads,Commando Bumpers,SS Belly Pan & Air Pickup,Straight-Shot EMT Chassis & Tower Braces,Scorpius Alloys,2 Belt No AC Conversion,Black POR-15 No Glare Front End
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Sure. They are all the same (B16, B18, B20 and B30, anyway)
I'm not sure the direction is important but you start with the two bolts
nearest the center and then alternate front and back in a spiral pattern
till you get them all. Then go over in the same order at the next torque
level, etc. I usually go around twice at the highest level and sometimes
I get some more takeup which I conclude is gasket compression.
I've noted with the headbolt-mounted idler bracket that the bolt heads
are usually 5/8" where the OEM headbolts are normally 11/16", which gives
a bit larger clamping surface engagement. Also the OEM bolts are usually
necked down in the center, which is also a good deal since otherwise
the highest stress is at the root of the first engaged thread.
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George Downs Bartlesville, Heart of the USA!
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Determining torque by undoing bolts with a torque wrench is meaningless, just torque them up to the Volvo setting. The headgasket are pretty much bullet proof since 4everything is cast iron.
Pete
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I didn't unbolt with the torque wrench. That'd screw it up pretty fast. I used the torque wrench to apply ever-so-slightly more torque. I noted where I felt the bolt move (120 lb-ft). Then I removed the bolt using a much stronger breaker bar. and re-torqued the bolts to bit below the initial torque setting (~110 lb-ft).
I realize that unlike an aluminum B230 head, the B18 is almost bullet-proof, but if spec is really 61-69 lb-ft, then these bolts were way over-torqued.
--
1967 P220 (My every-other-daily driver...), 1971 P1800 (The Parts Car), 1972 145S (1993-1997), 1977 245 DL (1993-1999), 1983 245 (1998-2001), 1986 745 GLE (1997-2005), 1990 745 GL (2003-4), 1995 945 (2005-Present)....
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Guys;
Headbolt torque spec is for OILED BOLTS, to minimize stiction and allow a smooth approach to the specified torque...that breakaway torque (in both directions) will be much higher once the oil has cooked away should be pretty obvious...
BTW...what would be "screwed up pretty fast", when removing with a torque gauge???
Cheers
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oily huh... heck. It was still rather oily down the bolt hole so maybe I'm ok. Anyway, There's a new engine in the works and I already have a replacement head gasket on hand, just in case I screwed it up seriously. This is the price I pay for choosing humanistic and biological sciences for my degrees.
Anyway, what I meant about the screwing up the torque gauge is that all the mechanics guides I've read warn about *never* using a torque wrench to break a bolt free. It's supposed to screw them up in some unspecified way. I imagine it would affect tension and reduce accurracy.
So.. the torque should be as listed in the Haynes manual?
--
1967 P220 (My every-other-daily driver...), 1971 P1800 (The Parts Car), 1972 145S (1993-1997), 1977 245 DL (1993-1999), 1983 245 (1998-2001), 1986 745 GLE (1997-2005), 1990 745 GL (2003-4), 1995 945 (2005-Present)....
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posted by
someone claiming to be src
on
Sun Oct 29 09:00 CST 2006 [ RELATED]
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Yep. 61-69ft lbs is correct. I'd be apprehensive of relieving pressure on the gasket too, but in reality there probably isn't going to be much expansion between the two values.
And I knew what you menat by checking the prior torque setting, I do it myself.
Good luck -Sean
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