Help!!! 3.8 Torque Specs
Hotshot
Joined: Aug 2002
Posts: 12,679
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From: BC, Canada
CAUTION: Always use new cylinder head bolts to ensure a leak-tight assembly. Torque retention with used bolts can vary, which may result in coolant or compression leakage at the cylinder head mating surface area.
For 3.8L engine, tighten cylinder head retaining bolts in sequence as follows:
Tighten long and short bolts to 50 Nm (37 lb-ft).
CAUTION: Do not loosen all of the bolts at the same time, only work on one bolt at a time.
Back off all bolts one at a time two to three revolutions.
Tighten in numerical sequence:
Long bolts to 15-25 Nm (11-18 lb-ft). Short bolts to 10-20 Nm (7-15 lb-ft).
Rotate an additional 85-95 degrees.
Go to next bolt in sequence.
For 3.8L engine, tighten cylinder head retaining bolts in sequence as follows:
Tighten long and short bolts to 50 Nm (37 lb-ft).
CAUTION: Do not loosen all of the bolts at the same time, only work on one bolt at a time.
Back off all bolts one at a time two to three revolutions.
Tighten in numerical sequence:
Long bolts to 15-25 Nm (11-18 lb-ft). Short bolts to 10-20 Nm (7-15 lb-ft).
Rotate an additional 85-95 degrees.
Go to next bolt in sequence.
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
37 lb-ft is only the initial torque setting. That gets the head sitting flat on the block then the bolts get backed off and retorqued to a lower value and then the bolts are turned an additional 90 degrees.
Lots of newer engines use "torque to yield" bolts and that's how they are tightened. The bolts stretch more than normal bolts.
Another example is a 4.6 or 5.4 in an F-150. The instructions for tightening the head bolts are.........
Stage 1: Tighten to 40 Nm (30 lb-ft).
Stage 2: Tighten an additional 90 degrees.
Stage 3: Tighten an additional 90 degrees.
Lots of newer engines use "torque to yield" bolts and that's how they are tightened. The bolts stretch more than normal bolts.
Another example is a 4.6 or 5.4 in an F-150. The instructions for tightening the head bolts are.........
Stage 1: Tighten to 40 Nm (30 lb-ft).
Stage 2: Tighten an additional 90 degrees.
Stage 3: Tighten an additional 90 degrees.
Postmaster
Joined: Apr 2001
Posts: 3,818
Likes: 3
Racerguy Please Reply
Same situation as original post, 3.8L engine using TTY bolts. First time experience with these and using same torquing format. My problem is the two long, outer bolts will not torque down to the proper setting. I ran the inital four torque settings, then was to loosen (one at a time) each bolt 2-3 turns then re-torque to 85 ft lbs. The outside bolts would only torque to 80# (using beam scale torque wrench). After two full turns the bolt snapped without ever being torqued beyond 80#.
Even stranger, when the head was pulled back off, I could unscrew that broken bolt with my fingers! (The original bolts required a 24" breaker bar to crack them loose.) The inner head bolts and the lower (shorter) bolts all take torque just fine but the two outside long bolts will not torque beyond 80#. Repeated this with new gasket and bolt set with same results - only left the outer bolts at 80#.
Your comments or experiences appreciated.
Even stranger, when the head was pulled back off, I could unscrew that broken bolt with my fingers! (The original bolts required a 24" breaker bar to crack them loose.) The inner head bolts and the lower (shorter) bolts all take torque just fine but the two outside long bolts will not torque beyond 80#. Repeated this with new gasket and bolt set with same results - only left the outer bolts at 80#.
Your comments or experiences appreciated.
Last edited by aerocolorado; Aug 30, 2004 at 11:21 AM.
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Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
Were you using new bolts? The TTY bolts need to be replaced. They can't be reused.
Is your torque wrench accurate?
Is your torque wrench accurate?
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Postmaster
Joined: Apr 2001
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Yes to both. (second set of bolts were new also). This realy bugs me. After breaking the bolt and removing the head again, all the bolts that "took the torque" made the familiar "snap" sound when they first released. I notice your initial instructions are to set the first four torques, loosen, re-torque to 37 fl lbs, then rotate the bolt 85-95 degrees, not ft. lbs. as stated in the Chiltons manual I have been using. Is there a typo error in one of these descriptions?
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
You didnt say what you're working on so I just picked a 95 Windstar in the manual. It says.............
NOTE: When cylinder head retaining bolts have been tightened using the following procedure, it is not necessary to retighten bolts after extended engine operation. However, bolts can be checked for tightness if desired.
Tighten left cylinder head bolts in sequence as follows: Stage No.1: 20 Nm (15 lb-ft). Stage No. 2: 40 Nm (29 lb-ft). Stage No. 3: 50 Nm (37 lb-ft).
CAUTION: Do not loosen all of the bolts at same time. Only work on one bolt at a time or damage to engine or leakage may occur.
In sequence, loosen bolts two to three revolutions and retighten bolts one at a time in the following manner: Long bolts: 25 Nm (18 lb-ft). Tighten bolt an additional 90 degrees. Go to next bolt in sequence. Short bolts: 20 Nm (15 lb-ft). Tighten bolt an additional 90 degrees. Go to next bolt in sequence.
NOTE: When cylinder head retaining bolts have been tightened using the following procedure, it is not necessary to retighten bolts after extended engine operation. However, bolts can be checked for tightness if desired.
Tighten left cylinder head bolts in sequence as follows: Stage No.1: 20 Nm (15 lb-ft). Stage No. 2: 40 Nm (29 lb-ft). Stage No. 3: 50 Nm (37 lb-ft).
CAUTION: Do not loosen all of the bolts at same time. Only work on one bolt at a time or damage to engine or leakage may occur.
In sequence, loosen bolts two to three revolutions and retighten bolts one at a time in the following manner: Long bolts: 25 Nm (18 lb-ft). Tighten bolt an additional 90 degrees. Go to next bolt in sequence. Short bolts: 20 Nm (15 lb-ft). Tighten bolt an additional 90 degrees. Go to next bolt in sequence.
Postmaster
Joined: Apr 2001
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This is a '92 Taurus with the 3.8L engine. I note in Chilton's the later model ('93 and above) use a slightly modified format but essentially the same steps. I think there is a misprint in Chiltons since it calls for ft. lbs. and not degrees. However, in either case, those outside bolts never did acquire that "feel" that bolts do when setting torque. These are nearly 3/8" bolts and to have one break that easily was surprising to say the least. I'll never again complain about workspace in an Aerostar. The rearmost cylinder head on the Taurus is humanly impossible to remove without dropping the powertrain cradle.
Thanks for the help.
Thanks for the help.
Postmaster
Joined: Apr 2001
Posts: 3,818
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If there are worse jobs, then my idle daydreams of being a mechanic have suffered a rude awakening. You guys deserve combat pay for those jobs.
Yes, with a new gasket and bolts everything was buttoned up last night and it started right up, the most satisfying moment of a major repair. In fact, I was savoring the moment, allowing the engine to run a few minutes to check for leaks, when my daughter, the Taurus driver, wandered into the garage. "How's it going dad?" "Fine", I answered. "Fine?, Are you crazy dad, the car's on fire!" The spilled PS fluid and PB Blaster on those exhaust manifolds raised an impressive smoke signal for those few minutes until it burned off.
Everything seems okay so far. I will admit that when rereading the Chilton manual in a teeny, tiny superscript next to the 85 was the symbol for degrees, so the error was mine and not Chiltons. Another humbling experience for Walter Mitty the Mechanic.
Yes, with a new gasket and bolts everything was buttoned up last night and it started right up, the most satisfying moment of a major repair. In fact, I was savoring the moment, allowing the engine to run a few minutes to check for leaks, when my daughter, the Taurus driver, wandered into the garage. "How's it going dad?" "Fine", I answered. "Fine?, Are you crazy dad, the car's on fire!" The spilled PS fluid and PB Blaster on those exhaust manifolds raised an impressive smoke signal for those few minutes until it burned off.
Everything seems okay so far. I will admit that when rereading the Chilton manual in a teeny, tiny superscript next to the 85 was the symbol for degrees, so the error was mine and not Chiltons. Another humbling experience for Walter Mitty the Mechanic.
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
Good to hear that you got it done 
If you ever decide that you want to be a mechanic just go hang out at a Ford shop or at www.flatratetech.com
You'll change your mind
If you ever decide that you want to be a mechanic just go hang out at a Ford shop or at www.flatratetech.com
You'll change your mind