Head bolt torque
09-20-2013, 05:58 AM
#1
Head bolt torque
I have lost the only copy I had of the fsm due to hard drive crash and unfortunately I am mid rebuild on my 3.4.
Googling the torque specs I see some conflicting info. I have torqued my bolts down to 25ft/lbs then +90 degrees. I came across 25ft/lbs +90 then +90.
Any idea which is correct?
Googling the torque specs I see some conflicting info. I have torqued my bolts down to 25ft/lbs then +90 degrees. I came across 25ft/lbs +90 then +90.
Any idea which is correct?
09-20-2013, 08:21 AM
#2
Cylinder head x Cylinder block
12 pointed head
1st 25
2nd Turn 90°
3rd Turn 90°
Recessed head
12 pointed head
1st 25
2nd Turn 90°
3rd Turn 90°
Recessed head
1st 13
2nd Turn 90°
3rd Turn 90°
2nd Turn 90°
3rd Turn 90°
09-20-2013, 09:29 AM
#3
Crap, so now I have to remove the camshafts and turn the bolts another 90 degrees. Thats going to be damn near impossible. Thats some serious torque and I dont remember them being that hard to remove.
09-20-2013, 09:39 AM
#4
The head bolts used in this engine are designed to stretch and deform slightly. They should be carefully inspected. New service replacement head bolts are strongly recommended.
Place two new cylinder head gaskets in position on the cylinder block.
Place the two cylinder heads on the dowels of the cylinder block.
Apply a light coat of engine oil on the threads and under the heads of the cylinder head bolts.
Install and uniformly tighten the cylinder head bolts on each cylinder as follows:
In several passes and in the sequence shown, tighten the cylinder bolts to 25 ft. lbs. (34 Nm).
Mark the front of the cylinder head bolt with paint.
Retighten the cylinder head bolts by 90°, in order of sequence.
Check that the painted mark is now at a 90°-angle to the front.
Apply a light coat of engine oil on the threads and under the heads of the recessed cylinder head bolts. Using a 8mm hexagon wrench, install the cylinder head bolt on each cylinder head, then repeat for the other side. Tighten the bolts to 13 ft. lbs. (18 Nm).
Install the valve lifters and shims. Check that the valve lifter rotates smoothly by hand.
Place two new cylinder head gaskets in position on the cylinder block.
Place the two cylinder heads on the dowels of the cylinder block.
Apply a light coat of engine oil on the threads and under the heads of the cylinder head bolts.
Install and uniformly tighten the cylinder head bolts on each cylinder as follows:
In several passes and in the sequence shown, tighten the cylinder bolts to 25 ft. lbs. (34 Nm).
Mark the front of the cylinder head bolt with paint.
Retighten the cylinder head bolts by 90°, in order of sequence.
Check that the painted mark is now at a 90°-angle to the front.
Apply a light coat of engine oil on the threads and under the heads of the recessed cylinder head bolts. Using a 8mm hexagon wrench, install the cylinder head bolt on each cylinder head, then repeat for the other side. Tighten the bolts to 13 ft. lbs. (18 Nm).
Install the valve lifters and shims. Check that the valve lifter rotates smoothly by hand.
I honestly do not think I could turn the bolts another 90 degrees. 20 - 30 maybe.
09-20-2013, 09:49 AM
#5
It's similar on a 3VZ-E, 33 ft-lbs + 90° + 90°. So they're probably even tighter. I used a torque wrench for the last 90° on some of mine. It ended up about 115 ft-lbs average, + or - a couple ft-lbs. So yeah, it's some pretty serious torque.
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09-20-2013, 06:30 PM
#9
I wouldn't leave them like that. But that's just me.
B. Install 12 pointed head cylinder head bolts
HINT:
• The cylinder head bolts are tightened in 3 progressive
steps (steps (b), (d) and (e)). •
• If any bolt is broken or deformed, replace it.
(a) Apply a light coat of engine oil on the threads and
under the heads of the cylinder head bolts.
(b) Install and uniformly tighten the cylinder head bolts
on each cylinder head, in several passes, in the sequence
shown, then repeat for the other side, as
shown.
Torque: 34 N·m (350 kgf·cm, 25 ft·lbf)
If any of the cylinder head bolts does not meet the torque specification, replace the cylinder head bolt.
HINT:
• The cylinder head bolts are tightened in 3 progressive
steps (steps (b), (d) and (e)). •
• If any bolt is broken or deformed, replace it.
(a) Apply a light coat of engine oil on the threads and
under the heads of the cylinder head bolts.
(b) Install and uniformly tighten the cylinder head bolts
on each cylinder head, in several passes, in the sequence
shown, then repeat for the other side, as
shown.
Torque: 34 N·m (350 kgf·cm, 25 ft·lbf)
If any of the cylinder head bolts does not meet the torque specification, replace the cylinder head bolt.
09-20-2013, 07:23 PM
#10
Registered User
Just checking, but are you putting in NEW bolts? Because those torque specs are not intended to be used for old bolts, which you are not supposed to use at all. If those extra 90° turns are made on old bolts that have already been torqued to yield, you are trying to stretch something that is already stretched and it will be very hard to make it stretch any more. Something, probably the re-used bolt, will fail due to excessive longitudinal stress.
Last edited by TheDurk; 09-20-2013 at 07:24 PM.
09-21-2013, 04:24 AM
#11
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Difference between the 12pt and the recessed? I assume the 12pt is the star looking head, and recessed is if regular 6 pt bolts are recessed into the head?
Is there a model year break for the different bolts?
Is there a model year break for the different bolts?
07-27-2015, 04:01 PM
#14
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Is the socket a 12mm or 14mm. I got a regular 12mm 12pt on the bolt, but I wanna use the right star socket for the job. Every reference I can find says 14mm, and the nissan is a 12mm. I'm not wanting to buy a socket i will never use.
Is this the one I should be buying?
Is this the one I should be buying?
07-30-2015, 11:51 AM
#15
Yams
I just used a quality 1/2" drive 12 point socket out of the set, I don't think you need a special socket.
Clean, clean, clean everything when going together. Clean out the tapped hole the bolts are going into, put a little oil on the bolt, but DO NOT let any of that oil get on the head gaskets.
Put a drop of oil under the heads of the bolts as it said above. Follow the tightening pattern to a T and try not to get distracted while doing it. You might skip a bolt!
Follow FSM torque specs, the 90+90 degrees seems like a lot but that works ! After initial torquing, mark a line on each bolt with a silver sharpie, this way you can do the 90 degrees + 90 degrees and watch the lines to be assured you did not miss one. I had someone come in the garage and bother me while I was doing this, if all the bolts had not been marked, I would have not known where I left off !
This all helps getting all the bolts torqued uniformly.
I was SUPER careful about all these details and did my head gasket job in ONE shot. My buddy who just kind of slops things together carelessly did his three times to get it right and couldn't figure out why.
I just used a quality 1/2" drive 12 point socket out of the set, I don't think you need a special socket.
Clean, clean, clean everything when going together. Clean out the tapped hole the bolts are going into, put a little oil on the bolt, but DO NOT let any of that oil get on the head gaskets.
Put a drop of oil under the heads of the bolts as it said above. Follow the tightening pattern to a T and try not to get distracted while doing it. You might skip a bolt!
Follow FSM torque specs, the 90+90 degrees seems like a lot but that works ! After initial torquing, mark a line on each bolt with a silver sharpie, this way you can do the 90 degrees + 90 degrees and watch the lines to be assured you did not miss one. I had someone come in the garage and bother me while I was doing this, if all the bolts had not been marked, I would have not known where I left off !
This all helps getting all the bolts torqued uniformly.
I was SUPER careful about all these details and did my head gasket job in ONE shot. My buddy who just kind of slops things together carelessly did his three times to get it right and couldn't figure out why.
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