Why head bolts torque are different from 2003 and 2005 1.8 nissan sentra?

Question edited for clarity.

Nissan Note E11 EM.pdf

Academia.edu https://www.academia.edu > Nissan_Note_E11_EM_pdf
Remove cylinder head assembly. J INSTALLATION ? Install in the reverse order of removal paying attention to the following. Cylinder Head Bolts K NOTE: Use ...

Nissan CR14DE (1.4 L) engine

Engine Specs https://www.engine-specs.net > nissan

Step 1: 24.5-30.3 Nm; 2.5-3.0 kg·m; 18-22 ft·lb; Step 2: Turn all bolts 95-100°. After securing bearing cap bolts, make sure crankshaft turns smoothly by hand.
Pros and cons: Rough idle ? Loss of power ? View full list

Nissan HR15DE (1.5 L) engine - Engine Specs

Engine Specs https://www.engine-specs.net > nissan

Cylinder head · Step 1: 40 Nm; 4.1 kg·m; 30 ft·lb · Step 2: Turn all bolts 60° · Step 3: Loosen all bolts completely · Step 4: 40 Nm; 4.1 kg·m; 30 ft·lb · Step 5: ...
Pros and cons: Enhanced control and reduced system friction improve response ? High power output ? View full list

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Question edited for clarity.
Question moved to model category.

All here for the three engine types

https://www.autozone.com/diy/repair-guides/nissan-frontier-xterra-1998-05-torque-specifications-repair-guide-p-0996b43f8037fa5c

https://www.google.com/search?q=2004+Nissan+Xterra.+cylinder+head+bolt+sequence+and+torque+specs

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That 5th step is also 100 degree turn. This for 08 2.0L, note the engine code or what ever that is? If that mr2ode is correct, I'll see what I can find for crank and rod bolts.

Big difference between valve cover gasket and head gasket. To replace head gasket, you must dissamble top end of engine and send the head out to be resurfaced and then install new head gasket. If it is a leaking valve cover it is much easier. Simply dissasemble and then clean valve cover and top of head from all debris and remove all old gasket material. Tighten back down in sequence and do not over tighten. these small bolts can be overtightened easily so go in sequence just like when you tighten lug nuts by skipping one as you go around. 10mm bolts require about 10 pounds or less torque.

1.8L 4 cylinder

cylinder head bolt torque

bolts 1-10 ( large bolts )

step 1 21 ft lbs.
step 2 44 ft lbs.
step 3 loosen all bolts
step 4 21 ft lbs.
step 5 additional 50-55 degrees

bolts 11-15 small bolts

56-74 in. lbs

2.0L 4 cylinder

step 1 29 ft lbs.
step 2 58 ft lbs.
step 3 loosen all bolts
step 4 23-25 ft lbs.
step 5 additional 90-95 degrees
step 6 additional 90-95 degrees

1. For 1.8L engines, tighten the bolts in sequence, as follows:
   1. Step 1: Bolts 1-10 to 22 ft. lbs. (29 Nm).
   2. Step 2: Bolts 1-10 to 43 ft. lbs. (59 Nm).
   3. Step 3: Loosen bolts 1-10 completely.
   4. Step 4: Bolts 1-10 to 22 ft. lbs. (29 Nm).
   5. Step 5: Bolts 1-10 plus 50-55 degrees.
   6. Step 5: Bolts 11-14 to 74 inch lbs. (8 Nm).
      
      Fig. Cylinder head torque sequence-1.8L engine
      
      
      Fig. Tighten the valve cover bolts in sequence-1.6L and 1.8L engines
      

Tighten in sequence to 29ft.lbs then tighten in sequence to 58ft lbs. then loosen all bolts. Then tighten in sequence to 33ft lbs. then tighten each bolt in sequence 90 degrees then tighten each bolt again 90 degrees

this is a 6 step procedure first tighten to 37 ft pounds all bolts step 2 turn all bolts 60 degrees step 3 loosen all bolts step 4 retighten to 30 ft pounds step 5 turn bolts 75 degrees and step 6 turn all bolt another 75 degrees

heinrichkemp: The engine in your car is a GA16i
I venture you are asking about the head bolts when you refer to torque settings. The head bolts used on this motor are torque to yield (streach bolts) If you are reusing them, you need to check them to insure they are not stretched beyond limits.
The way you measure the bolt is with a micrometer.
Measuring close to the end where the bolt starts to thread in, about 10-12 threads up, take a reading. Now, go to the other end of the bolt where the threads end and measure about 10 threads in.
There should not be more than a .009 inch difference (.228mm). If there is, discard the bold and get a new one.

You must use a sequence to tighten the bolts, below is the sequence.
11
13 9 3 1 6 8

14 7 5 2 4 10
12 15

torque 11,12,13,14 & 15 to 8.3 Nm (6.1 ft lbs)
Torque the main head bolts by the numbered sequence to
29Nm (22 ft lbs) first pull
64Nm (47 ft lbs) second pull
Loosten all the bolts completely
Tighten the to 29Nm (22 ft lbs) first pull
Tighten bolt # 1 clockwise 85 degrees
Tighten bolts #2- 10 65 degrees
Nissan noted that if you do not have a torque angel meter, you can use a regular torque wrench and torque all the bolts to 69Nm (51 ft lbs)
The valves on this engine have hydraulic lifters, consequently require no adjustment.

hi.im a mechanic from the philippines.the torque of all your cylinder head for your nissan sentra 1997 is 60 nm.apply 30 nm of torque first on all the cylinderhead bolts then torque it agian directly to 60 nm. i also drive and repair nissan cars.