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Re: Head bolt Posted by sam96CS [Email]  (#852) [Profile/Gallery]
(more from sam96CS) on Mon, 10 Mar 2014 17:04:53
In Reply to: Head bolt, tz, Mon, 10 Mar 2014 14:27:19 Members do not see ads below this line. - Help Keep This Site Online - Signup |
The '96 had the stronger generation of bolts than the later models. You can find posts here by Anders who knows these engines saying he has no problem with reusing these bolts.
My notes on this procedure indicate that the final 1/4 turn is equivalent to 89 ft. lbs. Sorry, I didn't note my source for that information.
I don't think the bolts will snap if you go farther. But I also don't think that the weeping won't change much.
I did this procedure 4 years ago as a precaution. I found new old-style bolts and didn't reuse my old bolts. About 44,000 miles later I still have the original head gasket (knocking on wood) and weeping below the #10 bolt. The weeping slowed recently when I had my indy replace my front main seal and oil pump o-ring. One or both of them was leaking. I have no idea why that repair would make any difference. Maybe it is just a coincidence.
You didn't say whether you removed and cleaned each bolt and made sure the hole is dry before tightening to 44 ft lbs.
For what it may be worth, here is the procedure I followed and the things I observed, taken from my notes which are obsessive:
Specs for my head bolts
Stage 1: 60Nm (44 ft. lbs)
Stage 2: 80Nm (59 ft. lbs)
Stage 3: 1/4 turn (raises to approx 120Nm - 89 ft. lbs.)
Tightening sequence (facing the engine with the hood open):
8 4 1 5 9
7 3 2 6 10
This is assuming the threads are thoroughly clean, going into a clean hole, threads are lightly oiled and the underside of the head of the bolt is also lightly oiled. Engine should be cold. Cap on the cooling system expansion tank should be loosened to prevent coolant from seeping while the procedure is done. Do NOT over-oil the threads because the bolt is going into a blind hole where excess oil can result in hydraulic resistance to tightening. The standard oil for oiling automotive engine bolt threads is 30 weight motor oil.
My experience with replacing head bolts at 159,415 miles:
The original factory bolts were uniformly tight. It took some effort with a 2' long breaker bar to break them loose. The effort was greater than torqueing the new bolts to 59 ft. lbs, but less than the final 90 degree turn. The original bolts have BH stamped (and underlined) on the head. The bolts are green. At first they looked like they were grey with green heads. But the grey rubbed off, revealing the green underneath. The grey coating is the color of antisieze lubricant. Probably a factory coating so they could skip oiling the bolts before installing them.
The condition of each old bolt is as follows:
01. dry, a little crud on the threads
02. dry, crud on the last 1" or so of threads (the inch farthest from the head)
03. dry, light crud about 1" from end of threads
04. dry and clean
05. dry and clean
06. dry, light crud the last 1" or so of threads
07. oily, varnished, crud last 1" of threads, 2nd worst looking old bolt
08. oily, varnish on threads about 1" from end
09. dry and clean
10. oily, rusty, crud on last 1" of threads, worst bolt by far.
Procedure was done on a stone cold engine. New bolts same design as old bolts. Lightly oiled with Rotella 5W40, including underneath the bolt heads. Used telescoping magnet to retrieve old bolts. Used Q-tips held with needle nosed pliers to clean surface that the bolt heads contact.
Sequence:
1. Remove cap on expansion tank to prevent seepage.
2. Remove bolt 1. Clean mating surface with Q-tip. Blow out hole if dirty. Lightly oil new bolt and torque to 44 ft. lbs. Repeat this for all 10 bolts.
3. Torque all bolts to 59 ft. lbs. in the correct order.
4. Turn all bolts an additional 90 degrees in the correct order.
5. Replace cap on expansion tank.
, Mon, 10 Mar 2014 17:04:53 <-- Viewing This Message, Mon, 10 Mar 2014 18:44:14
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