have i overtightened my head bolts?

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  #1  
Old 05-19-04, 10:03 PM
Anth Seebel
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have i overtightened my head bolts?

just replaced head gasket on 4 cyl. nissan pulsar 89.

have i overtightened my head bolts?

car manual specs list for head torque: start 25nm (19foot pounds) then 3 stages on 60 degress then 1 stage of 30 degrees.

does the 60degress, mean 60 degress from where u start?

i started at 25 foot pounds and ended up with 60-70 foot pounds after 4 stages.
i foolishly didnt take notice of the notation until now , cos i got a oil leak in corner where gasket is.

considering my headbolts are at 60-70 foot pounds can i tighten further to try eliminate the leak? i know i should replace gasket again but i wanna know if any other way is worht a try. engine seems to run fine , no water in ex pipe, just that external leak. i think i saw a cpl small bubbles so i wud be loosen bit of compression...

cheers
Anth Seebel
 
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  #2  
Old 05-19-04, 10:57 PM
mike from nj
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one of two things happened.


1. the head or block surfaces weren't cleaned spotlessly, or the head is warped.


2. the head bolts have stretched.


i wouldn't tighten them any more, you run the risk of breaking a bolt or pulling the threads from the block.

sometimes you can feel the bolt stretching, you would feel the bolt getting easier to turn as you did the additional steps of tightening. when it says 60 degrees of turning, it means an additional 60 each time, which is exactly one bolt 'flat'

and only you know how clean the head surface was before it was assembled.



take it from me, the second time is ALWAYS much quicker
 
  #3  
Old 05-20-04, 04:43 AM
Desi501's Avatar
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Originally Posted by mike from nj
take it from me, the second time is ALWAYS much quicker

Hahaha........... We know that feeling.
 
  #4  
Old 05-20-04, 07:35 AM
Anth Seebel
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Originally Posted by mike from nj
one of two things happened.


1. the head or block surfaces weren't cleaned spotlessly, or the head is warped.


2. the head bolts have stretched.


i wouldn't tighten them any more, you run the risk of breaking a bolt or pulling the threads from the block.

sometimes you can feel the bolt stretching, you would feel the bolt getting easier to turn as you did the additional steps of tightening. when it says 60 degrees of turning, it means an additional 60 each time, which is exactly one bolt 'flat'

and only you know how clean the head surface was before it was assembled.



take it from me, the second time is ALWAYS much quicker

ta. yeah i know i have to re-do head gasket, i learning

another cpl questions.
1.how long do u think it is ok to run with this small leak ?

2. do those "stop gasket leak" fluid additives actually help?

3. i hear a faint rattling sometimes at idle and low gears. it comes and goes and sounds like metal tapping, it will happen also at low gear when i apply quite a bit of fuel/gas or when under a bit of load.. any ideas what it could be? (was there b4 too)

cheers
Anth Seebel
 
  #5  
Old 05-24-04, 06:14 PM
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Could be spark knock, could be timing off just a bit. I wouldnt continue to run with the leak. Too much of a chance of forgetting about it and running the engine dry of oil. If you have overtightened the bolts, which it doesnt sound like you have even done them completely yet, then you should measure them when you take it apart again as they are stretch bolts and are only good to a certain length. After that you wont get the head to the proper torque spec and it will leak on you again real quick.
I just re-did someone elses flub. The guy who replaced the head obviously didnt know what he was doing as he must have lost some of the head bolts and just used some that were lying around and they were the incorrect length. Needless to say his repair did not last long. Maybe a few hundred miles. There are supposed to be 2 short bolts but when we took it apart they werent in their proper place. Plus you are supposed to replace the bolts every time on this car. Hes lucky he didnt have to buy this guy an engine. The bad part is he was supposed to be a factory trained tech specializing in this car line. Oh well. I know it is right now.
Billy
 
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