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8 bolts for intake manifold. Replace?


hawaiianstyln

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I'm about to perform the intake manifold gasket job and can't seem to find new bolts.  Bakes Skidim and a few other sites didn't sell them.  Can I reuse the 8 bolts or do they need to be replaced?  A friend (mechanic) that is helping me told me I should replace the bolts.  MichiganMotorz has some, but I can't tell which ones I need based off their descriptions so that will be a Monday call.

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I can't imagine why you would replace them.  Unless they are damaged, just reuse. Head bolts are the ones that typically need to be replaced, as most of them are torque to yield now days. 

Edited by oldjeep
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Also I see that the second pass torque spec is 106lbs/in.  I was going to buy the 3/8 torque wrench but they only go up to 100 lb/in and would probably have to get the 1/2 wrench.  Might be wise to rent those wrenches from autozone, those wrenches aren't cheap.

Lower Intake Manifold Bolt

First Pass in Sequence 27 lb in

Second Pass in Sequence 106 lb in

Final Pass in Sequence 11 lb ft

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5 minutes ago, hawaiianstyln said:

Also I see that the second pass torque spec is 106lbs/in.  I was going to buy the 3/8 torque wrench but they only go up to 100 lb/in and would probably have to get the 1/2 wrench.  Might be wise to rent those wrenches from autozone, those wrenches aren't cheap.

Lower Intake Manifold Bolt

First Pass in Sequence 27 lb in

Second Pass in Sequence 106 lb in

Final Pass in Sequence 11 lb ft

You can get pretty cheap torque wrenches from harbor freight, ive got a couple and they work as well as the older craftsman ones i have.  Although for 6 lbs, just lean on it a little harder.  These engines are not assembled by scientists, there is such a thing as close enough. 

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2 minutes ago, oldjeep said:

You can get pretty cheap torque wrenches from harbor freight, ive got a couple and they work as well as the older craftsman ones i have.  Although for 6 lbs, just lean on it a little harder.  These engines are not assembled by scientists, there is such a thing as close enough. 

Yeah I was wondering if I could just wing it with a little more weight into it on the 1/2.  Just got back from Harbor Freight and looked at those.  Much cheaper solution.

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1) Buy/borrow/steal a decent torque wrench.  There is IME a huge difference in cheap vs. good torque wrenches (I use mine on carbon fiber parts which do not take kindly to over-torquing).

2) Replace the bolts (Again, IME I've seen some bolts that are  "torque-to-yield" or one-time use).  How much could 8 decent bolts cost?

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Just now, Eagleboy99 said:

1) Buy/borrow/steal a decent torque wrench.  There is IME a huge difference in cheap vs. good torque wrenches (I use mine on carbon fiber parts which do not take kindly to over-torquing).

2) Replace the bolts (Again, IME I've seen some bolts that are  "torque-to-yield" or one-time use).  How much could 8 decent bolts cost?

Never heard of a torque to yield intake manifold bolt, especially on a 5.7 gm

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2 minutes ago, Eagleboy99 said:

How much could 8 decent bolts cost?

MichiganMotorz has them for about $21-24 I believe.  Just don't know which ones until I call them

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1 minute ago, oldjeep said:

Never heard of a torque to yield intake manifold bolt, especially on a 5.7 gm

Not sure if manifold bolts are that category (drive shafts, differentials, etc. are...) but again - is it really worth reusing the old bolts?

 

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The manual on page 6-154 does talk about if you reuse them you will need the GM threadlock or equivalent

5. Install the lower intake manifold onto the engine block.

Notice: Refer to Fastener Notice in Cautions and Notices.

6. If reusing the fasteners, apply threadlock GM P/N 12345382

or equivalent to the threads of the lower intake manifold

bolts.

7. Install the lower intake manifold bolts.

 

Indmar_5.7RepairSpecs.pdf

Edited by hawaiianstyln
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3 minutes ago, Eagleboy99 said:

That is a useful reference.  NOte how the torque specs change on each tightening pass.  All the more reason to get a good torque wrench.

yep!  Super excited I found that.  It will be my boat bible going fwd.  :)

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21 minutes ago, Eagleboy99 said:

Not sure if manifold bolts are that category (drive shafts, differentials, etc. are...) but again - is it really worth reusing the old bolts?

 

Yes.  Out of curiosity, how many engines have you rebuilt?  You would go broke replacing every bolt you take out of one.  Also, can't say that I've ever run across torque to yield bolts in any differential I've regeared.

Edited by oldjeep
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15 minutes ago, hawaiianstyln said:

The manual on page 6-154 does talk about if you reuse them you will need the GM threadlock or equivalent

5. Install the lower intake manifold onto the engine block.

Notice: Refer to Fastener Notice in Cautions and Notices.

6. If reusing the fasteners, apply threadlock GM P/N 12345382

or equivalent to the threads of the lower intake manifold

bolts.

7. Install the lower intake manifold bolts.

 

Indmar_5.7RepairSpecs.pdf

Yes, which is normal since most new bolts come with a threadlocker pre-applied

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12 minutes ago, oldjeep said:

Yes.  Out of curiosity, how many engines have you rebuilt?  You would go broke replacing every bolt you take out of one.  Also, can't say that I've ever run across torque to yield bolts in any differential I've regeared.

I'm not an engine rebuilder, but a bike builder.  Built up many and rebuilt many more  than I would care to mention.  And of course now they are carbon fibre so torque is an issue.  I can also guarantee that the rear diff on a Pathfinder uses TTY bolts - the $2k (warranty thank Gawd!) repair bill shows them.   I know you can reuse bolts - but on an 8-9 old engine, I would replace them.  False economy IMHO to cheap out on such a critical item.  The BBSes are littered with the pros/cons of reuse so I am not going there, but  *I* would replace them.  YMMV

Edited by Eagleboy99
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I just checked - I have 5 torque wrenches including an "interesting' digital one that I never use.  Why so many?  I need two ranges of torque and one size does not fit all IME.  I've calibrated them which for the low end torque process is especially important for me.

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1 hour ago, hawaiianstyln said:

Also I see that the second pass torque spec is 106lbs/in.  I was going to buy the 3/8 torque wrench but they only go up to 100 lb/in and would probably have to get the 1/2 wrench.  Might be wise to rent those wrenches from autozone, those wrenches aren't cheap.

Lower Intake Manifold Bolt

First Pass in Sequence 27 lb in

Second Pass in Sequence 106 lb in

Final Pass in Sequence 11 lb ft

So that's:

First Pass = 2.25 ft-lb = firmly finger tight (or less, if you have a good grip)

Second Pass = 8.9 ft-lb = enough to feel it in your wrist with a 1/4" drive, but not bearing down

Third Pass = 11 ft-lb, your wrench will show this one

Slightly loose is probably better than way too tight since you will start to warp the manifold as you overtighten the bolts.  It's probably more important that you get them all the same each pass than the actual torque you get on that pass.

And I'm a fan of Aviation Shellac for bolts to both retain them and anti-seize them, especially on boats.

 

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6 minutes ago, justgary said:

...

And I'm a fan of Aviation Shellac for bolts to both retain them and anti-seize them, especially on boats.

 

 

Never heard of that stuff!  Will have to look it up I guess.  I've always used locker  or anti-seize.

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43 minutes ago, hawaiianstyln said:

if you reuse them you will need the GM threadlock or equivalent

If there is evidence of thread lok, then it would go without saying, to reapply some. 

ID be hesitant to rent a torque wrench from a parts house. Who knows how many times its been dropped or returned and stored at the previous torque setting (for click style).  

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