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Q about exhaust manifold to head bolts on a 86 2.8L V6...

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Old 09-03-2011, 09:37 PM
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Q about exhaust manifold to head bolts on a 86 2.8L V6...

Are all of the bolts on the manifold to head the same length? Is it true what I've heard about the bolts backing out and being lost over time on these 2.8L V6 engines?? I've not had any kind of experience with these V6 engines and am learning as I go along here....
I'm wondering this because my fiance bought a 86 Sport Coupe that has one of the bolts missing on the passenger side manifold.. I think its the 3rd bolt back from the front of the engine...
I'm thinking of using some of the blue loctite when I put the new bolt in there..
Any thoughts or comments is appreciated...
Old 09-04-2011, 02:10 PM
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Re: Q about exhaust manifold to head bolts on a 86 2.8L V6...

3 different bolts listed by GM in two sizes

M8 x 1.25 x 70mm hex head
M8 x 1.25 x 40mm hex head
m8 x 1.25 x 40mm with a M8 x 1.2516mm stud on the head

Locktite wont help on exhaust bolts. GM used tin bend tabs to hold the bolts. If the manifold has ever been off the mechanic likely threw them off in the distance because they are a huge PITA. Most likely the bolt just sheared off from rust and expansion/contraction over the decades. Happens alot esp on V6's

If its not leaking excessively, Id leave it alone and not worry about it. Messing with manifold bolts on an original engine is risky business

http://www.compnine.com/index.php?u=...00&grouptype=B
Old 09-04-2011, 06:59 PM
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Re: Q about exhaust manifold to head bolts on a 86 2.8L V6...

Thanks for the info... It is a noticeable leak especially when I drive it...
Old 02-25-2013, 05:49 PM
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Re: Q about exhaust manifold to head bolts on a 86 2.8L V6...

I've got the exact same problem on my 2.8L (lost the bottom front stud that also bolts on a bracket for the power steering pump). Got a new one from the scrap yard (GM Sports Salvage for San Jose CA residents) but the nut stops short and the stud doesn't thread into anything. My neighbor thinks its just too small in diameter. You can clearly hear the manifold leaking and the car is due for smog so I'm guessing this will HAVE to be fixed in order to pass. Question is were there any other lager stud sizes or do I have a much more serious issue?

Last edited by Brian Ochoa; 02-25-2013 at 05:57 PM.
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