CORRECT bolts for 3.0/3.0LX Manifolds

Aatcman

At-Sea-Man
Joined
Aug 20, 2004
Messages
166
Can anyone provide info on the CORRECT bolts to use to attach the manifold to the 3.0/3.0LX?

LOTS AND LOTS of posts everywhere are very helpful with the thread count and size (3/8 - 16), and length (4 7/8)

Good info -- EXCEPT it does NOT provide sufficient info to actually replace a bolt....

Can someone please provide an explanation to WHAT KIND, MATERIAL, AND/OR GRADE of bolt should be used?

Current owner has used grade 8 from the hardware store -- with lots of washers to take up the extra length.. (4 7/8 is not a standard size, 5" is too long, 4 1/2 is too short....)
-Not sure this is the right thing as the studs do not seem to be made of the same material.
-Pretty sure all bolts and studs holding the manifold on need to be same material and grade so they respond to heat the same (and avoid warps and leaks during heat/cool cycles).
--This would amount to basic metallurgy...

However, all I can find in the manuals is a part number -- and when you look up the part number all merc provides in the description is "bolt"...
Not helpful...
Especially since its discontinued...

Now here's the real grind of the mind: many of the manufacturers of replacement manifolds provide replacement bolts and studs with their new manifolds -- but no specs are to be found and no bolt sets are offered separately...
As if that's not enough, most of them include 3 studs and 2 bolts...
-Most of us have 2 studs (one at each end) and 3 bolts -- so which hole does this mystical 3rd stud go in? Again, no documentation seems to be able to be found.....

Seriously -- a simple bolt spec can't be this hard...

Can someone pls provide the correct specifications, ideally both for the bolts and the studs?

Thanks!!!
 

Aatcman

At-Sea-Man
Joined
Aug 20, 2004
Messages
166
Update.
Still no specs.............
Would be nice to have the specs so we can still get these once the stock out there is depleted.....

However, found stock on boats.net (too bad shopping right here on this site is broken btw)...

They have studs, bolts, washers, and nuts, all factory original for the 3.0/3.0lx
Parts list says bolts and studs use the same washer.

bolt 8M0214937
stud 8M2010364
washer 20553
nut 46335

Hope this helps someone!!!

:)
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
51,496
Stock bolts are grade 5

Grade 8 is fine

Cutting bolts down or using washers is fine

-Not sure this is the right thing as the studs do not seem to be made of the same material.
-Pretty sure all bolts and studs holding the manifold on need to be same material and grade so they respond to heat the same (and avoid warps and leaks during heat/cool cycles).
--This would amount to basic metallurgy...

Your overthinking it
 
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