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View Full Version : Rusty manifold screws.

mx3jmcb
03-06-2008, 03:45 PM
Hey guys,

Is anyone having the same deal as me were manifold screws around the blower are getting rusty with water actually getting under the bonnet? Has anyone done anything about that?

JM
Mathrips
03-06-2008, 08:35 PM
Mine did that right away. I replaced with stainless.
mx3jmcb
03-07-2008, 07:32 AM
ok...guess just have to get same grade screws...thats the only thing.


i meant WITHOUT water getting under the bonnet..:)
mx3jmcb
03-11-2008, 06:42 PM
What grade are these screws....??? (the black ones around the autotensioner and on the manifold)
Tom @ Fast Forward
03-11-2008, 07:01 PM
High grade screws only seem to be available in that black oxide finish. SS screws are typically a lower grade. The ones I use are grade 12.9. It is the black oxide finish that shows the surface discoloration.
mx3jmcb
03-12-2008, 08:17 AM
High grade screws only seem to be available in that black oxide finish. SS screws are typically a lower grade. The ones I use are grade 12.9. It is the black oxide finish that shows the surface discoloration.

Thats the deal, i wouldn't want to change grades.
Tom @ Fast Forward
03-12-2008, 01:16 PM
If you take a cloth and rub them down with WD40, they should look good again.
99mx5
03-12-2008, 01:56 PM
I just bought stainless bolts to replace the ones for the manifold top plate. I recently found two that were broken.
Tom @ Fast Forward
03-12-2008, 08:08 PM
The only bolts I have ever seen that broke were because they were too long and bottomed out in the holes before the heads clamped down on the plate. As the stainless bolts have lower tensile strength, they are more likely to snap under the same circumstances.
99mx5
03-12-2008, 11:03 PM
These bolts weren't bottomed out in my case. But, then again, I was snapping bolts on my IAC bracket too. ;) I seem to have a thing with breaking things. :devil: I noticed that most other automotive bolts are grade 8, so I figured a grade lower than 12 would suffice.
pumpkin
03-13-2008, 06:54 AM
Grade 8 is US, SAE rating. Grade 12.9 is Metric, I don't know how they equivalate.
But definitely not the same scale.
JD
99mx5
03-13-2008, 10:59 AM
That is true, they don't. I'm thinking that the 12.9 grade bolts may be too brittle for the vibration (in my case).