Suggestions on valve cover bolts

Shue Her

Member
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Mazda, Protege5
Which bolts would be better? The class 12.9 or just the Oem ones?
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I'd go OEM,.. they aren't threaded at the head so the grommet will seal better. (they don't need to be strong,... they're only squishing rubber)

The thread missing at the point helps to get them threaded (it lines itself up in the hole)


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Different story when you replace your fuel filter though,... avoid those OEM screws (apparently made from a Swiss cheese product).

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I agree, you really dont need to worry about the strength of the valve cover bolts. They are such a low torque bolt, that even if they were made of aluminum, you wouldnt break them if torqued correctly.
 
The reason I wanted to change it was because three of the Oem one broke inside when I replaced the valve cover gasket


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The reason I wanted to change it was because three of the Oem one broke inside when I replaced the valve cover gasket

I had one break off too. I couldn't get the stud out, tried to drill it out then gave up with a huge hole drilled... I siliconed the grommet and hole and was lucky that it hasn't leaked.
 
... You have to use screw extractors.

Yea that's what I was intending to do.

But first you have to drill a hole dead center in the remaining stud. After spending an hour screwing that up and breaking a screw extractor in the hole then accidentally cutting though my injector wires, I decided to quit while I was ahead and goop it up with silicone.
 
Yea that's what I was intending to do.

But first you have to drill a hole dead center in the remaining stud. After spending an hour screwing that up and breaking a screw extractor in the hole then accidentally cutting though my injector wires, I decided to quit while I was ahead and goop it up with silicone.

There are 2 sides to a screw extractor bit, you use one side to make the cavity and the other side (reverse threaded side) of the bit to extract the screw. No need to drill.

I guess I can see where you were coming from if you were scared to bugger up the threads.
 
There are 2 sides to a screw extractor bit,...

My set of extractors had square ends but I did manage to get a hole drilled pretty good. Then I broke the extractor in the hole (don't buy the $5 set like I did). Then I tried to drill a bigger hole and it wobbled off and I had a figure 8 type hole. Then I realized you can't drill through hardened steel so I got out the high speed grinder bits. That's when I ground through my wires.

The only option I had left was to get out my sledge hammer so I thought I would see if it would leak if I just goopped it up with silicone,... Good call I figure,.. I was quite irate by that point.
 
And they were torque at 7 lbs

My broken stud was seized at about 50 lbs.

And it was already broken by the last owner,... sometimes ya need to leave well enough alone,... or just start the job with the sledge hammer.
 
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That's how they looked. I got lucky


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Very lucky.

I have been through bolts that have had their heads spun off flush with the surface... not fun, Murphy must have been around. I have also had the heads off bolts shear off on the Cam cap bolts and it felt like I was pushing it too far but didn't get the confirmation from the torque wrench so kept going. I believe that thread locker and bolt stretching and aging was a factor for me though.
 
Same stud I tried to pull out...

Notice how you can thread it clockwise too...

That didn't work either...
 
Yeah. That sucks. That's why I wanted to upgrade the bolts due to the aging of the old ones.


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