Bolt question

[Myklle]

I am replacing the pistion rings on my 1989 90hp Evinrude and want to know if I can use harden bolts (grade 8) from my local hardware store? The bolts that came off the motor for the heads and exhaust cover are in good shape but the book says not to reuse them. Why is that? Any and all information is appreciated. Thank you in advance.

 

[BigB9000]

Re: Bolt question

Because the threads get used/dirty/bad/crudded up. with even slight resistance, it'll throw off the torque settings.
And the used hardware is no longer trusted, as it is used.
When you change the heads on your cars engine, you ALWAYS replace the hardware.

For true precision get new hardware.

Although, it probably doesn't mention anything about the block threads!
You could probably use your Tap & Die set to clean the threads?

 

[Chinewalker]

Re: Bolt question

I've never replaced head bolts - never had a problem doing so. The ONLY bolts I've replaced are ones that are clearly corroded or otherwise damaged.

 

[seahorse5]

Re: Bolt question

Where in the factory service manual does it say not to reuse head bolts and exhaust cover bolts? It doesn't.

Are you reading out of some off-brand book by chance?

Rod bolts are about the only hardware on that motor that you should not reuse.

 

[Myklle]

Re: Bolt question

For the bolts that are corroded, can I use hardened steel grade 8 bolts from my local hardware store?

 

[seahorse5]

Re: Bolt question

Your bolts should be stainless steel, not hardened regular steel like a grade 8 is. They do not have that much stress on them.

 

[Myklle]

Re: Bolt question

thank you to everyone that has replied. Please parden my ignorance, it is OK to use stainless steel bolts from my local hardware store instead of spending almost $300.00 on bolts from shop.evinrude.com?

 

[F_R]

Re: Bolt question

The fact of life is that stainless steel causes mor corrosion/siezing than steel because they are more dissimilar. Of course the stainless doesn't corrode, but the aluminum around it does. And not only that, they are more difficult to drill out if you do happen to break one in the future.

But not more difficult than a grade-8. Grade-5 is plenty good enough.

The real question here is does the hardware variety have suitable thread length? And what were the originals?

 

[wilde1j]

Re: Bolt question

Stainless hardware store bolts are fine, but make sure the lengths are right. OMC used some unusual bolt lengths, so you may have to cut the hardware store stuff.

 

[Myklle]

Re: Bolt question

Thank you all for your responses. I will see what I can find locally before I shell out $300.00 for bolts at shop.evinrude.com and then I think I will only replace the bolts that are damaged/corroded.

 

[wilde1j]

Re: Bolt question

Use a wire wheel to clean up bolts that are to be reused.

 

[Myklle]

Re: Bolt question

I planned on using a wire wheel as well as using my tap and die set to clean out the bolt holes as well.

 

[Tim Frank]

Re: Bolt question

If you are going to use taps and dies, make sure that yours are top quality and in good shape.....and North American made if possible.
I have found many off shore manufacturers use their metric equipment, setup to "converted"" measurements. For new fabrication, this is no problem, but may cause a problem when you are playing with threads that were originally cut with UN thread standard taps/dies.