Head and head cover bolts - BRASS ?

[bang4dabuck]

I recently pulled my heads off '87 90HP Evin. I ended up breaking 8 HEAD COVER bolts. I was considering replacing all these bolts (32). These bolts seemed to be not of great quality and rather expensive ( $2.50+ each).

1) Brass was a thought. I think I could find in bulk for .75 each or less

2) If I had to replace with equivalent what kind of bolt would I look for ? (I know the size - 1/4-20 x 3/4 and looks to be grade 5). I refuse to pay that much for a small bolt. If I am on the right path, True Value would have them at my door, 100 for $13.60.

http://www.idealtruevalue.com/servlet/the-72104/Detail

Didn't break any head bolts but would look at replacing them too if advised.

 

[wilde1j]

Re: Head and head cover bolts - BRASS ?

Brass is not a good choice for anything on a motor. Bronze is good, SS is better and monel the best (if motor is used in salt). Stick with head bolts motor came with.

 

[bang4dabuck]

Re: Head and head cover bolts - BRASS ?

Yeah, problem with using new bolts, they need to be painted or they'll rust. Not sure what that entails (cleaning, priming painting ???). Read somewhere about powder coating. Not sure, but I think my brother powder coats when he makes fishing jig heads so maybe he can do 32 small bolts for me.

Also read about soaking the old bolts in white vinegar overnight so I'll at least give that a try.

 

[Mas]

Re: Head and head cover bolts - BRASS ?

Brass is way too soft! Also, maybe too dissimilar on the galvanic series (brass with aluminum)...but that would have to be looked up.

Mas

 

[Mas]

Re: Head and head cover bolts - BRASS ?

Brass has an index of 0.40 whereas many aluminum alloys are upwards of 0.90. For salt water, differences 0.15 are acceptable.

From my quick research, brass with aluminum produces a difference of almost 0.50...too much! Corrosion will soon follow..not to mention a weaker/softer bolt.

I'm not an expert, but I wouldn't do it.

Mas

 

[dazk14]

Re: Head and head cover bolts - BRASS ?

Bolt Depot in Mass is where we buy all of our aftermarket fasteners.

Fast service excellent choices and prices.

This should get you started. Looks like .21ea or .13ea for box of 100 and they are Stainless.

http://www.boltdepot.com/product.aspx?cc=6&cs=7&cm=6&cd=61

The cover bolts are a low stress usage. To prevent them from sticking for future removals, coat them with blue loctite or a light coating of grease.

I wouldn't stress about the paint. Nearly any paint would work or simply spray the finished mounted head with a little light oil.

Head bolts are generally re-used. A wire wheel is ideal for cleaning off the shmutz on the threads. A small wire wheel that you can mount on a drill will also work.

To ease future removal, coat then with a little light oil and this will also yield more accurate torquing. Don't overdo the lubricant, since you don't want oil to seep onto the head gasket surface.

 

[G DANE]

Re: Head and head cover bolts - BRASS ?

I usually always break a head cover bolt or two. I've found that coating them with silicone gasket sealant prior to reinstallation will seal the water from leaking into the threads, and every one I did this way, turns right out, next time I have to disassemble. Extra important on the 20,25 or 35, where the thermostat is located behind the head cover. OMC gasket sealing compound is also fine, if you have it. Same procedure with the internal exhaust tube bolts, and Exhaust water jacket bolts, same problem.

 

[F_R]

Re: Head and head cover bolts - BRASS ?

Stainless steel is worse than steel about corroding in aluminum and harder to drill out if you break one. I doubt the originals were Grade 5, but may have been. Grade 5 is pretty tough.

 

[bang4dabuck]

Re: Head and head cover bolts - BRASS ?

The hex head has 3 slashes which I saw on a fastener site stood for Grade 5. 5 slashes = Grade 8 I believe.

Corrosion - gasket sealer is what the manual says to use ... on the threads. I was talking about the hex heads. I don't expect to be taking them out anytime soon so I guess I can coat them with something or paint in place if push comes to shove.

 

[1946Zephyr]

Re: Head and head cover bolts - BRASS ?

Stainless steel is worse than steel about corroding in aluminum and harder to drill out if you break one. I doubt the originals were Grade 5, but may have been. Grade 5 is pretty tough.

Aren't the lower unit bolts made of stainless?

 

[F_R]

Re: Head and head cover bolts - BRASS ?

Aren't the lower unit bolts made of stainless?

Of course they are. Don't they sieze and break? Of course they do. All in a normal day's work for a salt water outboard mechanic. But in that application, it is the lesser of two evils. At least the heads don't rust away. So you can get a good grip on them to break them off.

 

[1946Zephyr]

Re: Head and head cover bolts - BRASS ?

Well, anything that's lives underwater and is riddled with electrolysis is bound to sieze up and snap. That can be avoided with zincs and proper care (which is nonexhistant with most outboard these days) If you use anything else in the lower unit, then you'll have even more problems with them snapping off aside from the hexes being eaten away and making them harder to remove.
If stainless is used on the heads, you won't have to worry about them rusting. Stainless will last 1,000 years and not rust. So, I believe stainless is the lesser of two evils.