SS bolts & aluminum housing?

[NW Redneck]

Well, I pulled my drive ('75 OMC 175 stringer) to change the impeller. Taking off the exhaust housing cover resulted in 2 of 5 bolts snapping off.

To avoid this in the future, what's the best thing to do when re-installing ss bolts into aluminum? From what I've read regular copper based anti-sieze is a no-no, so what is the best way to go? Regular grease? Silicone grease? Something else? Your input is appreciated!

 

[Don S]

Re: SS bolts & aluminum housing?

SS Bolts + Aluminum housing & Threads = Oxy/act torch to warm the aluminum so the bolts don't break. Many times it takes a LOT of heat.
Permatex Aviation #3 Mercruiser perfect seal or what ever OMC called there form of it. Works great, prevent the corrosion and it all comes apart next time. Even in salt water.

 

[NW Redneck]

Re: SS bolts & aluminum housing?

Thanks Don.
I'll look for some #3 in NAPA or our marine shop after the weekend. Do you think a MAP gas torch is hot enough for the job? Don't have an O/A setup handy.

 

[Don S]

Re: SS bolts & aluminum housing?

Do you think a MAP gas torch is hot enough for the job?

In most cases no. The heat transfers away from the needed area too fast.

 

[starsnstripers]

Re: SS bolts & aluminum housing?

I was just discussing this last night with a Ziggy. He's had the pleasure of being in your shoes. I looked at mine only! I'm hoping mine doesn't leak when i test it. EEKS! scary item. Ziggy said he helicoiled his broken ones. tricky to drill though. Don have you ever succesfully removed broken bolts from this area and been able to reuse same threads or retapped?

 

[Don S]

Re: SS bolts & aluminum housing?

Don have you ever succesfully removed broken bolts from this area and been able to reuse same threads or retapped?

Not sure what "This Area" is, but in general when a SS bolt twists off flush in an aluminum housing I have very limited success in removing the broken bolt and saving threads, Being slightly off center and the alum. goes away quickly, eazy outs seldom work (in real life salt water boats) without heat and lots of it. Yes helicoils work sometime but take each bolt as it comes.
I seldom break a bolt anymore. It's easier to spend the time getting the old one out intact than repairing the broken ones

 

[starsnstripers]

Re: SS bolts & aluminum housing?

"Thia area" meaning exhaust cover in this thread. Thanks if mine does leak i'll get out the heat first no questions asked. WOW thats a hard area to even see let alone reach. Thanks Don, wish ya luck there redneck.

 

[Don S]

Re: SS bolts & aluminum housing?

Was just a little confused. You have a Merc 1 drive on a 165, he has a 175 OMC stringer drive. Nothing is even close to the same.

 

[starsnstripers]

Re: SS bolts & aluminum housing?

Oh I see, Sorry Don Hopefully his is eisier to get to.

 

[NW Redneck]

Re: SS bolts & aluminum housing?

You even had me confused for a minute there!
Mine are easy to get to as they're right at the top of the outdrive. You can see three of them in this pic:

And I got kinda lucky as they snapped off right below the heads. I was able to get the part off and have about 1 1/2" of bolt to work with. I'll double nut them and borrow an OA rig and be CAREFUL! Thanks again!

 

[NW Redneck]

Re: SS bolts & aluminum housing?

Update:

WOOOOOHOOOOO!
Got em out! Soaked em down with penetrating oil a couple of times yesterday and this morning, then took the torch to to it and viola! Picked up a can of permatex #3 on the way home. Took a tap and cleaned out all the threads, greased up all the splines and now just waiting on a couple of seals and o-rings. I was supprised at the condition of the impeller, considering it's at least 15 yrs old! It was still in good shape and pliable! It was running at a steady 150-160* last year, and I was getting plenty of water through to the engine when I disconnected the hose to the stat housing, I just figured it was better safe than sorry. I did find the oil in the upper gearcase a little milky, so it can't hurt to have all new seals/o-rings anyway.

Thanks again for the tips Don!

Hmmmm, I ordered those parts at about 5:00................. I wonder if they're here yet? The water is calling.............