How long for a muriatic acid bath?

J. Fenn

Seaman Apprentice
Joined
Aug 25, 2002
Messages
31
I'm removing a powerhead on a 1984 OMC 1.6L Sea Drive that was used in saltwater. I have the factory manual and have followed the removal steps scrupulously. I got all the bolts out and I've gotten the front part of the powerhead loose from the exhaust housing, but the two rear bolts that go through the exhaust housing are stuck fast. I removed the lower unit and hung the engine/mid-section upside down from a hoist. Yesterday I soaked the bolts with muriatic acid for a couple of hours, then soaked with Kroil overnight. I repeated the same procedure today, except I substituted PB Blaster for Kroil today. I ran nuts down flush onto the studs and tried to press the studs through the exhaust housing with a big pry bar. But they are still stuck fast.

So I'm thinking that perhaps a longer soak time with the acid is required, and figured there would be some more experienced people who could advise me.

As a last resort, I thought I'd try attaching the lifting ring to the flywheel and fasten it to the bottom legs of the hoist so I could put more pressure on the two stuck studs than just the weight that the powerhead is providing.
 

J. Fenn

Seaman Apprentice
Joined
Aug 25, 2002
Messages
31
Re: How long for a muriatic acid bath?

Replying to my own post here. I've now soaked in muriatic acid to the point that I have two little depressions about 1/8" deep around both bolts, but they still will not budge, even with two pry bars. The front part of the powerhead is free, but the back is still stuck fast. Those rear bolts are getting a final soak in Kroil tonight. If they won't budge tomorrow, I think an exhaust adaptor is going to get destroyed.
 

Daviet

Fleet Admiral
Joined
Sep 24, 2008
Messages
8,958
Re: How long for a muriatic acid bath?

Any way to apply any heat?
 

J. Fenn

Seaman Apprentice
Joined
Aug 25, 2002
Messages
31
Re: How long for a muriatic acid bath?

Yes. I've been doing that, too. I've been cycling between muriatic acid, let it sit until it quits fizzing, then sponge away, dig emulsified aluminum away from the base of the studs, apply heat to the studs only with a MAAP torch, followed by squirts of PB Blaster or Kroil at the base of the stud, followed by applied pressure with a couple of pry bars. I go through this cycle three times. Then I apply more acid and let it sit overnight. Been at it all week llike this, which is why I am ready to destroy something now.
 
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