Hex Bolts Lose Their Hex! Head Saga Continues…

Sometimes replacing just a few parts of a total isn’t necessarily the best idea.  You may recall, during last winter’s cruise, we were forced to leave the 10,000 Islands and head to the Keys (oh darn) to get parts for our head … first all new sanitation hose and then a new Raritan PHII pump assembly since our old one was cracked….   At the time we figured we were good for another 20 years – after all, what can go wrong with the remaining head bowl & base assembly?   HA!

During the shakedown cruise, we noticed a slow seeping from the base of the head – where there’s a gasket between the bowl and the base.  David figured it was either loose bolts or the gasket needed replaced.  No problem, we have extra gaskets aboard from our PHII maintenance kits (the ones with the all important joker valves!).

Extra gasket to go between the base and the bowl, no problem.

Extra gasket to go between the base and the bowl, no problem.

But first he decided to tighten the bolts to see if that was the problem.    The bolts had been originally installed by the prior owner with the nut on the top, making it easier to get the nut in place, we assume.   But when David tried to get a wrench on the bottom to hold the bolt so he could tighten the screws on top, he discovered three out of the four bolts had no top!  !!!!!!!!   Despite the fact that they were stainless bolts, they had no “hex”.

First David tried tightning the bolts that held the bowl to the base assembly.

First David tried tightning the bolts that held the bowl to the base assembly.

So the head bowl was being held in place by three bolts not fastened and one bolt that was fastened.  It’s a wonder the darn bowl didn’t fall off the base!  But as luck would have it, we noticed the slight seepage before the bowl fell entirely off.    (This is where I think maybe replacing the entire head last winter might have been a good idea…..)

Look!  Three of the four hex bolts has no hex!  YIKES!

Look! Three of the four hex bolts has no hex! YIKES!

We had no spare 1/4″ stainless 20 hex bolts aboard, so the project had to wait until we returned to the dock.  As soon as the boat was rinsed off yesterday, David headed for the hardware store, returning with the bolts in question and in short order, the challenge was fixed.

Gasket replaced, new stainless hex bolts -- WITH hexs -- and this project is almost done.

Gasket replaced, new stainless hex bolts — WITH hexs — and this project is almost done, just requires some serious cleaning.

So, the moral to this project is … don’t assume the head bowl is attached firmly to the base … best use a mirror or whatever to check the bottom side from time to time.   🙂

Back to normal!  Whew!

Back to normal! Whew!

We’re trying to determine what ate off the hex heads of the stainless bolts.  We’ve never noticed an odd hex bolt head laying on the floor in the head.   Anyone know what happened here?   Please leave a comment and share!  Thanks!  Jan

Comments

  1. Keith Davie says:

    Jan,
    Sounds like a classic case of corrosion to me. I don’t know where the heads went, but my guess is that the normal dampness of the bottom of the bowl, combined with a lack of air (oxygen) to the shank of the bolts just below the head, allowed corrosion to gradually weaken the shank of the bolt at that point until the normal stresses on the bowl from use popped them off, one at a time. They’d be small, might sneak down into the bilge, might even get accidentally kicked off into a corner and eventually swept up without being noticed when you were cleaning.

    Most folks think that stainless won’t corrode, but in fact it’s nearly as susceptible to corrosion as regular steel IF it’s in an environment where there’s limited oxygen. Often happens to stainless chainplates that are encased in fiberglass to “seal out moisture”. Moisture gets in anyway (as it always does!) and that, combined with a lack of oxygen, starts a special form of corrosion that will cause the metal to weaken and crack.

    Glad the bowl stayed put long enough for you to notice the leak, and glad nobody was sitting on the throne when the last bolt let go!

    Keith, s/v Honfleur

Speak Your Mind

*