Small crack in lower unit

[molzeppa]

Everyone was so helpful with my last question, I thought I'd throw this one out too. When I went to reinstall the bearing housing I found a small crack in the lower unit. I'm an OK aluminum tig welder, but have never welded cast. How hard is it to not blow a hole in this? Would you fix it? It's not causing a leak where it is, but it could maybe, possibly grow.

 

[Scott Danforth]

I would fix it.

With cast, you have to preheat, and slow cool

You will need to clean the crack and around the area

 

[Nordin]

As Scott says pre heat before welding.
Clean the area very well and I would drill a little hole at the end of the crack to end the crack.
Otherwise it may carry on to crack even after welding it.

 

[molzeppa]

Everyone was so helpful with my last question, I thought I'd throw this one out too. When I went to reinstall the bearing housing I found a small crack in the lower unit. I'm an OK aluminum tig welder, but have never welded cast. How hard is it to not blow a hole in this? Would you fix it? It's not causing a leak where it is, but it could maybe, possibly grow.

I applied some test heat to the skeg to see how the cast responded. Sanded, wire brushed, acetone, more wire brush on the front and back, then applied a little heat. There is so much porosity even after 3 or 4 passes that I chose not to do the repair. There isn't enough metal up there to make up for the mess. I'll keep an eye on it and pull the housing and weld it if it grows. Hope I don't regret my choice!

 

[Mc Tool]

Do drill a small hole as mentioned by both respondents above . There is a chance that this was caused by corrosion building up and forcing the lip out and cracking .....with that in mind when you refit the bearing carrier pack some sealing goo in there so as to keep water out of the joint area. Stiff maring grease like res q steel is good . Last time I saw this the guy ( not me ) assembled the bits and then warmed the case up to "just about couldnt hold your hand on it" temp and then tipped molten wax around the whole joint area ....sounds feasible and as fas as I know its still good . I have seen a couple of older 90hp yam 2 strokes that have done this recently .

 

[cwella]

Everyone was so helpful with my last question, I thought I'd throw this one out too. When I went to reinstall the bearing housing I found a small crack in the lower unit. I'm an OK aluminum tig welder, but have never welded cast. How hard is it to not blow a hole in this? Would you fix it? It's not causing a leak where it is, but it could maybe, possibly grow.

Cast aluminum can be tricky to TIG weld because it’s often porous and contaminated with oil. A small crack can sometimes be repaired, but the area needs to be completely cleaned, ground out, and preheated properly to avoid blowing through or trapping contamination.

If it’s not leaking and the crack isn’t spreading, many would leave it alone and monitor it. If you do repair it, consider having someone experienced with cast aluminum do it, especially on a lower unit where a failure could get expensive.

 

[Crosbyman]

Everyone was so helpful with my last question, I thought I'd throw this one out too. When I went to reinstall the bearing housing I found a small crack in the lower unit. I'm an OK aluminum tig welder, but have never welded cast. How hard is it to not blow a hole in this? Would you fix it? It's not causing a leak where it is, but it could maybe, possibly grow.

if not leaking ...still far from GC innards me I would drill a small hole maybe 1-16th up the crack
grind the surface a bit to rough it up

smooth out everything with high psi JB weld ......after a good wash of the crack with carb cleaner

inspect a few times and if JB does not show stress crack again seems you should be good.
jmho