1976 Evinrude 20HP Fast Twin impeller housing.

[Nick0151]

Hi guys been working on my old outboard not been ran in over 10 years done carbs and hoses. Tried to remove the screws for the impeller housing and no joke all 4 screws snapped so I have had to drill them out…

question anyone know the size and thread I need to tap them to? Iv looked in service manual doesn’t tell me.

my plan is to fill the holes I have made drilling them out with some aluminium welding rods and then drill and tap.

any help would be appreciated

 

[fdrgator]

Ever hear of Heli-Coils? Outboard mechanics cannot live without them. Warning: Drilling those stainless steel screws out of aluminum is an art that you only learn by experience. I've done thousands of them and every one still is a challenge. But hopefully you have experience (??)

 

[Nick0151]

Nah I went with dill and drill till nothing left I don’t have the space for a coil walls are to thin think one I may have even gone through. But can build up with some aluminium and start from scratch.

 

[Nick0151]

Il take some photos in the morning so you can see.

 

[Nick0151]

 

[racerone]

Post on ----aomci------Find a good used housing.-----Lots available I think.------Your location ?

 

[Nick0151]

I’m in Liverpool UK

 

[racerone]

Original thread is 10-24NC on the screws.----Any stainless screw , even metric will do as a repair.

 

[Nick0151]

Thank you so much does this tap and drill set look right I’m not really up on the imperial units.

Century Drill & Tool 95306 10-24 NC Tap and #25 Drill Combo Pack https://amzn.eu/d/cSPpwRd

thanks

Nick

 

[Nick0151]

It this one as next day delivery is available

sourcing map 10-24 UNC Straight Flute Thread Tap and 3.9mm Twist Drill Bit Set, Titanium Plated 6542 High Speed Steel Drilling Bit Machine Threading Tap https://amzn.eu/d/4tuvCJE

 

[racerone]

Stop-------Step #1 is to make a " dummy " water pump housing.----Use 1" steel plate.-------That would make a very good drill guide to keep drills from wandering to the side.

 

[fdrgator]

Looks like you have indeed gotten yourself into sort of a bind. Too bad it has gotten this far. Being in UK doesn't help, I suppose. I'll leave it up to you to figure out the best course of action. Perhaps welding might work. Hey, a last resort of drilling clear through and putting nuts on the bottom might be an option. Not pretty, but.......?
Good luck with your project.

 

[Nick0151]

Is that to drill the old screw out or is that to drill when it’s done? As it stands now the 3 holes are clear of old screw. Next going to fill with aluminium.

unless that’s wrong?

 

[racerone]

<p>
Oh well-----Hind sight is good here.----But I think stopping ( asking for help ) after the first screw broke should have been done.-----Too late now.</p>

 

[Nick0151]

So what do you think now?

 

[racerone]

I would look for a used housing.---Might not be easy in a salt water area.

 

[Nick0151]

Just tried eBay and gumtree nothing there really FB market nothing too il have to plod on down this route.. wish me luck will post results.

thanks

Nick

 

[Nick0151]

So get rid of any remaining screws I had to go bit nuclear on one will update with next stage when done

 

[Nick0151]

Used some aluminium welding rod to fill the holes not pretty but it’s strong and set will drill and tap when can get to use friends pillar drill.

 

[Nick0151]

Ok update the liquid aluminium didn’t hold its set hard but when tapping the hole it stripped the threads so next stage is a putty metal failing that it’s going to be welded.. will update

 

[Nick0151]

So getting some where slowly.

Got some liquid metal made drilled and taped now all is back as it should be done a service on it need to start in a barrel but it seems like it’s doing ok