35 hp Johnson Water Pump Housing (1958 - RD19C)

[yelraf]

I spent a few hours trying to change my impeller this weekend.

The lower unit came off great. I identified the 3 screws needed to remove the housing and had at it. This is going to be a cinch, I thought.

Well, in no time flat, two screws were snapped off and te hhproject ground to a halt. So, I bought an extractor. I drilled a hole in the top of the remaining screw and began extracting. It too snapped off (albeit a little deeper than the first two).

in any event, I now have three broken stainless steel screws, and I can't seem to get any farther. The screw remnants are about 1/4 inch below the surface of the aluminum housing AND they all have tapered points, making it impossible to set a pilot hole in the center. AND I have burned out/snapped off 4 bits trying to drill through the stainless steel.

Now, I can afford a couple more bits, but I am worried that if I drill off center, that I will damage the aluminum case. I have already damaged the housing when the bits slipped a couple of times.

The SELOC manual tells me to use a chisel to break away the housing (CAREFULLY) when this happens. I have tried to do so, but at this pace I won't be done for a week.

Has anyone been through this before. Do you have any thoughts on how to remove a damaged housing with a chisel? Or on how to remove stainless steel screws from an aluminum case.

Thanks,
Mike

 

[tashasdaddy]

Re: 35 hp Johnson Water Pump Housing (1958 - RD19C)

laingsoutboards.com has the kit. call and make sure it has the housing. i've use my dremel tool with a tile grout bit to cut a lot of metal. that bit never gets dull, and is spirialed all the way up, so you can lay it on it's side an cut. nothing say you can get the bolts out then. good set of vice grips.

 

[F_R]

Re: 35 hp Johnson Water Pump Housing (1958 - RD19C)

Quote: Has anyone been through this before. Do you have any thoughts on how to remove a damaged housing with a chisel? Or on how to remove stainless steel screws from an aluminum case.

Been thru it before?? You bet. Almost on a daily basis as a full time outboard mechanic in a salt water area.

It is too late for the first secret: Avoid breaking them off in the first place. That requires an acetylene torch which the average novice does not have. Ok, so now they are broken. Next step after getting the housing off is to heat the aluminum while you carefully take the screws out with vice grips. Back to the acetylene torch again, but do the best you can with propane or Mapp.

If you break them off flush, you are in deep do-do. It takes skill and practice to drill them out and install Heli-Coils. But that is the only way to go. As you said, the first 100 times you try it you will let the drill wander off to the side and screw it up royally. Use cobalt drill bits and take it very slowly. Stainless steel work hardens and gets almost impossible to drill when it does. NEVER try to use an easy-out. There is no such thing. It is not easy and it does not get them out. But it will break off in the screw and then you have had it. Same thing for thread taps. NEVER run a tap in the hole till you have 100% of the old screw out. If you do, you will break off the tap in the hole, and again, you've had it.

Stuff like this is why marine mechanics are worth their keep. Well, at least one reason.

 

[BoatBuoy]

Re: 35 hp Johnson Water Pump Housing (1958 - RD19C)

Many of the wrench's here have great luck drilling out broken bolts with left-hand drill bits. That's after they've established a center point to start drilling with a dremel or some other grinder. They say that many times the broken end will come loose while drilling. Here's the only place I've seen them http://www.mytoolstore.com/hanson/hanson.html

 

[yelraf]

Re: 35 hp Johnson Water Pump Housing (1958 - RD19C)

SUCCESS!

The housing came off grudgingly.

I used a small pair of vise grips to nibble away the old aluminum pump housing. This went a lot easier once I bought a new housing because I was able to see where the aluminum was thinner. In areas where it was too thick to nibble, I carefully drilled away the aluminum with a 3/8 bit. Eventually I was able to break the case into 3 pieces, each holding one snapped screw. I carefully lifted each remnant off the screw until I was left with three broken screw protruding 3/4 of an inch from the case. I left the steel wear plate in place.

I then hit each screw with PB Blaster, and used a propane torch to heat the case behind and under the screw. I think I actually saw the blaster fluid bubbling up from the threads (3-4 tiny bubbles). Then I used the small vise grips to get a bite on each screw and turned it about 1/16 of a revolution at a time. By looking closely at the screw as I turned it, I could see that it was backing out of the case. If the grips slipped, I tightened them a bit because I didn't want to strip the screws anymore. (If I noticed that the bits weren't backing out, I would've stopped and gone with Plan B - Cut the screw off flat, and use a Cobalt Right Hand Drill Bit). But before long I was able to back each screw out by hand.

Thank you to everyone, especially tashasdaddy, F_R and Boat Buoy.

Now to prevent this from happening again, I promise to change the impeller immediately at the end of every season.

 

[tashasdaddy]

Re: 35 hp Johnson Water Pump Housing (1958 - RD19C)

congrats. i also learned something from this, as i had never encountered the problem.