welding on a propoeller shaft housing

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Hello all,I was approached with a project involving welding a boat engine lower unit "outdrive".  In essence the job is to seal a damaged propeller shaft housing as shown in the pictures.If I take it on, the unit will be disassembled and the case brought to me for repair.  I have sealed holes and cracks on these thing but nothing to this extent.What I was thinking is to make up a circular concave patch that would go over the damaged area and weld it in short beads allowing them to cool before proceeding.The mechanic who is repairing the prop shaft has told the client that if it is welded, it will leak eventually as oil soaked aluminum cannot be reliably welded so recommends just packing it with some type of marine epoxy to seal it from the inside and take his chances as it may or may not leak down the road.So, has anyone done any of these and can they be welded reliably?I told the client I would do a little research on this project as I had not attempted that large a repair on a prop housing.  I have welded skeg plates back on so it seems to me that this should not be any different.What do you think?Thanks,Tony Attached Images
Reply:Shouldn't be to much of an issue.. In fact, if your doing a patch like you described I wouldn't expect it to leak any time soon. Did this boat come off the trailer by any chance? Had one just like that where it rolled off and get dragged a bit..
Reply:Hi mrusso,he didn't explain how it was damaged, but it must be something along those lines.  Thanks for the response.  Sounds pretty straight forward then.Tony
Reply:As far as oil-soaked al. castings go, they can be reliably welded. It usually involves cleaning, welding, grinding out all the crap weld, and redoing it several times.Miller: 200dx, Bobcat 225, Passport, Powermax 45, Milwaukee: Dry Saw, MagDrill, grinders
Reply:Hi JohnR,I have welded a number of cast aluminum oil pans, transmission housings and engine blocks using the same technique as you describe.  I did run into trouble with one job I took on that involved welding a large patch on an oil pan that started to develop cracks.  It was a nightmare job as I was chasing cracks and holes caused by gas pockets in the casting.I concluded that I should have welded it slowly, allowing it to cool and then weld again.  That's why I propose to do that with this repair as it will involve putting  a relatively large patch over the damaged area.However, not having done many prop housings, I was wondering if there are any "tricks" or gotchas that I needed to be aware of.Thanks,Tony
Reply:therrera,Hard to tell from the photos, but I can't see an obvious crack.Not sure about a "patch".  May be best to just build up the casing with filler and shape to dimension.Biggest thing to be concerned about is not to overheat/warp the housing.  Keep the heat down and let it cool between passes.  That housing contains seal and bearing seats and any distortion will ruin the foot (housing).A better picture of the actual damage would be helpful.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Originally Posted by SundownIIItherrera,Hard to tell from the photos, but I can't see an obvious crack.Not sure about a "patch".  May be best to just build up the casing with filler and shape to dimension.Biggest thing to be concerned about is not to overheat/warp the housing.  Keep the heat down and let it cool between passes.  That housing contains seal and bearing seats and any distortion will ruin the foot (housing).A better picture of the actual damage would be helpful.
Reply:Research "Nose Cones"  It is a common practice among high performance boats to have nose cones welded onto the front of the housings in the area you have pictured.
Reply:Hi all,thanks for the suggestions.  I think the client said that the engine dropped down and was dragged on the ground, getting banged up on the process.  It must have come off the trailer because I don't think the engine could hit while still mounted on it.These are the only pictures he sent and said that there is no obvious crack, just banged up and the propeller shaft was bent in the process.  It was the mechanic who will be taking it apart who told him it may leak despite the use of epoxy.The client wanted to explore the possibility of sealing the area, welding it as a preventive measure.I looked briefly into the nose cone approach.  They seem to be somewhat overkill for this project as they are designed to be added onto the outboard motor case to streamline it.  I attached a picture off of a web site.  In addition several web sites for nose cones explain that they are designed for boats capable of over 80mph.  It will create more drag for slower boats due to the increased drag of the mass of the added nose cone and reduce overall speed.I will report to the client that it can be successfully welded if he should decide to go that route.Thanks and I'll report how it goes if he decides to do it.Tony Attached Images
Reply:I'd just weld it up and reform the nose. Pull it apart first of course. Our work boat lower units get beat to hell all the time and need work just about every year after service. This unit was retired to our fishing boat after being in service for about 6 years which is an incredible amount of time for us. Got a rebuild with fresh seals and water pump and whatnot. I had the unit dressed to weld on its 4th or 5th skeg while it was dismantled but figured it wasn't worth it for the fishing boat.
Reply:i have repaired many of lower units like you describedit can be welded just take your time an keep it clean i would not trust just epoxy to repair for the price of a new/used unit  weld itidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:Does the unit shift alright yet? The front of the unit where the damage is, is where the shift assembly is inside.I agree, epoxy is not good enough for this repair.
Reply:therrera,Be careful about your "liability".  You don't want to get blamed for something you didn't do.The fact that the prop shaft is already bent would lead me to believe that there's also been internal damage to the bearing seats.  I'd go for a "hold harmless" waiver.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:What model engine is that out drive off of? I had a similar thing happen with my 140 mercruiser OB, the rod that holds the outdrive up fell off and i ground off ABOUT 3 " of the skag.     Just bought the boat at auction and the trim system had a cracked line...  normally they should not do that... unless there is a leak or bad seal somewhere in the trim systemLast edited by soutthpaw; 06-07-2011 at 12:00 PM.Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:Hi all,thanks for your input.  I don't know the model of this engine.  All I was sent was a picture of the damage and a request to repair or fill any dents or cracks that I find.  A mechanic is handling the inner workings of the engine and just the empty case will be brought to me to be welded.If he decides to go with it, I'll send a report with pictures.Thanks,Tony
Reply:Originally Posted by VPTDoes the unit shift alright yet? The front of the unit where the damage is, is where the shift assembly is inside.I agree, epoxy is not good enough for this repair.
Reply:Looks like an evinrude unit 90-150ish hp.  If another mech. is involved things can be ok or bad. Does someone along the lines have access to machine equipment to machine the inside of the unit if the weld breaks threw? Like I mentioned the shift mechanism is at the front of the unit where the damage is.
Reply:Hi VPT,I didn't think of the possibility of burning through as my limited experience welding on these things is that it the walls are thick enough to take the heat of welding.  I have been called on several times to seal holes on the nose like this one and I think it a remote possiblilty.  However when (if) the client calls back to follow up on the project I'll ask if his mechanic can machine it if necessary.The client was just asking if I could do a project like that and relayed to me his mechanic's reservations about the possibility of leakage.  I may never hear from him again.  I posted the request for advice as part of me doing my homework before tackling this type of job.I once attempted to TIG a reinforcement plate on a cracked chrome-molly bike frame and punched a whole in it in the blink of an eye it was so thin.  I sealed up the hole using a 1/16" tungsten and really low amps and switched to brazing rod right away.Thanks,Tony
Reply:Question:does welding on skeg plates require dis-assembly of the outboard case, it's gears, seals, etc.?If I use the technique of welding say an inch at a time and letting it cool and using "heat sink" putty, would that get around the need for that?  Or is it mandatory to take it apart regardless?When I welded my first skeg plate a few months ago a friend called me and asked me since I weld aluminum, could weld his plate back on?  It was a clean break, about three inches down from the actual outboard housing.  I told him I had never done one but that if it's weldable aluminum, sure.He brought it over, I cleaned and dressed up the break, beveled it and welded it back on without much consideration for possible heat damage.  He ground down the weld and painted it after I finished with it.After wards I did the research about how these repairs are done, where to obtain replacement plates and so on and I read mention that it should be taken apart to repair.  To my knowledge the case I welded on had no negative side effects.  He has taken the boat out several times and has not reported anything wrong.  Maybe I was lucky but it put me on notice that I needed to be careful when approaching these jobs. Take them apart?  What do you guys think?Thanks,Tony
Reply:i have done it both ways it is easyer to do if they are empty, a lot lighter to move and no seals to worry about. if they are complete keep the heat down as to not over heat and pop seals there is a place i get mine from called   skeg depot    just down the road from meor i have made my own  ( using plate alum)  i have all the specs for skegs as to how long and how wide and angle.. more work but it has helped in a pinchi perfer to have them empy and then clean them out when doneidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:Hi prop-doctor,Skeg Depot is the place I refer people to when they call me for such repairs.  I downloaded their catalog and fax order form and email these to people who call me requesting a replacement skeg plate.I don't know if they are carried locally but I am going to call around and see if the local boat shops stock them.  Then I'll know better where to refer people to get their plates and bring the project to me.I let people know that I'm not a boat mechanic but a welder and approach the job in this fashion.  I do the same when I get calls for bicycle frame repair or motorcycle repairs, etc.  Sometimes people think I'm a repairman for say motorcycles and they start talking to me cycle lingo and naming parts and so on to describe what they need and I have to slow them down and let them know I am a welder, period, so they need to speak to me in layman's language when describing their problem.  Same happens to me with boats and so on.For this reason I will prefer to do the welding on outboard casings and skeg plates with the motors assembled.  If I detect a situation where the motor needs to be disassembled then I'll send them to a marine mechanic and to bring me the case for repair.I think it's safer that way.Thanks,Tony
Reply:Hello all,well, the client called me to notify me that the mechanic was able to obtain a replacement case so he won't be bringing that job to me.  I asked him if he could let me have the old case but the deal is on an exchange basis.Oh well......Thanks,Tony