Welding leak in lower unit

[FEFIFOFUM]

My lower unit was damaged when i bought the boat and someone tried to bondo it. Its a 1988 85 hp force motor and I took it to a weld shop. The guy welded it and after returning from the lake we checked the lower and it was still leaking. After a week or so we discovered the lower was leaking where it had been welded. I took it back to the shop and the guy welded some more and we brought her home.After we put the lower unit back on for the uptenth time we found it to still be leaking. The guy at the weld shop says its the oil that is keeping the weld from sealing. My question is is there a way to flush the lower unit so the oil is flushed out? Should I take the unit to a new shop? thanks much ron

 

[zorak]

Re: Welding leak in lower unit

i would assume that you dissasembled the lower unit prior to welding it.Aluminum has to be clean to be welded properly as any crud ( especially oil ) will mess up the weld.You will probably have to grind the weld down and totally clean the gearcase with solvent.Then some carb cleaner spray to hopefully flush any oil residue out of the crack prior to welding.If you attempted to have the LU welded without taking it apart then the intense heat from welding it will probably do a number on anything rubber and there would be no practical way to weld it.

 

[5150abf]

Re: Welding leak in lower unit

Correct, there has to be pourosity in the weld form oil,tiny bubbles, and the oil is coming through them.

The only way to get rid of it is to grind the weld out completely, pourosity breeds so if there is any left it will grow so make sure you get it all.

I have welded aluminum for 23 years and cast is pretty hard to get right, throw in some oil and it is really hard.

I have rebuilt a skeg and repaired countless props and the cast is nothing like sheet to weld, you need really low heat and go slow, I have found too much heat makes alot of pourosity.

I would seriously conider going with the JB again, I had a lower that I jb'ed and it was water tight for the 3 years I owned it.

My concern is if you keep throwing that much heat on the lower you are going to warp it and then take out bearings or something.

Scuff it up goos and throw on some JB and I bet you are done with it.

 

[IWELD]

Re: Welding leak in lower unit

My lower unit was damaged when i bought the boat and someone tried to bondo it. Its a 1988 85 hp force motor and I took it to a weld shop. The guy welded it and after returning from the lake we checked the lower and it was still leaking. After a week or so we discovered the lower was leaking where it had been welded. I took it back to the shop and the guy welded some more and we brought her home.After we put the lower unit back on for the uptenth time we found it to still be leaking. The guy at the weld shop says its the oil that is keeping the weld from sealing. My question is is there a way to flush the lower unit so the oil is flushed out? Should I take the unit to a new shop? thanks much ron

This "guy" new better and welded it twice anyway? I would find a new shop. He should have told you it would have to be disassembled to weld it properly. Hope he didn't charge you for a failed repair. If you don't want to have it taken apart then JB weld or some other epoxy paste may be the best you get.

 

[sweezy722]

Re: Welding leak in lower unit

I have had similar problems in the past. I was able to take the unit apart and clean with brake cleaner. I then used Quick Steel and have been fine since. I have actually fixed 2 lower units and a tractor engine block like this where welding would not do the job. I like Quick Steel better than JB Weld. Buy a $4 tube and play with it. You will like it. I like to really press it into the bonding area for a strong bond.

 

[FEFIFOFUM]

Re: Welding leak in lower unit

You say you took it apart...disd you take the lower gear out and how hard is that? I would like to take the lower gear out so I can get a better cleaning but I have been reluctant because I figured I migh get into more than I could handle. Do you think? Thanks everyone for your input, I still am trying to get a ride in before winter