welding cast aluminum

[eurolarva]

I have an old outboard with a cast aluminum power head. Because of some bad advise I took the exhaust gaskets off and three screws broke. When I tried to use and easy out and pb blaster the easy out broke. The original screws were 1/4 20. I have attempted to use JB Weld and re tap however I can not get the torque on these screws tight enough before the JB weld strips out. The walls around the screws are very thin now. Is it possible to fill these holes with an aluminum type welder and then retap them? The motor still blows 145 compression and runs great. I have seen welding rods for aluminum at Home Depot that will melt at 400 degrees and require either mep gas or oxygen to get them hot enough to melt. Is this a solution?

 

[Trent]

Re: welding cast aluminum

Dont even look at the Home Depot stuff. Its junk in your situation. You got enough metal for a helicoil? If you have to weld..Find a welder that knows what he is doing! Sounds to me your at a machine shop trip.

 

[Homerr]

Re: welding cast aluminum

I wouldn't take the chance... take it to a pro.<br /><br />I had some exhaust manifolds welded some time ago.. the damage was less than $30.<br /><br />Welding cast is a big pain in the back-side. You have to keep 'peening' it to relieve the metal while you weld. You might even give the welder a tip in the end... Just ask about their experience with welding cast metal! <br /><br />Sometimes you get lucky with the epoxy fixes.<br /><br /><br />H.

 

[Peter J Fraser]

Re: welding cast aluminum

A good sheetmetal shop with a TIG welder is what I'd be looking for.<br />You need someone who can weld light gauge stuff to tackle that and do it well.<br /><br />Peter

 

[one more cast]

Re: welding cast aluminum

I repaired a stripped out spark plug hole in an aluminum head about 30 years ago in shop class by boring out the hole , making an aluminum plug to fit the hole and welding it in. Then drill and tap to the correct size. It is still in use today.

 

[Kenneth Brown]

Re: welding cast aluminum

Rgeardless of how you fix it I have advice. After the repair DON'T use a bolt. Use a stud. The stud will go in to a sufficent depth and torque. When you put the nut on the stud it will pull differently and not strip the hole again.

 

[eurolarva]

Re: welding cast aluminum

Because of the design of the cover I can not use a stud. I can not tighten the nut because the cover frame gets in the way. I cant find any welder open today so I will try on monday. Thanks for the replies

 

[Peter J Fraser]

Re: welding cast aluminum

If you are stuck with having to use a bolt, if after you have welded up the hole do you have enough metal thickness around the hole to allow for a HELICOIL insert to be installed as previously posted.<br />If you can the thread will be much stronger than without.<br />Regards<br /><br />Peter

 

[eurolarva]

Re: welding cast aluminum

There is not much room. The screw goes into an area that is like a circular stud that has only about a 1/2 inch diameter. I may be able to have a stud installed and use washers to build up the area in order to put a nut on the outside. I will see what the welder recommends. The motor is old but it runs good and If the cost is under a hundred bucks I will go ahead with it.

 

[eurolarva]

Re: welding cast aluminum

Well I took the powerhead to the welder and they said they can not weld it. He gave me some pointers on JB weld about making sure all the surfaces are ground and clean. I am going to try that route again. He said the welding rods from Home depot might work however they are mostly zinc and usually do not have the strength needed for screws.

 

[Peter J Fraser]

Re: welding cast aluminum

Try a sheetmetal shop eurolava. <br />They are usually very experienced with light gauge materials or if you have an airport nearby see if there is an airframe / engine shop. Everything can be repaired.<br /><br />Peter

 

[Rainmaker]

Re: welding cast aluminum

Since the motor runs fine I would give the Home Depot stuff a shot. Use Locktite on the bolts and reduce the torque a little bit.<br /><br />Worth a try.mike

 

[Bigfun]

Re: welding cast aluminum

Could you possibly weld our glue a threaded stud into the holes then attach the manifold with nuts.