Welding cast aluminum block - correctly
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  1. #1

    Welding cast aluminum block - correctly

    I'm currently in a debate with a "welder" who had welded a guys mounting points on his block due to cracking. His customers (after only one month) block ripped the bolts out of the repaired area, and he refused to pay for what happened. This is where I stepped in.



    From what it looks like (and what I've been told), he used a TIG-pulse welding configuration and laid pass after pass, only letting the block air cool to room temperature. He cut out 1/4 inch of material to weld the crack at its root, so there was at the very least 1/4 of material welded onto this (it looks like it was ground down as well). The block was not sent through a hot isostatic process, nor was it put in an oven prior to, or even after (he could have even used vermiculite...) doing any and all of his passes.

    This engine weighs approximately 300lbs and in a FWD configuration, has a lot of torque and engine movement. I feel this weld was not done to an acceptable standard whatsoever, and he should be back charged for his shoddy workmanship. I feel that his work is the direct cause of the malfunction of the rear engine mount (leading it to be ripped out of the block), as this has NEVER happened on any block that has not had to have been repaired.

    From what I've been told from several veteran welders, is that the block should have been replaced in the first place. If a repair WAS attempted, MAPP/Propain gas torch and special filler metals are preferred over TIG because higher tensile strength can be achived. The block should have been prepped properly (HIP, heat oven cooling).

    Your opinions on the matter, along with references to sources of information would be very appreciated.

    Thanks guys/girls.

  2. #2
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    Re: Welding cast aluminum block - correctly

    Why did the welder have to repair the block to begin with? I am assuming that it ripped the bolts out once before? Or was the engine dropped on the mount or something?

    If it cracked due to torque originally- well, of course it did it again.

    In that case it isn't the welder's fault, it is the customer's for deciding that rather than look for a fix for a design that has proven inadequate, they would just have it welded up and try again.

    The welder did what was asked and there's nothing at all wrong with the procedure he used, unfortunately what SHOULD have happened is someone should have stopped and said "ok, so this mounting point failed, does it make sense to weld it up and jam the motor back in, or should we engineer something that will prevent this from happening in the future?"

    The problem appears to be that the motor either does not have a 3rd engine mount, or the 3rd mount needs to be stiffer.

    You can expect a high torque transverse motor to tear up engine mounts real bad without a good, stiff 3rd mount that ties the top of the motor to the firewall.

  3. #3
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    Re: Welding cast aluminum block - correctly

    Quote Originally Posted by Code-Red View Post
    I'm currently in a debate with a "welder" who had welded a guys mounting points on his block due to cracking. His customers (after only one month) block ripped the bolts out of the repaired area, and he refused to pay for what happened. This is where I stepped in. A customer complaint is not a "debate", it's a formal complaint that needs to be formally resolved. Did the weldor get paid, and the customer is requesting a refund, or is the weldor requesting customer payment?

    From what it looks like (and what I've been told), he used a TIG-pulse welding From all the spatter and globs surrounding the repair area in your photo, I would have assumed the bosses were built up using a MIG configuration and laid pass after pass, only letting the block air cool to room temperature. He cut out 1/4 inch of material to weld the crack at its root, so there was at the very least 1/4 of material welded onto this (it looks like it was ground down as well). I would hope so The block was not sent through a hot isostatic process, nor was it put in an oven prior to, or even after (he could have even used vermiculite...) doing any and all of his passes. As far as I can tell Hot Isostatic Pressing is a manufacturing technology applicable to a raw unfinished casting, not a process applicable to a dimensionally finished part. Do you have any idea what you are talking about, or is this something you read about in an engineering book? Seriously?

    This engine weighs approximately 300lbs and in a FWD configuration, has a lot of torque and engine movement. I feel this weld was not done to an acceptable standard whatsoever, and he should be back charged for his shoddy workmanship. Did the the weldor guarantee his repair indestructible when the block left the shop? Are you suing him, or just refusing payment? If there was a business agreement - He needs to quit crying and pay his bill. Next time, take it to a better weldorI feel that his work is the direct cause of the malfunction of the rear engine mount (leading it to be ripped out of the block), as this has NEVER happened on any block that has not had to have been repaired. So you're saying "it broke again because it broke the first time, and if it had never broken before it wouldn't be broken now" - Well duh!

    From what I've been told from several veteran welders, is that the block should have been replaced in the first place. Replacement is almost always preferable to repair If a repair WAS attempted, MAPP/Propain gas torch and special filler metals are preferred over TIG because higher tensile strength can be achived. Do they have TIG experience with Aluminum alloys? It sounds like they've been watching "miracle braze" commercials on late night TV.. The block should have been prepped properly (HIP, heat oven cooling).I don't know what your fascination with HIP is, extended oven cooling is a cast iron repair procedure, not necessary for AL. Prep would be a thorough chemical degreasing, mechanical removal of damaged area, preheat with torch, and probably a "clean up " pass to remove oil contamination. If you want to know the correct filler for a 356 casting in a high temp application, that was discussed two days ago.

    Your opinions on the matter, along with references to sources of information would be very appreciated.

    Thanks guys/girls.
    My opinion is in red. If you want references for a legal case, hire a lawyer - that's what they get paid for.
    Last edited by Hephaestus; 08-22-2008 at 05:04 PM.
    -Matt
    ------------------------------------------

  4. #4
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    Re: Welding cast aluminum block - correctly

    Not the best pic to work from but if i 'read' it right the repaired areas are the bits i've highlighted in red? The rest of the area has too much pattina to have been repaired recently
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    Matt, the 'spatter' i believe is casting flash/debris

    Code-Red,
    As the others have said if the stock part broke then repairing it without finding out the root cause is unlikely to end well- as happened here. A tired engine mount for example would allow excess movement causing problems. If failure of this area is rare/unheard of AND everything else checked out then maybe this block had a casting flaw that led to the initial failure. If this sort of failure is 'known' then obviously some re-engineering is needed

    The visible damage to the edge of the bolt holes makes me wonder if the bolts were loose

    As to the repair itself,...
    You can't weld over a crack to fix it- it WILL grow back. Removing enough material to eliminiate the crack and then building up fresh metal via welding is what i would do on this type of repair. Some interpass temperature control is a good idea as it involves a lot of welding in a small area. Pulse isn't what i would use but it can help with regardes to temperature control

    Air cooling is not a problem with cast Al. No preheat would be in this situation but i find it hard believe that none was used, getting enough heat input from the arc would be an issue without it- the block would likely crack at the adjacent webs immediatly. For cast Al the trick is to keep the temperature gradient through the part sensible.

    We can't talk other aspects of the repair without more infomation- more (better) pics would help, did it crack along the repair boundary or elsewhere? Did you find out what filler was used and the alloy the block was cast from?

    A comment Matt made has me thinking,... You're not a lawer yourself are you? If not then i sincerely apologise for such a nasty insult
    Last edited by hotrodder; 08-22-2008 at 09:23 PM.

  5. #5

    Re: Welding cast aluminum block - correctly

    Quote Originally Posted by hotrodder View Post
    You can't weld over a crack to fix it- it WILL grow back.
    That is much too broad of a statement to be substantiated. I have welded over hundreds of cracks in my days, each one given a guarantee that if it breaks again, I'll fix it at no charge... and I've not had one come back yet. Do consider that many welding codes will allow partial joint penetration welds, which are effectively like welding over a crack without getting full penetration.
    Quote Originally Posted by hotrodder View Post
    Air cooling is not a problem with cast Al. No preheat would be in this situation but i find it hard believe that none was used, getting enough heat input from the arc would be an issue without it- the block would likely crack at the adjacent webs immediatly. For cast Al the trick is to keep the temperature gradient through the part sensible.
    All cast aluminum is not created equally.

    My thoughts on this topic:
    So, one welder's fix broke? Big deal? So if somebody brought it to you to repair it this time, just do a better job than the guy before you...and stay out of the dealings between the car owner and the first guy that did the job.

  6. #6
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    Re: Welding cast aluminum block - correctly

    Quote Originally Posted by hotrodder View Post
    You can't weld over a crack to fix it- it WILL grow back.
    Quote Originally Posted by Engloid View Post
    That is much too broad of a statement to be substantiated. I have welded over hundreds of cracks in my days, each one given a guarantee that if it breaks again, I'll fix it at no charge... and I've not had one come back yet. Do consider that many welding codes will allow partial joint penetration welds, which are effectively like welding over a crack without getting full penetration.
    Taken out of context, then yes, i agree but given that this thread is about an engine block with cracked mounts...

    While there's plenty of applications that call for partial pen welds it's a bit of a stretch to compare them to a part that's cracked through fatigue/overload IMO

    Quote Originally Posted by Engloid View Post
    All cast aluminum is not created equally.
    Very true but as we don't know the alloys involved yet...
    Quote Originally Posted by Engloid View Post
    My thoughts on this topic:
    So, one welder's fix broke? Big deal? So if somebody brought it to you to repair it this time, just do a better job than the guy before you...and stay out of the dealings between the car owner and the first guy that did the job.
    After re-reading the OP i'm thinking that Code-Red is representing the customer or acting as a mediator

  7. #7

    Re: Welding cast aluminum block - correctly

    Quote Originally Posted by hotrodder View Post
    Very true but as we don't know the alloys involved yet...
    ..and probably never will. That's the bad thing about cast. You rarely know exactly what it is you're welding.

    Quote Originally Posted by hotrodder View Post
    After re-reading the OP i'm thinking that Code-Red is representing the customer or acting as a mediator
    Yes, which is rarely a good idea. You make one customer a good friend, but you have a competitor that is a bad enemy..and can harm you through word of mouth more than the one customer can help you.

  8. #8
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    Re: Welding cast aluminum block - correctly

    hotrodder,

    I'm sure you noticed Code-Red never responded to your question "You're not a lawer yourself are you?". If not, quite possibly a legal assistant doing a little research and didn't expect any of the "guys/girls" to catch on.
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