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CX stainless steel engine mount fix with mig

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So long story short, I need to cut and reweld some tabs on my engine mount in addition to fixing a split.

 

I intelligently managed to pile nearly everything onto my welder as I pulled the car apart, I have access to the bottle and the controls, but it is stuck up against a wall and my car is trapping it in so I can't easily replace the wire.

 

According to the listing, the mounts are stainless steel. 

 

How bad would it be to weld it together with my current mild steel mig setup? I know I will loose the stainless property and I am perfectly fine with that, not sure why it was there in the first place to be honest.

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Posted (edited)

Well, you can weld it and it will hold, the beads will rust but you know that. Are these after market engine mounts? I've never heard of SS being used for that purpose, SS isn't know for it's strength, it's hard but not that strong. I would turn up the juice and make sure you were really getting good penetration.

An engine mount is a crucial, highly stressed assembly, can't say I'm very comfortable giving you this advise, personally I would re make them out of cold rolled plate. Better that then having that doubt every time you push the car hard that the welds might crack.

Edited by grannyknot

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They are aftermarket for sure. Not sure why they do it, but that company makes all of them out of stainless and I would even venture to say all of them are fusion welded so limited filler. 

 

The temptation is there to just do it that way. Turn it on max and just do what I need to do, but what you say is correct it is an engine mount and going half ass because I don't want to move a couple hundred pounds is lazy. If I had the room I definitely would make my own, I've done it before, but half my fabrication tools are on racks that are behind my jacked up car that I pushed far in to give myself some space to work with the door closed. Not to mention the engine is hanging via hoist in front of the car so short of pulling it back out I don't have a way of moving the car.

 

I asked on a welding section in another forum and was told that apparently welding with non stainless filler wire will pull chromium and nickel from the stainless and cause carbides that will fracture the weld, I think the consensus was to at least use a stainless filler wire. Apparently using the regular 75% Argon 25% CO2 will only hurt the anti-rust properties and not affect the viability of the weld.

 

Alternatively someone else said that it isn't worth any effort as all the stuff from ebay/china are not as advertised and without a decent analysis you couldn't take the material at what is listed and to just go ahead and weld it with whatever and keep an eye on it.

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I am about 50% sure that I will be doing that, stainless wire with C25, unless the welding shop can cut me a deal on renting a bottle of trigas over the weekend or something.

 

I have been so self sufficient for putting things together that people borrow my welder to do stuff, and I only had one welding buddy who moved earlier this year. I'll have to ask the welding shop if they have any recommendations, at the very least I can tac this thing in and have someone finish it off if I can find someone.

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Sounds like plan, if you do end up doing it yourself make sure you have some scrap ss on hand to practice on, very different metal than mild steel.  It heats up really fast, hangs onto the heat much longer and is so easy to blow holes in.

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For anyone looking on the topic.

 

Tank costs about 150-180 to "buy" (unless you have your own tank that you want to keep, most places will swap tanks out with filled ones so you never really keep the same tank) and about 70 to rent for the year.

 

I ended up borrowing a tank from a supplier, he said if I could get it to him on monday he wouldn't charge me for renting the tank over the weekend, just have to pay for the fill. It was about 60-70 for helistar which is their helium, argon, co2 or what not blend.

 

So I bought 308L wire and went to town. Stainless does require you to be quite a bit closer to your welding material, and it seems like it likes to go pretty slow or at least run with more amperage, other then that I didn't notice too much of a difference. The way the mounts were moved made it feel flimsy even with triple pass welds whenever I could, so I ended up welding in some mild steel reinforcements with the stainless mig setup.

 

One thing to keep note and this applies to all welding is that heat really is a consideration. I had the gap for the bushing shrink enough to the point where the bushing wouldn't fit anymore, so I ended up hammering it back out. Afterwards I employed an all thread with some correctly spaced nuts to help keep the parts apart while I put in the reinforcements.

 

Thanks grannyknot for letting me bounce my concerns and your advice.

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