Welding Advice

[ALEX 98 1 Cars]

I had one of these welded up in it's usual place where they start to crack a few years ago and it did the trick perfectly.

I have another manifold that's starting to go, but the guy who did the last one has left the place where I work.

His replacement isn't sure what to use to weld it up as it's cast.

 

I remember something about using dissimilar metal welding rods and heating it up first before welding it.

Anyone managed to get there's welded, if so what welding rods did you use?

[Flix 0]

You can get rods specifically for cast iron.

The manifold should be pre-heated before welding and also cooled down slowly to avoid cracking.

We have bins of vermiculite to put components in after welding.

[DamirGTI 342]

I did a few myself you'll need nickel welding rods for this job but preparation is most important part , it is essential that you warm up the manifold prior to welding , keep it warm during the welding , and most-most important few hours after the welding as well (so that it cools down slowly/gently .. if done too fast it'll crack straight away ..)

 

So first clean it toughly around the crack , take the grinder and make a slight V groove on top of the crack , then it's up to you how will you heat it up ,i usually fit it in the oven and turn on the temp on the maxi value for say 2-3 hours ,the more you can heat it up the better, then start welding immediately while it's still hot (i keep on preheating the manifold with a blow torch while im welding in order to keep the temp at constant level) but do practice first on the scrap part so that you can learn how to handle/weld with nickel rods (they burn rather fast and need to keep constant clearance in between the rod tip and the workpiece of say 5mm during the welding..)

 

Afterwards , when you're done with the welding , you'll need to cool it down one step at a time very gently (cooling down period is critical !!) i use to wrap the manifold straight after the welding in aluminium foil , then i fit it inside the bucket filled with ash (could use fine builders sand as well me thinks) fill it up with ash all the way so that the ash covers the manifold completely - back into the oven and keep it on warm as long as possible (say 6hours) then take it out and leave it in the ash bucket for additional 12/24hours, let it cool down slowly ..

 

But apart from welding “metal spraying” (metal powder sprayed with oxyacetylene heated torch) is by far the best option for repairing this crack stuff on the cast iron parts .

 

Damir

Edited January 28, 2009 by DamirGTI

[GTI6BOY 29]

then i fit it inside the bucket filled with ash (could use fine builders sand as well me thinks) fill it up with ash all the way so that the ash covers the manifold completely - back into the oven

 

You must have a Big f*** Off oven...lol

[ALEX 98 1 Cars]

I've bought a pack of 5 cast Iron welding rods off Ebay for £6.50.

I'll not be doing the welding I'm going to leave it up to someone else.

He did say he will have to heat it up first to do it.

[DamirGTI 342]

You must have a Big f*** Off oven...lol

 

yes , it's an big old grandma's oven ! and it heats up parts like pure hell

 

But using the bucket as such is not essential could use anything really in which you can stick the manifold/ash and then all that inside the oven for baking job

 

Damir