Welding question

[rfcom]

My EGT gauge came with a steel fitting that you can weld into a pipe and then thread the probe into. Can I weld it into the elbow between the turbo and the downpipe or should I just drill and tap the elbow? The elbow appears to be cast iron. I would be using a mig with flux core steel wire. TIA



Jim

 

[RHARVEY]

That elbow is cast... I have heard of people that can weld it but I would not try it. There are kits that have the probe and a screw clamp that goes around the exhaust system.

I prefer the 'pre' turbo drill and tap into the exhaust manifold method myself. This way I know exactly what the EGT's are without having to do the math. The math is not rocket science but I want to know at a glance how hot they are...



Rick

 

[Joseph Donnelly]

The elbow is thick enough--not generous but a bit over marginal--to drill and tap it directly. You also need not worrry about shavings since it is post turbo. Add 10 degrees F per pound of boost to arrive at the pre-turbo temperature. For example, at 900 deg elbow and 20 psi, you get 900 + 20(10) = 1100 deg.

 

[countryboy]

I don't know which is best to weld or drill and tap but I do know you can't weld it with flux core wire,the only way to weld cast is with an arc welder with a special rod you have to heat the piece your welding with an acetalyne torch when it gets red hot strike your arc then ping it with a chiping hammer. Cast is tough to weld because the weld always cracks as it cools.

 

[rfcom]

Thanks guys.

I guess I'll be tapping it then. This place is well worth the price of admission.



Jim

 

[Case500D]

Jim,



Just a thought, but have you considered brazing it in? I have seen several cast pieces brazed back together that worked fine. A friend brazed his pyrometer probe in his Power Stroke and it works great.



Jeremy

 

[JTMcCracken]

It can be successfully welded with TIG, stick or oxy-acytelene, by someone experienced with cast iron, normally using a very high nickle content filler. Lots of sound cast iron welds have been made with stainless filler but nickle is widely available these days. You might have to do some looking to find someone, depending on how big of a town you live in. Pre heat and slow cooling is required. It would be easier and quicker for most folks to tap it. JTMcC

 

[Boomer II]

Nickle rod or brass, tapping would be the route I'd go and I can weld cast.

 

[mschoenheider]

You can weld to the cast with a stick welder and some rod you pick up at Ace. If you want to preheat the cast iron, just drive your truck. It's pretty easy to get your exhaust hot.

Mark

 

[Andy Perreault]

I'm not sure if all the exhaust elbows are the same, but on my '97, there is a round flat spot about 1/2" diameter cast into the elbow on the side of the elbow. It has a dimple in the center for centering a drill bit. It looks like Cummins had pre-planned a drill-and-tap location for us. That's where I installed my EGT probe, and it's been there since '97 with no problems. There's plenty of thickness there for tapping the threads.

Andy

 

[rkressg]

Tap it

Welding on cast is a PITA, it likes to spit at you Oo.