Welding Cast Iron? Repairable...?

[SanJosesSteve]

So you may have heard me screaming in my driveway Saturday as I snapped this thing off. I bet it can't but I'm going to ask the question anyway. Can this be welded back? It sees some force when re-installing. I bet it would just snap back off. Anyone ever repair one?

I got in this boat as I had lost one of the 4 big oval clamp washers. (Or whatever it's called.) Was able to get another locally but it was a slightly different shape. I wasn't seeing the gasket getting squished down as I tightened it......so I kept going. "SNAP!" Followed by a quite animated "Happy Dance" and some colorful language.

Anyone have luck welding theses back on? Thanks, -Steve

[MARTINSR]

I have seen some welded, but damn that's pretty funky. How hard is it to find another intake?

Brian

[SanJosesSteve]

As I'm discovering, GMC 270 manifolds are not all that common. Easier if it were a Chevy, but its not.

While still in "freak-out" mode yesterday, I looked at brand new Chevy crate motors from Speedway and Jegs. Hahahahaha! Now I know why I never see original motors in these trucks when I go to the local shows. Too easy to buy a new one! -Steve

[MARTINSR]

Originally Posted by SanJosesSteve

As I'm discovering, GMC 270 manifolds are not all that common. Easier if it were a Chevy, but its not.

While still in "freak-out" mode yesterday, I looked at brand new Chevy crate motors from Speedway and Jegs. Hahahahaha! Now I know why I never see original motors in these trucks when I go to the local shows. Too easy to buy a new one! -Steve

There are LOTS of swaps started because of something small like this, unless you REALLY want that V8, solve this little problem and go on with life.

Brian

[sack54]

It can be welded ,check out muggy welding rod on Amazon. or you can braze it and hope for the best, Also you can weld with special rod for cast iron heat cast weld, peen weld, bury in sand until cool. All the above will work. I would use muggy weld it is by far easy.
Also try here lot of GMC guys https://oldgmctrucks.infopop.cc/eve?s=272004236&csra=Y

[joedoh]

welding cast is possible, but not by the layperson. its about the prep, the broken part needs to be ground out for penetration, preheated to some crazy temperature, and welded while smoking hot.

sack54, the manifold is clamped to the block in that location, I dont think muggyweld would be a strong enough repair, but I am not that familiar with it. I did research it a bit for the windshield regulator on my 41.

I would guess you can find a 270 GMC intake manifold easily though, because its the exhaust manifolds that crack, so there should be some intake manifolds attached to cracked exhausts. alternatively there is a good aftermarket intake manifold still sold for the 270 that honestly would cost less than welding, but its set up for a four barrel.

[lv2tri2]

Cast can be welded. It may be necessary to surface grind after welding is complete.

[fourspeedwagon]

I recently bought a square body pickup with a chunked off starter mount hole. I called around to several welding shops in my area and more than a couple said they could weld it up and machine it into shape again—- but they all wanted to do it on the on the bench in the shop. I figured out another path because I didn’t want to pull the engine- but it isn’t impossible for them and especially since you can take it in and let them work on it like that.
Good luck —

[b-mac]

https://www.powernationtv.com/episod...request-part-1

Just re-watched this. First 3rd is a decent little video on welding cast using 99 nickel rod.

[Russell Ashley]

I would guess that a good welding shop would charge almost as much as that new four barrel intake would cost. Think of this as a good excuse to get a dual exhaust and four barrel carb setup.

[joedoh]

Originally Posted by b-mac

https://www.powernationtv.com/episod...request-part-1

Just re-watched this. First 3rd is a decent little video on welding cast using 99 nickel rod.

thats a good tip, if I had the equipment I might try it.

[SanJosesSteve]

While waiting for my manifold to come back from the welder I noticed about a tablespoon of coolant puddled in the exposed exhaust port of my head. I wiped it out only to have it reappear a few days later.

I had not seen any milky oil under the filler cap or noticed anything odd out the tail pipe. Truck had been running great up until the manifold gasket failed. Not sure what is going on. Could I have cracked the head when I overtightened and broke the manifold? Is a head gasket/valve job now in my future too? Ugh.... suddenly life is getting complicated in my driveway....Ha!

[SanJosesSteve]

While waiting for my manifold to come back from the welder I noticed about a tablespoon of coolant puddled in the exposed exhaust port of my head. I wiped it out only to have it reappear a few days later.

I had not seen any milky oil under the filler cap or noticed anything odd out the tail pipe. Truck had been running great up until the manifold gasket failed. Not sure what is going on. Could I have cracked the head when I overtightened and broke the manifold? Is a head gasket/valve job now in my future too? Ugh.... suddenly life is getting complicated in my driveway....Ha!

[1project2many]

Use carburetor cleaner and clean the carbon out of the port. Inspect closely for coolant coming in. You may be able to rent a "pressure tester" from Advance Auto to put some pressure on the cooling system.

I looked at Ebay for replacement heads... holy mackeral! Prices range from $600 to $1400. It's hard to imagine how they can be so expensive.

[rustycars63]

I have a head and possible the part of 270 GMC manifold going to scrap . Send reply to rustycars63@gmail.com

[MARTINSR]

Originally Posted by SanJosesSteve

While waiting for my manifold to come back from the welder I noticed about a tablespoon of coolant puddled in the exposed exhaust port of my head. I wiped it out only to have it reappear a few days later.

I had not seen any milky oil under the filler cap or noticed anything odd out the tail pipe. Truck had been running great up until the manifold gasket failed. Not sure what is going on. Could I have cracked the head when I overtightened and broke the manifold? Is a head gasket/valve job now in my future too? Ugh.... suddenly life is getting complicated in my driveway....Ha!

Hope you don't have to go to far, but pulling the head isn't that big of a deal. It's worth it damn it! That truck is worth it!

Brian

[SanJosesSteve]

So $100 later, I have my broken intake manifold back. Seems like the furnace weld technique was the answer. All bolted back up and finally fired up last night.

After a few minutes the motor develops a very LOUD ticking/knocking sound from the top of the motor. All looks to be in order, no exhaust leak evident. Engine seems to run strong, temperature is normal.

After my wife talks me down from the roof...... I pull the fan belt. The noise immediately goes away, engine sounds great. Spinning the fan and generator by hand reveals no rough spots, play or unusual resistance to free spinning.

I replace the fan belt, start it up and the motor is knocking again. LOUD. Fan blade is not striking anything. Could it be the water pump impeller? No leaking visible. Ugh........ Check out my video clip. -Steve
https://youtu.be/LEN59OvK2XM

[mongocanfly]

Sounds like it's gonna be pump or gen based on what you did...it really sounds like the fan hitting something though....

[joedoh]

Originally Posted by SanJosesSteve

reveals no rough spots, play or unusual resistance to free spinning.

dont forget the fan blades will change shape slightly when turning at speed, I put an overflow tank what I thought was an appropriate distance from the fan, started it and the airflow changed the blade shape and poked a hole in the overflow. lesson learned.