Cracked mixer elbow

I have a Westerbeke WMD 7.7 with a crack in the exhaust mixer elbow . I'm guessing this is cast iron . Has anybody had any luck welding something this bad ?
I don't think I will be lucky enough to get this from tractor parts house like I got my fresh water pump from .
I know somebody that might could fab one up , but I'm betting this ain't standard pipe threads . Any suggestions other than a new one from Westerbeke distributor?

Cast iron is welded all the time. It takes a welder with that experience. The best method, after grinding out the crack, is to preheat the piece, the hotter the better, but under 1200°. Welding shops often have an oven for preheating. The point in preheating is if the whole part is hot, it cools more slowly after welding. Also, after welding the part is wrapped in an insulating blanket or buried in sand. In my day we used asbestos blankets or a tub filled with loose asbestos.
Welding is done in short beads, about an inch long. I usually weld an inch, skip an inch and weld the next segment in the opposite direction. The heat from welding induces stresses and long continuous welds almost always cause cracking. Skip welding keeps the temps lower.
Foundries often weld new castings to fix flaws. It really is no big deal to a professional welder.
Brazing can be done, but doesn't hold as well and on a rigid diesel exhaust would crack again.

Thanks Lepke . I'm not sure the guy I know could handle the welding but I know he could fab up the whole piece. Would 304 heavy wall stainless steel work ? He builds custom exhaust for hot rods all the time . I'm in fresh water.

I doubt if you can weld that crack and have it last any time. I would have your guy fab a new mixer out of schedule 40 SS. It isn't that difficult and you can use the existing one for a pattern.

But is it self draining and do you have enough height above the water line to limit sea water backing up. If you are going to have a new one fabricated, now is the time to address those issues.

David

I'm pretty sure this is the replacement from Westerbeke . I'm thinking I can just take off the end cap on heat exchanger and unscrew this . The internet says it's $ 220 . If that's right it's not ridiculous .

Shouldn't water be shooting out of the crack when running? I'm getting plenty of water out of the exhaust . The water injection point is lower than this crack, but shouldn't there be raw water also here or is it just exhaust fumes? I was just curious.

If all you are getting out the crack is exhaust and not water, I might try drill stopping the crack and marine tex it or JB weld it.

Put a CO2 detector next to it after tbe repair, sniff well and see what you have...bubble test it too.

Other than that, the $200 or so replacemenrt seems fair enough.

Thanks for the info everyone . I've got some JB weld on my elbow on the Perkins but it's just a small hole .
I guess when I try to sell the boat again I won't be able to hide anything, all my mistakes are right here on the TF for everyone to see . It's just a boat and I'm trying to keep it running. The wife says if we ever get another one she'll be the one to pick it out

Replaced my cast iron Northern Lights' cracked elbow with a new one. NL did not come through with their stainless steel replacement in time. Same cost, approx $250. Mine obviously had been leaking for quite some time but never enough to leave a puddle in the pan.

You can certainly weld a simple shape like this one, given the preheat oven, the welder and the knowledge. More complex shapes can be stitched together(!). I've welded cast iron on really simple shapes using the correct rods. I welded a new steel end on an 1840's special cast iron hinge for a folding Melodian; ground the weld metal to shape and only the lack of the sand-cast texture is the give-away.

Stick Electrodes - Welding Cast Iron

I removed this today . It was worse than I thought. The inside had deteriorated to only 1/8" thick on the side that was cracked.The repairs on William are whopping my ass this year.

That elbow is toast, and not a good place to try and save a buck by repairing.
It's also an indication that the OEM part is not up to snuff.
I would have one fabricated of heavy wall 316 SS, regardless of the price.
Adding a support bracket might be beneficial too.

kapnd said:

That elbow is toast, and not a good place to try and save a buck by repairing.
It's also an indication that the OEM part is not up to snuff.
I would have one fabricated of heavy wall 316 SS, regardless of the price.
Adding a support bracket might be beneficial too.

Click to expand...

I busted it up getting it off . I drove a big screwdriver into the crack and split the one side off. To install the new one I'll have to dismantle more of the generator. There's not enough room for the new elbow to rotate to tighten.
I'm in fresh water and not sure I need stainless, but I'll get it priced out from the fab guy. A new OEM part will probably last longer than me .

kapnd said:

It's also an indication that the OEM part is not up to snuff.
.

Click to expand...

I am not ready to agree on that point. I have what looks like the same elbow on my 1983 Westerbeke. That ain't bad service.

Ok I decided to replace the 6" nipple between exhaust box and mixer elbow. It also has some deterioration.The thing is married to the box . I can't get it to budge with the room I have , even with a long cheater pipe. You can see the pipe is starting to collapse. The motor mounts are letting the engine flex too much . What about cutting the pipe off flush with the box and maybe cutting a couple slits in the ID of the piece of pipe that's left in the box an try to collapse it to get it out . Anybody ever done this ?

Yes. Room to work is desirable, though. Cut the nipple off leaving enough to swat the remains 'with authority' to peel it inwards. You may have to - may wish to - cut a slice out: two parallel cuts, then pop/peel the slice inwards. The rest should give up easily.

Another idea is to cut the bad end off the pipe , screw another piece of pipe in the elbow , slide a piece of
1-5/8" wet exhaust over both and clamp with two or three clamps on each end . The two pieces of pipe would be butted up to each other .

Greetings,
Mr. PM. Post #16...That sounds, to me to be the easiest, most straight forward solution IF the rubber hose will not catch fire and burn...

RT Firefly said:

Greetings,
Mr. PM. Post #16...That sounds, to me to be the easiest, most straight forward solution IF the rubber hose will not catch fire and burn...

Click to expand...

There is hot water and exhaust right here right? I know it's taking the easy way out and there is a better way but I'm whopped after today ,bruised and cut to pieces . If it's a bad idea please say so .

Greetings,
Mr. PM. Ahhh...So it's "downstream" of the water injection? If so, seems like a perfect solution. Simple and elegant. Now have that cold beverage you so richly deserve. Well done!

RT Firefly said:

Greetings,
Mr. PM. Ahhh...So it's "downstream" of the water injection? If so, seems like a perfect solution. Simple and elegant. Now have that cold beverage you so richly deserve. Well done!

Click to expand...

No this is right before the water injection about 3"before the elbow and water injection ,but I was thinking that there was water here also. I'm thinking now the exhaust goes through the center of the tank with coolent on each side . Is the water inecton the only water that gets in the exhaust ? If this is the case and this is just dry hot air I'm gonna go back and do post #14 .

Greetings,
Mr. PM. Given the pipe is before the water injection, I fear, #14 is your only option unless you can find a heat/fireproof coupling. Dang! So close...

Another issue that kept me awake last night . I don't have enough room to turn the new 90 degree elbow because of a deck beam . Can I use a union here ? It would before the elbow .

Yes, you can use an iron or steel union. Just wrap it with insulation as it will not be cooled. 2" fiberglass tape will work as insul.

Another option is to put a 90deg elbow on outlet pipe, then a short nipple, then screw on mixer. It will rotate in a different plane and you might have clearance there.

Worst case would be to unbolt the manifold from cylinder head and then you can screw on the mixer on the bench.

Greetings,
Mr. PM. Union? Now you're back to where you started trying to get that bent section of pipe out...I know there's a heat proof coupling out there. I just don't know what to call it or where to find it. Surely a member with industrial experience can say...."This is what will work". Alas, it's not me....

There certainly are bolted, flanged connections for exhaust systems. The Perkins 6.354's and the Northern Lights genset have exhaust elbows bolted to the heat exchanger so bolts and gaskets are doable.

It's cheaper for the mfr to thread the exhaust elbow to a pipe nipple and then to the heat exchanger, and gives the installer flexibility to mount the exhaust system in various ways. My Yanmar 3GM30 in the sailboat had the exhaust elbow mounted well above the engine since the engine was so low within the boat. (My nipple broke and I had to peel the remains out of the elbow.)

I fear you'd be hard pressed to have a flange welded to your broken pipe nipple while in the boat, and you said the nipple was in poor shape.

To get room to work, can you not unbolt the genset from its mounting and turn it in place? (Our genset sits on a flat plywood base and it would be possible to turn it.)

I've got about 5 hrs in this piece of pipe , but it's out now and I can fix it right .

Beer time!

Dang! Sometimes we kick butt....sometimes we get our butts kicked.

Either way, it beats not having a boat! Nice work! You're halfway there.

Cheers!

Well done. Take the rest of the day off.

1. Pipe wrench
2. PB blaster
3. Pipe wrench with 2ft cheater pipe
4. Sawzall (cut off pipe and cut two grooves in pipe)
5 . Cold chisel and 4 pound persuader ( busted out the piece)
6 . Two crescent wrenches ( one to grip the pipe the other to lock onto the other to bend pipe inwards ) .
7 . Two pairs vice grips one large one small to grip what was left of the pipe and twist it out.
8 . Six pack beer between Joy and I
9 . Filets on grill later with full bottle of La Crema Pinot Noir .
10. Lights out 8:00 pm