L2501 - broke the exhaust manifold

muddhogg

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Kubota L2501DT, Ford 3910
May 20, 2018
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I'm good at breaking things.

Was clearing up some woods today, pushing over some small trees, etc... and then, whammo! I was backing up after pushing a small tree and the tree decided it would attack me and as I backed up it snuck up in the tractor got hung on the exhaust tip and cracked the manifold. How in the world can such a small tree break this steel. Oh well, it did. Tractor got LOUD immediately so I figured something with the exhaust, sure enough. At least it didn't get the radiator/fan.

Thinking I might just tack weld it, would you do that? vs buying another manifold.


manifold1.jpg


manifold2.jpg
 

GreensvilleJay

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easy, it's called 'leverage' ( guy who can move the Earth thing.....)

repair is simple
remove from engine
lightly 'V' the break lines
bolt to steel plate
BRAZE the joint
WAIT until STONE COLD before removing from plate
install onto engine

takes 1-2 hours

or.....

order a new one
and open wallet wide ???
 
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DustyRusty

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Not worth messing with it. Just buy a new one and be done with it once. Cast iron isn't that easy to weld and it will be like a dog chasing his tail. A new manifold is $201.36 and a new manifold gasket is $15.49. Just have your local dealer order it on his regular parts order so there should be no shipping expense, just the cost of the parts.


MANIFOLD, EXHAUS
Part # 1G866-12310
-MANIFOLD(EXHAUST)
$201.36
 
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rbargeron

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If you're in the woods a lot maybe a low-routed exhaust would be an answer. Another idea would be to cut the muffler pipe above the bolted flange and install a "weak" coupling of thin tubing. It could even be an inside slip-over. Something that can buckle more easily, sacrificing itself and saving the exhaust manifold.

GreesnsvilleJay's idea is good - maybe vee it out, bolt the pieces securely back on with the old gasket, and pile up the vee groove with JBweld epoxy.

Or maybe go full rock-bouncer and weld some struts back to the ROPS ! I'll shut up now. Dick B.
 
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jimh406

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To make a good repair, I think you have to take it off. It looks like it might take a couple of gaskets. I'm sure that part gets really hot. I'd replace it with new. I don't think JB Weld is a long term fix, but maybe it is.

I don't think there are enough guards to put on the tractor to stop everything from being broken. I have filter guards, but there are other things like tie-rods etc that you can break. So, I suggest just being more careful ... from now on, and count it as a learning experience.
 
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muddhogg

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To make a good repair, I think you have to take it off. It looks like it might take a couple of gaskets. I'm sure that part gets really hot. I'd replace it with new. I don't think JB Weld is a long term fix, but maybe it is.

I don't think there are enough guards to put on the tractor to stop everything from being broken. I have filter guards, but there are other things like tie-rods etc that you can break. So, I suggest just being more careful ... from now on, and count it as a learning experience.
Yeah, I just ordered the manifold. Funny thing is when I saw what I did Im thinking, heck I’ll straight pipe this sucker, but I’m getting older and prefer the silence. :D

I guess I’m going to have to road armor this thing like Mad Max…
 
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muddhogg

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May 20, 2018
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To make a good repair, I think you have to take it off. It looks like it might take a couple of gaskets. I'm sure that part gets really hot. I'd replace it with new. I don't think JB Weld is a long term fix, but maybe it is.

I don't think there are enough guards to put on the tractor to stop everything from being broken. I have filter guards, but there are other things like tie-rods etc that you can break. So, I suggest just being more careful ... from now on, and count it as a learning experience.
Bad thing is, I thought I was being very careful. Guess I was going forward just not backing up. :(
 
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fried1765

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If you're in the woods a lot maybe a low-routed exhaust would be an answer. Another idea would be to cut the muffler pipe above the bolted flange and install a "weak" coupling of thin tubing. It could even be an inside slip-over. Something that can buckle more easily, sacrificing itself and saving the exhaust manifold.

GreesnsvilleJay's idea is good - maybe vee it out, bolt the pieces securely back on with the old gasket, and pile up the vee groove with JBweld epoxy.

Or maybe go full rock-bouncer and weld some struts back to the ROPS ! I'll shut up now. Dick B.
In post #2, GreensvilleJay actually recommended brazing....not JB Weld.
 

Yooper

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Problem with welding cast is you don’t know what the composition of the metal is, especially the amount of carbon. If it broke that easy your chances of a successful weld is pretty low. Add in the heat cycling and eventually it will fail. You made the right call!
 
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rbargeron

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Without getting too far into Metalurgy 101, suffice it to say that cast iron's most identifying trait is it has WAY too much carbon to form anything strong - like steel for instance which is between 0.2 and 0.95 percent carbon. Yes, the whole vast worldwide steel industry lives between zero and one percent carbon. (look up "iron-carbide diagram"). Dead-soft steel has around 0.2 % C and the highest-zoot tool steels have around 0.95% C.

Cast irons typically contain 4 to 6 percent carbon. The excess C forms tiny islands in the grain structure, greatly reducing tensile strength. Its cheap and easy to make in odd shapes, so its used for lots of things. Just don't pull on it too hard. Most cast iron is 3 or 4 times weaker in tension than in compression - like concrete. Welding it causes widespread thermal micro-cracks all around the area that can't be eliminated without re-melting the whole thing. The part is always compromised after that.

There are lower-carbon alloys like ductile or malleable iron which are stronger but also more expen$ive to make. Sorry for the lecture, I used to teach this stuff to engineering students, and I fully recognize "a little knowledge is a dangerous thing". There are a lot of people sticking cast iron back together thinking they are "welding" it - but in almost all cases it's just a bigger bag of invisible internal cracks with way less than original strength. Dick B.
 
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TedWoodbutcher

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Brazing would probably not hold with the thermal cycling. Too much heat might warp flanges and end up with gasket leaks. I wonder abut salvage yard options. Replacing new probably best.
 
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muddhogg

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Without getting too far into Metalurgy 101, suffice it to say that cast iron's most identifying trait is it has WAY too much carbon to form anything strong - like steel for instance which is between 0.2 and 0.95 percent carbon. Yes, the whole vast worldwide steel industry lives between zero and one percent carbon. (look up "iron-carbide diagram"). Dead-soft steel has around 0.2 % C and the highest-zoot tool steels have around 0.95% C.

Cast irons typically contain 4 to 6 percent carbon. The excess C forms tiny islands in the grain structure, greatly reducing tensile strength. Its cheap and easy to make in odd shapes, so its used for lots of things. Just don't pull on it too hard. Most cast iron is 3 or 4 times weaker in tension than in compression - like concrete. Welding it causes widespread thermal micro-cracks all around the area that can't be eliminated without re-melting the whole thing. The part is always compromised after that.

There are lower-carbon alloys like ductile or malleable iron which are stronger but also more expen$ive to make. Sorry for the lecture, I used to teach this stuff to engineering students, and I fully recognize "a little knowledge is a dangerous thing". There are a lot of people sticking cast iron back together thinking they are "welding" it - but in almost all cases it's just a bigger bag of cracks with way less than original strength. Dick B.
Yep, didn’t think about it being iron until right after I posted about welding. Guess that is why it broke so easy also.
 

GreensvilleJay

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A friend's manifold held up for 25-28 years after he brazed it up. This was his dad's tractor on 100acres so used( abused) every day..,sold tractor when farm sold, so heck,might still be together.
IF done right, it's a tried and true method of repair.NO chance for warping if done as I posted,using a thick steel plate as a 'support' and wait until it slowly cools to room temperature.
$200 for a new manifold isn't a 'bad' price, today....but when money is tight, repairing is the best option.
 
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fried1765

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A friend's manifold held up for 25-28 years after he brazed it up. This was his dad's tractor on 100acres so used( abused) every day..,sold tractor when farm sold, so heck,might still be together.
IF done right, it's a tried and true method of repair.NO chance for warping if done as I posted,using a thick steel plate as a 'support' and wait until it slowly cools to room temperature.
$200 for a new manifold isn't a 'bad' price, today....but when money is tight, repairing is the best option.
There is a common lack of appreciation for brazing.
It can be a very effective fix in many situations.
 
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steveh

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If one an fix something like this on a tractor for $250 or so, time and effort and ultimately money ahead to just replace with new, as you decided. You could fool around with the old manifold and try out repairing it for a spare, at your leisure, and meanwhile your tractor is back up running and doing work.
 
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GreensvilleJay

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I could repair that manifold in less time than getting one ordered,let alone wait for delivery.
It gets down to how soon you need the tractor 'up and running' for chores on the farm. If a 'hobby' tractor, you can wait days,weeks, months for whatever parts you need.
 
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rbargeron

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I completely agree brazing can be a great solution - especially if it doesn't have to be full strength.

My Ford 8N's drawbar hitch broke out once, draining out the transmission oil. I'd been pulling my orchard sprayer which had serious tongue weight. Bouncing around the orchard was too much for the transmission casting and the hitch, 4 studs and big chunk broke out. (I discovered that the transmission casting was poorly molded - over-thickness along one side but very thin on the other. It was already 30 years old so it had done well)

To fix it I took the 8N's battery out, and rear fenders off. Then using my old IH backhoe and a chain I rolled the Ford over backward. With the bottom facing up, the broken piece went into place and my neighbor brazed all around the broken-out section. I removed the hitch tongue and never relied on the repair except to contain the transmission oil. Was drop-free for years.
 
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