Exhaust manifold modification



Please excuse this quick post as I have only scanned the current crop of cast iron welding threads and do not want to directly address any specific replies, but there are a couple of simple points that I think need to be made. All the following is just IMHO.
1) The exhaust system was welded during manufacture which seems to indicate that it can be welded during repair.
2) The photo is not enough of a close up for me to tell accurately but it seems to be a plain long radius pressure piping elbow which should be available at any quality industrial plumbing supply. These elbows are designed to be welded and usually come pre-bevelled. The long radius elbows are less common and more expensive than the short radius elbows. Both are also available as 45s and often as 22 1/2s but the 90s can be cut to any angle. They are not really expensive and are really handy for truck grill guards and handrails (1 1/4"). They are much cheaper and easier and faster to use than a pipe bender.
3)Fixation on welding cast iron is most common amongst the most inexperienced welders. Most of what people think is cast iron is really cast or forged steel. The easiest way to tell is to try to cut it with an OA cutting torch, if it cuts its steel, if it just melts and blows away then it is probably cast iron. This is much easier and a better indicator than a grinding spark test.
4) 6010 (6011 on AC not nearly as nice as DCRP) is IMHO the only real way to get a full penetration weld on pipe but without root grapes inside which can reduce or obstruct flow. Really good guys can sometimes do roots with 7018 DCSP on larger pipe, but few bother to try. I have never found a use for 6012. 6013 is handy for many special uses but IMHO is not a very good GP rod. 7018 is by far the best GP rod, (if your box won't run 7018 put major effort into finding one that will.)
5) Small pipe is harder to stick weld than big pipe, IMHO pipe smaller than ~1 1/2 or 2" is easier to weld with OA (or TIG), I like uncoated HT rod but I do remove the oxide with sandpaper before use. OA gas welding uses the same rod manipulation technique as TIG, and is great TIG practice
6) I seldom use any of the NI rods and find them too expensive and hard to weld with. They seem prone to lack of fusion failures. I do like using plain steel (trade name Ferroweld) sticks for making non machineable (grindable) welds on large cast iron pieces when necessary (preheat use short backstep welds, and frequently use an air chipper to peen the welds and control shrinkage) but prefer brazing WITH SPECIAL brazing FLUX, do NOT depend on flux coated rods to provide enough flux.
7) Why are welders even talking about clamps and overlapping type joints? Butt welds are almost always a superior joint.
Just my .02 YMMV
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hi,
Thanks for the thoughts.

This is my line of reasoning too.

Do you think I stand a fair chance of making a satisfactory repair with 6011 or 6013 rods? Which would be best? It looks like whoever welded the exhaust in the first place didn't use nickel or stainless steel filler metal.

Igor mentioned a lack of fusion when using a nickel rod in his recent post about his grinder guard repair.
I asked for advice at my local welding store this morning. They advised me not to use pure nickel rods, but to use nickel-chromium 309 rods instead. Apparently these are used for joining unknown steels. Doing a bit of research online, it seems that 309 rods are a kind of stainless steel.
Would I be best using 309 rods or 6011/6013?
Best wishes,
Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I think it would be less expensive to make a new flange and get a muffler shop to bend a new tube for you. 309 is a nice stainless rod with very high levels of nickel and chrome. But not cheap. Check with you welding shop for prices.
Dan
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 24 Jul 2009 05:53:15 -0700 (PDT), " snipped-for-privacy@krl.org"

If you can find a nice little axial muffler (in and out on the ends) the right size, I'd get a new header flange and a 90-degree bend pointed down, then hang the mufler that way. Then it drains
You can put a 90-degree bend at the bottom to send the muffled exhaust off to the side for final disposition. Oh, and a hanger strap of some sort, just to damp the vibrations.
Those side-inlet mufflers are application specific.
--<< Bruce >>--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I would prefer 6010 (6011 if AC) in 3/32" for root pass due to better penetration and faster puddle freeze. Second/final cap pass could be 7018. 6013 is best used when low penetration and fast puddle follow is desired, they could be made to work but would be my second choice.

I think I mentioned that I do not like NI rods and use them only when nothing else will work, normally due to a requirement for machineability (lathe/mill or drill and tap). Machineability is usually easier to achieve by brazing unless the repair object is very large such as a gearbox or engine block.

309 (or 310) are excellent for welding high alloy steels such as hardened or tool steels and are handy for difficult high impact load conditions like mounting high alloy tooth shanks on earth moving equipment. They are very similar to plain XX18 both in technique and in power supply required. If your power supply does not burn XX18 well, then you can expect similar performance with 3XX SS. If you do not regularly use XX18 you will also have trouble with 3XX SS as they tend to retain heat and may lead to an increased tendency to burn through due to slower puddle freeze. (Be careful not to burn your gloves when changing rods as they will be MUCH hotter than a similar XX18).
In your situation I would advise simply using the cutting torch test to confirm that you are not welding cast, then doing all the welding using OA. You mentioned that you have best success by rolling pipe and welding at the top or 12 o'clock position. This tends to indicate poor technique and experience as this position is actually harder than keeping the rolling puddle at about 2 o'clock. I suggest you try to get a 'rod dipping into the puddle' demo from a good OA torch or TIG welder as poor heat control and burn through with these processes is often due to poor rod manipulation technique. Practice (usually lots) is essential to master this.
In your situation I suggest you keep to the KISS principle and avoid 'exotic' rods. IF you master 6011, 7018 and OA welding and brazing then you can fab/fix almost anything and will be well on your way to TIG. 6013 (and 7014) is best reserved for use if you only have a low power AC buzz box. (If you do have a low power AC buzz box you may not be able to get acceptable results with anything else).
All above IMHO and YMMV
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Private wrote:

Do you think I'd have problems trying to do a single pass weld with 1/8" 6011 rods? I don't have any 3/32" rods. I also measured the thickness of the casting's wall today and it's 5/32". Most of the time I'm pretty good at avoiding burn throughs.
<snip>

I haven't tried 7018. I've just got 6011, 6012 and 6013. So it sounds like 309 wouldn't be a good choice. They're also really expensive. I was quoted 1 each for 309 rods this morning.

I don't have OA, so that's not an option. I've just got a propane torch and an oil-cooled AC welder.
I think you may be misunderstanding what I said about turning the pipe. I don't mean I was welding with the pipe turning continuously. I meant that I welded from roughly the 10 o'clock position to the 2 o'clock position with the pipe stationary, then rotated the pipe through 120 degrees and started again.
I'm pretty sure that if both these components were mild steel, I could do a decent job of the joint with 6011 rods. I think I could also do it with 6013, but don't feel so confident about that as 6013 is prone to slag inclusions.

Mine is an AC-only welder, but I don't think it falls into the category you're talking about. It gives 180 A at 100% duty cycle with a good open circuit voltage and a steady arc. I have heard people say that oil-cooled AC welders are very different from a buzz box to use.
Thanks for the advice.
Best wishes,
Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Unless you are very good, I suspect that if you are not having burn through problems then you are probably not getting full penetration. Since this is not a high pressure job this may not matter. I would normally use 1/8" 6010 for root and maybe hot pass and 1/8" 7018 for fill and cap on larger pipe, but on the small dia. and thin wall pipe you are working with I would suggest 3/32" unless you can handle very rapidly changing position and rod angles. I would also prefer 3/32" for the root as this will leave some room for the cap and 3/32" for the cap and will allow you to move a little slower and reduce the tendency for too high a cap.
You may not use 3/32" rods often but you should always keep a range of sizes of most of the rods you use as this will allow you to better match the rod size with the material thickness and mass. I normally keep and use 3/32 & 1/8" 6010, (5/32" for downhill pipeline), 5/64" to 1/8" 6013, but mostly use 3/32" to 3/16" 7018. . snip

Few people actually pay for SS themselves, most have some kind of 'connection'.
snip

There is no doubt that OA is becoming less popular due to cost of both acet and bottle rental (to say nothing about innsurance issues) and plasma can be much more cost effective as well as able to better cut thin material as well as aluminum and SS.. A propane only torch is not very useful for welding unless you mean oxy-propane which is very good for cutting thin material but not very useful for welding, I have not used but suspect that it would be usable but not ideal for brazing.

I normally consider this 'rolled' as opposed to 'fixed' or 'in position', it may be continuous roll or stop and roll. Just to complicate communication (especially for ESL) some will call this 'positioned' as opposed to 'out of position', a machine to turn work is often refered to as a 'positioner'.
It is usually easier to weld upslope as the flux will flow out of the puddle and help to prevent slag inclusion. I suggest you start a little lower on the pipe and keep moving your start lower as your skill improves. If you ground directly on the pipe you can roll with one hand and weld with the other or use a helper if you still need two hands to steady the rod.

snip
If you have 180 real amps @ 100% and with good OCV then you should have no trouble burning 7018. I suspect you will be pleasantly surprised at the nice smooth bead appearance that the iron powder provides. Restriking an arc requires a sharp tap and go to break off the flux cone and beginners and those using a scratch start technique often have better luck by first breaking off the flux cone. Use as short an arc as possible, a drag technique can give good results and excessive weaving should be avoided. Avoid allowing the rod to stick as ALL the flux breaks off easily, especially with 3/32". Large sizes are very nice for heavy work and will limit distortion caused by multipassing but 1/8" is the easiest to learn with and 3/32" is best for small work and thin sections.
Welding is not difficult but does require lots of practice and continuous learning.
Good luck, YMMV
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Chris - have you got the thing running yet? - ie, if its totally stuffed and your worrying about the muffler..... And a simple muffler fix is, (assuming its rusted out at the bottom), bend a piece of sheet metal round it - (hint- big tin cans are a good source- cost zilch) and clamp it on with big hose clamps. Will get it up and running and not annoy the neighbours too much.....
BTW - you will need a bowling green type lawn for it, pretty useless otherwise as a lawn mower, and sharpening the blades is a real bastard after hitting a few rocks......
Andrew VK3BFA.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Andrew VK3BFA wrote:

Not yet, but I've taken a close enough look at the engine to know that it's going to go. There isn't any noticeable bore wear and the compression is great. Valve seats look good. I'm working on the carburettor at the moment and am looking forward to receiving a magneto from Martin's friend soon.
I wouldn't be worrying about the silencer if there was any noticeable wear in the engine. But there isn't, so my thoughts have moved forward. Someone else has previously repaired the silencer in the way you suggest, but secured the sheet using soft solder. Problem is, that sheet is soldered to the entry tube, and I suspect is providing most of the strength. So I foresee a rather big mess if I try to dismantle the silencer. And it really needs dismantling because of the quantity of rust and soot shaking around inside it, which due to the design of the silencer won't come out. It's a lot worse than it looks in those pictures. Basically the whole of the bottom of the silencer is flaking away.

We've got a big lawn, with moles. I'm hoping a heavy mower might drive the moles away. The blades look fairly sharp, so I'm not going to worry about them just yet.
Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I made a mock-up of the joint today. Made from mild steel pipes as I didn't have anything cast. I ground the end of one of the pipes down a little, to give it a thinner wall so that the mock-up was accurate. The only thing that was different was that in the mock-up both parts of the joint were ERW pipe, whereas in the real job one part will be ERW pipe and the other will be the casting.
I put one pipe in the bench vice and held the other pipe in place using a retort stand, which allowed me to position it accurately. I then made four tack welds around the joint and removed the retort stand. I then attempted to weld the joint together, with the axis of the pipe vertical, using a 3.2 mm 6011 rod at 90 A (AC with 80 V OCV). 90 A was the lowest current at which the rod seemed happy. "Private" was right about 3.2 mm electrodes being too large for the job. It was difficult to control and I got almost immediate burn through.
I tried again with a thinner rod: 2.0 mm 6013, as that was what I had available. I set the current to 70 A. This was much better. I found it easier to keep the weld pool a sensible size. The 2.0 mm rod seemed a sensible size for the job, yet didn't burn down as fast as a 1.6 mm rod (something I always found a bit tricky). I rotated the pipe in the vice as I worked. I think it sat in a total of four positions. The weld bead sagged downwards in places, but the joint looked secure. I found it difficult to take a step to the side to reposition myself without stopping welding. For this reason, I welded in an awkward position at times, which I think contributed to the sagging. Can some people step to the side and reposition themselves without stopping welding, or does everyone have to stop?
I ran two more beads around the pipe to practise my technique (these two were not actually joints). I did another with the axis of the pipe vertical, which was better than my first attempt. Then I tried one with the axis horizontal. I welded approximately a 45 degree arc of the pipe at a time, starting just before the highest point and ending just after. I then rotated the pipe and restarted the weld. So in total I did about eight short welds, each one being a little less than an inch long. The restarts weren't bad and there were no slag inclusions. It was definitely the best weld of the three, and I was pleased with it.
So I've learnt that 3.2 mm rods are not a good idea. Based on my experience today, I'm not even inclined to go for 2.5 mm. 2.0 mm seemed a good, controllable size for the job. But there is the question of what type of rod to use. I could use the 6013 that I already have, or I could go to the welding store and buy 6011 or 309 stainless. My inclination is to buy 2.0 mm 6011. This is because whenever I've tested the strength of the deposited material, 6011 has been noticeably stronger than 6013. It is also more resistant to slag inclusions. But I'm unsure if 6011 is normally made in the 2.0 mm size. I think the smallest might be 2.5 mm and I'm not sure if this would be too large. If I can only get 2.0 mm 6013 or 2.5 mm 6011, I'm unsure which would be the best choice. The minimum and maximum current ratings for a 2.5 mm 6011 rod are only 5 A greater than the ratings for a 2.0 mm 6013 rod, but I'm unsure if I'd have problems controlling the size of the weld pool
Any suggestions as to what I should do?
Thanks for the help.
Best wishes,
Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Most of us do not (ever) look for 'cast iron' material for fab OR repair work.

I think this is what we would call 'bevelling', and is usually combined with a small 'land'ing and root 'gap' to allow full penetration root weld..

95% of a good weld is in the fitup.

ERW?
I still doubt that you are working with 'cast iron'. Cast or forged or molded or extruded steel is not normally refered to as 'cast' (even when it may in fact be formed by some variation of the casting process.)
snip

It may seem counterintuitive, but when testing, welders fail the horizontal weld test most often. (Usually due to lack of fusion caused by cold lapping or slag inclusion.)
snip

Lots of practice combined with pre-weld dry runs to check body position and freedom of movement.
snip

As I said before, it is easier to get quality welding uphill than on the flat and downhill is even harder than flat.

I can almost guaranty that you have a weld failure (slag inclusion or pinhole) at most of your starts. The more you start/stop the higher your chances of problems.

??? Did you grind your starts to thin and clean the bevel first? Did you start on top of the weld to get the rod hot before you dropped down into the bevel, then grind off your start to final bead height?

Good job, keep practicing. snip

6010 or 6011 = fast freeze puddle with deep penetration. 6013 = fast follow puddle with lower penetration.
IMHO 6013 is a speciality rod to be used only when 6010/11 will not work (or is not suitable due to poor welder or weldor performance).
Keep practicing and good luck.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hi folks,
It's a long time later, I know. But the exhaust worked out nicely. I butt welded the original cast elbow to a length of thick-walled mild steel tube using 2.0 mm 309 stainless rods at 70 A (AC, because my welder is AC only). Then I butt welded a modern mild steel elbow onto the other end of the mild steel pipe using 2.0 mm 6013 rods at 70 A. I was very careful to make sure that everything was the right length and fitted closely before I did the welding. Here's the finished exhaust:
http://www.mythic-beasts.com/~cdt22/exhaust_modified.jpg
Thanks for the advice.
Best wishes,
Chris
PS: "Private" was right. Those 309 rods get really hot, and the flux burns or melts things, even after you finish welding.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Nice job Chris. Thanks for the update.
Bob Swinney
Hi folks,
It's a long time later, I know. But the exhaust worked out nicely. I butt welded the original cast elbow to a length of thick-walled mild steel tube using 2.0 mm 309 stainless rods at 70 A (AC, because my welder is AC only). Then I butt welded a modern mild steel elbow onto the other end of the mild steel pipe using 2.0 mm 6013 rods at 70 A. I was very careful to make sure that everything was the right length and fitted closely before I did the welding. Here's the finished exhaust:
http://www.mythic-beasts.com/~cdt22/exhaust_modified.jpg
Thanks for the advice.
Best wishes,
Chris
PS: "Private" was right. Those 309 rods get really hot, and the flux burns or melts things, even after you finish welding.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Robert Swinney wrote:

Now I'm just wondering if I can paint it. Parts of it are galvanised, and it'll get hot, so it might be a lost cause. I tried some of that VHT paint that cures in the past, but it all went powdery and fell off...
Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The explanation for that is simple. If it cures in the past, you need to send it back in time, it is the future now. (Or it will be soon) :)
jk
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

If the formulation is still what it was, oh...<jeez> 43 years ago, baking it makes a BIG difference. Also, make sure you get any surface rust off of the part before painting it with VHT. It will bleed through in no time if you don't.
I don't recall the temperatures but I coated two different cast-iron manifolds with it, the second one following what I said above, after failures with the first, and baked the second one in our kitchen oven. It lasted for at least three years of everyday driving in my MG. 'Don't know after that -- the next owner crashed it at that point.
--
Ed Huntress



Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ed Huntress wrote:

Last time I used some, called Plastikote "Hot Paint", I baked it in the oven at about 250 deg. C. for 3 hours. When I fitted the manifold, all the paint had fallen off within a few months. It sucked.
I found a tin of etch primer rated at 220 deg. C. I'm hoping this will be enough, and will help a high temperature top coat stick to the remaining galvanising.
Best wishes,
Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

figure out why it didn't just bake on in place, because the manifold got a heck of a lot hotter than a kitchen oven. But it did seem to make all the difference.

Good luck with it. If someone finds a reliable, easy-to-use, readily available manifold and exhaust paint, I'd like to know about it.
--
Ed Huntress



Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Christopher Tidy wrote:

Just for interest, I tried to melt some lead-tin solder on the central pipe of the exhaust of a small Honda engine that had been working hard for about 40 minutes. It just melted, but nothing like as easily as it melts on a soldering iron. I'm guessing that means the temperature is about 250 deg. C. Hopefully with a larger and slower engine, my 220 deg. C. paint will be okay. We'll see...
Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 03 Jul 2010 04:26:42 +0000, Christopher Tidy

The manifold paint from eastwood works well and STAYS ON if applied as instructed to thoroughly cleaned parts. Ceramic header paint works too, if the pipe is CLEAN and you follow the instructions. Even BarBQ paint or stove enamel is good to well over 600F.
Eutectic solder (63-37) melts at 361F. (183C) 60-40 melts between 360 and 375F(183-190C), and 50-50 melts between 365 and 420F (185-215C) Leadfree melts around 482F (250C).
Brazing melts above 800F, and I've had exhausts hot enough to melt brazed repairs oftener than I'd like to remember!!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.