Exhaust Manifold question

[BLDFW]

Guys,
My exhaust manifold has taken to leaking at the rear of the manifold. Originally I thought it was leaking at the exhaust pipe clamp but discovered it was actually the manifold.

I've seen comments about just replacing them which I plan to do but not sure how best to get the last bolt off when I do. It appears to be a bit corroded/heat warped (not sure what to call it)

How might I work at getting that off without the risk of shearing the bolt? Maybe there's not enough exposed thread to worry about it?

Thanks![/img]

 

[Bruce(VA)]

If it's not a brass nut like it is supposed to be, it might round off. But don't worry about the threads. It's a stud. If you strip them, replace the stud. If you need to do that, drain the block because the stud goes into the water jacket.

Check the block for block erosion. If the block is badly pitted, (usually around # 4) you will have problems; get out the hi-temp metal epoxy. (Not JB Weld) VersaChem's exhaust manifold repair, or ThermoSteel, is said to be good to 2000 degrees. Clean the area real well with brake cleaner, put a little epoxy on it, put some wax paper over it and bolt down the manifold. After it dries take off the manifold and take a die grinder and clean the epoxy that might squish into the port. Look at the manifold, again around # 4. If it’s pitted & burned, it isn’t going to seal. Time to surface it or get a new one. Do not double the gaskets! The gasket has two pieces, left & right (or front & back.....whatever) Use hi-temp Permatex or even Copper coat. Make sure the surface is squeaky clean!

You can get your manifold resurfaced for about $30 -40 at most machine shops. If it is OEM & can be salvaged, do it.

While I'm a firm believer in "you get what you pay for", I've got nice fitting new manifolds for $85.

The nuts are brass, 7/16-20 x 5/8, NAPA part number STN104X, 27 lbs of torque. Fastenal has them for about $1.50 each; part number 75133. OEM studs are 1-5/8 long 7/16-14. NAPA doesn’t stock the 5/8’s length, but part number RFD 86644, 1 ¾ inch, works as does part number 86632, 2 inches. These studs are “Handi-Pack” items. (I’ve used these longer studs on my 50 & 51 N’s, but you should make sure they do not bottom out in the block on your N as they are longer than OEM). If you don’t get them at NAPA, make sure that the stud has an egg-shaped center between the different threads. Use washers under the nuts.

If you're really lucky, you can get the nuts off w/o removing a stud or damaging it. And, if you buy a ticket, you could win the lottery. Drain the block & plan on at least one stud getting replaced!

There are two distinctly different recommendations on tightening the studs in the block. Because the stud goes into the water jacket & is constantly undergoing extreme heat & cooling cycles, some folks like to double-nut them & tighten them down at 37 lbs of torque. Others say that it’s a stud & should only be finger tight w/ a good dose of thread sealer or high temp silicone on them.

I’ve replaced the studs on 3 of my 4 N’s w/ no leaks; I finger tighten the studs then take a ¼ turn on them w/ vice grips.

This method of attaching the exhaust pipe to the manifold was developed for the Model A Ford in 1927. If you pay attention to what you are doing, it will not leak. You do not need tinfoil or gasket sealer to prevent leaks. Use the correct parts & install them correctly & it will not leak.



Make sure you are using the correct clamp. An automotive muffler c-clamp will not work. You need a clamp made for the N. If you have the correct clamp, it has a top & bottom. Make sure you have the clamp on correctly; check out tip # 8, below. All clamps are not created equally; the correct clamp should have 9/16 brass nuts.

Slide the tail pipe into the hanger clamp & then place the end of the exhaust pipe against the manifold. Look at it! Remember, the pipe will most always fit snugly to the OEM manifold w/o any problem, but a replacement manifold will likely not be the exact same size as the OEM manifold, so you will have some work to do. If it does not mate all the way around, put a broomstick down the pipe & into the manifold & gently bend the pipe until both surfaces mate snugly & squarely. If the exhaust pipe flange is bent, you will never get a good seal; check it out. The clamp is not a gasket; if the pipe & manifold do not mate tightly, it will leak. Do not try & hold the exhaust pipe against the manifold w/ your hand & while you tighten the clamp. Get out your floor jack & a block of wood; put the jack under the pipe to hold it tightly against the manifold. Confirm that the pipe is mated squarely to the manifold; if it is crooked, it will not seat. With the pipe jacked snugly and squarely to the manifold use your ¾ lb ball peen hammer and tap the pipe tight to the manifold flange all the way around. Its soft metal and this will only take about a minute. Tighten the clamp. (Don't get carried away w/ the jack or you will bend the pipe. Or, overtighten the clamp & snap it in two. BTDT). Put equal pressure on the clamp by tightening one side a few turns then a few turns on the other. Do not expect the clamp sides to touch; about 1/8” gap is normal.

When the clamp is tightened equally on both sides, remove the jack. If the pipe flops around, start over because you put the clamp on upside down. (Remember tip # 8)
50 Tips

 

[Ken(Ark)]

(quoted from post at 20:26:48 03/14/12) Save yourself some troubles that no doubt will crop up in the future on this ongoing saga of all times...."how to cure the leaking of the exhaust and mainfold and tailpipe."

Here is the best solution that will stop that tailpipe-manifold leaking. It's the only way....the automobile people tried it and it worked.

Bolt the manifold to the head and attached the tailpipe to the manifold. Scribe a mark... with a screwdriver or similar object up about one inch on the manifold and one inch down on the tailpipe so this shows the correct alignment where the tailpipe has to be to extend out to the rear of the tractor.
Take your exhaust/intake manifold and the tailpipe/muffler items to a muffler repair business. Tell the person(s) you want a "outlet ball and socket flange, and tailpipe collector reducer inlet. (They are sold in pairs) And a graphite gasket.
Have them to cut the "lip" off the exhaust/intake mainfold....that would be the very end... and they to weld the "outlet ball socket flange to the exhaust/intake manifold. Also they to cut the tailpipe inlet lip off the tailpipe, and weld the "inlet tailpipe collector reducer to the tailpipe. The muffler repair place will also sell you a graphite gasket to go between the two flanges. When done, you will never have to worry about another leak there.


This is my 1000 tip, and I have many more.

If the Rube Goldberg tip is too much , just make sure you have a good fit on the tail pipe lip and the proper factory style clamp . If you still have doubts you can use a little high temp copper silicon .

 

[KKRRSS]

I can't imagine that the corner muffler shop is going to adequately pre-heat a cast iron manifold prior to welding it to DOM steel, and then maintain a constant post-weld heat in sand or some such thing to keep the weld from cracking.

Are you serious about welding DOM to cast?

KRS

 

[KKRRSS]

cut & paste from a welding site:

Cast iron is hard to weld. Golf is hard too. But welding cast iron is kind of like playing golf. Every now and then you have a good day and you are lulled into thinking it's not so bad.That is because welding cast iron is like flipping a coin. One job goes pretty good…the next job makes you cuss.

Why is that? 2 main reasons… Reason #1 There are many different grades of cast iron, some more weldable than others. And it is difficult to tell them apart. By looking at the sparks it makes when grinding, and also by looking at a fractured surface some old timers can tell the difference in cast iron. But that guy is rare. In fact, when is that last time you talked to an old timer welder about welding?...... Oh snap! I just realized something…….I am an old timer myself now. Son of a gun! What an epiphany? With 33 years of welding under my belt, what else would you call me? I don’t feel that old some days…at least I still take the stairs 2 at a time. Reason #2The environment the cast iron has been in makes more difference than anything else.Exhaust manifolds are by far the hardest cast iron welding job to tackle because they are just flat impregnated with carbon from years of heating and cooling and being exposed to burning fuel exhaust.

The author goes on the explain the difficulty and procedure... NOT a job for the corner muffler shop IMO

 

[Britcheflee]

(quoted from post at 11:06:25 03/14/12) Guys,
My exhaust manifold has taken to leaking at the rear of the manifold. Originally I thought it was leaking at the exhaust pipe clamp but discovered it was actually the manifold.

I've seen comments about just replacing them which I plan to do but not sure how best to get the last bolt off when I do. It appears to be a bit corroded/heat warped (not sure what to call it)

How might I work at getting that off without the risk of shearing the bolt? Maybe there's not enough exposed thread to worry about it?

Thanks![/img]

I bought a new manifold on e bay which came with gasket and was lucky enough to get nuts off without studs coming loose - cleaned everything up good and put it on - worked great - if you are planning on painting the manifold do it before putting on engine (I painted mine after and got some overspray on places I didnt want). Bet you didnt expect to raise such blood pressure from people with a simple question like that!!!

 

[Bruce(VA)]

" cut & paste from a welding site:"

Good find, KKRRSS. That is just so typical of our resident Troll, 8N1949. The link below is another example of his cut & paste diagnosis of engine noise on an 8N........it's in the valve train!
More cut & paste advice from the Troll