Manifold crack: a 35 Buick series 40 233 engine

[Buick35]

Other than removing the exhaust manifold can a hairline crack be repaired by using cast iron furnace cement? Anyone use it on manifolds? Just wondered.I don't think J.B.Weld will hold up to the heat.Thanks

[Bhigdog]

No.......bob

[Buick35]

13 minutes ago, Bhigdog said:

No.......bob

Do you mean no on the furnace cement or j.b. weld or both?

[MGRAB]

JB Weld makes an "Extreme Heat" product.  I've seen it used for emergency repairs in an industrial setting.  Used properly, it works.  Will it work for you? Maybe.  Should you take a pic and send back to mom to put on the fridge? Probably not..

[Buick35]

Thanks,I might try that.And why not take a picture?

[Bhigdog]

44 minutes ago, Buick35 said:

Do you mean no on the furnace cement or j.b. weld or both?

Neither will fill a hairline crack. Neither will adhere to the surface for any length of time.

It might be a very short term band aid but a poor one at best.

Sucessful permanent exhaust manifold repair depends on many factors and is iffy at best.......bob

Edited April 25 by Bhigdog (see edit history)

[Bloo]

Exhaust every possibility for just finding a manifold that is not cracked. If that is not possible, look into stitching. If that won't work because it is too thin to stitch, look into welding.

 

Welding is the "classic" method. There's a catch though, it almost never works for very long if it works at all. No cast iron welds easily, but exhaust manifolds have been exposed to extreme heat, and the metal changes somehow. I don't know how to explain it, but it is different and far worse than ordinary cast iron. Also an exhaust manifold is a highly stressed part. You can't take it to just anyone for welding and expect it to hold. You need someone with a bunch of previous experience and a success record. There *is* someone here on the forum with talent like that, but offhand I can't remember who. There is a thread where a manifold was welded, looked good, and was still holding a year later. That's amazing for a welded exhaust manifold. I'll post back if I can remember whose manifold that was.

 

Important note: the manifold needs to be able to move or slide on the head or block.  Sometimes there's special washers or other hardware. The manifold expands and contracts and gets longer and shorter much more than the head or block. The longer the engine is, the more of a problem it is. The head or block is usually full of water or coolant and doesn't expand much. If the manifold is tied down so solidly that it can't slide, it is going to break.

 

[MGRAB]

45 minutes ago, Buick35 said:

Thanks,I might try that.And why not take a picture?

What I meant is.. you wouldn't want to brag about it. Most proud moms will post an A+ on the fridge door.

[Buick35]

1 hour ago, Bloo said:

Exhaust every possibility for just finding a manifold that is not cracked. If that is not possible, look into stitching. If that won't work because it is too thin to stitch, look into welding.

 

Welding is the "classic" method. There's a catch though, it almost never works for very long if it works at all. No cast iron welds easily, but exhaust manifolds have been exposed to extreme heat, and the metal changes somehow. I don't know how to explain it, but it is different and far worse than ordinary cast iron. Also an exhaust manifold is a highly stressed part. You can't take it to just anyone for welding and expect it to hold. You need someone with a bunch of previous experience and a success record. There *is* someone here on the forum with talent like that, but offhand I can't remember who. There is a thread where a manifold was welded, looked good, and was still holding a year later. That's amazing for a welded exhaust manifold. I'll post back if I can remember whose manifold that was.

 

Important note: the manifold needs to be able to move or slide on the head or block.  Sometimes there's special washers or other hardware. The manifold expands and contracts and gets longer and shorter much more than the head or block. The longer the engine is, the more of a problem it is. The head or block is usually full of water or coolant and doesn't expand much. If the manifold is tied down so solidly that it can't slide, it is going to break.

 

I bought the special washers from Bob's and lubricated the gasket. Torqued the nuts to 20 ft.lbs.I guess it was too high. I'll probably try extreme heat j.b. weld until I can find a good manifold or  welder.Thanks

[edinmass]

If it’s only a minor crack……leave it alone.

 

Welding it……you probably won’t have anything to drive after they are done with it and it fails. 
 

Source another manifold before you attempt any repair.

 

“New” used manifolds will often crack just from shipping  and installing. There is no free lunch.

 

Or you can make a home made manifold using bends and Tig welding……..lots of time and money doing it that way.

 

 

[3macboys]

On the chance someone reading this thread just happens to have one, what manifold are you speaking of?  Never know you might get lucky

[Buick35]

39 minutes ago, 3macboys said:

On the chance someone reading this thread just happens to have one, what manifold are you speaking of?  Never know you might get lucky

It's for a 35 Buick 40 series 233 engine exhaust manifold.Thanks.

[Buick35]

50 minutes ago, edinmass said:

If it’s only a minor crack……leave it alone.

 

Welding it……you probably won’t have anything to drive after they are done with it and it fails. 
 

Source another manifold before you attempt any repair.

 

“New” used manifolds will often crack just from shipping  and installing. There is no free lunch.

 

Or you can make a home made manifold using bends and Tig welding……..lots of time and money doing it that way.

 

 

It's about 3" long. I'll start it up and hear how it sounds.

[Buick35]

I bought a can of j.b.weld extreme heat and applied to my manifold crack, I'll see how it holds up.

[edinmass]

42 minutes ago, Buick35 said:

I bought a can of j.b.weld extreme heat and applied to my manifold crack, I'll see how it holds up.

No mystery there………the answer is a foregone conclusion. 🥸