120 HP OMC Exhaust Manifold CRACK question

[oceaninabox]

So my mechanic told me I have 2 cracks in my exhaust manifold. I can see both cracks. One is on the outside that I am going to drill and use JB weld to fix. Here is my question to you guys. Inside the port"circled in red is a curved shape seperator. It has a crack on the manufacturer seam. Since both sides of where the seperator is goes back into the same area, which I believe is just hot exhaust. Will this have to be welded as well? I could see if it was water on one side and air on the other. But here they both go back and is an open channel. Hope this makes since. Basically I can stick my finger on each side of the seperator and touch my fingers so I know they are not seperate...

 

[HT32BSX115]

Re: 120 HP OMC Exhaust Manifold CRACK question

So my mechanic told me I have 2 cracks in my exhaust manifold. I can see both cracks. One is on the outside that I am going to drill and use JB weld to fix. Here is my question to you guys. Inside the port"circled in red is a curved shape seperator. It has a crack on the manufacturer seam. Since both sides of where the seperator is goes back into the same area, which I believe is just hot exhaust. Will this have to be welded as well? I could see if it was water on one side and air on the other. But here they both go back and is an open channel. Hope this makes since. Basically I can stick my finger on each side of the seperator and touch my fingers so I know they are not seperate...

View attachment 189840

Howdy,

I can't really see where those cracks are. Do you know why they cracked?
Having said that, I would not use any exhaust manifold that is cracked.

Internal cracks are just as likely as external cracks.
You run the risk of getting water into an open valve when you shut the engine down.

If that happens after you shut down for a couple of weeks, you'll have a frozen engine when you try to start it next time

 

[jerryjerry05]

Re: 120 HP OMC Exhaust Manifold CRACK question

JB weld will not work.It might work for a day??
The expansion,contaraction will just push it right back out.
Welding is the only possible fix.
Usually not to successfull.
Buy a new one.
If I was working on this,I wouldn't put it back on.
Profile? Location? You might be close to someone who can help?

 

[HT32BSX115]

Re: 120 HP OMC Exhaust Manifold CRACK question

Welding is the only possible fix.
Usually not to successfull.
Buy a new one.

I have "stick" (SMAW) welded, oxy-acetylene gas welded and brazed cast iron.

I have never tried TIG (GTAW) welding it. I have never been very successful. It's not all that bad on a casting that is simply a structural piece or a bracket etc.......

But with a manifold that will be subject to high and low temps, you really have to have a furnace that allows you to bring the casting up to the correct temp and hold it there while welding and then bring it down slowly to prevent uneven cooling (and stress-cracking) I wouldn't even try a jacketed manifold. It would look great on the outside and still be cracked on the inside. It could leak later with no warning......(and with catastrophic results)

There are places that do it for a "living" and have all the accoutrements for doing it. They usually won't mess with a jacketed manifold because they can't guarantee it. (you just cannot get inside to properly weld the interior)

The other downside is that the welding job is usually more costly than just buying another one.

Yeah. ......Unless you want to buy another engine, buy another manifold.