Found a loose copper tube in my exhaust manifold

Upon changing the headgasket on a Mitsubishi 4D31 I took off the exhaust manifold. Upon doing so I heard a rattling sound in there. Removed the frost plugs(yeahm they are called that when not installed in a block), and saw a piece of loose copper tubing in there. Does anyone want to guess what it is doing in there?

I did a leak test using acetone, but no leakage into the exhaust side.


Best snap I was able to make




The whole thing


Leak test in progress

 

Do any bolts go through the manifold" If so it could have been a sleeve to isolate the bolt from the water and came loose somehow. Just guessing?

 

Naaah man. Nothon going through it.

 

in the first pic it looks like the aluminum is cracked and fallen away, reveling it.

Can you get a sharper shot of the first pic?

Is it an evdiesel manifold?

 

Yess. A bit of support sheet or something is cracked in there. But most of it is left.

 

Why did you remove it?

Contact evdiesel?

If the exhaust stays in the exhaust tube, and the water in The jacket, then what could be wrong?

But I dont like the idea of copper and aluminum touching in the casting, bathed in salt water.

I have no help for you friend, but thanks for sharing such an interesting problem.

 

Removed it because I changed a leaky head gasket. had it sandblasted and painted while I was at it.
Only fresh water with green antifreeze on the water side. Direct salt water cooling is suicide IMO.

 

While trying to tackle an internal leak in the manifold, I decided to remove the pipe. Seems like it has broken off from the inlet stud, and has reached all across the manifold. To what use I do not know!

 

I suspect it is there to temper the incoming coolant so that it doesn't thermally shock any of the manifold. But why would you route the coolant supply over towards the outlet like that? Is there a longitudinal baffle that forces the coolant to backflow to the front, cross over, and return to aft to the outlet? And another thing - a cantilevered pipe that long is ridiculous. It has to have had some support, even if it is just pushed through holes in baffle plates. Is there an alternative manifold part with a rear supply and is this how they adapted a front supply?

 

Both hose connections are at the same end on the manifold. Without that pipe, the water would only circulate at one end and the other would overheat. The pipe's function is to route the water from one end to the other.

 

I think you are probably right. I was fooled by one of the photos that just shows a fitting sitting on the backside, but it doesn't go there, it goes where the bolthead is.

 

The outlet is at the other end, where the exhaust outlet is. So the water will have to move trough all of the manifold even with no pipe.

 

Still must help with equalizing cooling across the whole manifold somehow or why would they use it.
You can fix it with silver brazing.