Standpipe, New

[BadaBing]

Will be ordering a new SS standpipe from MM on Monday morning. My 1974 T30 has a copper one, which for one reason or another is leaking water back through the exhaust inlet connection, into the hot section exhaust pipe and manifold.

My hot section, just replaced, is made of black iron pipe. The new standpipe is SS. The SP has a 1.25" male connection on the base of the SP. My old one had a 1.25 copper female fitting.

So I have two male ends to mate, a treaded union will to the trick BUT of what material?

Im troubled that black iron pipe and SS (316) will rest together. Is this a reasonable worry?
Would it be wiser to use a brass female fitting between the Black Iron and 316 SS?

[67c&ccorv]

I wouldn't worry too much - put some s/s thread sealer in there and it should insulate the two dissimilar metals from one another.

No matter what material you use these things don't last forever.

[BadaBing]

I cant help myself. Though I will be ordering a new standpipe I have this need to see what's going on with the old one.

The outside cylinder is 20.5" tall. the inside tube is 17.5" tall and has a cap set 1" higher at 18.5". Looking inside it with a flashlight I can see that the openings in the top plate/cap have worn or been corroded back to allow water that is being pumped on top to enter the stack. I can also see that the inside of the exhaust stack is very caked with carbon deposits but also looks pitted, from the exhaust inside. No telling how badly eaten or clogged it is on the outside.

However, when I removed it there should have been about 2" of water laying at the base, below the exhaust/water exit opening. Hardly any water was left in it, just a few drops, and I did the hose test yesterday. I'm assuming the bottom is full of some sort of crud.

I may cut it in half tomorrow, just to see. That will depend on my motivations at the moment.

[BadaBing]

Found it. I started poking around with a 3' pc of 1/8SS rod (rocket launching rod) to knock off the carbon. found what seemed a hole about 1/2" up from the base of the water chamber. I stuck a rotary wire brush on a flex shaft in to clean our more carbon and then flushed it with water. After the water flush that little hole showed up as a real hole. Hard to judge the size but big enough to let the water drain back into the hot section.

The wife said we need to apologize to the engine for drowning her.

[hanleyclifford]

Use a black iron coupling - no need to introduce another metal into the system. In general, brass and bronze are not good in exhaust systems due to expansion and electrochemical characteristics.

[BadaBing]

Inside the standpipe.

I just had to know, so I cut it open and pulled out the center tube.

Note one hole but 8 or 9

Even if I wanted to I doubt if I could fix this short of just replacing the entire center tube. btw, the center tube is slightly tapered. The little tab at the very top felt like it may have been connected to the top diverter plate that was supposed to keep water from entering at the top.

[ndutton]

Give your wife a hug for us. She knows her stuff.

[romantic comedy]

I have wondered about making a standpipe out of fiberglass. The inner tube would be make of metal, but the outside could be of FRP.

[BadaBing]

Plastic and fiberglass Water lift mufflers fail at the first sign of water flow problems. Standpipe would be at least as prone to this failure and probably more so.

[romantic comedy]

Bill, I just showed my wife a picture of your stand pipe. Now she knows what I will be checking next time I have it apart.

BTW, our stand pipes might have been built at the exact same time. I have a 74 tartan 34. My stand pipe has worked fine with no sign of leaks. I replaced the 1 1/4 pipe 2 years ago, and pressure tested it. However, it does not seem possible to test the inside tube.

[BadaBing]

I came to the same conclusion about testing. It seemed I could come.up with no way, at least in my mind, that I could detect this kind of a leak other than the method I tried to explain.
I disconnected the coupling at the bottom exhaust input. Attached a slow garden hose, guessing about 2-4 gph ( less then half of what it can do) and watched where water came out.

It seems to me that if the stand pope.is not leaking it should not let water come out the bottom exhaust entry connection.

The worst part is that this has obviously been going on for some time and progressively getting worse. Right up till I drowned it.

[BadaBing]

I was very surprised at how thick the copper jacket is. These were very well thought out. I'm also impressed with the little.chamber at the top, where the water enters. It is obviously more then just an inlet. Almost a little box skupper up their but I would.have to hack it apart to get a better look.

[BadaBing]

I took my destructive investigation one step further.
I wanted to see how the design intended to keep coolant water, in our case sea water, from entering the exhaust pipe.
AS previously shown in the photos the center exhaust tube is cut on an angle at the top where the exhaust exits the tube to mix with the water.
Attached is a crude drawing of how it works.

Water enters from the engine discharge at #1, This entry is above a copper plate #5 that is welded about 2/3 of the way around with the last 1/3 edge bent over , down, 90 degrees from the exhaust exit #3 from the exhaust tube. This allows water to flow across the top blocking plate# 5 to cool the plate from the exhaust gasses. and directs the water down into the chamber around the exhaust tube. The water mixes with the exhaust gasses and gravity takes the water out the exhaust/water tube while the exhaust pressure pushes the cooled exhaust gasses out the shared through hull.

It appears that unless the center tube is compromised by holes, like mine was or the exhaust pipe after the standpipe becomes clogged, it should be just about impossible for water to find its way back to the manifold.

[BadaBing]

pictures of the distruction

That about ends this presentation.

The new standpipe should arrive Thursday

[romantic comedy]

That looks pretty thick. What is the center tube made of?