Missing gasket?

[Craig Schmidt]

I recently had to repair a leak in the copper pipe that delivers the cooling water into the exhaust system on my 1938 KA engine. When I removed the pipe from the engine I noticed there was no gasket or seal where the pipe enters the iron exhaust elbow. I was getting a bit of exhaust blowing into the engine compartment previously, and now it is worse. The copper pipe at the exhaust end has no flange: It is just cut off straight and sticks into the exhaust elbow about an inch and a half or so. Am I missing a gasket or some sort of a seal here? How can I stop or reduce the exhaust leak?

[cenger]

Wrap the pipe in Graphite Rope. I got the rope from VanNess but I'm pretty sure you can get it from anywhere.

[Don Ayers]

The pipe does not need the flange but it should have a pin across it through two holes. This keeps it from coming out of the collar. Your rope goes around the pipe and fits in the tapper of the nut. The compression makes the seal. The rope is high temp stuff and is pretty big.

[Don Ayers]

I'd post a pic but I'm in a plane at 35,000 feet.

Sometimes you have to put a lot on that nut to seal it.

[Craig Schmidt]

Thanks, fellas. Graphite rope is now added to my list of things I need but didn't know existed.

I searched auto supply web sites and was surprised to find nobody stocks graphite rope.

I Googled graphite rope and eventually found I may already have a suitable material in hand: PolyTetraFluroEtheylene (PTFE) packing gland rope should serve. It is rated up to temps just above 500 F, which seems about 5X hotter than the copper pipe gets. The square 1/4 inch stuff I've got will fit nicely.

Again, thanks fellas.

[JohnKadimik]

You might try your local plumbing supply store. Find the oldest guy there and ask him.

[Bill Basler]

Craig, I just reread this post this morning. Just so I can be sure you're getting good advice, can you clarify a point? In your original post you said, "I recently had to repair a leak in the copper pipe that delivers the cooling water into the exhaust system..." and "I noticed there was no gasket or seal where the pipe enters the iron exhaust elbow"

Are you referring to the smaller diameter cooling water tubing that follows along the top of the cylinder head then dumps raw water into the elbow?

Or are you referring to the larger 2.5-2.75 diameter copper exhaust pipe that follows from the elbow to the transom.

All of these guys, (very knowledgeable) are referring to graphite rope for your main exhaust pipe....not the raw water cooling tube.

When you say "The copper pipe at the exhaust end has no flange: It is just cut off straight and sticks into the exhaust elbow about an inch and a half or so" I am thinking you may be referring to the cooling waste water tube.

Please clarify. If this is the case, this should terminate in the elbow in a special fitting. See photo. Thanks to Chad Durren for the photo.

[mcisaac inc]

Bill, there is a compression fitting of rope in that fitting as well.I add a bead of non hardening permatex along with the rope .................markmcisaacinc.com

[Craig Schmidt]

Bill: Yes, it is the small diameter copper pipe that runs across the top of the engine and dumps the cooling water into the exhaust system, as in the photo. The threaded compression nut on the cast iron exhaust elbow had nothing by way of a gasket (or graphite rope) under it when I took off the cooling water pipe. This was the reason for the exhaust leak. The plumber who sweat soldered shut the pin hole leak in a joint on the copper pipe for me (for free!) may have some high temp graphite rope.

In any case, this is going to be a very easy fix, way easier than the time I was looking for a welsh plug for my water pump, but didn't know they existed either!

Again, thanks fellas.

[Craig Schmidt]

Post Script
Today I purchased "graphite valve packing" (AKA graphite rope) at my local True Value hardware store. I thought I was looking for an auto parts related item, but what I needed is actually found in plumbing supply. The graphite rope came in a bubble packet and measured 3/32" diameter by two feet. It cost $4. I double wrapped a length of it around the 3/4 inch diameter cooling water copper pipe just behind the packing nut that screws into the exhaust manifold. The nut is designed to compress the packing material against the copper pipe and make a tight seal when tightened. It is strange looking stuff, kind of black and shiny.
The boat gets launched tomorrow.
Thanks for all the advice, fellows.

[57 chris]

Just as a sidebar, I used the rope gasket material that is used to seal doors on airtight wood stoves/pellet stoves, in days past this would have been made of asbestos, I don't believe that's what it's made of now. This is designed to withstand even greater temperatures and for longer periods of time. Available anywhere wood stoves and accessories are sold it's available in many shapes and sizes, I used the round 1/4" diameter and made about two turns around the copper pipe before tightening the packing nut. I also used the same for the packing nut on my exhaust elbow.

Craig

[Craig Schmidt]

ANOTHER POST SCRIPT: The graphite rope I installed didn't get the job done. It was too thin. I didn't know it, but the compression nut doesn't screw tight against the bottom of the socket into which it fits. The socket in the exhaust manifold is about a half inch deeper than the compression nut is long, so there was no compression whatsoever on the little graphite rope I used. Since the size I used was the only size True Value had on hand, I'm off to the local wood and pellet stove dealer for the big 1/4 inch stuff mentioned above by Craig/57chris. My boat lives in northern Wisconsin, I've lots of stove dealers from which to choose.

Oh, and thanks for the new lead, 57chris. I'm actually having fun trying to solve this little problem.