I completed the fixtures for the 2.0L and the 1.7-1.8 type flanges. They work fine.
Apreaciate all of the input from others. I think the chance of blowing up a thick wall tube is very unlikely with low presure. I worry more about my air compressor tank blowing at 150 PSI.
I did find one leak and not where I expected one. It is where the pipe is welded to the flange which mounts to the head. It took several minutes to see pressure decay. I then placed each fixtue under water and found the leak. Looks like the PO did a "make it fit" by drilling out the hole on the boss that goes to the head. It is a very is a slight leak which did show at 60 PSI and may not have leak under normal use. See video.

If anyone wants to test their heat exchangers I will lend these out for the $10 cost of shipping. I have two sets. one for 2.0 and one for 1.7 and 1.8 pattern.

Heat exchanger pipes can develop cracks that can cause carbon monoxide poisoning.
I made a set of test plates to be able to pressurize the pipes and check for leaks. I used 1/2" aluminum remnants that cost about $8. I added tire stem valves to the small plates that will bolt to the cylinder head ends of the pipe. Another plate bolts to the muffler end of the heat exchanger flange. They are lined with 1/8 Neoprene rubber to seal. I have a bicycle pump with a built in pressure gauge I am going to used to pressurize both pipes. They should hold pressure for an extender time. At this time O just made a 2.0 style plate but have material to make one for the 1.7 & 1.8 pattern.
After I test the ones I have I can lend them is $8 USPS Priority mail shipping is paid both ways.
The first attempt used 1/16" cork/rubber as a gasket and they had slow leaks as there was not enough compression.

Great stuff, Bruce, well done, Sir!

Installed

That's some good stuff !!!

I might be reaching out to borrow those in the very near future

Handy tool ! Need to make one for the six HE's next !

I had not thought about the 914-6 heat exchangers m. And 911 boxes should be tested too.
I have some aluminum plate left. Might be abke to make them too.
For the 914-6 test plates i would put the stem in the muffler end.

Why not just make a plate for one end with a rubber gasket (therefore usable on both HEs) and fill with water to test? KISS

That's what I did also, but having been involved with pressure testing at work, the air pressurized method would give me much more confidence.

Personally, as a B31.1/3 guy I would do what Bruce did except fill with water too. So hydrotest with air-over-water to pressurize. Safer than air-only from the stored energy perspective but better performance than looking for gross cracks through mass fluid leakage.

What is a B31.1/3 ?
I would think that a leak would be detected if there was a drop in pressure over extended time.

@Jd74914

https://www.engineeringtoolbox.com/asme-b31...iping-d_39.html

If you look at Bill's link it explains-it's a piping/pressure vessel code.

You are still looking for a drop in pressure. The difference is that you have less air in the chamber so if there is a weak spot that ruptures there is less chance of metal flying.

I made a set of these using rubber stoppers with through bolts to squeeze them to seal. Worked great

Pressurize with air and immerse in a bath tub

I have a way easier and faster method.

I use an Airlift tool for vacuuming out watercooled cooling systems (Porsche 996) and a scrap chunk of rubber.
I flap wheel sand the muffler outlets, put the tool in a hole with a provided adaptor and cover the head flange with the rubber. Then I hook it to the compressor and pull 20+ pounds of vacuum, at this point the chunk of rubber sticks to the flange.

If the rubber doesn't fall off and it will hold the vacuum then it's a pass, with even a tiny hole it will not pull vacuum.

More simple I agree but I am convinced that pressure testing is better than vacuum testing as is is more likely to expand the crack than contract it for leak identification. It only take about 5 minutes to install and let them sit for a while to check for pressure decay.

Bath tub immersion let’s you find the leak if you are so inclined to attempt a repair

@gereed75

If a pipe leaks I would scrap them. It most likly will develop another leak. I am going to weld the leak on the one I have as I think it as caused by work in that area by the PO and not heat hardened pipes cracking.
This can also happen with SSI heat exchangers as those tubes are thinner. I spoke with SSI year ago about tube cracking and they reported they had encountered cracking and were changing at fully annealed 904 ( i think) grade stainless. Who knows what Dansk is using. I helped install a new set and they had several problems. Biggest one was that the oval opening for the warm air elbow was 2mm too small. We had to slit the warm air elbow in 6 places and squeeze down and pound it in.