I have some SS heat exchangers for sale and someone asked if I had tested them for leaks. I had not. A few people chimed in with some procedures to test them. Thought I would document my test so anyone selling a set could easily check for leaks.

Needed.
1 valve stem. Long for alloy wheels.
1 one x six or similar
6 bolt
12 washers
6 nuts
Some gasket material/ pond liner/ vinyl or similar

You can get rubber plugs from Home Depot or make the with the items below.

Home made plugs
4 lg fender washers
4 med fender washer smaller than exhaust tube at head.
4 small rubber washers
4 lg o rings
3 bolts/nuts

Some basic tools.

Cut some gasket material to fit the muffler end of the exchangers.
Place it against the flange and mark the holes.

Punch out the holes

Place the 1x6 against the exchanger flanges.
Mark the holes
Drill the holes where marked

Bolt the exchangers to the wood

Fill the exchangers with water. Make sure you lift the head ends up where you fill the so they are full or close to full of water.

Insert the plugs. If you made some like I did you will need an air gun to tighten them since you can't hold the nut.

Insert the plug made with the valve stem.

Lay them flat on the floor.

Use about 20 PSI at the valve stem.

The flanges started leaking at the gaskets but the heated air ducts showed no signs of leakage

More pics

More

More

certainly more than one way to skin a cat

I used pool plugs on muffler end and mouth pressure on head end, and found this was sufficient to detect a hairline fissure.

thanks to brad for making us aware of the need for testing these prior to sale.

I bought these because of how thorough he tested them. Great method using stuff I have in garage.

I have two sets (non-SSI) here I will be testing now too!

Amazing idea, not something I would have gone through to sell a part....

Good man.

Rich

I did a simpler test, corked the outlet ends with large cap plugs (and sone grease), then filled the pipes with water with the H/E's angled such that the inlet ends were higher than the outlets, (At about 30 degree angle to horizontal) but level, so both inlets on one H/E were on same plane. Then filled with water up to full level and let sit for a day, then checked to see if water level had gone down, they checked OK, no change in level.

I don't think the sitting water is a great test. The surface tension of water will keep it from wicking out of some hairline fractures. I think a pressure test is needed.

To be fair to those who deserve credit (as Jim Kelly pointed out) this was not my idea.
It was brought to my attention by the person whom ultimately purchased them in the form of a question concerning whether I had tested them. I replied with a request for a procedure, and as the result of several responses, came up with the above method.

Thanks for the dawn of the 914 Clean Air Act!

I've worked on literally hundreds, maybe even as many as a couple thousand, 914s over the last 40 years. While I've seen many cracked late model HEs, always in the small section that bolts to the head, I've never seen an early version crack. Lest I forget, I HAVE seen some SSIs where the muffler flange broke off, but that's way downstream of the HE portion and CO in the heater wouldn't have been an issue.

The Cap'n

The small section that bolts to the heads possibly suffer from heat stress (hot/cold cycles) Is a cold pressure test sufficient? $2.k is a tall dollar for replacements

Holy necro thread batman!

I use a coolant Airlift and a compressor, it can suck -27" of vacuum and it has the right size adapter for the muffler flange tube end. Then I just hold a thick chunk of rubber conveyor belt on the head pipe end and apply vacuum. If you have a crack you can see results instantly with the gauge needle falling fast, for a big hole you won't be able to pull vacuum. Once I have vacuum I shut the valve, I don't have hold the rubber belt pieces, good seal and the losses will be very slow. If I'm still at -25 to-26" over a minute to me it's a pass, at 5 minutes -24 to-25 is still a good pass. The loose rubber piece will fall off in 15-25 minutes just from seal losses, which is normal and is still a pass.

There's more to it of course, you have to make a stand to hold the exchanger upright securely (important), flap wheel the insides of the flange tubes for a good tool seal, do all 4 tubes, plus all the other work that goes into fixing up an exchanger.

Tool isn't cheap and you always have to take care not to knock the gauge end. About $140 for the one I have, UView Airlift Kit 550000 Cooling System Refiller, which is the best of the cheaper units. I have it to work on the 996 and many other WC projects.