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Old 04-11-2019, 12:00 PM   #1
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Aftercooler Pressure Testing

I have two Yanmar 6LYA2-STPs. I'm in the process of cleaning my raw water cooling system. Before I flush with Rydlyme, I'm taking apart the aftercoolers and cleaning / greasing / o-ring replacement. I've read that I should pressure test them, but I haven't found any good description of what that entails.



What I'm thinking of doing is to reassemble the aftercooler. Plug the raw water outlet. Pressurize (via raw water inlet) to about 20-25psi. Then submerge the entire aftercooler in to water and look for bubbles out of the air side of the system.


Does this sound ok? Am I missing something?


Thanks!
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Old 04-11-2019, 01:50 PM   #2
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Sounds fine to me. I did much the same with mine but pressurized with water, then shut off the supply for fifteen minutes to see if it would hold pressure. But holding air pressure is even better.



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Old 04-11-2019, 02:09 PM   #3
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Air is compressible, water is not. A hydro test is always safer than an air test. If you do the air test, 10 psi is lots.
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Old 04-11-2019, 03:56 PM   #4
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Air is compressible, water is not. A hydro test is always safer than an air test. If you do the air test, 10 psi is lots.
Absolutely correct! The other part about hydrostatic testing is that if there is a pressure gauge in the test, when you shut the water off, the leakage of a few drops will drop the gauge pressure to zero (quick results).

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Old 04-11-2019, 04:25 PM   #5
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Thanks for the info. I'm not sure how to go about testing with water. Testing with air is what I can easily manage. I'll reduce the planned pressure to 10 psi and look for bubbles.
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Old 04-11-2019, 09:19 PM   #6
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Thanks for the info. I'm not sure how to go about testing with water. Testing with air is what I can easily manage. I'll reduce the planned pressure to 10 psi and look for bubbles.
Where you plan to connect the air, adapt it so you can connect it to an outside faucet. With a pressure gauge in the plumbing, fill the unit with water, attach it to the faucet, and pressurize it to 10 psi. When you shut the water off, if the pressure gauge decreases, you have a leak.

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Old 04-12-2019, 08:41 AM   #7
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When I do aftercoolers, I pressurize the water side with water at about 25-30psi. I leave it for a few hours and observe for water in the air side. No water dribbling from air side, I call it good to go. I do not bother with a pressure drop test. Dry on the air side is good enough.

I use radiator hose bits, PVC random fittings and hose clamps to cap off and supply water. I test using well pump water, which I have set at a lower pressure than most city water systems. If your water pressure is high, you need to do something to limit the pressure. I don't know what pressure aftercoolers can handle, but I would get a bit queasy going over 30psi. Heck, 10-20psi is fine for a test and safer on the hardware. Normal operating pressure on the engine is going to be under 15psi.

Can also do the oil cooler this way as the Yanmar is raw water cooled. Just look for water coming out the oil fittings. likewise for coolant HX, pressurize the RW side and look for drips coming out of the coolant side and endcap leaks. Same with gear cooler.

You can do it with air, but on the oil coolers I would not want to submerge the whole thing in water and then have water residue in the oil side. Hard to get all the water out.
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Old 04-12-2019, 10:26 AM   #8
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You can get the effect of hydrostatic testing with air, for the most part by doing air-over-water. Fill it with water first, then pressurize with air if that is what you have handy. The advantage is you can see water leaking better than air, the air volume will be very small so a small leak will show up very quickly.
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Old 04-12-2019, 10:29 AM   #9
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If you like to pressurize with air just pour water in until the unit is 99 % full of water then use the air to create the pressure. Observe as detailed in previous posts. I did my Perkins Multicoolers to Perkins specifications. The multi cooler is a bundle that is the oil cooler, transmission cooler and after cooler in one unit. I will post some details later.
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Old 04-12-2019, 10:40 AM   #10
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Do a search on the forum for Perkins muticoolrer and you should find my post when I did mine. Any test pressures stated were Perkins recommendations.
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Old 04-12-2019, 11:35 AM   #11
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I'd pressure with 5psi of air, then hold the thing underwater for the fastest test (gross leak testing).
At work we pressure with helium then sniff it for stray exterior He molecules. (fine leak testing)
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