Acceptable pressure drop when testing a charge air cooler?

[joefromperry]

I'm replacing the leaking radiator on my 2003 Signature, but before I put it all back together, I want to check the charge air cooler. To be clear, when driving the coach the boost pressure was easily up to 30, so I'm pretty sure all is okay. I'll be closing off one 4" end of the cooler, and putting a tester with a gauge and air fitting on the other end. Everything I read says these coolers are not air-tight, nor do they need to be. So I'm asking those of you who have specific knowledge of this, if I take the pressure to 10-15 psi, how rapid of a pressure drop is acceptable? I've seen in more than one place that a drop of 1 psi every couple of seconds is to be expected. I'm thinking it would be acceptable if it builds/holds any pressure at all. I'll have my handy spray bottle of dish soap and water to help find any big problems. Thanks in advance for your help.

[timaz996]

I would truly want no leakage in the charger cooler to be accepted especially at low pressure as 15 psi. When you have leakage on the blue side of your engine, it drives the exhaust temperatures very high. I also recommend anyone with a turbocharged diesel to have a pyrometer or EGT gauge to make sure that they are not running a high exhaust temperature. My banks system on my little 8.3 routinely makes 35 pounds of boost when pulling a grade. So as you have said you have a boost gage I would hope that you also have a parameter , or have plans to add one. I had an air cooler leak. , or have plans to add one. My bank system uses the pyrometer to protect the engine in the event of high exhaust temperature.

[joefromperry]

6 hours ago, timaz996 said:

I would truly want no leakage in the charger cooler to be accepted especially at low pressure as 15 psi. When you have leakage on the blue side of your engine, it drives the exhaust temperatures very high. I also recommend anyone with a turbocharged diesel to have a pyrometer or EGT gauge to make sure that they are not running a high exhaust temperature. My banks system on my little 8.3 routinely makes 35 pounds of boost when pulling a grade. So as you have said you have a boost gage I would hope that you also have a parameter , or have plans to add one. I had an air cooler leak. , or have plans to add one. My bank system uses the pyrometer to protect the engine in the event of high exhaust temperature.

That's a very good suggestion about the gauge. I'll definitely look into it. Thanks.

 

[jacwjames]

When I had to have my radiator replaced in 2015 I took the time to have the CAC cleaned and tested, I had no reason to believe it was bad.  I got the name of the shop the company I use to work for sends all their radiator/CAC's, in the past was my old company was particular on which companies they sent work to so I thought good enough for me.

I waited a week and called the shop, they said the CAC was bad and need to be replaced/rebuilt.  I was skeptical so I went down there and they showed me by dipping the CAC into large tank and then turning some air into the CAC.   I was stunned, it looked like a jacuzzi.  The guy testing it said that pretty much all CAC's leak but mine was excessive.    So I gave the go ahead to rebuild, $1600.  

It did help, I have a ISC 8.3 and would usually see 22psi of boost, I now see 24psi, so a ~9% improvement.  $800/psi of boost but was it worth it, maybe not!!!!

My only constellation was that this was an insurance claim for the radiator but I got enough of a settlement to cover the CAC

 

Edited May 31 by jacwjames

[Dr4Film]

I had a similar experience with the shop installing my new radiator. They put it into a large water bath then put air pressure to it. As Jim stated, the water was boiling with air. They took my CAC tanks and rebuilt the core part for about $1250. I did NOT want to have the entire stack removed again later just to have the CAC repaired.

As they say, pay me now or pay me more later.

[Benjamin]

Another way to look at it, if it's a 2003 you're probably not expecting to run 20,000 miles a year for the next twenty years trouble free.  If I found a few pitted spots leaking, I'd clean them up and use JBweld.  Re check until it holds 15PSI and run it.  

Now, if you're intending to boost the HP, and use it all to stay ahead of traffic in any situation, maybe you want a higher standard than the typical RV delivers.  I don't see a patched CAC as a big breakdown risk on a  20+ year old RV, lots of fuel, electrical, brake and tire issues that are far more likely to leave you stranded. 

[timaz996]

12 hours ago, timaz996 said:

I would truly want no leakage in the charger cooler to be accepted especially at low pressure as 15 psi. When you have leakage on the blue side of your engine, it drives the exhaust temperatures very high. I also recommend anyone with a turbocharged diesel to have a pyrometer or EGT gauge to make sure that they are not running a high exhaust temperature. My banks system on my little 8.3 routinely makes 35 pounds of boost when pulling a grade. So as you have said you have a boost gage I would hope that you also have a parameter , or have plans to add one. I had an air cooler leak. , or have plans to add one. My bank system uses the pyrometer to protect the engine in the event of high exhaust temperature.

Sorry for all of the errors in this post, I was voice texting it and should have proof read it.

[joefromperry]

On 5/31/2024 at 10:21 AM, Benjamin said:

Another way to look at it, if it's a 2003 you're probably not expecting to run 20,000 miles a year for the next twenty years trouble free.  If I found a few pitted spots leaking, I'd clean them up and use JBweld.  Re check until it holds 15PSI and run it.  

Now, if you're intending to boost the HP, and use it all to stay ahead of traffic in any situation, maybe you want a higher standard than the typical RV delivers.  I don't see a patched CAC as a big breakdown risk on a  20+ year old RV, lots of fuel, electrical, brake and tire issues that are far more likely to leave you stranded. 

I like the way you think, Ben. So, here's an update: I set up a pressure test on my CAC, and was not able to build any pressure at all. Spraying with soapy water,  the one side of the CAC, which was slightly pulled away from the core, bubbled/leaked profusely. First thing I did was lightly tap the header back toward the core with a wooden hammer; it closed the gap. I then replaced broken and missing screws that were holding the header to the corner support. When all seemed tight, I stood the CAC on end, the leaking side down, and poured two-part epoxy all along where the tubes entered the header and the leaks were. After a couple hours, I repeated the process, building up maybe an eighth inch or more of epoxy all along the side.

After 24 hours, I again tried to pressurize the CAC and sprayed to find leaks. I only tried to get to 7 psi, and was able to do so. It did not drop to zero until 11 minutes had passed, and the only leak I found was at the plug I had put on the other end of the CAC. I had NO leaking at the side I had epoxied, which previously bubbled freely. I  plan to replace the leaking plug and pressurize to 15-20 psi. If it pressurizes and holds for even a few minutes, I'll feel like I saved myself around $4k. Remember, prior to removing to replace the radiator, I was able to reach 30 psi boost while driving, even with the leaks, so I feel pretty good about where I am now.

For those who might be interested, the epoxy I used was West System, 105 resin and 206 hardener.

[jacwjames]

I keep a gallon container of the West 105 and keep both the 206 & 205 hardener so I can have different set times.  I've used this on lots of different projects.