wiserfrombud Posted July 3, 2022 Share Posted July 3, 2022 Good morning peeps. I have a 2016 cxu with a 505c+ and have been chasing an audible boost leak for a month or so now. My CAC cooler has been replaced with a Duralite just over a year ago. I have also gone ahead and replaced all boots/clamps on the CAC piping and the 2 o rings at the inlet/outlet of CAC. I also changed the smaller o ring at the elbow off the turbo. I went over various other clamps with an Allen key. I can still hear a leak. If I mash it to the floor I won't see more then 35lbs of boost. (Used to bury the needle at 40). Last week I had a CEL come on. I have an inexpensive scanner just to read Nd clear codes. It's a p2200 NOX bank 1 code. If cleared, it is back on within an hour. I feel these 2 issues are possibly related. Any thoughts/advice on where to look next fr the boost leak and thoughts on one of the NOX sensors actually failing or is it just a generic code due to high NOX levels from boost leak or what? Truck has 700,000 miles on it. Truck runs fantastic. Otherwise. Any help appreciated. Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted July 3, 2022 Share Posted July 3, 2022 maybe a cracked intake manifold, or missing bolts... jojo Quote Link to comment Share on other sites More sharing options...
wiserfrombud Posted July 3, 2022 Author Share Posted July 3, 2022 I have seen that can be an issue on these engines. I will take a closer look over there. Quote Link to comment Share on other sites More sharing options...
Mark T Posted July 3, 2022 Share Posted July 3, 2022 Could be leaking after your EGR cooler too. Quote Link to comment Share on other sites More sharing options...
JoeH Posted July 4, 2022 Share Posted July 4, 2022 You can buy a PVC pipe end cap that should fit into an intake boot somewhere; install a valve stem into it and pressurize with shop air. Does the turbo have a wastegate? Could have something going on there... 1 1 Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted July 4, 2022 Share Posted July 4, 2022 And when Appling pressure keep you head away from the plug.I have had them to shoot out of there like a cannon.It happens sometimes.You will never hear it say get out of my way cause i am going to blow up.I never use more than 20 lbs on the system.You can also leave the intake connected to the engine and with pressure on the system rotate the engine slow till the pressure gauge reads the highest.There will always be some valves open leaking pressure down but i have found many leaks on the intake manifold by pressure that may not have been found otherwise.Be safe and the method of spraying starting fluid around the hoses is not a sure thing. 1 Quote glenn akers Link to comment Share on other sites More sharing options...
wiserfrombud Posted July 20, 2022 Author Share Posted July 20, 2022 Just an update, there was no correlation with the boost leak and CEL. I bought an inexpensive nexus scan tool. P2200. Open circuit bank 1 NOX sensor I think is what it said. I called Mack, inlet NOX sensors on back order indefinitely with no ETA. I tried Volvo, same answer BUT they had the Dinex ones in stock. OEM was 850 bucks with a 130 dollar core. Dinex was 340 dollars so I bought the Dinex. I installed it, cleared the codes and the truck is running fantastic. As for the boost leak, I still havent tracked it down since to get to that EGR plumbing I need to pull the pipe off behind the turbo where the 7th injector is and I havent had time. Quote Link to comment Share on other sites More sharing options...
Mackpro Posted July 21, 2022 Share Posted July 21, 2022 Awhile back we were able to get the inlet NOX sensors but not the outlet ones . Now that has reversed and the inlet ones are impossible to get. The dealership we get parts from heard yesterday from corporate that things are going to get worse. We did buy 4 of the Dinex outlet nox sensors about 4-5 months ago due to trucks down . 3 of the 4 failed but it got us out of a jam till the factory ones came in. The failure rate and issues caused by the aftermarket and counterfeit nox sensors was so great that Mack released a bulletin on how to spot counterfeit and aftermarket nox sensors. . As far as the boost leak , don’t take the rear EGR elbow pipe off unless you have a way to pressurize the intake system. You can actually make things worse. The elbow has a floating collar and is a extreme pain to get sealed. We have a tool that goes on the aftercooler and pressurizes it and the intake manifold which in turn pressurizes the EGR system and you can locate your leak. If it is the elbow connection , use new gaskets and clamps . You will find you will need to readjust the clamp and collar a few times between pressure testing to get it air tight. There has been times I’d wished for a super greasy clutch job than to reseal that elbow. 2 Quote Link to comment Share on other sites More sharing options...
wiserfrombud Posted July 24, 2022 Author Share Posted July 24, 2022 Seems like good advice. I appreciate it. My go to shop has the CAC test kit which works on every truck other then Volvo/Mack thanks to their brilliant V clamp and o ring plumbing fittings. Would have been easy to find otherwise. 🙄🤷♂️ Quote Link to comment Share on other sites More sharing options...
wiserfrombud Posted December 22, 2022 Author Share Posted December 22, 2022 Haven't been on here in a while. That boost leak ended up being the gasket between the egr valve and the manifold. I found it by spraying it down with soapy water whe idling. 1 Quote Link to comment Share on other sites More sharing options...
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